| Message ID | 1423115089-12904-22-git-send-email-jiang.liu@linux.intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Delegated to: | Bjorn Helgaas |
| Headers | show |
Hi, I'm getting a regression from this patch when using VFIO for device assignment to a QEMU VM. I have a device initially bound to the nouveau driver, which is unbound from that driver and bound to vfio-pci for use by userspace. vfio-pci calls pci_enable_device, but when userspace attempts to setup the legacy INTx interrupt, pci_dev->irq is zero and vfio-pci errors with -ENODEV. Where is pci_dev->irq supposed to be getting re-initialized in this case? Am I missing an important initialization step in vfio-pci? I certainly don't think I should be calling request_irq(pci_dev->irq, ... when pci_dev->irq is zero. Thanks, Alex On Thu, 2015-02-05 at 13:44 +0800, Jiang Liu wrote: > Some PCI device drivers assume that pci_dev->irq won't change after > calling pci_disable_device() and pci_enable_device() during suspend and > resume. > > Commit c03b3b0738a5 ("x86, irq, mpparse: Release IOAPIC pin when > PCI device is disabled") frees PCI IRQ resources when pci_disable_device() > is called and reallocate IRQ resources when pci_enable_device() is > called again. This breaks above assumption. So commit 3eec595235c1 > ("x86, irq, PCI: Keep IRQ assignment for PCI devices during > suspend/hibernation") and 9eabc99a635a ("x86, irq, PCI: Keep IRQ > assignment for runtime power management") fix the issue by avoiding > freeing/reallocating IRQ resources during PCI device suspend/resume. > They achieve this by checking dev.power.is_prepared and > dev.power.runtime_status. PM maintainer, Rafael, then pointed out that > it's really an ugly fix which leaking PM internal state information to > IRQ subsystem. > > Recently David Vrabel <david.vrabel@citrix.com> also reports an > regression in pciback driver caused by commit cffe0a2b5a34 ("x86, irq: > Keep balance of IOAPIC pin reference count"). Please refer to: > http://lkml.org/lkml/2015/1/14/546 > > So this patch refine the way to release PCI IRQ resources. Instead of > releasing PCI IRQ resources in pci_disable_device()/ > pcibios_disable_device(), we now release it at driver unbinding > notification BUS_NOTIFY_UNBOUND_DRIVER. In other word, we only release > PCI IRQ resources when there's no driver bound to the PCI device, and > it keeps the assumption that pci_dev->irq won't through multiple > invocation of pci_enable_device()/pci_disable_device(). > > Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com> > --- > arch/x86/include/asm/pci_x86.h | 2 -- > arch/x86/pci/common.c | 34 ++++++++++++++++++++++++++++------ > arch/x86/pci/intel_mid_pci.c | 4 ++-- > arch/x86/pci/irq.c | 15 +-------------- > drivers/acpi/pci_irq.c | 9 +-------- > 5 files changed, 32 insertions(+), 32 deletions(-) > > diff --git a/arch/x86/include/asm/pci_x86.h b/arch/x86/include/asm/pci_x86.h > index 164e3f8d3c3d..fa1195dae425 100644 > --- a/arch/x86/include/asm/pci_x86.h > +++ b/arch/x86/include/asm/pci_x86.h > @@ -93,8 +93,6 @@ extern raw_spinlock_t pci_config_lock; > extern int (*pcibios_enable_irq)(struct pci_dev *dev); > extern void (*pcibios_disable_irq)(struct pci_dev *dev); > > -extern bool mp_should_keep_irq(struct device *dev); > - > struct pci_raw_ops { > int (*read)(unsigned int domain, unsigned int bus, unsigned int devfn, > int reg, int len, u32 *val); > diff --git a/arch/x86/pci/common.c b/arch/x86/pci/common.c > index 7b20bccf3648..ff1f0afa5ed1 100644 > --- a/arch/x86/pci/common.c > +++ b/arch/x86/pci/common.c > @@ -497,6 +497,31 @@ void __init pcibios_set_cache_line_size(void) > } > } > > +/* > + * Some device drivers assume dev->irq won't change after calling > + * pci_disable_device(). So delay releasing of IRQ resource to driver > + * unbinding time. Otherwise it will break PM subsystem and drivers > + * like xen-pciback etc. > + */ > +static int pci_irq_notifier(struct notifier_block *nb, unsigned long action, > + void *data) > +{ > + struct pci_dev *dev = to_pci_dev(data); > + > + if (action != BUS_NOTIFY_UNBOUND_DRIVER) > + return NOTIFY_DONE; > + > + if (pcibios_disable_irq) > + pcibios_disable_irq(dev); > + > + return NOTIFY_OK; > +} > + > +static struct notifier_block pci_irq_nb = { > + .notifier_call = pci_irq_notifier, > + .priority = INT_MIN, > +}; > + > int __init pcibios_init(void) > { > if (!raw_pci_ops) { > @@ -509,6 +534,9 @@ int __init pcibios_init(void) > > if (pci_bf_sort >= pci_force_bf) > pci_sort_breadthfirst(); > + > + bus_register_notifier(&pci_bus_type, &pci_irq_nb); > + > return 0; > } > > @@ -667,12 +695,6 @@ int pcibios_enable_device(struct pci_dev *dev, int mask) > return 0; > } > > -void pcibios_disable_device (struct pci_dev *dev) > -{ > - if (!pci_dev_msi_enabled(dev) && pcibios_disable_irq) > - pcibios_disable_irq(dev); > -} > - > int pci_ext_cfg_avail(void) > { > if (raw_pci_ext_ops) > diff --git a/arch/x86/pci/intel_mid_pci.c b/arch/x86/pci/intel_mid_pci.c > index 44b9271580b5..95c2471f6819 100644 > --- a/arch/x86/pci/intel_mid_pci.c > +++ b/arch/x86/pci/intel_mid_pci.c > @@ -234,10 +234,10 @@ static int intel_mid_pci_irq_enable(struct pci_dev *dev) > > static void intel_mid_pci_irq_disable(struct pci_dev *dev) > { > - if (!mp_should_keep_irq(&dev->dev) && dev->irq_managed && > - dev->irq > 0) { > + if (dev->irq_managed && dev->irq > 0) { > mp_unmap_irq(dev->irq); > dev->irq_managed = 0; > + dev->irq = 0; > } > } > > diff --git a/arch/x86/pci/irq.c b/arch/x86/pci/irq.c > index 5dc6ca5e1741..e71b3dbd87b8 100644 > --- a/arch/x86/pci/irq.c > +++ b/arch/x86/pci/irq.c > @@ -1256,22 +1256,9 @@ static int pirq_enable_irq(struct pci_dev *dev) > return 0; > } > > -bool mp_should_keep_irq(struct device *dev) > -{ > - if (dev->power.is_prepared) > - return true; > -#ifdef CONFIG_PM > - if (dev->power.runtime_status == RPM_SUSPENDING) > - return true; > -#endif > - > - return false; > -} > - > static void pirq_disable_irq(struct pci_dev *dev) > { > - if (io_apic_assign_pci_irqs && !mp_should_keep_irq(&dev->dev) && > - dev->irq_managed && dev->irq) { > + if (io_apic_assign_pci_irqs && dev->irq_managed && dev->irq) { > mp_unmap_irq(dev->irq); > dev->irq = 0; > dev->irq_managed = 0; > diff --git a/drivers/acpi/pci_irq.c b/drivers/acpi/pci_irq.c > index b1def411c0b8..e7f718d6918a 100644 > --- a/drivers/acpi/pci_irq.c > +++ b/drivers/acpi/pci_irq.c > @@ -485,14 +485,6 @@ void acpi_pci_irq_disable(struct pci_dev *dev) > if (!pin || !dev->irq_managed || dev->irq <= 0) > return; > > - /* Keep IOAPIC pin configuration when suspending */ > - if (dev->dev.power.is_prepared) > - return; > -#ifdef CONFIG_PM > - if (dev->dev.power.runtime_status == RPM_SUSPENDING) > - return; > -#endif > - > entry = acpi_pci_irq_lookup(dev, pin); > if (!entry) > return; > @@ -513,5 +505,6 @@ void acpi_pci_irq_disable(struct pci_dev *dev) > if (gsi >= 0) { > acpi_unregister_gsi(gsi); > dev->irq_managed = 0; > + dev->irq = 0; > } > } -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Wed, 2015-03-04 at 09:06 -0700, Alex Williamson wrote: > Hi, > > I'm getting a regression from this patch when using VFIO for device > assignment to a QEMU VM. I have a device initially bound to the nouveau > driver, which is unbound from that driver and bound to vfio-pci for use > by userspace. vfio-pci calls pci_enable_device, but when userspace > attempts to setup the legacy INTx interrupt, pci_dev->irq is zero and > vfio-pci errors with -ENODEV. > > Where is pci_dev->irq supposed to be getting re-initialized in this > case? Am I missing an important initialization step in vfio-pci? I > certainly don't think I should be calling request_irq(pci_dev->irq, ... > when pci_dev->irq is zero. Thanks, It looks like the imbalance is in pci_dev->enable_cnt. Any call to pci_disable_device() will clear pci_dev->irq, but pci_enable_device() does effectively nothing unless it's called with enable_cnt == zero. So I'm at the mercy of the previous driver behaving relatively sanely in order to re-enable legacy interrupts for a device :-\ Maybe the unbound notifier needs to do some sanitizing of the device? Thanks, Alex -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/arch/x86/include/asm/pci_x86.h b/arch/x86/include/asm/pci_x86.h index 164e3f8d3c3d..fa1195dae425 100644 --- a/arch/x86/include/asm/pci_x86.h +++ b/arch/x86/include/asm/pci_x86.h @@ -93,8 +93,6 @@ extern raw_spinlock_t pci_config_lock; extern int (*pcibios_enable_irq)(struct pci_dev *dev); extern void (*pcibios_disable_irq)(struct pci_dev *dev); -extern bool mp_should_keep_irq(struct device *dev); - struct pci_raw_ops { int (*read)(unsigned int domain, unsigned int bus, unsigned int devfn, int reg, int len, u32 *val); diff --git a/arch/x86/pci/common.c b/arch/x86/pci/common.c index 7b20bccf3648..ff1f0afa5ed1 100644 --- a/arch/x86/pci/common.c +++ b/arch/x86/pci/common.c @@ -497,6 +497,31 @@ void __init pcibios_set_cache_line_size(void) } } +/* + * Some device drivers assume dev->irq won't change after calling + * pci_disable_device(). So delay releasing of IRQ resource to driver + * unbinding time. Otherwise it will break PM subsystem and drivers + * like xen-pciback etc. + */ +static int pci_irq_notifier(struct notifier_block *nb, unsigned long action, + void *data) +{ + struct pci_dev *dev = to_pci_dev(data); + + if (action != BUS_NOTIFY_UNBOUND_DRIVER) + return NOTIFY_DONE; + + if (pcibios_disable_irq) + pcibios_disable_irq(dev); + + return NOTIFY_OK; +} + +static struct notifier_block pci_irq_nb = { + .notifier_call = pci_irq_notifier, + .priority = INT_MIN, +}; + int __init pcibios_init(void) { if (!raw_pci_ops) { @@ -509,6 +534,9 @@ int __init pcibios_init(void) if (pci_bf_sort >= pci_force_bf) pci_sort_breadthfirst(); + + bus_register_notifier(&pci_bus_type, &pci_irq_nb); + return 0; } @@ -667,12 +695,6 @@ int pcibios_enable_device(struct pci_dev *dev, int mask) return 0; } -void pcibios_disable_device (struct pci_dev *dev) -{ - if (!pci_dev_msi_enabled(dev) && pcibios_disable_irq) - pcibios_disable_irq(dev); -} - int pci_ext_cfg_avail(void) { if (raw_pci_ext_ops) diff --git a/arch/x86/pci/intel_mid_pci.c b/arch/x86/pci/intel_mid_pci.c index 44b9271580b5..95c2471f6819 100644 --- a/arch/x86/pci/intel_mid_pci.c +++ b/arch/x86/pci/intel_mid_pci.c @@ -234,10 +234,10 @@ static int intel_mid_pci_irq_enable(struct pci_dev *dev) static void intel_mid_pci_irq_disable(struct pci_dev *dev) { - if (!mp_should_keep_irq(&dev->dev) && dev->irq_managed && - dev->irq > 0) { + if (dev->irq_managed && dev->irq > 0) { mp_unmap_irq(dev->irq); dev->irq_managed = 0; + dev->irq = 0; } } diff --git a/arch/x86/pci/irq.c b/arch/x86/pci/irq.c index 5dc6ca5e1741..e71b3dbd87b8 100644 --- a/arch/x86/pci/irq.c +++ b/arch/x86/pci/irq.c @@ -1256,22 +1256,9 @@ static int pirq_enable_irq(struct pci_dev *dev) return 0; } -bool mp_should_keep_irq(struct device *dev) -{ - if (dev->power.is_prepared) - return true; -#ifdef CONFIG_PM - if (dev->power.runtime_status == RPM_SUSPENDING) - return true; -#endif - - return false; -} - static void pirq_disable_irq(struct pci_dev *dev) { - if (io_apic_assign_pci_irqs && !mp_should_keep_irq(&dev->dev) && - dev->irq_managed && dev->irq) { + if (io_apic_assign_pci_irqs && dev->irq_managed && dev->irq) { mp_unmap_irq(dev->irq); dev->irq = 0; dev->irq_managed = 0; diff --git a/drivers/acpi/pci_irq.c b/drivers/acpi/pci_irq.c index b1def411c0b8..e7f718d6918a 100644 --- a/drivers/acpi/pci_irq.c +++ b/drivers/acpi/pci_irq.c @@ -485,14 +485,6 @@ void acpi_pci_irq_disable(struct pci_dev *dev) if (!pin || !dev->irq_managed || dev->irq <= 0) return; - /* Keep IOAPIC pin configuration when suspending */ - if (dev->dev.power.is_prepared) - return; -#ifdef CONFIG_PM - if (dev->dev.power.runtime_status == RPM_SUSPENDING) - return; -#endif - entry = acpi_pci_irq_lookup(dev, pin); if (!entry) return; @@ -513,5 +505,6 @@ void acpi_pci_irq_disable(struct pci_dev *dev) if (gsi >= 0) { acpi_unregister_gsi(gsi); dev->irq_managed = 0; + dev->irq = 0; } }
Some PCI device drivers assume that pci_dev->irq won't change after calling pci_disable_device() and pci_enable_device() during suspend and resume. Commit c03b3b0738a5 ("x86, irq, mpparse: Release IOAPIC pin when PCI device is disabled") frees PCI IRQ resources when pci_disable_device() is called and reallocate IRQ resources when pci_enable_device() is called again. This breaks above assumption. So commit 3eec595235c1 ("x86, irq, PCI: Keep IRQ assignment for PCI devices during suspend/hibernation") and 9eabc99a635a ("x86, irq, PCI: Keep IRQ assignment for runtime power management") fix the issue by avoiding freeing/reallocating IRQ resources during PCI device suspend/resume. They achieve this by checking dev.power.is_prepared and dev.power.runtime_status. PM maintainer, Rafael, then pointed out that it's really an ugly fix which leaking PM internal state information to IRQ subsystem. Recently David Vrabel <david.vrabel@citrix.com> also reports an regression in pciback driver caused by commit cffe0a2b5a34 ("x86, irq: Keep balance of IOAPIC pin reference count"). Please refer to: http://lkml.org/lkml/2015/1/14/546 So this patch refine the way to release PCI IRQ resources. Instead of releasing PCI IRQ resources in pci_disable_device()/ pcibios_disable_device(), we now release it at driver unbinding notification BUS_NOTIFY_UNBOUND_DRIVER. In other word, we only release PCI IRQ resources when there's no driver bound to the PCI device, and it keeps the assumption that pci_dev->irq won't through multiple invocation of pci_enable_device()/pci_disable_device(). Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com> --- arch/x86/include/asm/pci_x86.h | 2 -- arch/x86/pci/common.c | 34 ++++++++++++++++++++++++++++------ arch/x86/pci/intel_mid_pci.c | 4 ++-- arch/x86/pci/irq.c | 15 +-------------- drivers/acpi/pci_irq.c | 9 +-------- 5 files changed, 32 insertions(+), 32 deletions(-)