[v1] vfio/igd: Detect IGD by OpRegion and enable OpRegion automatically

[PATCH 5/9] vfio/igd: Check OpRegion support on GVT-g mdev

Posted by Tomita Moeko 9 months, 2 weeks ago

The Intel GVT-g backend `kvmgt` always emulates OpRegion for vGPU,
make sure the OpRegion is present for enabling access to it
automatically later.

Also, hotplugging GVT-g vGPU is now always disallowed regardless of
OpRegion to prevent potential issues. Intel has never claimed support
for GVT-g hotplugging.

Signed-off-by: Tomita Moeko <tomitamoeko@gmail.com>
---
 hw/vfio/igd.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/hw/vfio/igd.c b/hw/vfio/igd.c
index c6ecbefb35..496d3df598 100644
--- a/hw/vfio/igd.c
+++ b/hw/vfio/igd.c
@@ -684,9 +684,13 @@ static bool vfio_pci_kvmgt_config_quirk(VFIOPCIDevice *vdev, Error **errp)
         return true;
     }
 
+    if (!vfio_pci_igd_opregion_detect(vdev, &opregion, errp)) {
+        /* Should never reach here, KVMGT always emulates OpRegion */
+        return false;
+    }
+
     if ((vdev->features & VFIO_FEATURE_ENABLE_IGD_OPREGION) &&
-        (!vfio_pci_igd_opregion_detect(vdev, &opregion, errp) ||
-         !vfio_pci_igd_opregion_init(vdev, opregion, errp))) {
+        !vfio_pci_igd_opregion_init(vdev, opregion, errp)) {
         return false;
     }
 
-- 
2.47.2

Re: [PATCH 5/9] vfio/igd: Check OpRegion support on GVT-g mdev

Posted by Corvin Köhne 9 months, 1 week ago

On Tue, 2025-04-29 at 00:10 +0800, Tomita Moeko wrote:
> CAUTION: External Email!!
> The Intel GVT-g backend `kvmgt` always emulates OpRegion for vGPU,
> make sure the OpRegion is present for enabling access to it
> automatically later.
> 
> Also, hotplugging GVT-g vGPU is now always disallowed regardless of
> OpRegion to prevent potential issues. Intel has never claimed support
> for GVT-g hotplugging.
> 
> Signed-off-by: Tomita Moeko <tomitamoeko@gmail.com>
> ---
>  hw/vfio/igd.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/vfio/igd.c b/hw/vfio/igd.c
> index c6ecbefb35..496d3df598 100644
> --- a/hw/vfio/igd.c
> +++ b/hw/vfio/igd.c
> @@ -684,9 +684,13 @@ static bool vfio_pci_kvmgt_config_quirk(VFIOPCIDevice
> *vdev, Error **errp)
>          return true;
>      }
>  
> +    if (!vfio_pci_igd_opregion_detect(vdev, &opregion, errp)) {
> +        /* Should never reach here, KVMGT always emulates OpRegion */
> +        return false;
> +    }
> +
>      if ((vdev->features & VFIO_FEATURE_ENABLE_IGD_OPREGION) &&
> -        (!vfio_pci_igd_opregion_detect(vdev, &opregion, errp) ||
> -         !vfio_pci_igd_opregion_init(vdev, opregion, errp))) {
> +        !vfio_pci_igd_opregion_init(vdev, opregion, errp)) {
>          return false;
>      }
>  

Reviewed-by: Corvin Köhne <c.koehne@beckhoff.com>


-- 
Kind regards,
Corvin