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vfio/igd: Always emulate ASLS (OpRegion) register

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ASLS register represents the base address of OpRegion, and it is
programmed with HPA. In IGD passthrough scenario, it needs to be
reprogrammed with GPA by guest firmware. To prevent guest accessing
wrong memory range, ASLS should always be emulated and cleared.

In GVT-g scenario, emulating ASLS is unnecessary as access is handled
by kvmgt backend [1].

[1]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/gpu/drm/i915/gvt/cfg_space.c?h=v6.14#n295

Signed-off-by: Tomita Moeko <tomitamoeko@gmail.com>
Reviewed-by: Corvin Köhne <c.koehne@beckhoff.com>
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
Tested-by: Alex Williamson <alex.williamson@redhat.com>
Link: https://lore.kernel.org/qemu-devel/20250505170305.23622-3-tomitamoeko@gmail.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>
This commit is contained in:
Tomita Moeko 2025-05-06 01:02:58 +08:00 • committed by Cédric Le Goater
parent dd69d84604
commit 1d5f84f349
1 changed files with 9 additions and 5 deletions
Download patch file Download diff file Expand all files Collapse all files

14
hw/vfio/igd.c
View file

@ -182,10 +182,6 @@ static bool vfio_pci_igd_opregion_init(VFIOPCIDevice *vdev,
trace_vfio_pci_igd_opregion_enabled(vdev->vbasedev.name);
pci_set_long(vdev->pdev.config + IGD_ASLS, 0);
pci_set_long(vdev->pdev.wmask + IGD_ASLS, ~0);
pci_set_long(vdev->emulated_config_bits + IGD_ASLS, ~0);
return true;
}
@ -584,7 +580,15 @@ static bool vfio_pci_igd_config_quirk(VFIOPCIDevice *vdev, Error **errp)
if ((vdev->features & VFIO_FEATURE_ENABLE_IGD_LPC) &&
!vfio_pci_igd_setup_lpc_bridge(vdev, errp)) {
goto error;
}
}
/*
* ASLS (OpRegion address) is read-only, emulated
* It contains HPA, guest firmware need to reprogram it with GPA.
*/
pci_set_long(vdev->pdev.config + IGD_ASLS, 0);
pci_set_long(vdev->pdev.wmask + IGD_ASLS, ~0);
pci_set_long(vdev->emulated_config_bits + IGD_ASLS, ~0);
/*
* Allow user to override dsm size using x-igd-gms option, in multiples of