| Message ID | 20230727072410.135743-3-jing2.liu@intel.com |
|---|---|
| State | New |
| Headers | show |
| Series | Support dynamic MSI-X allocation | expand |
On 7/27/23 09:24, Jing Liu wrote: > The vector_use callback is used to enable vector that is unmasked in > guest. The kernel used to only support static MSI-X allocation. When > allocating a new interrupt using "static MSI-X allocation" kernels, > Qemu first disables all previously allocated vectors and then > re-allocates all including the new one. The nr_vectors of VFIOPCIDevice > indicates that all vectors from 0 to nr_vectors are allocated (and may > be enabled), which is used to to loop all the possibly used vectors > When, e.g., disabling MSI-X interrupts. > > Extend the vector_use function to support dynamic MSI-X allocation when > host supports the capability. Qemu therefore can individually allocate > and enable a new interrupt without affecting others or causing interrupts > lost during runtime. > > Utilize nr_vectors to calculate the upper bound of enabled vectors in > dynamic MSI-X allocation mode since looping all msix_entries_nr is not > efficient and unnecessary. > > Signed-off-by: Jing Liu <jing2.liu@intel.com> > Tested-by: Reinette Chatre <reinette.chatre@intel.com> > --- > hw/vfio/pci.c | 40 +++++++++++++++++++++++++++------------- > 1 file changed, 27 insertions(+), 13 deletions(-) > > diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c > index 0c4ac0873d40..8c485636445c 100644 > --- a/hw/vfio/pci.c > +++ b/hw/vfio/pci.c > @@ -512,12 +512,20 @@ static int vfio_msix_vector_do_use(PCIDevice *pdev, unsigned int nr, > } > > /* > - * We don't want to have the host allocate all possible MSI vectors > - * for a device if they're not in use, so we shutdown and incrementally > - * increase them as needed. > + * When dynamic allocation is not supported, we don't want to have the > + * host allocate all possible MSI vectors for a device if they're not > + * in use, so we shutdown and incrementally increase them as needed. > + * And nr_vectors stands for the number of vectors being allocated. > + * > + * When dynamic allocation is supported, let the host only allocate > + * and enable a vector when it is in use in guest. nr_vectors stands > + * for the upper bound of vectors being enabled (but not all of the > + * ranges is allocated or enabled). > */ > - if (vdev->nr_vectors < nr + 1) { > + if ((vdev->msix->irq_info_flags & VFIO_IRQ_INFO_NORESIZE) && I would add a small helper for this test: vfio_msix_can_alloc_dyn(vdev) Thanks, C. > + (vdev->nr_vectors < nr + 1)) { > vdev->nr_vectors = nr + 1; > + > if (!vdev->defer_kvm_irq_routing) { > vfio_disable_irqindex(&vdev->vbasedev, VFIO_PCI_MSIX_IRQ_INDEX); > ret = vfio_enable_vectors(vdev, true); > @@ -529,16 +537,22 @@ static int vfio_msix_vector_do_use(PCIDevice *pdev, unsigned int nr, > Error *err = NULL; > int32_t fd; > > - if (vector->virq >= 0) { > - fd = event_notifier_get_fd(&vector->kvm_interrupt); > - } else { > - fd = event_notifier_get_fd(&vector->interrupt); > - } > + if (!vdev->defer_kvm_irq_routing) { > + if (vector->virq >= 0) { > + fd = event_notifier_get_fd(&vector->kvm_interrupt); > + } else { > + fd = event_notifier_get_fd(&vector->interrupt); > + } > > - if (vfio_set_irq_signaling(&vdev->vbasedev, > - VFIO_PCI_MSIX_IRQ_INDEX, nr, > - VFIO_IRQ_SET_ACTION_TRIGGER, fd, &err)) { > - error_reportf_err(err, VFIO_MSG_PREFIX, vdev->vbasedev.name); > + if (vfio_set_irq_signaling(&vdev->vbasedev, > + VFIO_PCI_MSIX_IRQ_INDEX, nr, > + VFIO_IRQ_SET_ACTION_TRIGGER, fd, &err)) { > + error_reportf_err(err, VFIO_MSG_PREFIX, vdev->vbasedev.name); > + } > + } > + /* Increase for dynamic allocation case. */ > + if (vdev->nr_vectors < nr + 1) { > + vdev->nr_vectors = nr + 1; > } > } >
On Thu, 27 Jul 2023 03:24:09 -0400 Jing Liu <jing2.liu@intel.com> wrote: > The vector_use callback is used to enable vector that is unmasked in > guest. The kernel used to only support static MSI-X allocation. When > allocating a new interrupt using "static MSI-X allocation" kernels, > Qemu first disables all previously allocated vectors and then > re-allocates all including the new one. The nr_vectors of VFIOPCIDevice > indicates that all vectors from 0 to nr_vectors are allocated (and may > be enabled), which is used to to loop all the possibly used vectors > When, e.g., disabling MSI-X interrupts. > > Extend the vector_use function to support dynamic MSI-X allocation when > host supports the capability. Qemu therefore can individually allocate > and enable a new interrupt without affecting others or causing interrupts > lost during runtime. > > Utilize nr_vectors to calculate the upper bound of enabled vectors in > dynamic MSI-X allocation mode since looping all msix_entries_nr is not > efficient and unnecessary. > > Signed-off-by: Jing Liu <jing2.liu@intel.com> > Tested-by: Reinette Chatre <reinette.chatre@intel.com> > --- > hw/vfio/pci.c | 40 +++++++++++++++++++++++++++------------- > 1 file changed, 27 insertions(+), 13 deletions(-) > > diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c > index 0c4ac0873d40..8c485636445c 100644 > --- a/hw/vfio/pci.c > +++ b/hw/vfio/pci.c > @@ -512,12 +512,20 @@ static int vfio_msix_vector_do_use(PCIDevice *pdev, unsigned int nr, > } > > /* > - * We don't want to have the host allocate all possible MSI vectors > - * for a device if they're not in use, so we shutdown and incrementally > - * increase them as needed. > + * When dynamic allocation is not supported, we don't want to have the > + * host allocate all possible MSI vectors for a device if they're not > + * in use, so we shutdown and incrementally increase them as needed. > + * And nr_vectors stands for the number of vectors being allocated. "nr_vectors represents the total number of vectors allocated." > + * > + * When dynamic allocation is supported, let the host only allocate > + * and enable a vector when it is in use in guest. nr_vectors stands > + * for the upper bound of vectors being enabled (but not all of the > + * ranges is allocated or enabled). s/stands for/represents/ > */ > - if (vdev->nr_vectors < nr + 1) { > + if ((vdev->msix->irq_info_flags & VFIO_IRQ_INFO_NORESIZE) && Testing vdev->msix->noresize would be cleaner. > + (vdev->nr_vectors < nr + 1)) { > vdev->nr_vectors = nr + 1; > + > if (!vdev->defer_kvm_irq_routing) { > vfio_disable_irqindex(&vdev->vbasedev, VFIO_PCI_MSIX_IRQ_INDEX); > ret = vfio_enable_vectors(vdev, true); > @@ -529,16 +537,22 @@ static int vfio_msix_vector_do_use(PCIDevice *pdev, unsigned int nr, > Error *err = NULL; > int32_t fd; > > - if (vector->virq >= 0) { > - fd = event_notifier_get_fd(&vector->kvm_interrupt); > - } else { > - fd = event_notifier_get_fd(&vector->interrupt); > - } > + if (!vdev->defer_kvm_irq_routing) { > + if (vector->virq >= 0) { > + fd = event_notifier_get_fd(&vector->kvm_interrupt); > + } else { > + fd = event_notifier_get_fd(&vector->interrupt); > + } > > - if (vfio_set_irq_signaling(&vdev->vbasedev, > - VFIO_PCI_MSIX_IRQ_INDEX, nr, > - VFIO_IRQ_SET_ACTION_TRIGGER, fd, &err)) { > - error_reportf_err(err, VFIO_MSG_PREFIX, vdev->vbasedev.name); > + if (vfio_set_irq_signaling(&vdev->vbasedev, > + VFIO_PCI_MSIX_IRQ_INDEX, nr, > + VFIO_IRQ_SET_ACTION_TRIGGER, fd, &err)) { > + error_reportf_err(err, VFIO_MSG_PREFIX, vdev->vbasedev.name); > + } > + } > + /* Increase for dynamic allocation case. */ > + if (vdev->nr_vectors < nr + 1) { > + vdev->nr_vectors = nr + 1; > } We now have two branches where the bulk of the code is skipped when defer_kvm_irq_routing is enabled and doing effectively the same update to nr_vectors otherwise. This suggests we should move the defer_kvm_irq_routing test out and create a common place to update nr_vectors. Thanks, Alex
Hi Alex, > On July 28, 2023 1:25 AM, Alex Williamson <alex.williamson@redhat.com> wrote: > > On Thu, 27 Jul 2023 03:24:09 -0400 > Jing Liu <jing2.liu@intel.com> wrote: > > > The vector_use callback is used to enable vector that is unmasked in > > guest. The kernel used to only support static MSI-X allocation. When > > allocating a new interrupt using "static MSI-X allocation" kernels, > > Qemu first disables all previously allocated vectors and then > > re-allocates all including the new one. The nr_vectors of > > VFIOPCIDevice indicates that all vectors from 0 to nr_vectors are > > allocated (and may be enabled), which is used to to loop all the > > possibly used vectors When, e.g., disabling MSI-X interrupts. > > > > Extend the vector_use function to support dynamic MSI-X allocation > > when host supports the capability. Qemu therefore can individually > > allocate and enable a new interrupt without affecting others or > > causing interrupts lost during runtime. > > > > Utilize nr_vectors to calculate the upper bound of enabled vectors in > > dynamic MSI-X allocation mode since looping all msix_entries_nr is not > > efficient and unnecessary. > > > > Signed-off-by: Jing Liu <jing2.liu@intel.com> > > Tested-by: Reinette Chatre <reinette.chatre@intel.com> > > --- > > hw/vfio/pci.c | 40 +++++++++++++++++++++++++++------------- > > 1 file changed, 27 insertions(+), 13 deletions(-) > > > > diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c index > > 0c4ac0873d40..8c485636445c 100644 > > --- a/hw/vfio/pci.c > > +++ b/hw/vfio/pci.c > > @@ -512,12 +512,20 @@ static int vfio_msix_vector_do_use(PCIDevice > *pdev, unsigned int nr, > > } > > > > /* > > - * We don't want to have the host allocate all possible MSI vectors > > - * for a device if they're not in use, so we shutdown and incrementally > > - * increase them as needed. > > + * When dynamic allocation is not supported, we don't want to have the > > + * host allocate all possible MSI vectors for a device if they're not > > + * in use, so we shutdown and incrementally increase them as needed. > > + * And nr_vectors stands for the number of vectors being allocated. > > "nr_vectors represents the total number of vectors allocated." Will change. > > > + * > > + * When dynamic allocation is supported, let the host only allocate > > + * and enable a vector when it is in use in guest. nr_vectors stands > > + * for the upper bound of vectors being enabled (but not all of the > > + * ranges is allocated or enabled). > > s/stands for/represents/ Will change. > > > */ > > - if (vdev->nr_vectors < nr + 1) { > > + if ((vdev->msix->irq_info_flags & VFIO_IRQ_INFO_NORESIZE) && > > Testing vdev->msix->noresize would be cleaner. > > > + (vdev->nr_vectors < nr + 1)) { > > vdev->nr_vectors = nr + 1; > > + > > if (!vdev->defer_kvm_irq_routing) { > > vfio_disable_irqindex(&vdev->vbasedev, VFIO_PCI_MSIX_IRQ_INDEX); > > ret = vfio_enable_vectors(vdev, true); @@ -529,16 +537,22 > > @@ static int vfio_msix_vector_do_use(PCIDevice *pdev, unsigned int nr, > > Error *err = NULL; > > int32_t fd; > > > > - if (vector->virq >= 0) { > > - fd = event_notifier_get_fd(&vector->kvm_interrupt); > > - } else { > > - fd = event_notifier_get_fd(&vector->interrupt); > > - } > > + if (!vdev->defer_kvm_irq_routing) { > > + if (vector->virq >= 0) { > > + fd = event_notifier_get_fd(&vector->kvm_interrupt); > > + } else { > > + fd = event_notifier_get_fd(&vector->interrupt); > > + } > > > > - if (vfio_set_irq_signaling(&vdev->vbasedev, > > - VFIO_PCI_MSIX_IRQ_INDEX, nr, > > - VFIO_IRQ_SET_ACTION_TRIGGER, fd, &err)) { > > - error_reportf_err(err, VFIO_MSG_PREFIX, vdev->vbasedev.name); > > + if (vfio_set_irq_signaling(&vdev->vbasedev, > > + VFIO_PCI_MSIX_IRQ_INDEX, nr, > > + VFIO_IRQ_SET_ACTION_TRIGGER, fd, &err)) { > > + error_reportf_err(err, VFIO_MSG_PREFIX, vdev->vbasedev.name); > > + } > > + } > > + /* Increase for dynamic allocation case. */ > > + if (vdev->nr_vectors < nr + 1) { > > + vdev->nr_vectors = nr + 1; > > } > > We now have two branches where the bulk of the code is skipped when > defer_kvm_irq_routing is enabled and doing effectively the same update to > nr_vectors otherwise. This suggests we should move the > defer_kvm_irq_routing test out and create a common place to update > nr_vectors. Thanks, I make a new logic as follows that moves the defer_kvm_irq_routing test out. Since the vfio_enable_vectors() function need an updated nr_vectors value so need first update and test the different conditions using old value, e.g. old_nr_vec. int old_nr_vec = vdev->nr_vectors; ... ... if (vdev->nr_vectors < nr + 1) { vdev->nr_vectors = nr + 1; } if (!vdev->defer_kvm_irq_routing) { if (vdev->msix->noresize && (old_nr_vec < nr + 1)) { vfio_disable_irqindex(&vdev->vbasedev, VFIO_PCI_MSIX_IRQ_INDEX); ret = vfio_enable_vectors(vdev, true); // use updated nr_vectors ... } else { if (vector->virq >= 0) { fd = event_notifier_get_fd(&vector->kvm_interrupt); } else { fd = event_notifier_get_fd(&vector->interrupt); } if (vfio_set_irq_signaling(&vdev->vbasedev, VFIO_PCI_MSIX_IRQ_INDEX, nr, VFIO_IRQ_SET_ACTION_TRIGGER, fd, &err)) { error_reportf_err(err, VFIO_MSG_PREFIX, vdev->vbasedev.name); } } } Thanks, Jing > > Alex
diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c index 0c4ac0873d40..8c485636445c 100644 --- a/hw/vfio/pci.c +++ b/hw/vfio/pci.c @@ -512,12 +512,20 @@ static int vfio_msix_vector_do_use(PCIDevice *pdev, unsigned int nr, } /* - * We don't want to have the host allocate all possible MSI vectors - * for a device if they're not in use, so we shutdown and incrementally - * increase them as needed. + * When dynamic allocation is not supported, we don't want to have the + * host allocate all possible MSI vectors for a device if they're not + * in use, so we shutdown and incrementally increase them as needed. + * And nr_vectors stands for the number of vectors being allocated. + * + * When dynamic allocation is supported, let the host only allocate + * and enable a vector when it is in use in guest. nr_vectors stands + * for the upper bound of vectors being enabled (but not all of the + * ranges is allocated or enabled). */ - if (vdev->nr_vectors < nr + 1) { + if ((vdev->msix->irq_info_flags & VFIO_IRQ_INFO_NORESIZE) && + (vdev->nr_vectors < nr + 1)) { vdev->nr_vectors = nr + 1; + if (!vdev->defer_kvm_irq_routing) { vfio_disable_irqindex(&vdev->vbasedev, VFIO_PCI_MSIX_IRQ_INDEX); ret = vfio_enable_vectors(vdev, true); @@ -529,16 +537,22 @@ static int vfio_msix_vector_do_use(PCIDevice *pdev, unsigned int nr, Error *err = NULL; int32_t fd; - if (vector->virq >= 0) { - fd = event_notifier_get_fd(&vector->kvm_interrupt); - } else { - fd = event_notifier_get_fd(&vector->interrupt); - } + if (!vdev->defer_kvm_irq_routing) { + if (vector->virq >= 0) { + fd = event_notifier_get_fd(&vector->kvm_interrupt); + } else { + fd = event_notifier_get_fd(&vector->interrupt); + } - if (vfio_set_irq_signaling(&vdev->vbasedev, - VFIO_PCI_MSIX_IRQ_INDEX, nr, - VFIO_IRQ_SET_ACTION_TRIGGER, fd, &err)) { - error_reportf_err(err, VFIO_MSG_PREFIX, vdev->vbasedev.name); + if (vfio_set_irq_signaling(&vdev->vbasedev, + VFIO_PCI_MSIX_IRQ_INDEX, nr, + VFIO_IRQ_SET_ACTION_TRIGGER, fd, &err)) { + error_reportf_err(err, VFIO_MSG_PREFIX, vdev->vbasedev.name); + } + } + /* Increase for dynamic allocation case. */ + if (vdev->nr_vectors < nr + 1) { + vdev->nr_vectors = nr + 1; } }