[PATCH] x86/PCI: Don't alloc pcibios-irq when MSI is enabled

[PATCH] x86/PCI: Don't alloc pcibios-irq when MSI is enabled

[Joerg Roedel]

From: Joerg Roedel <jroedel@suse.de>

The pcibios-irq and MSI both use dev->irq to store the IRQ
number. While the MSI code checks for that and frees the
pcibios-irq before overwriting dev->irq, the
pcibios_alloc_irq function does not.

Usually this is not a problem, as the pcibios-irq is
allocated before probe time of the device and the MSI irq is
allocted from the drivers probe path.

But there are PCI devices handled by the core kernel and not
by a standard pci driver, like the AMD IOMMU for example.
For the AMD IOMMU a normal pci device driver does not make
sense, because a driver can be forcibly unbound from its
device, which is not a good idea for an IOMMU.

Nevertheless the PCI core code tries to match the PCI device
implementing the AMD IOMMU against drivers, and
allocates/frees a pcibios IRQ every time it tries out a new
driver. This overwrites the dev->irq field set by
pci_enable_msi() and sets it to 0 in the end (because the
probe fails and the pcibios-irq is freed again).

On suspend/resume this breaks the kernel, because the irq
descriptor for irq 0 is NULL.

Fix this by not allocating a pcibios-irq when MSI is
already active. This also has the benefit, that a device
claimed by the core kernel can not be probed by a pci driver
later.

Cc: Jiang Liu <jiang.liu@linux.intel.com>
Reported-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
 arch/x86/pci/common.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/x86/pci/common.c b/arch/x86/pci/common.c
index dc78a4a..6254c06 100644
--- a/arch/x86/pci/common.c
+++ b/arch/x86/pci/common.c
@@ -675,6 +675,14 @@ int pcibios_add_device(struct pci_dev *dev)
 
 int pcibios_alloc_irq(struct pci_dev *dev)
 {
+	/*
+	 * If the PCI device was already claimed by core code and has
+	 * MSI enabled, probing of the pcibios irq will overwrite
+	 * dev->irq.  So bail out if MSI is already enabled.
+	 */
+	if (pci_dev_msi_enabled(dev))
+		return -EBUSY;
+
 	return pcibios_enable_irq(dev);
 }
 
-- 
1.9.1

Re: [PATCH] x86/PCI: Don't alloc pcibios-irq when MSI is enabled

[Thomas Gleixner]

On Fri, 9 Oct 2015, Joerg Roedel wrote:
> From: Joerg Roedel <jroedel@suse.de>
> 
> The pcibios-irq and MSI both use dev->irq to store the IRQ
> number. While the MSI code checks for that and frees the
> pcibios-irq before overwriting dev->irq, the
> pcibios_alloc_irq function does not.
> 
> Usually this is not a problem, as the pcibios-irq is
> allocated before probe time of the device and the MSI irq is
> allocted from the drivers probe path.
> 
> But there are PCI devices handled by the core kernel and not
> by a standard pci driver, like the AMD IOMMU for example.
> For the AMD IOMMU a normal pci device driver does not make
> sense, because a driver can be forcibly unbound from its
> device, which is not a good idea for an IOMMU.
> 
> Nevertheless the PCI core code tries to match the PCI device
> implementing the AMD IOMMU against drivers, and
> allocates/frees a pcibios IRQ every time it tries out a new
> driver. This overwrites the dev->irq field set by
> pci_enable_msi() and sets it to 0 in the end (because the
> probe fails and the pcibios-irq is freed again).
> 
> On suspend/resume this breaks the kernel, because the irq
> descriptor for irq 0 is NULL.
> 
> Fix this by not allocating a pcibios-irq when MSI is
> already active. This also has the benefit, that a device
> claimed by the core kernel can not be probed by a pci driver
> later.
> 
> Cc: Jiang Liu <jiang.liu@linux.intel.com>
> Reported-by: Borislav Petkov <bp@alien8.de>
> Signed-off-by: Joerg Roedel <jroedel@suse.de>

Reviewed-by: Thomas Gleixner <tglx@linutronix.de>

> ---
>  arch/x86/pci/common.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/arch/x86/pci/common.c b/arch/x86/pci/common.c
> index dc78a4a..6254c06 100644
> --- a/arch/x86/pci/common.c
> +++ b/arch/x86/pci/common.c
> @@ -675,6 +675,14 @@ int pcibios_add_device(struct pci_dev *dev)
>  
>  int pcibios_alloc_irq(struct pci_dev *dev)
>  {
> +	/*
> +	 * If the PCI device was already claimed by core code and has
> +	 * MSI enabled, probing of the pcibios irq will overwrite
> +	 * dev->irq.  So bail out if MSI is already enabled.
> +	 */
> +	if (pci_dev_msi_enabled(dev))
> +		return -EBUSY;
> +
>  	return pcibios_enable_irq(dev);
>  }
>  
> -- 
> 1.9.1
> 
> 

[Bugfix v4 0/2] Prevent binding PCI drivers to PCI devices used by non-pci drivers

[Jiang Liu]

Hi Joerg,
	I prepared this patchset yesterday but forgot to send them out.
I think it still worth sending out for review, so here we go:)

---
Commit 991de2e59090 ("PCI, x86: Implement pcibios_alloc_irq() and
pcibios_free_irq()") breaks suspend/resume on some AMD platforms.
The root cause is:
1) AMD IOMMU drivers enables MSI on IOMMU PCI devices at early boot stage
2) PCI driver binding code tries to allocate/free PCI legacy IRQ when
   binding other PCI drivers to IOMMU PCI devices at later boot stage,
   and breaks PCI MSI allocation information.
3) System resume breaks when restoring PCI MSI state using the damaged
   data.

We have tried on solution to detect that a PCI is in use by IOMMU driver
by checking pci_msi_enabled(). But that's too specific, actually we should
prevent binding PCI drivers to PCI devices used by non-PCI drivers.

Fortunately, we could prevent binding PCI drivers to PCI devices by setting
pci_dev->match_driver to false. If needed, we could implement a helper
function to manipulate pci_dev->match_driver.

Jiang Liu (2):
  iommu/amd: Prevent binding other PCI drivers to IOMMU PCI devices
  ACPI, PCI: Prevent binding other PCI drivers to IOAPIC PCI devices

 drivers/acpi/ioapic.c          |    7 +++++--
 drivers/iommu/amd_iommu_init.c |    3 +++
 2 files changed, 8 insertions(+), 2 deletions(-)

-- 
1.7.10.4

[Bugfix v4 1/2] iommu/amd: Prevent binding other PCI drivers to IOMMU PCI devices

[Jiang Liu]

AMD IOMMU driver makes use of IOMMU PCI devices, so prevent binding other
PCI drivers to IOMMU PCI devices.

This fixes a bug reported by Boris that system suspend/resume gets broken
on AMD platforms. For more information, please refer to:
	https://lkml.org/lkml/2015/9/26/89

Fixes: 991de2e59090 ("PCI, x86: Implement pcibios_alloc_irq() and pcibios_free_irq()")
Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
---
 drivers/iommu/amd_iommu_init.c |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c
index 5ef347a13cb5..1b066e7d144d 100644
--- a/drivers/iommu/amd_iommu_init.c
+++ b/drivers/iommu/amd_iommu_init.c
@@ -1256,6 +1256,9 @@ static int iommu_init_pci(struct amd_iommu *iommu)
 	if (!iommu->dev)
 		return -ENODEV;
 
+	/* Prevent binding other PCI device drivers to IOMMU devices */
+	iommu->dev->match_driver = false;
+
 	pci_read_config_dword(iommu->dev, cap_ptr + MMIO_CAP_HDR_OFFSET,
 			      &iommu->cap);
 	pci_read_config_dword(iommu->dev, cap_ptr + MMIO_RANGE_OFFSET,
-- 
1.7.10.4

[Bugfix v4 2/2] ACPI, PCI: Prevent binding other PCI drivers to IOAPIC PCI devices

[Jiang Liu]

The ACPI IOAPIC driver makes use of IOAPIC PCI devices, so prevent
binding other PCI drivers to IOAPIC PCI devices used by ACPI IOAPIC
driver.

Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
---
 drivers/acpi/ioapic.c |    7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/acpi/ioapic.c b/drivers/acpi/ioapic.c
index ccdc8db16bb8..da71b274fc21 100644
--- a/drivers/acpi/ioapic.c
+++ b/drivers/acpi/ioapic.c
@@ -162,12 +162,14 @@ done:
 	list_add(&ioapic->list, &ioapic_list);
 	mutex_unlock(&ioapic_list_lock);
 
-	if (dev)
+	if (dev) {
+		dev->match_driver = false;
 		dev_info(&dev->dev, "%s at %pR, GSI %u\n",
 			 type, res, (u32)gsi_base);
-	else
+	} else {
 		acpi_handle_info(handle, "%s at %pR, GSI %u\n",
 				 type, res, (u32)gsi_base);
+	}
 
 	return AE_OK;
 
@@ -216,6 +218,7 @@ int acpi_ioapic_remove(struct acpi_pci_root *root)
 		if (ioapic->pdev) {
 			pci_release_region(ioapic->pdev, 0);
 			pci_disable_device(ioapic->pdev);
+			ioapic->pdev->match_driver = true;
 			pci_dev_put(ioapic->pdev);
 		} else if (ioapic->res.flags && ioapic->res.parent) {
 			release_resource(&ioapic->res);
-- 
1.7.10.4

Re: [Bugfix v4 2/2] ACPI, PCI: Prevent binding other PCI drivers to IOAPIC PCI devices

[Joerg Roedel]

On Fri, Oct 09, 2015 at 10:07:32PM +0800, Jiang Liu wrote:
> The ACPI IOAPIC driver makes use of IOAPIC PCI devices, so prevent
> binding other PCI drivers to IOAPIC PCI devices used by ACPI IOAPIC
> driver.
> 
> Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
> ---
>  drivers/acpi/ioapic.c |    7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)

Reviewed-by: Joerg Roedel <jroedel@suse.de>

Re: [Bugfix v4 1/2] iommu/amd: Prevent binding other PCI drivers to IOMMU PCI devices

[Joerg Roedel]

On Fri, Oct 09, 2015 at 10:07:31PM +0800, Jiang Liu wrote:
> AMD IOMMU driver makes use of IOMMU PCI devices, so prevent binding other
> PCI drivers to IOMMU PCI devices.
> 
> This fixes a bug reported by Boris that system suspend/resume gets broken
> on AMD platforms. For more information, please refer to:
> 	https://lkml.org/lkml/2015/9/26/89
> 
> Fixes: 991de2e59090 ("PCI, x86: Implement pcibios_alloc_irq() and pcibios_free_irq()")
> Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
> Cc: Borislav Petkov <bp@alien8.de>

Applied to iommu/fixes, thanks Jiang.

Re: [PATCH] x86/PCI: Don't alloc pcibios-irq when MSI is enabled

[Bjorn Helgaas]

On Fri, Oct 09, 2015 at 12:23:34PM +0200, Joerg Roedel wrote:
> From: Joerg Roedel <jroedel@suse.de>
> 
> The pcibios-irq and MSI both use dev->irq to store the IRQ
> number. While the MSI code checks for that and frees the
> pcibios-irq before overwriting dev->irq, the
> pcibios_alloc_irq function does not.
> 
> Usually this is not a problem, as the pcibios-irq is
> allocated before probe time of the device and the MSI irq is
> allocted from the drivers probe path.
> 
> But there are PCI devices handled by the core kernel and not
> by a standard pci driver, like the AMD IOMMU for example.
> For the AMD IOMMU a normal pci device driver does not make
> sense, because a driver can be forcibly unbound from its
> device, which is not a good idea for an IOMMU.
> 
> Nevertheless the PCI core code tries to match the PCI device
> implementing the AMD IOMMU against drivers, and
> allocates/frees a pcibios IRQ every time it tries out a new
> driver. This overwrites the dev->irq field set by
> pci_enable_msi() and sets it to 0 in the end (because the
> probe fails and the pcibios-irq is freed again).
> 
> On suspend/resume this breaks the kernel, because the irq
> descriptor for irq 0 is NULL.
> 
> Fix this by not allocating a pcibios-irq when MSI is
> already active. This also has the benefit, that a device
> claimed by the core kernel can not be probed by a pci driver
> later.
> 
> Cc: Jiang Liu <jiang.liu@linux.intel.com>
> Reported-by: Borislav Petkov <bp@alien8.de>
> Signed-off-by: Joerg Roedel <jroedel@suse.de>

Applied with Thomas' reviewed-by to pci/msi for v4.4, thanks, Joerg!

> ---
>  arch/x86/pci/common.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/arch/x86/pci/common.c b/arch/x86/pci/common.c
> index dc78a4a..6254c06 100644
> --- a/arch/x86/pci/common.c
> +++ b/arch/x86/pci/common.c
> @@ -675,6 +675,14 @@ int pcibios_add_device(struct pci_dev *dev)
>  
>  int pcibios_alloc_irq(struct pci_dev *dev)
>  {
> +	/*
> +	 * If the PCI device was already claimed by core code and has
> +	 * MSI enabled, probing of the pcibios irq will overwrite
> +	 * dev->irq.  So bail out if MSI is already enabled.
> +	 */
> +	if (pci_dev_msi_enabled(dev))
> +		return -EBUSY;
> +
>  	return pcibios_enable_irq(dev);
>  }
>  
> -- 
> 1.9.1
> 
> --
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Re: [PATCH] x86/PCI: Don't alloc pcibios-irq when MSI is enabled

[Jiang Liu]

On 2015/10/22 0:23, Bjorn Helgaas wrote:
> On Fri, Oct 09, 2015 at 12:23:34PM +0200, Joerg Roedel wrote:
>> From: Joerg Roedel <jroedel@suse.de>
>>
>> The pcibios-irq and MSI both use dev->irq to store the IRQ
>> number. While the MSI code checks for that and frees the
>> pcibios-irq before overwriting dev->irq, the
>> pcibios_alloc_irq function does not.
>>
>> Usually this is not a problem, as the pcibios-irq is
>> allocated before probe time of the device and the MSI irq is
>> allocted from the drivers probe path.
>>
>> But there are PCI devices handled by the core kernel and not
>> by a standard pci driver, like the AMD IOMMU for example.
>> For the AMD IOMMU a normal pci device driver does not make
>> sense, because a driver can be forcibly unbound from its
>> device, which is not a good idea for an IOMMU.
>>
>> Nevertheless the PCI core code tries to match the PCI device
>> implementing the AMD IOMMU against drivers, and
>> allocates/frees a pcibios IRQ every time it tries out a new
>> driver. This overwrites the dev->irq field set by
>> pci_enable_msi() and sets it to 0 in the end (because the
>> probe fails and the pcibios-irq is freed again).
>>
>> On suspend/resume this breaks the kernel, because the irq
>> descriptor for irq 0 is NULL.
>>
>> Fix this by not allocating a pcibios-irq when MSI is
>> already active. This also has the benefit, that a device
>> claimed by the core kernel can not be probed by a pci driver
>> later.
>>
>> Cc: Jiang Liu <jiang.liu@linux.intel.com>
>> Reported-by: Borislav Petkov <bp@alien8.de>
>> Signed-off-by: Joerg Roedel <jroedel@suse.de>
> 
> Applied with Thomas' reviewed-by to pci/msi for v4.4, thanks, Joerg!
Hi Bjorn,
	There's another patch already merged into mainstream kernel,
which solves this issue in another way by making use of
pci_dev->match_driver flag. Please refer to:
cbbc00be2ce3 ("iommu/amd: Prevent binding other PCI drivers to IOMMU PCI
devices")
	So I think this patch is redundant now.
Thanks,
Gerry

> 
>> ---
>>  arch/x86/pci/common.c | 8 ++++++++
>>  1 file changed, 8 insertions(+)
>>
>> diff --git a/arch/x86/pci/common.c b/arch/x86/pci/common.c
>> index dc78a4a..6254c06 100644
>> --- a/arch/x86/pci/common.c
>> +++ b/arch/x86/pci/common.c
>> @@ -675,6 +675,14 @@ int pcibios_add_device(struct pci_dev *dev)
>>  
>>  int pcibios_alloc_irq(struct pci_dev *dev)
>>  {
>> +	/*
>> +	 * If the PCI device was already claimed by core code and has
>> +	 * MSI enabled, probing of the pcibios irq will overwrite
>> +	 * dev->irq.  So bail out if MSI is already enabled.
>> +	 */
>> +	if (pci_dev_msi_enabled(dev))
>> +		return -EBUSY;
>> +
>>  	return pcibios_enable_irq(dev);
>>  }
>>  
>> -- 
>> 1.9.1
>>
>> --
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>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>> Please read the FAQ at  http://www.tux.org/lkml/

Re: [PATCH] x86/PCI: Don't alloc pcibios-irq when MSI is enabled

[Joerg Roedel]

On Fri, Oct 23, 2015 at 10:02:11AM +0800, Jiang Liu wrote:
> 	There's another patch already merged into mainstream kernel,
> which solves this issue in another way by making use of
> pci_dev->match_driver flag. Please refer to:
> cbbc00be2ce3 ("iommu/amd: Prevent binding other PCI drivers to IOMMU PCI
> devices")
> 	So I think this patch is redundant now.

Yeah, it fixes the same problem already fixed by your match_driver fix.
But I think this fix makes still sense as it avoids that the problem can
reappear in the future with other drivers. Setting pci_dev->match_driver
could be easily forgotten when writing new code.


	Joerg