| Message ID | 20210706093358.1036387-5-its@irrelevant.dk |
|---|---|
| State | New |
| Headers | show |
| Series | hw/nvme: fix controller hotplugging | expand |
On 7/6/21 11:33 AM, Klaus Jensen wrote: > From: Klaus Jensen <k.jensen@samsung.com> > > Prior to this patch the nvme-ns devices are always children of the > NvmeBus owned by the NvmeCtrl. This causes the namespaces to be > unrealized when the parent device is removed. However, when subsystems > are involved, this is not what we want since the namespaces may be > attached to other controllers as well. > > This patch adds an additional NvmeBus on the subsystem device. When > nvme-ns devices are realized, if the parent controller device is linked > to a subsystem, the parent bus is set to the subsystem one instead. This > makes sure that namespaces are kept alive and not unrealized. > > Signed-off-by: Klaus Jensen <k.jensen@samsung.com> > --- > hw/nvme/nvme.h | 18 ++++++++++-------- > hw/nvme/ctrl.c | 8 +++++--- > hw/nvme/ns.c | 32 +++++++++++++++++++++++++------- > hw/nvme/subsys.c | 4 ++++ > 4 files changed, 44 insertions(+), 18 deletions(-) > > diff --git a/hw/nvme/nvme.h b/hw/nvme/nvme.h > index c4065467d877..9401e212f9f7 100644 > --- a/hw/nvme/nvme.h > +++ b/hw/nvme/nvme.h > @@ -33,12 +33,21 @@ QEMU_BUILD_BUG_ON(NVME_MAX_NAMESPACES > NVME_NSID_BROADCAST - 1); > typedef struct NvmeCtrl NvmeCtrl; > typedef struct NvmeNamespace NvmeNamespace; > > +#define TYPE_NVME_BUS "nvme-bus" > +OBJECT_DECLARE_SIMPLE_TYPE(NvmeBus, NVME_BUS) > + > +typedef struct NvmeBus { > + BusState parent_bus; > + bool is_subsys; > +} NvmeBus; > + > #define TYPE_NVME_SUBSYS "nvme-subsys" > #define NVME_SUBSYS(obj) \ > OBJECT_CHECK(NvmeSubsystem, (obj), TYPE_NVME_SUBSYS) > > typedef struct NvmeSubsystem { > DeviceState parent_obj; > + NvmeBus bus; > uint8_t subnqn[256]; > > NvmeCtrl *ctrls[NVME_MAX_CONTROLLERS]; > @@ -365,13 +374,6 @@ typedef struct NvmeCQueue { > QTAILQ_HEAD(, NvmeRequest) req_list; > } NvmeCQueue; > > -#define TYPE_NVME_BUS "nvme-bus" > -#define NVME_BUS(obj) OBJECT_CHECK(NvmeBus, (obj), TYPE_NVME_BUS) > - > -typedef struct NvmeBus { > - BusState parent_bus; > -} NvmeBus; > - > #define TYPE_NVME "nvme" > #define NVME(obj) \ > OBJECT_CHECK(NvmeCtrl, (obj), TYPE_NVME) > @@ -463,7 +465,7 @@ typedef struct NvmeCtrl { > > static inline NvmeNamespace *nvme_ns(NvmeCtrl *n, uint32_t nsid) > { > - if (!nsid || nsid > NVME_MAX_NAMESPACES) { > + if (!n || !nsid || nsid > NVME_MAX_NAMESPACES) { > return NULL; > } > > diff --git a/hw/nvme/ctrl.c b/hw/nvme/ctrl.c > index 90e3ee2b70ee..7c8fca36d9a5 100644 > --- a/hw/nvme/ctrl.c > +++ b/hw/nvme/ctrl.c > @@ -6516,11 +6516,13 @@ static void nvme_exit(PCIDevice *pci_dev) > > for (i = 1; i <= NVME_MAX_NAMESPACES; i++) { > ns = nvme_ns(n, i); > - if (!ns) { > - continue; > + if (ns) { > + ns->attached--; > } > + } > > - nvme_ns_cleanup(ns); > + if (n->subsys) { > + nvme_subsys_unregister_ctrl(n->subsys, n); > } > > if (n->subsys) { > diff --git a/hw/nvme/ns.c b/hw/nvme/ns.c > index 3c4f5b8c714a..612a2786d75d 100644 > --- a/hw/nvme/ns.c > +++ b/hw/nvme/ns.c > @@ -444,13 +444,29 @@ void nvme_ns_cleanup(NvmeNamespace *ns) > static void nvme_ns_realize(DeviceState *dev, Error **errp) > { > NvmeNamespace *ns = NVME_NS(dev); > - BusState *s = qdev_get_parent_bus(dev); > - NvmeCtrl *n = NVME(s->parent); > - NvmeSubsystem *subsys = n->subsys; > + BusState *qbus = qdev_get_parent_bus(dev); > + NvmeBus *bus = NVME_BUS(qbus); > + NvmeCtrl *n = NULL; > + NvmeSubsystem *subsys = NULL; > uint32_t nsid = ns->params.nsid; > int i; > > - if (!n->subsys) { > + if (bus->is_subsys) { > + subsys = NVME_SUBSYS(qbus->parent); > + } else { > + n = NVME(qbus->parent); > + subsys = n->subsys; > + } > + > + if (subsys) { > + /* > + * If this namespace belongs to a subsystem (through a link on the > + * controller device), reparent the device. > + */ > + if (!qdev_set_parent_bus(dev, &subsys->bus.parent_bus, errp)) { > + return; > + } > + } else { > if (ns->params.detached) { > error_setg(errp, "detached requires that the nvme device is " > "linked to an nvme-subsys device"); > @@ -470,7 +486,7 @@ static void nvme_ns_realize(DeviceState *dev, Error **errp) > > if (!nsid) { > for (i = 1; i <= NVME_MAX_NAMESPACES; i++) { > - if (nvme_ns(n, i) || nvme_subsys_ns(subsys, i)) { > + if (nvme_subsys_ns(subsys, i) || nvme_ns(n, i)) { > continue; > } > > @@ -483,7 +499,7 @@ static void nvme_ns_realize(DeviceState *dev, Error **errp) > return; > } > } else { > - if (nvme_ns(n, nsid) || nvme_subsys_ns(subsys, nsid)) { > + if (nvme_subsys_ns(subsys, nsid) || nvme_ns(n, nsid)) { > error_setg(errp, "namespace id '%d' already allocated", nsid); > return; > } > @@ -509,7 +525,9 @@ static void nvme_ns_realize(DeviceState *dev, Error **errp) > } > } > > - nvme_attach_ns(n, ns); > + if (n) { > + nvme_attach_ns(n, ns); > + } > } > > static Property nvme_ns_props[] = { > diff --git a/hw/nvme/subsys.c b/hw/nvme/subsys.c > index 92caa604a280..fb7c3a7c55fc 100644 > --- a/hw/nvme/subsys.c > +++ b/hw/nvme/subsys.c > @@ -50,6 +50,10 @@ static void nvme_subsys_realize(DeviceState *dev, Error **errp) > { > NvmeSubsystem *subsys = NVME_SUBSYS(dev); > > + qbus_create_inplace(&subsys->bus, sizeof(NvmeBus), TYPE_NVME_BUS, dev, > + dev->id); > + subsys->bus.is_subsys = true; > + > nvme_subsys_setup(subsys); > } > > Why not always create a subsystem, and distinguish between 'shared' and 'non-shared' subsystems instead of the ->subsys pointer? That way all namespaces can be children of the subsystem, we won't need any reparenting, and the whole thing will be more in-line with qdev, no? Cheers, Hannes
On Jul 7 09:49, Hannes Reinecke wrote: >On 7/6/21 11:33 AM, Klaus Jensen wrote: >>From: Klaus Jensen <k.jensen@samsung.com> >> >>Prior to this patch the nvme-ns devices are always children of the >>NvmeBus owned by the NvmeCtrl. This causes the namespaces to be >>unrealized when the parent device is removed. However, when subsystems >>are involved, this is not what we want since the namespaces may be >>attached to other controllers as well. >> >>This patch adds an additional NvmeBus on the subsystem device. When >>nvme-ns devices are realized, if the parent controller device is linked >>to a subsystem, the parent bus is set to the subsystem one instead. This >>makes sure that namespaces are kept alive and not unrealized. >> >>Signed-off-by: Klaus Jensen <k.jensen@samsung.com> >>--- >> hw/nvme/nvme.h | 18 ++++++++++-------- >> hw/nvme/ctrl.c | 8 +++++--- >> hw/nvme/ns.c | 32 +++++++++++++++++++++++++------- >> hw/nvme/subsys.c | 4 ++++ >> 4 files changed, 44 insertions(+), 18 deletions(-) >> >>diff --git a/hw/nvme/nvme.h b/hw/nvme/nvme.h >>index c4065467d877..9401e212f9f7 100644 >>--- a/hw/nvme/nvme.h >>+++ b/hw/nvme/nvme.h >>@@ -33,12 +33,21 @@ QEMU_BUILD_BUG_ON(NVME_MAX_NAMESPACES > NVME_NSID_BROADCAST - 1); >> typedef struct NvmeCtrl NvmeCtrl; >> typedef struct NvmeNamespace NvmeNamespace; >>+#define TYPE_NVME_BUS "nvme-bus" >>+OBJECT_DECLARE_SIMPLE_TYPE(NvmeBus, NVME_BUS) >>+ >>+typedef struct NvmeBus { >>+ BusState parent_bus; >>+ bool is_subsys; >>+} NvmeBus; >>+ >> #define TYPE_NVME_SUBSYS "nvme-subsys" >> #define NVME_SUBSYS(obj) \ >> OBJECT_CHECK(NvmeSubsystem, (obj), TYPE_NVME_SUBSYS) >> typedef struct NvmeSubsystem { >> DeviceState parent_obj; >>+ NvmeBus bus; >> uint8_t subnqn[256]; >> NvmeCtrl *ctrls[NVME_MAX_CONTROLLERS]; >>@@ -365,13 +374,6 @@ typedef struct NvmeCQueue { >> QTAILQ_HEAD(, NvmeRequest) req_list; >> } NvmeCQueue; >>-#define TYPE_NVME_BUS "nvme-bus" >>-#define NVME_BUS(obj) OBJECT_CHECK(NvmeBus, (obj), TYPE_NVME_BUS) >>- >>-typedef struct NvmeBus { >>- BusState parent_bus; >>-} NvmeBus; >>- >> #define TYPE_NVME "nvme" >> #define NVME(obj) \ >> OBJECT_CHECK(NvmeCtrl, (obj), TYPE_NVME) >>@@ -463,7 +465,7 @@ typedef struct NvmeCtrl { >> static inline NvmeNamespace *nvme_ns(NvmeCtrl *n, uint32_t nsid) >> { >>- if (!nsid || nsid > NVME_MAX_NAMESPACES) { >>+ if (!n || !nsid || nsid > NVME_MAX_NAMESPACES) { >> return NULL; >> } >>diff --git a/hw/nvme/ctrl.c b/hw/nvme/ctrl.c >>index 90e3ee2b70ee..7c8fca36d9a5 100644 >>--- a/hw/nvme/ctrl.c >>+++ b/hw/nvme/ctrl.c >>@@ -6516,11 +6516,13 @@ static void nvme_exit(PCIDevice *pci_dev) >> for (i = 1; i <= NVME_MAX_NAMESPACES; i++) { >> ns = nvme_ns(n, i); >>- if (!ns) { >>- continue; >>+ if (ns) { >>+ ns->attached--; >> } >>+ } >>- nvme_ns_cleanup(ns); >>+ if (n->subsys) { >>+ nvme_subsys_unregister_ctrl(n->subsys, n); >> } >> if (n->subsys) { >>diff --git a/hw/nvme/ns.c b/hw/nvme/ns.c >>index 3c4f5b8c714a..612a2786d75d 100644 >>--- a/hw/nvme/ns.c >>+++ b/hw/nvme/ns.c >>@@ -444,13 +444,29 @@ void nvme_ns_cleanup(NvmeNamespace *ns) >> static void nvme_ns_realize(DeviceState *dev, Error **errp) >> { >> NvmeNamespace *ns = NVME_NS(dev); >>- BusState *s = qdev_get_parent_bus(dev); >>- NvmeCtrl *n = NVME(s->parent); >>- NvmeSubsystem *subsys = n->subsys; >>+ BusState *qbus = qdev_get_parent_bus(dev); >>+ NvmeBus *bus = NVME_BUS(qbus); >>+ NvmeCtrl *n = NULL; >>+ NvmeSubsystem *subsys = NULL; >> uint32_t nsid = ns->params.nsid; >> int i; >>- if (!n->subsys) { >>+ if (bus->is_subsys) { >>+ subsys = NVME_SUBSYS(qbus->parent); >>+ } else { >>+ n = NVME(qbus->parent); >>+ subsys = n->subsys; >>+ } >>+ >>+ if (subsys) { >>+ /* >>+ * If this namespace belongs to a subsystem (through a link on the >>+ * controller device), reparent the device. >>+ */ >>+ if (!qdev_set_parent_bus(dev, &subsys->bus.parent_bus, errp)) { >>+ return; >>+ } >>+ } else { >> if (ns->params.detached) { >> error_setg(errp, "detached requires that the nvme device is " >> "linked to an nvme-subsys device"); >>@@ -470,7 +486,7 @@ static void nvme_ns_realize(DeviceState *dev, Error **errp) >> if (!nsid) { >> for (i = 1; i <= NVME_MAX_NAMESPACES; i++) { >>- if (nvme_ns(n, i) || nvme_subsys_ns(subsys, i)) { >>+ if (nvme_subsys_ns(subsys, i) || nvme_ns(n, i)) { >> continue; >> } >>@@ -483,7 +499,7 @@ static void nvme_ns_realize(DeviceState *dev, Error **errp) >> return; >> } >> } else { >>- if (nvme_ns(n, nsid) || nvme_subsys_ns(subsys, nsid)) { >>+ if (nvme_subsys_ns(subsys, nsid) || nvme_ns(n, nsid)) { >> error_setg(errp, "namespace id '%d' already allocated", nsid); >> return; >> } >>@@ -509,7 +525,9 @@ static void nvme_ns_realize(DeviceState *dev, Error **errp) >> } >> } >>- nvme_attach_ns(n, ns); >>+ if (n) { >>+ nvme_attach_ns(n, ns); >>+ } >> } >> static Property nvme_ns_props[] = { >>diff --git a/hw/nvme/subsys.c b/hw/nvme/subsys.c >>index 92caa604a280..fb7c3a7c55fc 100644 >>--- a/hw/nvme/subsys.c >>+++ b/hw/nvme/subsys.c >>@@ -50,6 +50,10 @@ static void nvme_subsys_realize(DeviceState *dev, Error **errp) >> { >> NvmeSubsystem *subsys = NVME_SUBSYS(dev); >>+ qbus_create_inplace(&subsys->bus, sizeof(NvmeBus), TYPE_NVME_BUS, dev, >>+ dev->id); >>+ subsys->bus.is_subsys = true; >>+ >> nvme_subsys_setup(subsys); >> } >> >Why not always create a subsystem, and distinguish between 'shared' >and 'non-shared' subsystems instead of the ->subsys pointer? >That way all namespaces can be children of the subsystem, we won't >need any reparenting, and the whole thing will be more in-line with >qdev, no? > Hi Hannes, Thanks for your reviews and comments! So, I have actually considered what you suggest. The problem is that the nvme-ns device currently expects to plug into a bus (an 'nvme-bus') and we cannot really get rid of that 'bus' parameter without breaking compatibility. I experimented with removing the bus from the nvme device and instead creating it in the nvme-subsys device. My idea here was to implicitly always create an nvme-subsys if not explicitly created by the user, but since nvme-subsys does not plug into any bus itself, it is not exposed in the qtree and thus not reachable (i.e., when realizing the nvme-ns device, it will complain that there are no 'nvme-bus' available to plug into). To make this work, I believe we'd have to have the nvme-subsys plug into the main system bus (or some other bus rooted at main-system-bus), and I'd prefer not to do that since this is already a flawed design and I think it would be more intrusive than what my patch does. I raised these issues on the mailinglist some time ago[1]. We didn't really find a good solution, but I think the conclusion is that the bus/device design of subsystems and namespaces is flawed. That's why I am working on an "objectification" of the two devices as suggested by Stefan[2] as a proper fix for this mess. [1]: https://lore.kernel.org/qemu-devel/YJrKRsF4%2F38QheKn@apples.localdomain/T/#u [2]: https://lore.kernel.org/qemu-devel/YKI9zh2AqX35S8wd@stefanha-x1.localdomain/
On Jul 6 11:33, Klaus Jensen wrote: >From: Klaus Jensen <k.jensen@samsung.com> > >Prior to this patch the nvme-ns devices are always children of the >NvmeBus owned by the NvmeCtrl. This causes the namespaces to be >unrealized when the parent device is removed. However, when subsystems >are involved, this is not what we want since the namespaces may be >attached to other controllers as well. > >This patch adds an additional NvmeBus on the subsystem device. When >nvme-ns devices are realized, if the parent controller device is linked >to a subsystem, the parent bus is set to the subsystem one instead. This >makes sure that namespaces are kept alive and not unrealized. > >Signed-off-by: Klaus Jensen <k.jensen@samsung.com> >--- > hw/nvme/nvme.h | 18 ++++++++++-------- > hw/nvme/ctrl.c | 8 +++++--- > hw/nvme/ns.c | 32 +++++++++++++++++++++++++------- > hw/nvme/subsys.c | 4 ++++ > 4 files changed, 44 insertions(+), 18 deletions(-) > >diff --git a/hw/nvme/nvme.h b/hw/nvme/nvme.h >index c4065467d877..9401e212f9f7 100644 >--- a/hw/nvme/nvme.h >+++ b/hw/nvme/nvme.h >@@ -33,12 +33,21 @@ QEMU_BUILD_BUG_ON(NVME_MAX_NAMESPACES > NVME_NSID_BROADCAST - 1); > typedef struct NvmeCtrl NvmeCtrl; > typedef struct NvmeNamespace NvmeNamespace; > >+#define TYPE_NVME_BUS "nvme-bus" >+OBJECT_DECLARE_SIMPLE_TYPE(NvmeBus, NVME_BUS) >+ >+typedef struct NvmeBus { >+ BusState parent_bus; >+ bool is_subsys; >+} NvmeBus; >+ > #define TYPE_NVME_SUBSYS "nvme-subsys" > #define NVME_SUBSYS(obj) \ > OBJECT_CHECK(NvmeSubsystem, (obj), TYPE_NVME_SUBSYS) > > typedef struct NvmeSubsystem { > DeviceState parent_obj; >+ NvmeBus bus; > uint8_t subnqn[256]; > > NvmeCtrl *ctrls[NVME_MAX_CONTROLLERS]; >@@ -365,13 +374,6 @@ typedef struct NvmeCQueue { > QTAILQ_HEAD(, NvmeRequest) req_list; > } NvmeCQueue; > >-#define TYPE_NVME_BUS "nvme-bus" >-#define NVME_BUS(obj) OBJECT_CHECK(NvmeBus, (obj), TYPE_NVME_BUS) >- >-typedef struct NvmeBus { >- BusState parent_bus; >-} NvmeBus; >- > #define TYPE_NVME "nvme" > #define NVME(obj) \ > OBJECT_CHECK(NvmeCtrl, (obj), TYPE_NVME) >@@ -463,7 +465,7 @@ typedef struct NvmeCtrl { > > static inline NvmeNamespace *nvme_ns(NvmeCtrl *n, uint32_t nsid) > { >- if (!nsid || nsid > NVME_MAX_NAMESPACES) { >+ if (!n || !nsid || nsid > NVME_MAX_NAMESPACES) { > return NULL; > } > >diff --git a/hw/nvme/ctrl.c b/hw/nvme/ctrl.c >index 90e3ee2b70ee..7c8fca36d9a5 100644 >--- a/hw/nvme/ctrl.c >+++ b/hw/nvme/ctrl.c >@@ -6516,11 +6516,13 @@ static void nvme_exit(PCIDevice *pci_dev) > > for (i = 1; i <= NVME_MAX_NAMESPACES; i++) { > ns = nvme_ns(n, i); >- if (!ns) { >- continue; >+ if (ns) { >+ ns->attached--; > } >+ } > >- nvme_ns_cleanup(ns); >+ if (n->subsys) { >+ nvme_subsys_unregister_ctrl(n->subsys, n); > } > > if (n->subsys) { >diff --git a/hw/nvme/ns.c b/hw/nvme/ns.c >index 3c4f5b8c714a..612a2786d75d 100644 >--- a/hw/nvme/ns.c >+++ b/hw/nvme/ns.c >@@ -444,13 +444,29 @@ void nvme_ns_cleanup(NvmeNamespace *ns) > static void nvme_ns_realize(DeviceState *dev, Error **errp) > { > NvmeNamespace *ns = NVME_NS(dev); >- BusState *s = qdev_get_parent_bus(dev); >- NvmeCtrl *n = NVME(s->parent); >- NvmeSubsystem *subsys = n->subsys; >+ BusState *qbus = qdev_get_parent_bus(dev); >+ NvmeBus *bus = NVME_BUS(qbus); >+ NvmeCtrl *n = NULL; >+ NvmeSubsystem *subsys = NULL; > uint32_t nsid = ns->params.nsid; > int i; > >- if (!n->subsys) { >+ if (bus->is_subsys) { >+ subsys = NVME_SUBSYS(qbus->parent); >+ } else { >+ n = NVME(qbus->parent); >+ subsys = n->subsys; >+ } So, I realized that this if is not needed, since the device will always attach to the bus from the nvme device, never the 'fake' one from the subsystem. >+ >+ if (subsys) { >+ /* >+ * If this namespace belongs to a subsystem (through a link on the >+ * controller device), reparent the device. >+ */ >+ if (!qdev_set_parent_bus(dev, &subsys->bus.parent_bus, errp)) { >+ return; >+ } >+ } else { > if (ns->params.detached) { > error_setg(errp, "detached requires that the nvme device is " > "linked to an nvme-subsys device"); >@@ -470,7 +486,7 @@ static void nvme_ns_realize(DeviceState *dev, Error **errp) > > if (!nsid) { > for (i = 1; i <= NVME_MAX_NAMESPACES; i++) { >- if (nvme_ns(n, i) || nvme_subsys_ns(subsys, i)) { >+ if (nvme_subsys_ns(subsys, i) || nvme_ns(n, i)) { > continue; > } > >@@ -483,7 +499,7 @@ static void nvme_ns_realize(DeviceState *dev, Error **errp) > return; > } > } else { >- if (nvme_ns(n, nsid) || nvme_subsys_ns(subsys, nsid)) { >+ if (nvme_subsys_ns(subsys, nsid) || nvme_ns(n, nsid)) { > error_setg(errp, "namespace id '%d' already allocated", nsid); > return; > } >@@ -509,7 +525,9 @@ static void nvme_ns_realize(DeviceState *dev, Error **errp) > } > } > >- nvme_attach_ns(n, ns); >+ if (n) { >+ nvme_attach_ns(n, ns); >+ } > } > > static Property nvme_ns_props[] = { >diff --git a/hw/nvme/subsys.c b/hw/nvme/subsys.c >index 92caa604a280..fb7c3a7c55fc 100644 >--- a/hw/nvme/subsys.c >+++ b/hw/nvme/subsys.c >@@ -50,6 +50,10 @@ static void nvme_subsys_realize(DeviceState *dev, Error **errp) > { > NvmeSubsystem *subsys = NVME_SUBSYS(dev); > >+ qbus_create_inplace(&subsys->bus, sizeof(NvmeBus), TYPE_NVME_BUS, dev, >+ dev->id); >+ subsys->bus.is_subsys = true; >+ > nvme_subsys_setup(subsys); > } > >-- >2.32.0 > >
On 7/7/21 11:53 AM, Klaus Jensen wrote: > On Jul 7 09:49, Hannes Reinecke wrote: >> On 7/6/21 11:33 AM, Klaus Jensen wrote: >>> From: Klaus Jensen <k.jensen@samsung.com> >>> >>> Prior to this patch the nvme-ns devices are always children of the >>> NvmeBus owned by the NvmeCtrl. This causes the namespaces to be >>> unrealized when the parent device is removed. However, when subsystems >>> are involved, this is not what we want since the namespaces may be >>> attached to other controllers as well. >>> >>> This patch adds an additional NvmeBus on the subsystem device. When >>> nvme-ns devices are realized, if the parent controller device is linked >>> to a subsystem, the parent bus is set to the subsystem one instead. This >>> makes sure that namespaces are kept alive and not unrealized. >>> >>> Signed-off-by: Klaus Jensen <k.jensen@samsung.com> >>> --- >>> hw/nvme/nvme.h | 18 ++++++++++-------- >>> hw/nvme/ctrl.c | 8 +++++--- >>> hw/nvme/ns.c | 32 +++++++++++++++++++++++++------- >>> hw/nvme/subsys.c | 4 ++++ >>> 4 files changed, 44 insertions(+), 18 deletions(-) >>> >>> diff --git a/hw/nvme/nvme.h b/hw/nvme/nvme.h >>> index c4065467d877..9401e212f9f7 100644 >>> --- a/hw/nvme/nvme.h >>> +++ b/hw/nvme/nvme.h >>> @@ -33,12 +33,21 @@ QEMU_BUILD_BUG_ON(NVME_MAX_NAMESPACES > >>> NVME_NSID_BROADCAST - 1); >>> typedef struct NvmeCtrl NvmeCtrl; >>> typedef struct NvmeNamespace NvmeNamespace; >>> +#define TYPE_NVME_BUS "nvme-bus" >>> +OBJECT_DECLARE_SIMPLE_TYPE(NvmeBus, NVME_BUS) >>> + >>> +typedef struct NvmeBus { >>> + BusState parent_bus; >>> + bool is_subsys; >>> +} NvmeBus; >>> + >>> #define TYPE_NVME_SUBSYS "nvme-subsys" >>> #define NVME_SUBSYS(obj) \ >>> OBJECT_CHECK(NvmeSubsystem, (obj), TYPE_NVME_SUBSYS) >>> typedef struct NvmeSubsystem { >>> DeviceState parent_obj; >>> + NvmeBus bus; >>> uint8_t subnqn[256]; >>> NvmeCtrl *ctrls[NVME_MAX_CONTROLLERS]; >>> @@ -365,13 +374,6 @@ typedef struct NvmeCQueue { >>> QTAILQ_HEAD(, NvmeRequest) req_list; >>> } NvmeCQueue; >>> -#define TYPE_NVME_BUS "nvme-bus" >>> -#define NVME_BUS(obj) OBJECT_CHECK(NvmeBus, (obj), TYPE_NVME_BUS) >>> - >>> -typedef struct NvmeBus { >>> - BusState parent_bus; >>> -} NvmeBus; >>> - >>> #define TYPE_NVME "nvme" >>> #define NVME(obj) \ >>> OBJECT_CHECK(NvmeCtrl, (obj), TYPE_NVME) >>> @@ -463,7 +465,7 @@ typedef struct NvmeCtrl { >>> static inline NvmeNamespace *nvme_ns(NvmeCtrl *n, uint32_t nsid) >>> { >>> - if (!nsid || nsid > NVME_MAX_NAMESPACES) { >>> + if (!n || !nsid || nsid > NVME_MAX_NAMESPACES) { >>> return NULL; >>> } >>> diff --git a/hw/nvme/ctrl.c b/hw/nvme/ctrl.c >>> index 90e3ee2b70ee..7c8fca36d9a5 100644 >>> --- a/hw/nvme/ctrl.c >>> +++ b/hw/nvme/ctrl.c >>> @@ -6516,11 +6516,13 @@ static void nvme_exit(PCIDevice *pci_dev) >>> for (i = 1; i <= NVME_MAX_NAMESPACES; i++) { >>> ns = nvme_ns(n, i); >>> - if (!ns) { >>> - continue; >>> + if (ns) { >>> + ns->attached--; >>> } >>> + } >>> - nvme_ns_cleanup(ns); >>> + if (n->subsys) { >>> + nvme_subsys_unregister_ctrl(n->subsys, n); >>> } >>> if (n->subsys) { >>> diff --git a/hw/nvme/ns.c b/hw/nvme/ns.c >>> index 3c4f5b8c714a..612a2786d75d 100644 >>> --- a/hw/nvme/ns.c >>> +++ b/hw/nvme/ns.c >>> @@ -444,13 +444,29 @@ void nvme_ns_cleanup(NvmeNamespace *ns) >>> static void nvme_ns_realize(DeviceState *dev, Error **errp) >>> { >>> NvmeNamespace *ns = NVME_NS(dev); >>> - BusState *s = qdev_get_parent_bus(dev); >>> - NvmeCtrl *n = NVME(s->parent); >>> - NvmeSubsystem *subsys = n->subsys; >>> + BusState *qbus = qdev_get_parent_bus(dev); >>> + NvmeBus *bus = NVME_BUS(qbus); >>> + NvmeCtrl *n = NULL; >>> + NvmeSubsystem *subsys = NULL; >>> uint32_t nsid = ns->params.nsid; >>> int i; >>> - if (!n->subsys) { >>> + if (bus->is_subsys) { >>> + subsys = NVME_SUBSYS(qbus->parent); >>> + } else { >>> + n = NVME(qbus->parent); >>> + subsys = n->subsys; >>> + } >>> + >>> + if (subsys) { >>> + /* >>> + * If this namespace belongs to a subsystem (through a link >>> on the >>> + * controller device), reparent the device. >>> + */ >>> + if (!qdev_set_parent_bus(dev, &subsys->bus.parent_bus, errp)) { >>> + return; >>> + } >>> + } else { >>> if (ns->params.detached) { >>> error_setg(errp, "detached requires that the nvme device >>> is " >>> "linked to an nvme-subsys device"); >>> @@ -470,7 +486,7 @@ static void nvme_ns_realize(DeviceState *dev, >>> Error **errp) >>> if (!nsid) { >>> for (i = 1; i <= NVME_MAX_NAMESPACES; i++) { >>> - if (nvme_ns(n, i) || nvme_subsys_ns(subsys, i)) { >>> + if (nvme_subsys_ns(subsys, i) || nvme_ns(n, i)) { >>> continue; >>> } >>> @@ -483,7 +499,7 @@ static void nvme_ns_realize(DeviceState *dev, >>> Error **errp) >>> return; >>> } >>> } else { >>> - if (nvme_ns(n, nsid) || nvme_subsys_ns(subsys, nsid)) { >>> + if (nvme_subsys_ns(subsys, nsid) || nvme_ns(n, nsid)) { >>> error_setg(errp, "namespace id '%d' already allocated", >>> nsid); >>> return; >>> } >>> @@ -509,7 +525,9 @@ static void nvme_ns_realize(DeviceState *dev, >>> Error **errp) >>> } >>> } >>> - nvme_attach_ns(n, ns); >>> + if (n) { >>> + nvme_attach_ns(n, ns); >>> + } >>> } >>> static Property nvme_ns_props[] = { >>> diff --git a/hw/nvme/subsys.c b/hw/nvme/subsys.c >>> index 92caa604a280..fb7c3a7c55fc 100644 >>> --- a/hw/nvme/subsys.c >>> +++ b/hw/nvme/subsys.c >>> @@ -50,6 +50,10 @@ static void nvme_subsys_realize(DeviceState *dev, >>> Error **errp) >>> { >>> NvmeSubsystem *subsys = NVME_SUBSYS(dev); >>> + qbus_create_inplace(&subsys->bus, sizeof(NvmeBus), >>> TYPE_NVME_BUS, dev, >>> + dev->id); >>> + subsys->bus.is_subsys = true; >>> + >>> nvme_subsys_setup(subsys); >>> } >>> >> Why not always create a subsystem, and distinguish between 'shared' >> and 'non-shared' subsystems instead of the ->subsys pointer? >> That way all namespaces can be children of the subsystem, we won't >> need any reparenting, and the whole thing will be more in-line with >> qdev, no? >> > > Hi Hannes, > > Thanks for your reviews and comments! > > So, I have actually considered what you suggest. > > The problem is that the nvme-ns device currently expects to plug into a > bus (an 'nvme-bus') and we cannot really get rid of that 'bus' parameter > without breaking compatibility. I experimented with removing the bus > from the nvme device and instead creating it in the nvme-subsys device. > My idea here was to implicitly always create an nvme-subsys if not > explicitly created by the user, but since nvme-subsys does not plug into > any bus itself, it is not exposed in the qtree and thus not reachable > (i.e., when realizing the nvme-ns device, it will complain that there > are no 'nvme-bus' available to plug into). To make this work, I believe > we'd have to have the nvme-subsys plug into the main system bus (or some > other bus rooted at main-system-bus), and I'd prefer not to do that > since this is already a flawed design and I think it would be more > intrusive than what my patch does. > Sigh. _Again_. I seem to trip over issues for which no patch can possibly be accepted as first the infrastructure has to be reworked. ... there is a reason why I'm avoiding posting patches to qemu-devel :-( > I raised these issues on the mailinglist some time ago[1]. We didn't > really find a good solution, but I think the conclusion is that the > bus/device design of subsystems and namespaces is flawed. That's why I > am working on an "objectification" of the two devices as suggested by > Stefan[2] as a proper fix for this mess. > Actually, I _do_ think that it would be good to have an nvme-subsystem bus, providing a list of all namespaces for that subsystem. Creating a controller would then mean that one has to create a controller and a namespace _separately_, as then the namespace would _not_ be a child of the controller. But that's arguably a good thing, as the namespaces _do_ have a separate lifetime from controllers. And the lifetime of the subsystem could be completely self-contained; the controller would be looking up subsystems via the subsystem NQN if present; I guess we'll need to create ad-hoc subsystems for PCIe. But nothing insurmountable. And certainly nothing which require a large-scale rework of qemu internals, I would think. But _if_ you work on the rework, please ensure that not only NVMe is represented here. SCSI multipathing has the same issue currently; there is a strict host->lun->block->OS device relationship currently in SCSI, making it impossible to represent a multipathed SCSI device in qemu. The only sneaky way is to allow for a shared OS device (ie specifying the filename more than once), but that completely sidesteps qemu internals, too. Cheers, Hannes
On Jul 7 12:43, Hannes Reinecke wrote: >On 7/7/21 11:53 AM, Klaus Jensen wrote: >>On Jul 7 09:49, Hannes Reinecke wrote: >>>On 7/6/21 11:33 AM, Klaus Jensen wrote: >>>>From: Klaus Jensen <k.jensen@samsung.com> >>>> >>>>Prior to this patch the nvme-ns devices are always children of the >>>>NvmeBus owned by the NvmeCtrl. This causes the namespaces to be >>>>unrealized when the parent device is removed. However, when subsystems >>>>are involved, this is not what we want since the namespaces may be >>>>attached to other controllers as well. >>>> >>>>This patch adds an additional NvmeBus on the subsystem device. When >>>>nvme-ns devices are realized, if the parent controller device is linked >>>>to a subsystem, the parent bus is set to the subsystem one instead. This >>>>makes sure that namespaces are kept alive and not unrealized. >>>> >>>>Signed-off-by: Klaus Jensen <k.jensen@samsung.com> >>>>--- >>>> hw/nvme/nvme.h | 18 ++++++++++-------- >>>> hw/nvme/ctrl.c | 8 +++++--- >>>> hw/nvme/ns.c | 32 +++++++++++++++++++++++++------- >>>> hw/nvme/subsys.c | 4 ++++ >>>> 4 files changed, 44 insertions(+), 18 deletions(-) >>>> >>>>diff --git a/hw/nvme/nvme.h b/hw/nvme/nvme.h >>>>index c4065467d877..9401e212f9f7 100644 >>>>--- a/hw/nvme/nvme.h >>>>+++ b/hw/nvme/nvme.h >>>>@@ -33,12 +33,21 @@ QEMU_BUILD_BUG_ON(NVME_MAX_NAMESPACES > >>>>NVME_NSID_BROADCAST - 1); >>>> typedef struct NvmeCtrl NvmeCtrl; >>>> typedef struct NvmeNamespace NvmeNamespace; >>>>+#define TYPE_NVME_BUS "nvme-bus" >>>>+OBJECT_DECLARE_SIMPLE_TYPE(NvmeBus, NVME_BUS) >>>>+ >>>>+typedef struct NvmeBus { >>>>+ BusState parent_bus; >>>>+ bool is_subsys; >>>>+} NvmeBus; >>>>+ >>>> #define TYPE_NVME_SUBSYS "nvme-subsys" >>>> #define NVME_SUBSYS(obj) \ >>>> OBJECT_CHECK(NvmeSubsystem, (obj), TYPE_NVME_SUBSYS) >>>> typedef struct NvmeSubsystem { >>>> DeviceState parent_obj; >>>>+ NvmeBus bus; >>>> uint8_t subnqn[256]; >>>> NvmeCtrl *ctrls[NVME_MAX_CONTROLLERS]; >>>>@@ -365,13 +374,6 @@ typedef struct NvmeCQueue { >>>> QTAILQ_HEAD(, NvmeRequest) req_list; >>>> } NvmeCQueue; >>>>-#define TYPE_NVME_BUS "nvme-bus" >>>>-#define NVME_BUS(obj) OBJECT_CHECK(NvmeBus, (obj), TYPE_NVME_BUS) >>>>- >>>>-typedef struct NvmeBus { >>>>- BusState parent_bus; >>>>-} NvmeBus; >>>>- >>>> #define TYPE_NVME "nvme" >>>> #define NVME(obj) \ >>>> OBJECT_CHECK(NvmeCtrl, (obj), TYPE_NVME) >>>>@@ -463,7 +465,7 @@ typedef struct NvmeCtrl { >>>> static inline NvmeNamespace *nvme_ns(NvmeCtrl *n, uint32_t nsid) >>>> { >>>>- if (!nsid || nsid > NVME_MAX_NAMESPACES) { >>>>+ if (!n || !nsid || nsid > NVME_MAX_NAMESPACES) { >>>> return NULL; >>>> } >>>>diff --git a/hw/nvme/ctrl.c b/hw/nvme/ctrl.c >>>>index 90e3ee2b70ee..7c8fca36d9a5 100644 >>>>--- a/hw/nvme/ctrl.c >>>>+++ b/hw/nvme/ctrl.c >>>>@@ -6516,11 +6516,13 @@ static void nvme_exit(PCIDevice *pci_dev) >>>> for (i = 1; i <= NVME_MAX_NAMESPACES; i++) { >>>> ns = nvme_ns(n, i); >>>>- if (!ns) { >>>>- continue; >>>>+ if (ns) { >>>>+ ns->attached--; >>>> } >>>>+ } >>>>- nvme_ns_cleanup(ns); >>>>+ if (n->subsys) { >>>>+ nvme_subsys_unregister_ctrl(n->subsys, n); >>>> } >>>> if (n->subsys) { >>>>diff --git a/hw/nvme/ns.c b/hw/nvme/ns.c >>>>index 3c4f5b8c714a..612a2786d75d 100644 >>>>--- a/hw/nvme/ns.c >>>>+++ b/hw/nvme/ns.c >>>>@@ -444,13 +444,29 @@ void nvme_ns_cleanup(NvmeNamespace *ns) >>>> static void nvme_ns_realize(DeviceState *dev, Error **errp) >>>> { >>>> NvmeNamespace *ns = NVME_NS(dev); >>>>- BusState *s = qdev_get_parent_bus(dev); >>>>- NvmeCtrl *n = NVME(s->parent); >>>>- NvmeSubsystem *subsys = n->subsys; >>>>+ BusState *qbus = qdev_get_parent_bus(dev); >>>>+ NvmeBus *bus = NVME_BUS(qbus); >>>>+ NvmeCtrl *n = NULL; >>>>+ NvmeSubsystem *subsys = NULL; >>>> uint32_t nsid = ns->params.nsid; >>>> int i; >>>>- if (!n->subsys) { >>>>+ if (bus->is_subsys) { >>>>+ subsys = NVME_SUBSYS(qbus->parent); >>>>+ } else { >>>>+ n = NVME(qbus->parent); >>>>+ subsys = n->subsys; >>>>+ } >>>>+ >>>>+ if (subsys) { >>>>+ /* >>>>+ * If this namespace belongs to a subsystem (through a >>>>link on the >>>>+ * controller device), reparent the device. >>>>+ */ >>>>+ if (!qdev_set_parent_bus(dev, &subsys->bus.parent_bus, errp)) { >>>>+ return; >>>>+ } >>>>+ } else { >>>> if (ns->params.detached) { >>>> error_setg(errp, "detached requires that the nvme >>>>device is " >>>> "linked to an nvme-subsys device"); >>>>@@ -470,7 +486,7 @@ static void nvme_ns_realize(DeviceState >>>>*dev, Error **errp) >>>> if (!nsid) { >>>> for (i = 1; i <= NVME_MAX_NAMESPACES; i++) { >>>>- if (nvme_ns(n, i) || nvme_subsys_ns(subsys, i)) { >>>>+ if (nvme_subsys_ns(subsys, i) || nvme_ns(n, i)) { >>>> continue; >>>> } >>>>@@ -483,7 +499,7 @@ static void nvme_ns_realize(DeviceState >>>>*dev, Error **errp) >>>> return; >>>> } >>>> } else { >>>>- if (nvme_ns(n, nsid) || nvme_subsys_ns(subsys, nsid)) { >>>>+ if (nvme_subsys_ns(subsys, nsid) || nvme_ns(n, nsid)) { >>>> error_setg(errp, "namespace id '%d' already >>>>allocated", nsid); >>>> return; >>>> } >>>>@@ -509,7 +525,9 @@ static void nvme_ns_realize(DeviceState >>>>*dev, Error **errp) >>>> } >>>> } >>>>- nvme_attach_ns(n, ns); >>>>+ if (n) { >>>>+ nvme_attach_ns(n, ns); >>>>+ } >>>> } >>>> static Property nvme_ns_props[] = { >>>>diff --git a/hw/nvme/subsys.c b/hw/nvme/subsys.c >>>>index 92caa604a280..fb7c3a7c55fc 100644 >>>>--- a/hw/nvme/subsys.c >>>>+++ b/hw/nvme/subsys.c >>>>@@ -50,6 +50,10 @@ static void nvme_subsys_realize(DeviceState >>>>*dev, Error **errp) >>>> { >>>> NvmeSubsystem *subsys = NVME_SUBSYS(dev); >>>>+ qbus_create_inplace(&subsys->bus, sizeof(NvmeBus), >>>>TYPE_NVME_BUS, dev, >>>>+ dev->id); >>>>+ subsys->bus.is_subsys = true; >>>>+ >>>> nvme_subsys_setup(subsys); >>>> } >>>> >>>Why not always create a subsystem, and distinguish between >>>'shared' and 'non-shared' subsystems instead of the ->subsys >>>pointer? >>>That way all namespaces can be children of the subsystem, we won't >>>need any reparenting, and the whole thing will be more in-line >>>with qdev, no? >>> >> >>Hi Hannes, >> >>Thanks for your reviews and comments! >> >>So, I have actually considered what you suggest. >> >>The problem is that the nvme-ns device currently expects to plug >>into a bus (an 'nvme-bus') and we cannot really get rid of that >>'bus' parameter without breaking compatibility. I experimented with >>removing the bus from the nvme device and instead creating it in the >>nvme-subsys device. My idea here was to implicitly always create an >>nvme-subsys if not explicitly created by the user, but since >>nvme-subsys does not plug into any bus itself, it is not exposed in >>the qtree and thus not reachable (i.e., when realizing the nvme-ns >>device, it will complain that there are no 'nvme-bus' available to >>plug into). To make this work, I believe we'd have to have the >>nvme-subsys plug into the main system bus (or some other bus rooted >>at main-system-bus), and I'd prefer not to do that since this is >>already a flawed design and I think it would be more intrusive than >>what my patch does. >> >Sigh. >_Again_. > >I seem to trip over issues for which no patch can possibly be accepted >as first the infrastructure has to be reworked. > >... there is a reason why I'm avoiding posting patches to qemu-devel :-( > Actually, I'm the one to blame for making nvme-ns a -device and partly for why nvme-subsys is one as well... It's made sense at the time and thats why the infrastructure is biting me in the behind now ;) >>I raised these issues on the mailinglist some time ago[1]. We didn't >>really find a good solution, but I think the conclusion is that the >>bus/device design of subsystems and namespaces is flawed. That's why >>I am working on an "objectification" of the two devices as suggested >>by Stefan[2] as a proper fix for this mess. >> >Actually, I _do_ think that it would be good to have an nvme-subsystem >bus, providinga list of all namespaces for that subsystem. My goal was to *not* use a qbus I don't think the subsystem should be modelled as a device. The same can be accomplished with -objects and links. >Creating a controller would then mean that one has to create a >controller and a namespace _separately_, as then the namespace would >_not_ be a child of the controller. >But that's arguably a good thing, as the namespaces _do_ have a >separate lifetime from controllers. >And the lifetime of the subsystem could be completely self-contained; >the controller would be looking up subsystems via the subsystem NQN if >present; I guess we'll need to create ad-hoc subsystems for PCIe. >But nothing insurmountable. >And certainly nothing which require a large-scale rework of qemu >internals, I would think. > Yes, exactly, totally agree. >But _if_ you work on the rework, please ensure that not only NVMe is >represented here. SCSI multipathing has the same issue currently; >there is a strict host->lun->block->OS device relationship currently >in SCSI, making it impossible to represent a multipathed SCSI device >in qemu. >The only sneaky way is to allow for a shared OS device (ie specifying >the filename more than once), but that completely sidesteps qemu >internals, too. > I'm only very superficially familiar with hw/scsi, but this sounds more like the scsi subsystem also has some similar design problems like hw/nvme, not an inherent issue with QDEV/QOM.
On Wed, Jul 07, 2021 at 12:43:56PM +0200, Hannes Reinecke wrote: > On 7/7/21 11:53 AM, Klaus Jensen wrote: > > On Jul 7 09:49, Hannes Reinecke wrote: > > > On 7/6/21 11:33 AM, Klaus Jensen wrote: > > > > From: Klaus Jensen <k.jensen@samsung.com> > > > > > > > > Prior to this patch the nvme-ns devices are always children of the > > > > NvmeBus owned by the NvmeCtrl. This causes the namespaces to be > > > > unrealized when the parent device is removed. However, when subsystems > > > > are involved, this is not what we want since the namespaces may be > > > > attached to other controllers as well. > > > > > > > > This patch adds an additional NvmeBus on the subsystem device. When > > > > nvme-ns devices are realized, if the parent controller device is linked > > > > to a subsystem, the parent bus is set to the subsystem one instead. This > > > > makes sure that namespaces are kept alive and not unrealized. > > > > > > > > Signed-off-by: Klaus Jensen <k.jensen@samsung.com> > > > > --- > > > > hw/nvme/nvme.h | 18 ++++++++++-------- > > > > hw/nvme/ctrl.c | 8 +++++--- > > > > hw/nvme/ns.c | 32 +++++++++++++++++++++++++------- > > > > hw/nvme/subsys.c | 4 ++++ > > > > 4 files changed, 44 insertions(+), 18 deletions(-) > > > > > > > > diff --git a/hw/nvme/nvme.h b/hw/nvme/nvme.h > > > > index c4065467d877..9401e212f9f7 100644 > > > > --- a/hw/nvme/nvme.h > > > > +++ b/hw/nvme/nvme.h > > > > @@ -33,12 +33,21 @@ QEMU_BUILD_BUG_ON(NVME_MAX_NAMESPACES > > > > > NVME_NSID_BROADCAST - 1); > > > > typedef struct NvmeCtrl NvmeCtrl; > > > > typedef struct NvmeNamespace NvmeNamespace; > > > > +#define TYPE_NVME_BUS "nvme-bus" > > > > +OBJECT_DECLARE_SIMPLE_TYPE(NvmeBus, NVME_BUS) > > > > + > > > > +typedef struct NvmeBus { > > > > + BusState parent_bus; > > > > + bool is_subsys; > > > > +} NvmeBus; > > > > + > > > > #define TYPE_NVME_SUBSYS "nvme-subsys" > > > > #define NVME_SUBSYS(obj) \ > > > > OBJECT_CHECK(NvmeSubsystem, (obj), TYPE_NVME_SUBSYS) > > > > typedef struct NvmeSubsystem { > > > > DeviceState parent_obj; > > > > + NvmeBus bus; > > > > uint8_t subnqn[256]; > > > > NvmeCtrl *ctrls[NVME_MAX_CONTROLLERS]; > > > > @@ -365,13 +374,6 @@ typedef struct NvmeCQueue { > > > > QTAILQ_HEAD(, NvmeRequest) req_list; > > > > } NvmeCQueue; > > > > -#define TYPE_NVME_BUS "nvme-bus" > > > > -#define NVME_BUS(obj) OBJECT_CHECK(NvmeBus, (obj), TYPE_NVME_BUS) > > > > - > > > > -typedef struct NvmeBus { > > > > - BusState parent_bus; > > > > -} NvmeBus; > > > > - > > > > #define TYPE_NVME "nvme" > > > > #define NVME(obj) \ > > > > OBJECT_CHECK(NvmeCtrl, (obj), TYPE_NVME) > > > > @@ -463,7 +465,7 @@ typedef struct NvmeCtrl { > > > > static inline NvmeNamespace *nvme_ns(NvmeCtrl *n, uint32_t nsid) > > > > { > > > > - if (!nsid || nsid > NVME_MAX_NAMESPACES) { > > > > + if (!n || !nsid || nsid > NVME_MAX_NAMESPACES) { > > > > return NULL; > > > > } > > > > diff --git a/hw/nvme/ctrl.c b/hw/nvme/ctrl.c > > > > index 90e3ee2b70ee..7c8fca36d9a5 100644 > > > > --- a/hw/nvme/ctrl.c > > > > +++ b/hw/nvme/ctrl.c > > > > @@ -6516,11 +6516,13 @@ static void nvme_exit(PCIDevice *pci_dev) > > > > for (i = 1; i <= NVME_MAX_NAMESPACES; i++) { > > > > ns = nvme_ns(n, i); > > > > - if (!ns) { > > > > - continue; > > > > + if (ns) { > > > > + ns->attached--; > > > > } > > > > + } > > > > - nvme_ns_cleanup(ns); > > > > + if (n->subsys) { > > > > + nvme_subsys_unregister_ctrl(n->subsys, n); > > > > } > > > > if (n->subsys) { > > > > diff --git a/hw/nvme/ns.c b/hw/nvme/ns.c > > > > index 3c4f5b8c714a..612a2786d75d 100644 > > > > --- a/hw/nvme/ns.c > > > > +++ b/hw/nvme/ns.c > > > > @@ -444,13 +444,29 @@ void nvme_ns_cleanup(NvmeNamespace *ns) > > > > static void nvme_ns_realize(DeviceState *dev, Error **errp) > > > > { > > > > NvmeNamespace *ns = NVME_NS(dev); > > > > - BusState *s = qdev_get_parent_bus(dev); > > > > - NvmeCtrl *n = NVME(s->parent); > > > > - NvmeSubsystem *subsys = n->subsys; > > > > + BusState *qbus = qdev_get_parent_bus(dev); > > > > + NvmeBus *bus = NVME_BUS(qbus); > > > > + NvmeCtrl *n = NULL; > > > > + NvmeSubsystem *subsys = NULL; > > > > uint32_t nsid = ns->params.nsid; > > > > int i; > > > > - if (!n->subsys) { > > > > + if (bus->is_subsys) { > > > > + subsys = NVME_SUBSYS(qbus->parent); > > > > + } else { > > > > + n = NVME(qbus->parent); > > > > + subsys = n->subsys; > > > > + } > > > > + > > > > + if (subsys) { > > > > + /* > > > > + * If this namespace belongs to a subsystem (through a > > > > link on the > > > > + * controller device), reparent the device. > > > > + */ > > > > + if (!qdev_set_parent_bus(dev, &subsys->bus.parent_bus, errp)) { > > > > + return; > > > > + } > > > > + } else { > > > > if (ns->params.detached) { > > > > error_setg(errp, "detached requires that the nvme > > > > device is " > > > > "linked to an nvme-subsys device"); > > > > @@ -470,7 +486,7 @@ static void nvme_ns_realize(DeviceState > > > > *dev, Error **errp) > > > > if (!nsid) { > > > > for (i = 1; i <= NVME_MAX_NAMESPACES; i++) { > > > > - if (nvme_ns(n, i) || nvme_subsys_ns(subsys, i)) { > > > > + if (nvme_subsys_ns(subsys, i) || nvme_ns(n, i)) { > > > > continue; > > > > } > > > > @@ -483,7 +499,7 @@ static void nvme_ns_realize(DeviceState > > > > *dev, Error **errp) > > > > return; > > > > } > > > > } else { > > > > - if (nvme_ns(n, nsid) || nvme_subsys_ns(subsys, nsid)) { > > > > + if (nvme_subsys_ns(subsys, nsid) || nvme_ns(n, nsid)) { > > > > error_setg(errp, "namespace id '%d' already > > > > allocated", nsid); > > > > return; > > > > } > > > > @@ -509,7 +525,9 @@ static void nvme_ns_realize(DeviceState > > > > *dev, Error **errp) > > > > } > > > > } > > > > - nvme_attach_ns(n, ns); > > > > + if (n) { > > > > + nvme_attach_ns(n, ns); > > > > + } > > > > } > > > > static Property nvme_ns_props[] = { > > > > diff --git a/hw/nvme/subsys.c b/hw/nvme/subsys.c > > > > index 92caa604a280..fb7c3a7c55fc 100644 > > > > --- a/hw/nvme/subsys.c > > > > +++ b/hw/nvme/subsys.c > > > > @@ -50,6 +50,10 @@ static void nvme_subsys_realize(DeviceState > > > > *dev, Error **errp) > > > > { > > > > NvmeSubsystem *subsys = NVME_SUBSYS(dev); > > > > + qbus_create_inplace(&subsys->bus, sizeof(NvmeBus), > > > > TYPE_NVME_BUS, dev, > > > > + dev->id); > > > > + subsys->bus.is_subsys = true; > > > > + > > > > nvme_subsys_setup(subsys); > > > > } > > > > > > > Why not always create a subsystem, and distinguish between 'shared' > > > and 'non-shared' subsystems instead of the ->subsys pointer? > > > That way all namespaces can be children of the subsystem, we won't > > > need any reparenting, and the whole thing will be more in-line with > > > qdev, no? > > > > > > > Hi Hannes, > > > > Thanks for your reviews and comments! > > > > So, I have actually considered what you suggest. > > > > The problem is that the nvme-ns device currently expects to plug into a > > bus (an 'nvme-bus') and we cannot really get rid of that 'bus' parameter > > without breaking compatibility. I experimented with removing the bus > > from the nvme device and instead creating it in the nvme-subsys device. > > My idea here was to implicitly always create an nvme-subsys if not > > explicitly created by the user, but since nvme-subsys does not plug into > > any bus itself, it is not exposed in the qtree and thus not reachable > > (i.e., when realizing the nvme-ns device, it will complain that there > > are no 'nvme-bus' available to plug into). To make this work, I believe > > we'd have to have the nvme-subsys plug into the main system bus (or some > > other bus rooted at main-system-bus), and I'd prefer not to do that > > since this is already a flawed design and I think it would be more > > intrusive than what my patch does. > > > Sigh. > _Again_. > > I seem to trip over issues for which no patch can possibly be accepted as > first the infrastructure has to be reworked. > > ... there is a reason why I'm avoiding posting patches to qemu-devel :-( > > > I raised these issues on the mailinglist some time ago[1]. We didn't > > really find a good solution, but I think the conclusion is that the > > bus/device design of subsystems and namespaces is flawed. That's why I > > am working on an "objectification" of the two devices as suggested by > > Stefan[2] as a proper fix for this mess. > > > Actually, I _do_ think that it would be good to have an nvme-subsystem bus, > providing a list of all namespaces for that subsystem. > Creating a controller would then mean that one has to create a controller > and a namespace _separately_, as then the namespace would _not_ be a child > of the controller. > But that's arguably a good thing, as the namespaces _do_ have a separate > lifetime from controllers. > And the lifetime of the subsystem could be completely self-contained; the > controller would be looking up subsystems via the subsystem NQN if present; > I guess we'll need to create ad-hoc subsystems for PCIe. > But nothing insurmountable. > And certainly nothing which require a large-scale rework of qemu internals, > I would think. I don't remember the reason to use --object instead of --device. Maybe the --device approach is viable and it makes some sense because this is a "device" (like a SCSI LUN) that exposed to the guest. It would be necessary to have a nvme-subsys device on the system bus to act as the bus for nvme-ns devices as Klaus described. > But _if_ you work on the rework, please ensure that not only NVMe is > represented here. SCSI multipathing has the same issue currently; there is a > strict host->lun->block->OS device relationship currently in SCSI, making it > impossible to represent a multipathed SCSI device in qemu. > The only sneaky way is to allow for a shared OS device (ie specifying the > filename more than once), but that completely sidesteps qemu internals, too. Do you want one SCSIDevice to be accessible via multiple SCSIBus instances for multipathing in QEMU? Stefan
On Jul 7 17:14, Stefan Hajnoczi wrote: >On Wed, Jul 07, 2021 at 12:43:56PM +0200, Hannes Reinecke wrote: >> On 7/7/21 11:53 AM, Klaus Jensen wrote: >> > On Jul 7 09:49, Hannes Reinecke wrote: >> > > On 7/6/21 11:33 AM, Klaus Jensen wrote: >> > > > From: Klaus Jensen <k.jensen@samsung.com> >> > > > >> > > > Prior to this patch the nvme-ns devices are always children of the >> > > > NvmeBus owned by the NvmeCtrl. This causes the namespaces to be >> > > > unrealized when the parent device is removed. However, when subsystems >> > > > are involved, this is not what we want since the namespaces may be >> > > > attached to other controllers as well. >> > > > >> > > > This patch adds an additional NvmeBus on the subsystem device. When >> > > > nvme-ns devices are realized, if the parent controller device is linked >> > > > to a subsystem, the parent bus is set to the subsystem one instead. This >> > > > makes sure that namespaces are kept alive and not unrealized. >> > > > >> > > > Signed-off-by: Klaus Jensen <k.jensen@samsung.com> >> > > > --- >> > > > hw/nvme/nvme.h | 18 ++++++++++-------- >> > > > hw/nvme/ctrl.c | 8 +++++--- >> > > > hw/nvme/ns.c | 32 +++++++++++++++++++++++++------- >> > > > hw/nvme/subsys.c | 4 ++++ >> > > > 4 files changed, 44 insertions(+), 18 deletions(-) >> > > > >> > > > diff --git a/hw/nvme/nvme.h b/hw/nvme/nvme.h >> > > > index c4065467d877..9401e212f9f7 100644 >> > > > --- a/hw/nvme/nvme.h >> > > > +++ b/hw/nvme/nvme.h >> > > > @@ -33,12 +33,21 @@ QEMU_BUILD_BUG_ON(NVME_MAX_NAMESPACES > >> > > > NVME_NSID_BROADCAST - 1); >> > > > typedef struct NvmeCtrl NvmeCtrl; >> > > > typedef struct NvmeNamespace NvmeNamespace; >> > > > +#define TYPE_NVME_BUS "nvme-bus" >> > > > +OBJECT_DECLARE_SIMPLE_TYPE(NvmeBus, NVME_BUS) >> > > > + >> > > > +typedef struct NvmeBus { >> > > > + BusState parent_bus; >> > > > + bool is_subsys; >> > > > +} NvmeBus; >> > > > + >> > > > #define TYPE_NVME_SUBSYS "nvme-subsys" >> > > > #define NVME_SUBSYS(obj) \ >> > > > OBJECT_CHECK(NvmeSubsystem, (obj), TYPE_NVME_SUBSYS) >> > > > typedef struct NvmeSubsystem { >> > > > DeviceState parent_obj; >> > > > + NvmeBus bus; >> > > > uint8_t subnqn[256]; >> > > > NvmeCtrl *ctrls[NVME_MAX_CONTROLLERS]; >> > > > @@ -365,13 +374,6 @@ typedef struct NvmeCQueue { >> > > > QTAILQ_HEAD(, NvmeRequest) req_list; >> > > > } NvmeCQueue; >> > > > -#define TYPE_NVME_BUS "nvme-bus" >> > > > -#define NVME_BUS(obj) OBJECT_CHECK(NvmeBus, (obj), TYPE_NVME_BUS) >> > > > - >> > > > -typedef struct NvmeBus { >> > > > - BusState parent_bus; >> > > > -} NvmeBus; >> > > > - >> > > > #define TYPE_NVME "nvme" >> > > > #define NVME(obj) \ >> > > > OBJECT_CHECK(NvmeCtrl, (obj), TYPE_NVME) >> > > > @@ -463,7 +465,7 @@ typedef struct NvmeCtrl { >> > > > static inline NvmeNamespace *nvme_ns(NvmeCtrl *n, uint32_t nsid) >> > > > { >> > > > - if (!nsid || nsid > NVME_MAX_NAMESPACES) { >> > > > + if (!n || !nsid || nsid > NVME_MAX_NAMESPACES) { >> > > > return NULL; >> > > > } >> > > > diff --git a/hw/nvme/ctrl.c b/hw/nvme/ctrl.c >> > > > index 90e3ee2b70ee..7c8fca36d9a5 100644 >> > > > --- a/hw/nvme/ctrl.c >> > > > +++ b/hw/nvme/ctrl.c >> > > > @@ -6516,11 +6516,13 @@ static void nvme_exit(PCIDevice *pci_dev) >> > > > for (i = 1; i <= NVME_MAX_NAMESPACES; i++) { >> > > > ns = nvme_ns(n, i); >> > > > - if (!ns) { >> > > > - continue; >> > > > + if (ns) { >> > > > + ns->attached--; >> > > > } >> > > > + } >> > > > - nvme_ns_cleanup(ns); >> > > > + if (n->subsys) { >> > > > + nvme_subsys_unregister_ctrl(n->subsys, n); >> > > > } >> > > > if (n->subsys) { >> > > > diff --git a/hw/nvme/ns.c b/hw/nvme/ns.c >> > > > index 3c4f5b8c714a..612a2786d75d 100644 >> > > > --- a/hw/nvme/ns.c >> > > > +++ b/hw/nvme/ns.c >> > > > @@ -444,13 +444,29 @@ void nvme_ns_cleanup(NvmeNamespace *ns) >> > > > static void nvme_ns_realize(DeviceState *dev, Error **errp) >> > > > { >> > > > NvmeNamespace *ns = NVME_NS(dev); >> > > > - BusState *s = qdev_get_parent_bus(dev); >> > > > - NvmeCtrl *n = NVME(s->parent); >> > > > - NvmeSubsystem *subsys = n->subsys; >> > > > + BusState *qbus = qdev_get_parent_bus(dev); >> > > > + NvmeBus *bus = NVME_BUS(qbus); >> > > > + NvmeCtrl *n = NULL; >> > > > + NvmeSubsystem *subsys = NULL; >> > > > uint32_t nsid = ns->params.nsid; >> > > > int i; >> > > > - if (!n->subsys) { >> > > > + if (bus->is_subsys) { >> > > > + subsys = NVME_SUBSYS(qbus->parent); >> > > > + } else { >> > > > + n = NVME(qbus->parent); >> > > > + subsys = n->subsys; >> > > > + } >> > > > + >> > > > + if (subsys) { >> > > > + /* >> > > > + * If this namespace belongs to a subsystem (through a >> > > > link on the >> > > > + * controller device), reparent the device. >> > > > + */ >> > > > + if (!qdev_set_parent_bus(dev, &subsys->bus.parent_bus, errp)) { >> > > > + return; >> > > > + } >> > > > + } else { >> > > > if (ns->params.detached) { >> > > > error_setg(errp, "detached requires that the nvme >> > > > device is " >> > > > "linked to an nvme-subsys device"); >> > > > @@ -470,7 +486,7 @@ static void nvme_ns_realize(DeviceState >> > > > *dev, Error **errp) >> > > > if (!nsid) { >> > > > for (i = 1; i <= NVME_MAX_NAMESPACES; i++) { >> > > > - if (nvme_ns(n, i) || nvme_subsys_ns(subsys, i)) { >> > > > + if (nvme_subsys_ns(subsys, i) || nvme_ns(n, i)) { >> > > > continue; >> > > > } >> > > > @@ -483,7 +499,7 @@ static void nvme_ns_realize(DeviceState >> > > > *dev, Error **errp) >> > > > return; >> > > > } >> > > > } else { >> > > > - if (nvme_ns(n, nsid) || nvme_subsys_ns(subsys, nsid)) { >> > > > + if (nvme_subsys_ns(subsys, nsid) || nvme_ns(n, nsid)) { >> > > > error_setg(errp, "namespace id '%d' already >> > > > allocated", nsid); >> > > > return; >> > > > } >> > > > @@ -509,7 +525,9 @@ static void nvme_ns_realize(DeviceState >> > > > *dev, Error **errp) >> > > > } >> > > > } >> > > > - nvme_attach_ns(n, ns); >> > > > + if (n) { >> > > > + nvme_attach_ns(n, ns); >> > > > + } >> > > > } >> > > > static Property nvme_ns_props[] = { >> > > > diff --git a/hw/nvme/subsys.c b/hw/nvme/subsys.c >> > > > index 92caa604a280..fb7c3a7c55fc 100644 >> > > > --- a/hw/nvme/subsys.c >> > > > +++ b/hw/nvme/subsys.c >> > > > @@ -50,6 +50,10 @@ static void nvme_subsys_realize(DeviceState >> > > > *dev, Error **errp) >> > > > { >> > > > NvmeSubsystem *subsys = NVME_SUBSYS(dev); >> > > > + qbus_create_inplace(&subsys->bus, sizeof(NvmeBus), >> > > > TYPE_NVME_BUS, dev, >> > > > + dev->id); >> > > > + subsys->bus.is_subsys = true; >> > > > + >> > > > nvme_subsys_setup(subsys); >> > > > } >> > > > >> > > Why not always create a subsystem, and distinguish between 'shared' >> > > and 'non-shared' subsystems instead of the ->subsys pointer? >> > > That way all namespaces can be children of the subsystem, we won't >> > > need any reparenting, and the whole thing will be more in-line with >> > > qdev, no? >> > > >> > >> > Hi Hannes, >> > >> > Thanks for your reviews and comments! >> > >> > So, I have actually considered what you suggest. >> > >> > The problem is that the nvme-ns device currently expects to plug into a >> > bus (an 'nvme-bus') and we cannot really get rid of that 'bus' parameter >> > without breaking compatibility. I experimented with removing the bus >> > from the nvme device and instead creating it in the nvme-subsys device. >> > My idea here was to implicitly always create an nvme-subsys if not >> > explicitly created by the user, but since nvme-subsys does not plug into >> > any bus itself, it is not exposed in the qtree and thus not reachable >> > (i.e., when realizing the nvme-ns device, it will complain that there >> > are no 'nvme-bus' available to plug into). To make this work, I believe >> > we'd have to have the nvme-subsys plug into the main system bus (or some >> > other bus rooted at main-system-bus), and I'd prefer not to do that >> > since this is already a flawed design and I think it would be more >> > intrusive than what my patch does. >> > >> Sigh. >> _Again_. >> >> I seem to trip over issues for which no patch can possibly be accepted as >> first the infrastructure has to be reworked. >> >> ... there is a reason why I'm avoiding posting patches to qemu-devel :-( >> >> > I raised these issues on the mailinglist some time ago[1]. We didn't >> > really find a good solution, but I think the conclusion is that the >> > bus/device design of subsystems and namespaces is flawed. That's why I >> > am working on an "objectification" of the two devices as suggested by >> > Stefan[2] as a proper fix for this mess. >> > >> Actually, I _do_ think that it would be good to have an nvme-subsystem bus, >> providing a list of all namespaces for that subsystem. >> Creating a controller would then mean that one has to create a controller >> and a namespace _separately_, as then the namespace would _not_ be a child >> of the controller. >> But that's arguably a good thing, as the namespaces _do_ have a separate >> lifetime from controllers. >> And the lifetime of the subsystem could be completely self-contained; the >> controller would be looking up subsystems via the subsystem NQN if present; >> I guess we'll need to create ad-hoc subsystems for PCIe. >> But nothing insurmountable. >> And certainly nothing which require a large-scale rework of qemu internals, >> I would think. > >I don't remember the reason to use --object instead of --device. Maybe >the --device approach is viable and it makes some sense because this is >a "device" (like a SCSI LUN) that exposed to the guest. It would be >necessary to have a nvme-subsys device on the system bus to act as the >bus for nvme-ns devices as Klaus described. > A namespace (-device nvme-ns) does not expose anything on its own to the guest. Whatever the namespace provides (basically the association to a -drive) is accessed through the pcie controller (-device nvme). Similarly, the subsystem is just a concept for allowing multiple controllers to access the same namespace. And this is where the model clash because the parent/child relationship doesnt fit. Reversing the relationship (controller is a child of a namespace) also doesnt work since a contrller may have multiple namespace attached. A many-to-many relationship is required which cannot be expresseed with QDEV as far as I understand. Talk is cheap, but I have a WIP that shims the -device's and moves the core functionality of namespaces and subsystems to -objects. This makes the setup much more flexible and fits QDEV/QOM much better.
On 7/7/21 6:14 PM, Stefan Hajnoczi wrote: > On Wed, Jul 07, 2021 at 12:43:56PM +0200, Hannes Reinecke wrote: >> On 7/7/21 11:53 AM, Klaus Jensen wrote: >>> On Jul 7 09:49, Hannes Reinecke wrote: >>>> On 7/6/21 11:33 AM, Klaus Jensen wrote: >>>>> From: Klaus Jensen <k.jensen@samsung.com> >>>>> >>>>> Prior to this patch the nvme-ns devices are always children of the >>>>> NvmeBus owned by the NvmeCtrl. This causes the namespaces to be >>>>> unrealized when the parent device is removed. However, when subsystems >>>>> are involved, this is not what we want since the namespaces may be >>>>> attached to other controllers as well. >>>>> >>>>> This patch adds an additional NvmeBus on the subsystem device. When >>>>> nvme-ns devices are realized, if the parent controller device is linked >>>>> to a subsystem, the parent bus is set to the subsystem one instead. This >>>>> makes sure that namespaces are kept alive and not unrealized. >>>>> >>>>> Signed-off-by: Klaus Jensen <k.jensen@samsung.com> >>>>> --- >>>>> hw/nvme/nvme.h | 18 ++++++++++-------- >>>>> hw/nvme/ctrl.c | 8 +++++--- >>>>> hw/nvme/ns.c | 32 +++++++++++++++++++++++++------- >>>>> hw/nvme/subsys.c | 4 ++++ >>>>> 4 files changed, 44 insertions(+), 18 deletions(-) >>>>> >>>>> diff --git a/hw/nvme/nvme.h b/hw/nvme/nvme.h >>>>> index c4065467d877..9401e212f9f7 100644 >>>>> --- a/hw/nvme/nvme.h >>>>> +++ b/hw/nvme/nvme.h >>>>> @@ -33,12 +33,21 @@ QEMU_BUILD_BUG_ON(NVME_MAX_NAMESPACES > >>>>> NVME_NSID_BROADCAST - 1); >>>>> typedef struct NvmeCtrl NvmeCtrl; >>>>> typedef struct NvmeNamespace NvmeNamespace; >>>>> +#define TYPE_NVME_BUS "nvme-bus" >>>>> +OBJECT_DECLARE_SIMPLE_TYPE(NvmeBus, NVME_BUS) >>>>> + >>>>> +typedef struct NvmeBus { >>>>> + BusState parent_bus; >>>>> + bool is_subsys; >>>>> +} NvmeBus; >>>>> + >>>>> #define TYPE_NVME_SUBSYS "nvme-subsys" >>>>> #define NVME_SUBSYS(obj) \ >>>>> OBJECT_CHECK(NvmeSubsystem, (obj), TYPE_NVME_SUBSYS) >>>>> typedef struct NvmeSubsystem { >>>>> DeviceState parent_obj; >>>>> + NvmeBus bus; >>>>> uint8_t subnqn[256]; >>>>> NvmeCtrl *ctrls[NVME_MAX_CONTROLLERS]; >>>>> @@ -365,13 +374,6 @@ typedef struct NvmeCQueue { >>>>> QTAILQ_HEAD(, NvmeRequest) req_list; >>>>> } NvmeCQueue; >>>>> -#define TYPE_NVME_BUS "nvme-bus" >>>>> -#define NVME_BUS(obj) OBJECT_CHECK(NvmeBus, (obj), TYPE_NVME_BUS) >>>>> - >>>>> -typedef struct NvmeBus { >>>>> - BusState parent_bus; >>>>> -} NvmeBus; >>>>> - >>>>> #define TYPE_NVME "nvme" >>>>> #define NVME(obj) \ >>>>> OBJECT_CHECK(NvmeCtrl, (obj), TYPE_NVME) >>>>> @@ -463,7 +465,7 @@ typedef struct NvmeCtrl { >>>>> static inline NvmeNamespace *nvme_ns(NvmeCtrl *n, uint32_t nsid) >>>>> { >>>>> - if (!nsid || nsid > NVME_MAX_NAMESPACES) { >>>>> + if (!n || !nsid || nsid > NVME_MAX_NAMESPACES) { >>>>> return NULL; >>>>> } >>>>> diff --git a/hw/nvme/ctrl.c b/hw/nvme/ctrl.c >>>>> index 90e3ee2b70ee..7c8fca36d9a5 100644 >>>>> --- a/hw/nvme/ctrl.c >>>>> +++ b/hw/nvme/ctrl.c >>>>> @@ -6516,11 +6516,13 @@ static void nvme_exit(PCIDevice *pci_dev) >>>>> for (i = 1; i <= NVME_MAX_NAMESPACES; i++) { >>>>> ns = nvme_ns(n, i); >>>>> - if (!ns) { >>>>> - continue; >>>>> + if (ns) { >>>>> + ns->attached--; >>>>> } >>>>> + } >>>>> - nvme_ns_cleanup(ns); >>>>> + if (n->subsys) { >>>>> + nvme_subsys_unregister_ctrl(n->subsys, n); >>>>> } >>>>> if (n->subsys) { >>>>> diff --git a/hw/nvme/ns.c b/hw/nvme/ns.c >>>>> index 3c4f5b8c714a..612a2786d75d 100644 >>>>> --- a/hw/nvme/ns.c >>>>> +++ b/hw/nvme/ns.c >>>>> @@ -444,13 +444,29 @@ void nvme_ns_cleanup(NvmeNamespace *ns) >>>>> static void nvme_ns_realize(DeviceState *dev, Error **errp) >>>>> { >>>>> NvmeNamespace *ns = NVME_NS(dev); >>>>> - BusState *s = qdev_get_parent_bus(dev); >>>>> - NvmeCtrl *n = NVME(s->parent); >>>>> - NvmeSubsystem *subsys = n->subsys; >>>>> + BusState *qbus = qdev_get_parent_bus(dev); >>>>> + NvmeBus *bus = NVME_BUS(qbus); >>>>> + NvmeCtrl *n = NULL; >>>>> + NvmeSubsystem *subsys = NULL; >>>>> uint32_t nsid = ns->params.nsid; >>>>> int i; >>>>> - if (!n->subsys) { >>>>> + if (bus->is_subsys) { >>>>> + subsys = NVME_SUBSYS(qbus->parent); >>>>> + } else { >>>>> + n = NVME(qbus->parent); >>>>> + subsys = n->subsys; >>>>> + } >>>>> + >>>>> + if (subsys) { >>>>> + /* >>>>> + * If this namespace belongs to a subsystem (through a >>>>> link on the >>>>> + * controller device), reparent the device. >>>>> + */ >>>>> + if (!qdev_set_parent_bus(dev, &subsys->bus.parent_bus, errp)) { >>>>> + return; >>>>> + } >>>>> + } else { >>>>> if (ns->params.detached) { >>>>> error_setg(errp, "detached requires that the nvme >>>>> device is " >>>>> "linked to an nvme-subsys device"); >>>>> @@ -470,7 +486,7 @@ static void nvme_ns_realize(DeviceState >>>>> *dev, Error **errp) >>>>> if (!nsid) { >>>>> for (i = 1; i <= NVME_MAX_NAMESPACES; i++) { >>>>> - if (nvme_ns(n, i) || nvme_subsys_ns(subsys, i)) { >>>>> + if (nvme_subsys_ns(subsys, i) || nvme_ns(n, i)) { >>>>> continue; >>>>> } >>>>> @@ -483,7 +499,7 @@ static void nvme_ns_realize(DeviceState >>>>> *dev, Error **errp) >>>>> return; >>>>> } >>>>> } else { >>>>> - if (nvme_ns(n, nsid) || nvme_subsys_ns(subsys, nsid)) { >>>>> + if (nvme_subsys_ns(subsys, nsid) || nvme_ns(n, nsid)) { >>>>> error_setg(errp, "namespace id '%d' already >>>>> allocated", nsid); >>>>> return; >>>>> } >>>>> @@ -509,7 +525,9 @@ static void nvme_ns_realize(DeviceState >>>>> *dev, Error **errp) >>>>> } >>>>> } >>>>> - nvme_attach_ns(n, ns); >>>>> + if (n) { >>>>> + nvme_attach_ns(n, ns); >>>>> + } >>>>> } >>>>> static Property nvme_ns_props[] = { >>>>> diff --git a/hw/nvme/subsys.c b/hw/nvme/subsys.c >>>>> index 92caa604a280..fb7c3a7c55fc 100644 >>>>> --- a/hw/nvme/subsys.c >>>>> +++ b/hw/nvme/subsys.c >>>>> @@ -50,6 +50,10 @@ static void nvme_subsys_realize(DeviceState >>>>> *dev, Error **errp) >>>>> { >>>>> NvmeSubsystem *subsys = NVME_SUBSYS(dev); >>>>> + qbus_create_inplace(&subsys->bus, sizeof(NvmeBus), >>>>> TYPE_NVME_BUS, dev, >>>>> + dev->id); >>>>> + subsys->bus.is_subsys = true; >>>>> + >>>>> nvme_subsys_setup(subsys); >>>>> } >>>>> >>>> Why not always create a subsystem, and distinguish between 'shared' >>>> and 'non-shared' subsystems instead of the ->subsys pointer? >>>> That way all namespaces can be children of the subsystem, we won't >>>> need any reparenting, and the whole thing will be more in-line with >>>> qdev, no? >>>> >>> >>> Hi Hannes, >>> >>> Thanks for your reviews and comments! >>> >>> So, I have actually considered what you suggest. >>> >>> The problem is that the nvme-ns device currently expects to plug into a >>> bus (an 'nvme-bus') and we cannot really get rid of that 'bus' parameter >>> without breaking compatibility. I experimented with removing the bus >>> from the nvme device and instead creating it in the nvme-subsys device. >>> My idea here was to implicitly always create an nvme-subsys if not >>> explicitly created by the user, but since nvme-subsys does not plug into >>> any bus itself, it is not exposed in the qtree and thus not reachable >>> (i.e., when realizing the nvme-ns device, it will complain that there >>> are no 'nvme-bus' available to plug into). To make this work, I believe >>> we'd have to have the nvme-subsys plug into the main system bus (or some >>> other bus rooted at main-system-bus), and I'd prefer not to do that >>> since this is already a flawed design and I think it would be more >>> intrusive than what my patch does. >>> >> Sigh. >> _Again_. >> >> I seem to trip over issues for which no patch can possibly be accepted as >> first the infrastructure has to be reworked. >> >> ... there is a reason why I'm avoiding posting patches to qemu-devel :-( >> >>> I raised these issues on the mailinglist some time ago[1]. We didn't >>> really find a good solution, but I think the conclusion is that the >>> bus/device design of subsystems and namespaces is flawed. That's why I >>> am working on an "objectification" of the two devices as suggested by >>> Stefan[2] as a proper fix for this mess. >>> >> Actually, I _do_ think that it would be good to have an nvme-subsystem bus, >> providing a list of all namespaces for that subsystem. >> Creating a controller would then mean that one has to create a controller >> and a namespace _separately_, as then the namespace would _not_ be a child >> of the controller. >> But that's arguably a good thing, as the namespaces _do_ have a separate >> lifetime from controllers. >> And the lifetime of the subsystem could be completely self-contained; the >> controller would be looking up subsystems via the subsystem NQN if present; >> I guess we'll need to create ad-hoc subsystems for PCIe. >> But nothing insurmountable. >> And certainly nothing which require a large-scale rework of qemu internals, >> I would think. > > I don't remember the reason to use --object instead of --device. Maybe > the --device approach is viable and it makes some sense because this is > a "device" (like a SCSI LUN) that exposed to the guest. It would be > necessary to have a nvme-subsys device on the system bus to act as the > bus for nvme-ns devices as Klaus described. > Which is what I've had in mind. The only issue here is that a nvme controller will also generate or attach to a nvme subsys, and the subsys will have a different lifetime than the controller. But it should be possible to key the lifetime of the subsys to the attached controllers (via refcounting, say), so that once the last controller is detached from a subsystem the subsystem itself is also detached. >> But _if_ you work on the rework, please ensure that not only NVMe is >> represented here. SCSI multipathing has the same issue currently; there is a >> strict host->lun->block->OS device relationship currently in SCSI, making it >> impossible to represent a multipathed SCSI device in qemu. >> The only sneaky way is to allow for a shared OS device (ie specifying the >> filename more than once), but that completely sidesteps qemu internals, too. > > Do you want one SCSIDevice to be accessible via multiple SCSIBus > instances for multipathing in QEMU? > Precisely. Some things like ALUA or multipath issues in general are tricky to reproduce, and qemu would be a neat way here. But currently we can't as we cannot emulate multipathing. Any hints are welcome; I've tried several times to implement it but inevitably failed :-( Cheers, Hannes
diff --git a/hw/nvme/nvme.h b/hw/nvme/nvme.h index c4065467d877..9401e212f9f7 100644 --- a/hw/nvme/nvme.h +++ b/hw/nvme/nvme.h @@ -33,12 +33,21 @@ QEMU_BUILD_BUG_ON(NVME_MAX_NAMESPACES > NVME_NSID_BROADCAST - 1); typedef struct NvmeCtrl NvmeCtrl; typedef struct NvmeNamespace NvmeNamespace; +#define TYPE_NVME_BUS "nvme-bus" +OBJECT_DECLARE_SIMPLE_TYPE(NvmeBus, NVME_BUS) + +typedef struct NvmeBus { + BusState parent_bus; + bool is_subsys; +} NvmeBus; + #define TYPE_NVME_SUBSYS "nvme-subsys" #define NVME_SUBSYS(obj) \ OBJECT_CHECK(NvmeSubsystem, (obj), TYPE_NVME_SUBSYS) typedef struct NvmeSubsystem { DeviceState parent_obj; + NvmeBus bus; uint8_t subnqn[256]; NvmeCtrl *ctrls[NVME_MAX_CONTROLLERS]; @@ -365,13 +374,6 @@ typedef struct NvmeCQueue { QTAILQ_HEAD(, NvmeRequest) req_list; } NvmeCQueue; -#define TYPE_NVME_BUS "nvme-bus" -#define NVME_BUS(obj) OBJECT_CHECK(NvmeBus, (obj), TYPE_NVME_BUS) - -typedef struct NvmeBus { - BusState parent_bus; -} NvmeBus; - #define TYPE_NVME "nvme" #define NVME(obj) \ OBJECT_CHECK(NvmeCtrl, (obj), TYPE_NVME) @@ -463,7 +465,7 @@ typedef struct NvmeCtrl { static inline NvmeNamespace *nvme_ns(NvmeCtrl *n, uint32_t nsid) { - if (!nsid || nsid > NVME_MAX_NAMESPACES) { + if (!n || !nsid || nsid > NVME_MAX_NAMESPACES) { return NULL; } diff --git a/hw/nvme/ctrl.c b/hw/nvme/ctrl.c index 90e3ee2b70ee..7c8fca36d9a5 100644 --- a/hw/nvme/ctrl.c +++ b/hw/nvme/ctrl.c @@ -6516,11 +6516,13 @@ static void nvme_exit(PCIDevice *pci_dev) for (i = 1; i <= NVME_MAX_NAMESPACES; i++) { ns = nvme_ns(n, i); - if (!ns) { - continue; + if (ns) { + ns->attached--; } + } - nvme_ns_cleanup(ns); + if (n->subsys) { + nvme_subsys_unregister_ctrl(n->subsys, n); } if (n->subsys) { diff --git a/hw/nvme/ns.c b/hw/nvme/ns.c index 3c4f5b8c714a..612a2786d75d 100644 --- a/hw/nvme/ns.c +++ b/hw/nvme/ns.c @@ -444,13 +444,29 @@ void nvme_ns_cleanup(NvmeNamespace *ns) static void nvme_ns_realize(DeviceState *dev, Error **errp) { NvmeNamespace *ns = NVME_NS(dev); - BusState *s = qdev_get_parent_bus(dev); - NvmeCtrl *n = NVME(s->parent); - NvmeSubsystem *subsys = n->subsys; + BusState *qbus = qdev_get_parent_bus(dev); + NvmeBus *bus = NVME_BUS(qbus); + NvmeCtrl *n = NULL; + NvmeSubsystem *subsys = NULL; uint32_t nsid = ns->params.nsid; int i; - if (!n->subsys) { + if (bus->is_subsys) { + subsys = NVME_SUBSYS(qbus->parent); + } else { + n = NVME(qbus->parent); + subsys = n->subsys; + } + + if (subsys) { + /* + * If this namespace belongs to a subsystem (through a link on the + * controller device), reparent the device. + */ + if (!qdev_set_parent_bus(dev, &subsys->bus.parent_bus, errp)) { + return; + } + } else { if (ns->params.detached) { error_setg(errp, "detached requires that the nvme device is " "linked to an nvme-subsys device"); @@ -470,7 +486,7 @@ static void nvme_ns_realize(DeviceState *dev, Error **errp) if (!nsid) { for (i = 1; i <= NVME_MAX_NAMESPACES; i++) { - if (nvme_ns(n, i) || nvme_subsys_ns(subsys, i)) { + if (nvme_subsys_ns(subsys, i) || nvme_ns(n, i)) { continue; } @@ -483,7 +499,7 @@ static void nvme_ns_realize(DeviceState *dev, Error **errp) return; } } else { - if (nvme_ns(n, nsid) || nvme_subsys_ns(subsys, nsid)) { + if (nvme_subsys_ns(subsys, nsid) || nvme_ns(n, nsid)) { error_setg(errp, "namespace id '%d' already allocated", nsid); return; } @@ -509,7 +525,9 @@ static void nvme_ns_realize(DeviceState *dev, Error **errp) } } - nvme_attach_ns(n, ns); + if (n) { + nvme_attach_ns(n, ns); + } } static Property nvme_ns_props[] = { diff --git a/hw/nvme/subsys.c b/hw/nvme/subsys.c index 92caa604a280..fb7c3a7c55fc 100644 --- a/hw/nvme/subsys.c +++ b/hw/nvme/subsys.c @@ -50,6 +50,10 @@ static void nvme_subsys_realize(DeviceState *dev, Error **errp) { NvmeSubsystem *subsys = NVME_SUBSYS(dev); + qbus_create_inplace(&subsys->bus, sizeof(NvmeBus), TYPE_NVME_BUS, dev, + dev->id); + subsys->bus.is_subsys = true; + nvme_subsys_setup(subsys); }