[PATCH v2] PCI: hv: Fix a crash in hv_pci_restore_msi_msg() during hibernation

[PATCH v2] PCI: hv: Fix a crash in hv_pci_restore_msi_msg() during hibernation

[Dexuan Cui]

When a Linux VM with an assigned PCI device runs on Hyper-V, if the PCI
device driver is not loaded yet (i.e. MSI-X/MSI is not enabled on the
device yet), doing a VM hibernation triggers a panic in
hv_pci_restore_msi_msg() -> msi_lock_descs(&pdev->dev), because
pdev->dev.msi.data is still NULL.

Avoid the panic by checking if MSI-X/MSI is enabled.

Fixes: dc2b453290c4 ("PCI: hv: Rework MSI handling")
Signed-off-by: Dexuan Cui <decui@microsoft.com>
---

Changes in v2:
    Replaced the test "if (!pdev->dev.msi.data)" with
		      "if (!pdev->msi_enabled && !pdev->msix_enabled)".
      Thanks Michael!
    Updated the changelog accordingly.

 drivers/pci/controller/pci-hyperv.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
index 2d93d0c4f10d..bed3cefdaf19 100644
--- a/drivers/pci/controller/pci-hyperv.c
+++ b/drivers/pci/controller/pci-hyperv.c
@@ -3983,6 +3983,9 @@ static int hv_pci_restore_msi_msg(struct pci_dev *pdev, void *arg)
 	struct msi_desc *entry;
 	int ret = 0;
 
+	if (!pdev->msi_enabled && !pdev->msix_enabled)
+		return 0;
+
 	msi_lock_descs(&pdev->dev);
 	msi_for_each_desc(entry, &pdev->dev, MSI_DESC_ASSOCIATED) {
 		irq_data = irq_get_irq_data(entry->irq);
-- 
2.25.1

RE: [PATCH v2] PCI: hv: Fix a crash in hv_pci_restore_msi_msg() during hibernation

[Dexuan Cui]

> From: Dexuan Cui <decui@microsoft.com>
> Sent: Wednesday, August 16, 2023 11:00 AM
>  [...]
> When a Linux VM with an assigned PCI device runs on Hyper-V, if the PCI
> device driver is not loaded yet (i.e. MSI-X/MSI is not enabled on the
> device yet), doing a VM hibernation triggers a panic in
> hv_pci_restore_msi_msg() -> msi_lock_descs(&pdev->dev), because
> pdev->dev.msi.data is still NULL.
> 
> Avoid the panic by checking if MSI-X/MSI is enabled.
> 
> Fixes: dc2b453290c4 ("PCI: hv: Rework MSI handling")
> Signed-off-by: Dexuan Cui <decui@microsoft.com>

Sorry, I forgot to add 
Cc: stable@vger.kernel.org

Re: [PATCH v2] PCI: hv: Fix a crash in hv_pci_restore_msi_msg() during hibernation

[Kuppuswamy Sathyanarayanan]

On 8/16/2023 10:59 AM, Dexuan Cui wrote:
> When a Linux VM with an assigned PCI device runs on Hyper-V, if the PCI
> device driver is not loaded yet (i.e. MSI-X/MSI is not enabled on the
> device yet), doing a VM hibernation triggers a panic in
> hv_pci_restore_msi_msg() -> msi_lock_descs(&pdev->dev), because
> pdev->dev.msi.data is still NULL.
>
> Avoid the panic by checking if MSI-X/MSI is enabled.
>
> Fixes: dc2b453290c4 ("PCI: hv: Rework MSI handling")
> Signed-off-by: Dexuan Cui <decui@microsoft.com>
> ---
>
> Changes in v2:
>      Replaced the test "if (!pdev->dev.msi.data)" with
> 		      "if (!pdev->msi_enabled && !pdev->msix_enabled)".
>        Thanks Michael!
>      Updated the changelog accordingly.
>
>   drivers/pci/controller/pci-hyperv.c | 3 +++
>   1 file changed, 3 insertions(+)
>
> diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
> index 2d93d0c4f10d..bed3cefdaf19 100644
> --- a/drivers/pci/controller/pci-hyperv.c
> +++ b/drivers/pci/controller/pci-hyperv.c
> @@ -3983,6 +3983,9 @@ static int hv_pci_restore_msi_msg(struct pci_dev *pdev, void *arg)
>   	struct msi_desc *entry;
>   	int ret = 0;
>   
> +	if (!pdev->msi_enabled && !pdev->msix_enabled)
> +		return 0;
Isn't this is a error condition? Don't you want to return error here?
> +
>   	msi_lock_descs(&pdev->dev);
>   	msi_for_each_desc(entry, &pdev->dev, MSI_DESC_ASSOCIATED) {
>   		irq_data = irq_get_irq_data(entry->irq);

RE: [PATCH v2] PCI: hv: Fix a crash in hv_pci_restore_msi_msg() during hibernation

[Dexuan Cui]

> From: Kuppuswamy Sathyanarayanan
> <sathyanarayanan.kuppuswamy@linux.intel.com>
> Sent: Wednesday, August 16, 2023 11:12 AM
> [...]
> On 8/16/2023 10:59 AM, Dexuan Cui wrote:
> > When a Linux VM with an assigned PCI device runs on Hyper-V, if the PCI
> > device driver is not loaded yet (i.e. MSI-X/MSI is not enabled on the
> > device yet), doing a VM hibernation triggers a panic in
> > hv_pci_restore_msi_msg() -> msi_lock_descs(&pdev->dev), because
> > pdev->dev.msi.data is still NULL.
> >
> > Avoid the panic by checking if MSI-X/MSI is enabled.
> >
> > Fixes: dc2b453290c4 ("PCI: hv: Rework MSI handling")
> > Signed-off-by: Dexuan Cui <decui@microsoft.com>
> > ---
> >
> > Changes in v2:
> >      Replaced the test "if (!pdev->dev.msi.data)" with
> > 		      "if (!pdev->msi_enabled && !pdev->msix_enabled)".
> >        Thanks Michael!
> >      Updated the changelog accordingly.
> >
> >   drivers/pci/controller/pci-hyperv.c | 3 +++
> >   1 file changed, 3 insertions(+)
> >
> > diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-
> hyperv.c
> > index 2d93d0c4f10d..bed3cefdaf19 100644
> > --- a/drivers/pci/controller/pci-hyperv.c
> > +++ b/drivers/pci/controller/pci-hyperv.c
> > @@ -3983,6 +3983,9 @@ static int hv_pci_restore_msi_msg(struct pci_dev
> *pdev, void *arg)
> >   	struct msi_desc *entry;
> >   	int ret = 0;
> >
> > +	if (!pdev->msi_enabled && !pdev->msix_enabled)
> > +		return 0;
> Isn't this is a error condition? Don't you want to return error here?

This is not an error.  If a PCI device driver is not loaded or not installed, 
MSI-X/MSI is not enabled on the device, so pdev->msi_enabled is 0
and pdev->msix_enabled is 0. In this case, it's still legit for a user to request
the system (i.e. here it's a Linux VM running on Hyper-V) to hibernate -- in
this case, we should not try to save/restore the MSI/MSI-X state, and we
should not let the hibernation fail; here we should just ignore the device
by returning a success ("return 0;").

> > +
> >   	msi_lock_descs(&pdev->dev);
> >   	msi_for_each_desc(entry, &pdev->dev, MSI_DESC_ASSOCIATED) {
> >   		irq_data = irq_get_irq_data(entry->irq);

Re: [PATCH v2] PCI: hv: Fix a crash in hv_pci_restore_msi_msg() during hibernation

[Kuppuswamy Sathyanarayanan]

On 8/16/2023 12:30 PM, Dexuan Cui wrote:
>> From: Kuppuswamy Sathyanarayanan
>> <sathyanarayanan.kuppuswamy@linux.intel.com>
>> Sent: Wednesday, August 16, 2023 11:12 AM
>> [...]
>> On 8/16/2023 10:59 AM, Dexuan Cui wrote:
>>> When a Linux VM with an assigned PCI device runs on Hyper-V, if the PCI
>>> device driver is not loaded yet (i.e. MSI-X/MSI is not enabled on the
>>> device yet), doing a VM hibernation triggers a panic in
>>> hv_pci_restore_msi_msg() -> msi_lock_descs(&pdev->dev), because
>>> pdev->dev.msi.data is still NULL.
>>>
>>> Avoid the panic by checking if MSI-X/MSI is enabled.
>>>
>>> Fixes: dc2b453290c4 ("PCI: hv: Rework MSI handling")
>>> Signed-off-by: Dexuan Cui <decui@microsoft.com>
>>> ---
>>>
>>> Changes in v2:
>>>       Replaced the test "if (!pdev->dev.msi.data)" with
>>> 		      "if (!pdev->msi_enabled && !pdev->msix_enabled)".
>>>         Thanks Michael!
>>>       Updated the changelog accordingly.
>>>
>>>    drivers/pci/controller/pci-hyperv.c | 3 +++
>>>    1 file changed, 3 insertions(+)
>>>
>>> diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-
>> hyperv.c
>>> index 2d93d0c4f10d..bed3cefdaf19 100644
>>> --- a/drivers/pci/controller/pci-hyperv.c
>>> +++ b/drivers/pci/controller/pci-hyperv.c
>>> @@ -3983,6 +3983,9 @@ static int hv_pci_restore_msi_msg(struct pci_dev
>> *pdev, void *arg)
>>>    	struct msi_desc *entry;
>>>    	int ret = 0;
>>>
>>> +	if (!pdev->msi_enabled && !pdev->msix_enabled)
>>> +		return 0;
>> Isn't this is a error condition? Don't you want to return error here?
> This is not an error.  If a PCI device driver is not loaded or not installed,
> MSI-X/MSI is not enabled on the device, so pdev->msi_enabled is 0
> and pdev->msix_enabled is 0. In this case, it's still legit for a user to request
> the system (i.e. here it's a Linux VM running on Hyper-V) to hibernate -- in
> this case, we should not try to save/restore the MSI/MSI-X state, and we
> should not let the hibernation fail; here we should just ignore the device
> by returning a success ("return 0;").

Got it. Looks good to me.

Reviewed-by: sathyanarayanan.kuppuswamy@linux.intel.com

>
>>> +
>>>    	msi_lock_descs(&pdev->dev);
>>>    	msi_for_each_desc(entry, &pdev->dev, MSI_DESC_ASSOCIATED) {
>>>    		irq_data = irq_get_irq_data(entry->irq);

RE: [PATCH v2] PCI: hv: Fix a crash in hv_pci_restore_msi_msg() during hibernation

[Michael Kelley (LINUX)]

From: Dexuan Cui <decui@microsoft.com> Sent: Wednesday, August 16, 2023 11:00 AM
> 
> When a Linux VM with an assigned PCI device runs on Hyper-V, if the PCI
> device driver is not loaded yet (i.e. MSI-X/MSI is not enabled on the
> device yet), doing a VM hibernation triggers a panic in
> hv_pci_restore_msi_msg() -> msi_lock_descs(&pdev->dev), because
> pdev->dev.msi.data is still NULL.
> 
> Avoid the panic by checking if MSI-X/MSI is enabled.
> 
> Fixes: dc2b453290c4 ("PCI: hv: Rework MSI handling")
> Signed-off-by: Dexuan Cui <decui@microsoft.com>
> ---
> 
> Changes in v2:
>     Replaced the test "if (!pdev->dev.msi.data)" with
> 		      "if (!pdev->msi_enabled && !pdev->msix_enabled)".
>       Thanks Michael!
>     Updated the changelog accordingly.
> 
>  drivers/pci/controller/pci-hyperv.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
> index 2d93d0c4f10d..bed3cefdaf19 100644
> --- a/drivers/pci/controller/pci-hyperv.c
> +++ b/drivers/pci/controller/pci-hyperv.c
> @@ -3983,6 +3983,9 @@ static int hv_pci_restore_msi_msg(struct pci_dev *pdev, void *arg)
>  	struct msi_desc *entry;
>  	int ret = 0;
> 
> +	if (!pdev->msi_enabled && !pdev->msix_enabled)
> +		return 0;
> +
>  	msi_lock_descs(&pdev->dev);
>  	msi_for_each_desc(entry, &pdev->dev, MSI_DESC_ASSOCIATED) {
>  		irq_data = irq_get_irq_data(entry->irq);
> --
> 2.25.1

Reviewed-by: Michael Kelley <mikelley@microsoft.com>

Re: [PATCH v2] PCI: hv: Fix a crash in hv_pci_restore_msi_msg() during hibernation

[Wei Liu]

On Wed, Aug 16, 2023 at 08:10:25PM +0000, Michael Kelley (LINUX) wrote:
> From: Dexuan Cui <decui@microsoft.com> Sent: Wednesday, August 16, 2023 11:00 AM
> > 
> > When a Linux VM with an assigned PCI device runs on Hyper-V, if the PCI
> > device driver is not loaded yet (i.e. MSI-X/MSI is not enabled on the
> > device yet), doing a VM hibernation triggers a panic in
> > hv_pci_restore_msi_msg() -> msi_lock_descs(&pdev->dev), because
> > pdev->dev.msi.data is still NULL.
> > 
> > Avoid the panic by checking if MSI-X/MSI is enabled.
> > 
> > Fixes: dc2b453290c4 ("PCI: hv: Rework MSI handling")
> > Signed-off-by: Dexuan Cui <decui@microsoft.com>
> > ---
> > 
> > Changes in v2:
> >     Replaced the test "if (!pdev->dev.msi.data)" with
> > 		      "if (!pdev->msi_enabled && !pdev->msix_enabled)".
> >       Thanks Michael!
> >     Updated the changelog accordingly.
> > 
> >  drivers/pci/controller/pci-hyperv.c | 3 +++
> >  1 file changed, 3 insertions(+)
> > 
> > diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
> > index 2d93d0c4f10d..bed3cefdaf19 100644
> > --- a/drivers/pci/controller/pci-hyperv.c
> > +++ b/drivers/pci/controller/pci-hyperv.c
> > @@ -3983,6 +3983,9 @@ static int hv_pci_restore_msi_msg(struct pci_dev *pdev, void *arg)
> >  	struct msi_desc *entry;
> >  	int ret = 0;
> > 
> > +	if (!pdev->msi_enabled && !pdev->msix_enabled)
> > +		return 0;
> > +
> >  	msi_lock_descs(&pdev->dev);
> >  	msi_for_each_desc(entry, &pdev->dev, MSI_DESC_ASSOCIATED) {
> >  		irq_data = irq_get_irq_data(entry->irq);
> > --
> > 2.25.1
> 
> Reviewed-by: Michael Kelley <mikelley@microsoft.com>
> 
> 

I expect this to go through the PCI tree. Just let me know if I should
pick this up.

Thanks,
Wei.

Re: [PATCH v2] PCI: hv: Fix a crash in hv_pci_restore_msi_msg() during hibernation

[Lorenzo Pieralisi]

On Wed, 16 Aug 2023 10:59:39 -0700, Dexuan Cui wrote:
> When a Linux VM with an assigned PCI device runs on Hyper-V, if the PCI
> device driver is not loaded yet (i.e. MSI-X/MSI is not enabled on the
> device yet), doing a VM hibernation triggers a panic in
> hv_pci_restore_msi_msg() -> msi_lock_descs(&pdev->dev), because
> pdev->dev.msi.data is still NULL.
> 
> Avoid the panic by checking if MSI-X/MSI is enabled.
> 
> [...]

Applied to controller/hv, thanks!

[1/1] PCI: hv: Fix a crash in hv_pci_restore_msi_msg() during hibernation
      https://git.kernel.org/pci/pci/c/04bbe863241a

Thanks,
Lorenzo