Re: [PATCH] PCI: vmd: Assign vmd irq domain before enumeration

Re: [PATCH] PCI: vmd: Assign vmd irq domain before enumeration

[Patel, Nirmal]

On 2/23/2022 12:52 AM, Nirmal Patel wrote:
> vmd creates and assigns separate irq domain only when MSI remapping is
> enabled. For example VMD-MSI. But vmd doesn't assign irq domain when
> MSI remapping is disabled resulting child devices getting default
> PCI-MSI irq domain. Now when Interrupt remapping is enabled all the
> pci devices are assigned INTEL-IR-MSI domain including vmd endpoints.
> But devices behind vmd gets PCI-MSI irq domain when vmd creates root
> bus and configures child devices.
>
> As a result DMAR errors were observed when interrupt remapping was
> enabled on Intel Icelake CPUs.
> For instance:
> DMAR: DRHD: handling fault status reg 2
> DMAR: [INTR-REMAP] Request device [0xe2:0x00.0] fault index 0xa00
> [fault reason 0x25] Blocked a compatibility format interrupt request
>
> So make sure vmd assigns proper irq domain. This patch also removes
> a placeholder patch 2565e5b69c44 (PCI: vmd: Do not disable MSI-X
> remapping if interrupt remapping is enabled by IOMMU.) MSI remapping
> should be enabled or disabled with and without Interrupt remap.
>
> Signed-off-by: Nirmal Patel <nirmal.patel@linux.intel.com>
> ---
>  drivers/pci/controller/vmd.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
> index cc166c683638..c8d73d75a1c0 100644
> --- a/drivers/pci/controller/vmd.c
> +++ b/drivers/pci/controller/vmd.c
> @@ -813,8 +813,7 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
>  	 * acceptable because the guest is usually CPU-limited and MSI
>  	 * remapping doesn't become a performance bottleneck.
>  	 */
> -	if (iommu_capable(vmd->dev->dev.bus, IOMMU_CAP_INTR_REMAP) ||
> -	    !(features & VMD_FEAT_CAN_BYPASS_MSI_REMAP) ||
> +	if (!(features & VMD_FEAT_CAN_BYPASS_MSI_REMAP) ||
>  	    offset[0] || offset[1]) {
>  		ret = vmd_alloc_irqs(vmd);
>  		if (ret)
> @@ -853,7 +852,9 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
>  	vmd_attach_resources(vmd);
>  	if (vmd->irq_domain)
>  		dev_set_msi_domain(&vmd->bus->dev, vmd->irq_domain);
> -
> +	else
> +		dev_set_msi_domain(&vmd->bus->dev, vmd->dev->dev.msi.domain);
> +	
>  	vmd_acpi_begin();
>  
>  	pci_scan_child_bus(vmd->bus);

Gentle ping!

Thanks

nirmal

Re: [PATCH] PCI: vmd: Assign vmd irq domain before enumeration

[Jonathan Derrick]

Hey Nirmal,

Sorry I didn't catch this earlier.

On 3/2/2022 10:41 AM, Patel, Nirmal wrote:
> On 2/23/2022 12:52 AM, Nirmal Patel wrote:
>> vmd creates and assigns separate irq domain only when MSI remapping is
>> enabled. For example VMD-MSI. But vmd doesn't assign irq domain when
>> MSI remapping is disabled resulting child devices getting default
>> PCI-MSI irq domain. Now when Interrupt remapping is enabled all the
>> pci devices are assigned INTEL-IR-MSI domain including vmd endpoints.
>> But devices behind vmd gets PCI-MSI irq domain when vmd creates root
>> bus and configures child devices.
can you capitalize VMD for consistency?

>>
>> As a result DMAR errors were observed when interrupt remapping was
>> enabled on Intel Icelake CPUs.
>> For instance:
>> DMAR: DRHD: handling fault status reg 2
>> DMAR: [INTR-REMAP] Request device [0xe2:0x00.0] fault index 0xa00
>> [fault reason 0x25] Blocked a compatibility format interrupt request
>>
>> So make sure vmd assigns proper irq domain. This patch also removes
>> a placeholder patch 2565e5b69c44 (PCI: vmd: Do not disable MSI-X
>> remapping if interrupt remapping is enabled by IOMMU.) MSI remapping
>> should be enabled or disabled with and without Interrupt remap.
>>
So this keeps the performance path working with remapping?
Great!


>> Signed-off-by: Nirmal Patel <nirmal.patel@linux.intel.com>
>> ---
>>   drivers/pci/controller/vmd.c | 7 ++++---
>>   1 file changed, 4 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
>> index cc166c683638..c8d73d75a1c0 100644
>> --- a/drivers/pci/controller/vmd.c
>> +++ b/drivers/pci/controller/vmd.c
>> @@ -813,8 +813,7 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
>>   	 * acceptable because the guest is usually CPU-limited and MSI
>>   	 * remapping doesn't become a performance bottleneck.
>>   	 */
>> -	if (iommu_capable(vmd->dev->dev.bus, IOMMU_CAP_INTR_REMAP) ||
>> -	    !(features & VMD_FEAT_CAN_BYPASS_MSI_REMAP) ||
>> +	if (!(features & VMD_FEAT_CAN_BYPASS_MSI_REMAP) ||
>>   	    offset[0] || offset[1]) {
>>   		ret = vmd_alloc_irqs(vmd);
>>   		if (ret)
>> @@ -853,7 +852,9 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
>>   	vmd_attach_resources(vmd);
>>   	if (vmd->irq_domain)
>>   		dev_set_msi_domain(&vmd->bus->dev, vmd->irq_domain);
>> -
>> +	else
>> +		dev_set_msi_domain(&vmd->bus->dev, vmd->dev->dev.msi.domain);
how about dev_get_msi_domain(vmd->dev) ?

>> +	
>>   	vmd_acpi_begin();
>>   
>>   	pci_scan_child_bus(vmd->bus);
> 
> Gentle ping!
> 
> Thanks
> 
> nirmal
> 

Re: [PATCH] PCI: vmd: Assign vmd irq domain before enumeration

[Bjorn Helgaas]

On Wed, Mar 02, 2022 at 12:35:20PM -0700, Jonathan Derrick wrote:
> Hey Nirmal,
> 
> Sorry I didn't catch this earlier.
> 
> On 3/2/2022 10:41 AM, Patel, Nirmal wrote:
> > On 2/23/2022 12:52 AM, Nirmal Patel wrote:
> > > vmd creates and assigns separate irq domain only when MSI remapping is
> > > enabled. For example VMD-MSI. But vmd doesn't assign irq domain when
> > > MSI remapping is disabled resulting child devices getting default
> > > PCI-MSI irq domain. Now when Interrupt remapping is enabled all the
> > > pci devices are assigned INTEL-IR-MSI domain including vmd endpoints.
> > > But devices behind vmd gets PCI-MSI irq domain when vmd creates root
> > > bus and configures child devices.
> can you capitalize VMD for consistency?

And IRQ, while you're at it.  Both occur several times above (and
below).  And PCI.

Also, s/Interrupt remapping/interrupt remapping/ above, since
there's no reason to capitalize "Interrupt" there.

s/behind vmd gets/behind VMD get/

> > > As a result DMAR errors were observed when interrupt remapping was
> > > enabled on Intel Icelake CPUs.
> > > For instance:
> > > DMAR: DRHD: handling fault status reg 2
> > > DMAR: [INTR-REMAP] Request device [0xe2:0x00.0] fault index 0xa00
> > > [fault reason 0x25] Blocked a compatibility format interrupt request

Quote material as in 2565e5b69c44, e.g.,

  As a result DMAR errors were observed ...  For instance:

    DMAR: DRHD: handling fault status reg 2
    DMAR: [INTR-REMAP] Request device [0xe2:0x00.0] fault index 0xa00 [fault reason 0x25] Blocked a compatibility format interrupt request

(Blank line before and after quoted material, indent quote two spaces,
don't break messages over lines, so they're easy to grep for.)

> > > So make sure vmd assigns proper irq domain. This patch also removes
> > > a placeholder patch 2565e5b69c44 (PCI: vmd: Do not disable MSI-X
> > > remapping if interrupt remapping is enabled by IOMMU.)

Usual commit citation style is

  2565e5b69c44 ("PCI: vmd: Do not disable MSI-X remapping if interrupt
  remapping is enabled by IOMMU")

Why is this revert part of this patch?  Could it be a separate patch?
Either way, we should explain why we can now revert it.

> > > MSI remapping
> > > should be enabled or disabled with and without Interrupt remap.
> > > 
> So this keeps the performance path working with remapping?
> Great!
> 
> 
> > > Signed-off-by: Nirmal Patel <nirmal.patel@linux.intel.com>
> > > ---
> > >   drivers/pci/controller/vmd.c | 7 ++++---
> > >   1 file changed, 4 insertions(+), 3 deletions(-)
> > > 
> > > diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
> > > index cc166c683638..c8d73d75a1c0 100644
> > > --- a/drivers/pci/controller/vmd.c
> > > +++ b/drivers/pci/controller/vmd.c
> > > @@ -813,8 +813,7 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
> > >   	 * acceptable because the guest is usually CPU-limited and MSI
> > >   	 * remapping doesn't become a performance bottleneck.
> > >   	 */
> > > -	if (iommu_capable(vmd->dev->dev.bus, IOMMU_CAP_INTR_REMAP) ||
> > > -	    !(features & VMD_FEAT_CAN_BYPASS_MSI_REMAP) ||
> > > +	if (!(features & VMD_FEAT_CAN_BYPASS_MSI_REMAP) ||
> > >   	    offset[0] || offset[1]) {
> > >   		ret = vmd_alloc_irqs(vmd);
> > >   		if (ret)
> > > @@ -853,7 +852,9 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
> > >   	vmd_attach_resources(vmd);
> > >   	if (vmd->irq_domain)
> > >   		dev_set_msi_domain(&vmd->bus->dev, vmd->irq_domain);
> > > -
> > > +	else
> > > +		dev_set_msi_domain(&vmd->bus->dev, vmd->dev->dev.msi.domain);
> how about dev_get_msi_domain(vmd->dev) ?
> 
> > > +	
> > >   	vmd_acpi_begin();
> > >   	pci_scan_child_bus(vmd->bus);
> > 
> > Gentle ping!
> > 
> > Thanks
> > 
> > nirmal
> > 

Re: [PATCH] PCI: vmd: Assign vmd irq domain before enumeration

[Patel, Nirmal]

On 3/2/2022 1:55 PM, Bjorn Helgaas wrote:
> On Wed, Mar 02, 2022 at 12:35:20PM -0700, Jonathan Derrick wrote:
>> Hey Nirmal,
>>
>> Sorry I didn't catch this earlier.
>>
>> On 3/2/2022 10:41 AM, Patel, Nirmal wrote:
>>> On 2/23/2022 12:52 AM, Nirmal Patel wrote:
>>>> vmd creates and assigns separate irq domain only when MSI remapping is
>>>> enabled. For example VMD-MSI. But vmd doesn't assign irq domain when
>>>> MSI remapping is disabled resulting child devices getting default
>>>> PCI-MSI irq domain. Now when Interrupt remapping is enabled all the
>>>> pci devices are assigned INTEL-IR-MSI domain including vmd endpoints.
>>>> But devices behind vmd gets PCI-MSI irq domain when vmd creates root
>>>> bus and configures child devices.
>> can you capitalize VMD for consistency?
> And IRQ, while you're at it.  Both occur several times above (and
> below).  And PCI.
>
> Also, s/Interrupt remapping/interrupt remapping/ above, since
> there's no reason to capitalize "Interrupt" there.
>
> s/behind vmd gets/behind VMD get/
Understood.
>
>>>> As a result DMAR errors were observed when interrupt remapping was
>>>> enabled on Intel Icelake CPUs.
>>>> For instance:
>>>> DMAR: DRHD: handling fault status reg 2
>>>> DMAR: [INTR-REMAP] Request device [0xe2:0x00.0] fault index 0xa00
>>>> [fault reason 0x25] Blocked a compatibility format interrupt request
> Quote material as in 2565e5b69c44, e.g.,
>
>   As a result DMAR errors were observed ...  For instance:
>
>     DMAR: DRHD: handling fault status reg 2
>     DMAR: [INTR-REMAP] Request device [0xe2:0x00.0] fault index 0xa00 [fault reason 0x25] Blocked a compatibility format interrupt request
>
> (Blank line before and after quoted material, indent quote two spaces,
> don't break messages over lines, so they're easy to grep for.)
>
>>>> So make sure vmd assigns proper irq domain. This patch also removes
>>>> a placeholder patch 2565e5b69c44 (PCI: vmd: Do not disable MSI-X
>>>> remapping if interrupt remapping is enabled by IOMMU.)
> Usual commit citation style is
>
>   2565e5b69c44 ("PCI: vmd: Do not disable MSI-X remapping if interrupt
>   remapping is enabled by IOMMU")
>
> Why is this revert part of this patch?  Could it be a separate patch?
> Either way, we should explain why we can now revert it.
I will add some more details.
>
>>>> MSI remapping
>>>> should be enabled or disabled with and without Interrupt remap.
>>>>
>> So this keeps the performance path working with remapping?
>> Great!
>>
>>
>>>> Signed-off-by: Nirmal Patel <nirmal.patel@linux.intel.com>
>>>> ---
>>>>   drivers/pci/controller/vmd.c | 7 ++++---
>>>>   1 file changed, 4 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
>>>> index cc166c683638..c8d73d75a1c0 100644
>>>> --- a/drivers/pci/controller/vmd.c
>>>> +++ b/drivers/pci/controller/vmd.c
>>>> @@ -813,8 +813,7 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
>>>>   	 * acceptable because the guest is usually CPU-limited and MSI
>>>>   	 * remapping doesn't become a performance bottleneck.
>>>>   	 */
>>>> -	if (iommu_capable(vmd->dev->dev.bus, IOMMU_CAP_INTR_REMAP) ||
>>>> -	    !(features & VMD_FEAT_CAN_BYPASS_MSI_REMAP) ||
>>>> +	if (!(features & VMD_FEAT_CAN_BYPASS_MSI_REMAP) ||
>>>>   	    offset[0] || offset[1]) {
>>>>   		ret = vmd_alloc_irqs(vmd);
>>>>   		if (ret)
>>>> @@ -853,7 +852,9 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
>>>>   	vmd_attach_resources(vmd);
>>>>   	if (vmd->irq_domain)
>>>>   		dev_set_msi_domain(&vmd->bus->dev, vmd->irq_domain);
>>>> -
>>>> +	else
>>>> +		dev_set_msi_domain(&vmd->bus->dev, vmd->dev->dev.msi.domain);
>> how about dev_get_msi_domain(vmd->dev) ?
Good idea.
>>
>>>> +	
>>>>   	vmd_acpi_begin();
>>>>   	pci_scan_child_bus(vmd->bus);
>>> Gentle ping!
>>>
>>> Thanks
>>>
>>> nirmal
>>>