Re: [PATCH v2 1/2] PCI: vmd: Assign VMD IRQ domain before enumeration

["Patel, Nirmal" <nirmal.patel@linux.intel.com>]

On 3/29/2022 4:27 PM, Dan Williams wrote:
> On Tue, Mar 29, 2022 at 3:48 PM Patel, Nirmal
> <nirmal.patel@linux.intel.com> wrote:
>> On 3/16/2022 8:51 AM, Nirmal Patel wrote:
>>> From: Nirmal Patel <nirmal.patel@linux.intel.com>
>>>
>>> VMD creates and assigns a 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 by
>>> intel-iommu all the PCI devices are assigned INTEL-IR-MSI domain
>>> including VMD endpoints. But devices behind VMD get PCI-MSI IRQ domain
>>> when VMD create a 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
>>>
>>> Acked-by: Dan Williams <dan.j.williams@intel.com>
>>> Signed-off-by: Nirmal Patel <nirmal.patel@linux.intel.com>
>>> ---
>>>  drivers/pci/controller/vmd.c | 2 ++
>>>  1 file changed, 2 insertions(+)
>>>
>>> diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
>>> index cc166c683638..3a6570e5b765 100644
>>> --- a/drivers/pci/controller/vmd.c
>>> +++ b/drivers/pci/controller/vmd.c
>>> @@ -853,6 +853,8 @@ 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, dev_get_msi_domain(&vmd->dev->dev));
>>>
>>>       vmd_acpi_begin();
>>>
>> Gentle ping!
> It helps to be explicit when you send a patch and a follow-up ping.
> Are you asking Lorenzo to take this? Is this urgent such that Bjorn
> should consider taking it directly? The changelog notes what happens,
> but not the severity of end user visible impact. The merge window is
> presently open so the natural inclination is to just wait until that
> closes to circle back to outstanding patches.

This patch removes a flag that bypasses MSI disable feature of VMD and
improves the performance. So it would be nice if the patch gets accepted
sooner. I tend to send follow-up ping after a week or so if I do not get any
feedback and to allow it to get accepted in time.

Thanks.