| Message ID | 146602104462.23192.4267928292361711364.stgit@bahia.lan (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
On Wed, 15 Jun 2016 22:26:41 +0200 Greg Kurz <gkurz@linux.vnet.ibm.com> wrote: > A strange behaviour is observed when comparing PCI hotplug in QEMU, between > x86 and pseries. If you consider the following steps: > - start a VM > - add a PCI device via the QEMU monitor before the rtasd has started (for > example starting the VM in paused state, or hotplug during FW or boot > loader) > - resume the VM execution > > The x86 kernel detects the PCI device, but the pseries one does not. > > This happens because the rtasd kernel worker is currently started under > device_initcall, while PCI probing happens earlier under subsys_initcall. > > As a consequence, if we have a pending RTAS event at boot time, a message > is printed and the event is dropped. > > This patch moves all the initialization of rtasd to arch_initcall, which is > run before subsys_call: this way, logging_enabled is true when the RTAS > event pops up and it is not lost anymore. > > The proc fs bits stay at device_initcall because they cannot be run before > fs_initcall. > > Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com> > --- > v2: - avoid behaviour change: don't create the proc entry if early init failed > I forgot to mention that Thomas had sent a Tested-by for v1, which I think is still valid for v2. > Michael, > > This was also tested under PowerVM: it doesn't fix anything there because the > HMC tells it won't honor DLPAR features as long as the RMC isn't here, which > happens later in the boot sequence. It hence seems impossible to have a pending > RTAS event at boot time. > > It doesn't seem to break anything either, the kernel boots and hotplug works > okay once the RMC is up. > > Cheers. > > -- > Greg > > --- > arch/powerpc/kernel/rtasd.c | 22 +++++++++++++++++----- > 1 file changed, 17 insertions(+), 5 deletions(-) > > diff --git a/arch/powerpc/kernel/rtasd.c b/arch/powerpc/kernel/rtasd.c > index e864b7c5884e..a26a02006576 100644 > --- a/arch/powerpc/kernel/rtasd.c > +++ b/arch/powerpc/kernel/rtasd.c > @@ -526,10 +526,8 @@ void rtas_cancel_event_scan(void) > } > EXPORT_SYMBOL_GPL(rtas_cancel_event_scan); > > -static int __init rtas_init(void) > +static int __init rtas_event_scan_init(void) > { > - struct proc_dir_entry *entry; > - > if (!machine_is(pseries) && !machine_is(chrp)) > return 0; > > @@ -562,13 +560,27 @@ static int __init rtas_init(void) > return -ENOMEM; > } > > + start_event_scan(); > + > + return 0; > +} > +arch_initcall(rtas_event_scan_init); > + > +static int __init rtas_init(void) > +{ > + struct proc_dir_entry *entry; > + > + if (!machine_is(pseries) && !machine_is(chrp)) > + return 0; > + > + if (!rtas_log_buf) > + return -ENODEV; > + > entry = proc_create("powerpc/rtas/error_log", S_IRUSR, NULL, > &proc_rtas_log_operations); > if (!entry) > printk(KERN_ERR "Failed to create error_log proc entry\n"); > > - start_event_scan(); > - > return 0; > } > __initcall(rtas_init); > >
Ping ? On Tue, 21 Jun 2016 11:02:01 +0200 Greg Kurz <groug@kaod.org> wrote: > On Wed, 15 Jun 2016 22:26:41 +0200 > Greg Kurz <gkurz@linux.vnet.ibm.com> wrote: > > > A strange behaviour is observed when comparing PCI hotplug in QEMU, between > > x86 and pseries. If you consider the following steps: > > - start a VM > > - add a PCI device via the QEMU monitor before the rtasd has started (for > > example starting the VM in paused state, or hotplug during FW or boot > > loader) > > - resume the VM execution > > > > The x86 kernel detects the PCI device, but the pseries one does not. > > > > This happens because the rtasd kernel worker is currently started under > > device_initcall, while PCI probing happens earlier under subsys_initcall. > > > > As a consequence, if we have a pending RTAS event at boot time, a message > > is printed and the event is dropped. > > > > This patch moves all the initialization of rtasd to arch_initcall, which is > > run before subsys_call: this way, logging_enabled is true when the RTAS > > event pops up and it is not lost anymore. > > > > The proc fs bits stay at device_initcall because they cannot be run before > > fs_initcall. > > > > Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com> > > --- > > v2: - avoid behaviour change: don't create the proc entry if early init failed > > > > I forgot to mention that Thomas had sent a Tested-by for v1, which I think is > still valid for v2. > > > Michael, > > > > This was also tested under PowerVM: it doesn't fix anything there because the > > HMC tells it won't honor DLPAR features as long as the RMC isn't here, which > > happens later in the boot sequence. It hence seems impossible to have a pending > > RTAS event at boot time. > > > > It doesn't seem to break anything either, the kernel boots and hotplug works > > okay once the RMC is up. > > > > Cheers. > > > > -- > > Greg > > > > --- > > arch/powerpc/kernel/rtasd.c | 22 +++++++++++++++++----- > > 1 file changed, 17 insertions(+), 5 deletions(-) > > > > diff --git a/arch/powerpc/kernel/rtasd.c b/arch/powerpc/kernel/rtasd.c > > index e864b7c5884e..a26a02006576 100644 > > --- a/arch/powerpc/kernel/rtasd.c > > +++ b/arch/powerpc/kernel/rtasd.c > > @@ -526,10 +526,8 @@ void rtas_cancel_event_scan(void) > > } > > EXPORT_SYMBOL_GPL(rtas_cancel_event_scan); > > > > -static int __init rtas_init(void) > > +static int __init rtas_event_scan_init(void) > > { > > - struct proc_dir_entry *entry; > > - > > if (!machine_is(pseries) && !machine_is(chrp)) > > return 0; > > > > @@ -562,13 +560,27 @@ static int __init rtas_init(void) > > return -ENOMEM; > > } > > > > + start_event_scan(); > > + > > + return 0; > > +} > > +arch_initcall(rtas_event_scan_init); > > + > > +static int __init rtas_init(void) > > +{ > > + struct proc_dir_entry *entry; > > + > > + if (!machine_is(pseries) && !machine_is(chrp)) > > + return 0; > > + > > + if (!rtas_log_buf) > > + return -ENODEV; > > + > > entry = proc_create("powerpc/rtas/error_log", S_IRUSR, NULL, > > &proc_rtas_log_operations); > > if (!entry) > > printk(KERN_ERR "Failed to create error_log proc entry\n"); > > > > - start_event_scan(); > > - > > return 0; > > } > > __initcall(rtas_init); > > > > > >
Greg Kurz <groug@kaod.org> writes:
> Ping ?
Thanks. It got lost in the flood.
It's in my testing tree and should show up in next soon.
cheers
On Wed, 2016-15-06 at 20:26:41 UTC, Greg Kurz wrote: > A strange behaviour is observed when comparing PCI hotplug in QEMU, between > x86 and pseries. If you consider the following steps: > - start a VM > - add a PCI device via the QEMU monitor before the rtasd has started (for > example starting the VM in paused state, or hotplug during FW or boot > loader) > - resume the VM execution > > The x86 kernel detects the PCI device, but the pseries one does not. > > This happens because the rtasd kernel worker is currently started under > device_initcall, while PCI probing happens earlier under subsys_initcall. > > As a consequence, if we have a pending RTAS event at boot time, a message > is printed and the event is dropped. > > This patch moves all the initialization of rtasd to arch_initcall, which is > run before subsys_call: this way, logging_enabled is true when the RTAS > event pops up and it is not lost anymore. > > The proc fs bits stay at device_initcall because they cannot be run before > fs_initcall. > > Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com> Applied to powerpc next, thanks. https://git.kernel.org/powerpc/c/8c6a0a1f4041f19559538649e0 cheers
diff --git a/arch/powerpc/kernel/rtasd.c b/arch/powerpc/kernel/rtasd.c index e864b7c5884e..a26a02006576 100644 --- a/arch/powerpc/kernel/rtasd.c +++ b/arch/powerpc/kernel/rtasd.c @@ -526,10 +526,8 @@ void rtas_cancel_event_scan(void) } EXPORT_SYMBOL_GPL(rtas_cancel_event_scan); -static int __init rtas_init(void) +static int __init rtas_event_scan_init(void) { - struct proc_dir_entry *entry; - if (!machine_is(pseries) && !machine_is(chrp)) return 0; @@ -562,13 +560,27 @@ static int __init rtas_init(void) return -ENOMEM; } + start_event_scan(); + + return 0; +} +arch_initcall(rtas_event_scan_init); + +static int __init rtas_init(void) +{ + struct proc_dir_entry *entry; + + if (!machine_is(pseries) && !machine_is(chrp)) + return 0; + + if (!rtas_log_buf) + return -ENODEV; + entry = proc_create("powerpc/rtas/error_log", S_IRUSR, NULL, &proc_rtas_log_operations); if (!entry) printk(KERN_ERR "Failed to create error_log proc entry\n"); - start_event_scan(); - return 0; } __initcall(rtas_init);
A strange behaviour is observed when comparing PCI hotplug in QEMU, between x86 and pseries. If you consider the following steps: - start a VM - add a PCI device via the QEMU monitor before the rtasd has started (for example starting the VM in paused state, or hotplug during FW or boot loader) - resume the VM execution The x86 kernel detects the PCI device, but the pseries one does not. This happens because the rtasd kernel worker is currently started under device_initcall, while PCI probing happens earlier under subsys_initcall. As a consequence, if we have a pending RTAS event at boot time, a message is printed and the event is dropped. This patch moves all the initialization of rtasd to arch_initcall, which is run before subsys_call: this way, logging_enabled is true when the RTAS event pops up and it is not lost anymore. The proc fs bits stay at device_initcall because they cannot be run before fs_initcall. Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com> --- v2: - avoid behaviour change: don't create the proc entry if early init failed Michael, This was also tested under PowerVM: it doesn't fix anything there because the HMC tells it won't honor DLPAR features as long as the RMC isn't here, which happens later in the boot sequence. It hence seems impossible to have a pending RTAS event at boot time. It doesn't seem to break anything either, the kernel boots and hotplug works okay once the RMC is up. Cheers. -- Greg --- arch/powerpc/kernel/rtasd.c | 22 +++++++++++++++++----- 1 file changed, 17 insertions(+), 5 deletions(-)