Re: [PATCH v3 00/10] vfio/igd: Decoupling quirks with legacy mode

["Cédric Le Goater" <clg@redhat.com>]

On 3/6/25 19:01, Tomita Moeko wrote:
> This patchset intends to decouple existing quirks from legacy mode.
> Currently all quirks depends on legacy mode (except x-igd-opregion),
> which includes following conditions:
> * Machine type is i440fx
> * IGD device is at guest BDF 00:02.0
> * VBIOS in ROM BAR or file
> * VGA IO/MMIO ranges are claimed by IGD
> * OpRegion
> * Same LPC bridge and Host bridge VID/DID/SVID/SSID as host
> 
> If one of the condition is not met, the quirks will not be applied.
> However, for recent generations, espcially Gen 11+ devices that removed
> VBIOS support, not all the conditions are required. For example, on EFI-
> based systems, VBIOS ROM is unnecessary, and VGA ranges are not used.
> 
> To have better support on newer UEFI-based VMs, this patchset makes the
> quirks independent of legacy mode. The BDSM and GGC register quirks are
> applied to all supported IGD devices, new x-igd-lpc option for the LPC
> bridge / Host bridge ID quirk is introduced for possible Q35 support.
> It also prepares for supporting IGD passthrough when it is not primary
> display later (kernel change will be merged in 6.15).
> 
> To maintain backward compatbility with exising configuration, legacy
> mode will automatically be enabled when:
> * Machine type is i440fx
> * IGD device is at guest BDF 00:02.0
> If the legacy mode behavior is unwanted, option x-igd-legacy-mode=off
> is provided for users to disable it. Setting x-igd-legacy-mode=on checks
> if the condition above are met, and set up all the required quirks.
> 
> The default value is x-igd-legacy-mode=auto. When the above conditions
> are all met, it acts as before and continues on any error. Otherwise it
> is equivalent to x-igd-legacy-mode=off.
> 
> When x-igd-legacy-mode is set to on or off, QEMU will fail immediately
> on error.
> 
> The first 2 patches of this patchset was taken from a previous one,
> details can be found at:
> https://lore.kernel.org/all/20250124191245.12464-1-tomitamoeko@gmail.com/
> 
> This patchest was mainly tested on Alder Lake UHD770, with Debian 12
> (kernel 6.1), Windows 11 (driver 32.0.101.6458) and Intel GOP driver
> 17.0.1081.
> 
> Due to I caught COVID these days, I am unable to deliver the proposed
> documentation update before QEMU 10.0 soft-freeze next week. Please help
> decide whether to make this patch series in 10.0 or next release.
> 
> Changelog:
> v3:
> * Use OnOffAuto for x-igd-legacy-mode option, default is auto, to keep
>    current behavior.
> * Added a new patch to solve the possible KVMGT/GVT-g fail.
> Link: https://lore.kernel.org/all/20250303175220.74917-1-tomitamoeko@gmail.com/
> 
> v2:
> * Keep legacy mode for compatbility
> * Renamed from "vfio/igd: Remove legacy mode"
> Link: https://lore.kernel.org/all/20250224182927.31519-1-tomitamoeko@gmail.com/
> 
> Tomita Moeko (10):
>    vfio/igd: Remove GTT write quirk in IO BAR 4
>    vfio/igd: Do not include GTT stolen size in etc/igd-bdsm-size
>    vfio/igd: Consolidate OpRegion initialization into a single function
>    vfio/igd: Move LPC bridge initialization to a separate function
>    vfio/pci: Add placeholder for device-specific config space quirks
>    vfio/igd: Refactor vfio_probe_igd_bar4_quirk into pci config quirk
>    vfio/igd: Decouple common quirks from legacy mode
>    vfio/igd: Handle x-igd-opregion option in config quirk
>    vfio/igd: Introduce x-igd-lpc option for LPC bridge ID quirk
>    vfio/igd: Fix broken KVMGT OpRegion support
> 
>   hw/vfio/igd.c        | 529 +++++++++++++++++++------------------------
>   hw/vfio/pci-quirks.c |  51 +----
>   hw/vfio/pci.c        |  33 +--
>   hw/vfio/pci.h        |  11 +-
>   4 files changed, 248 insertions(+), 376 deletions(-)
> 


Applied to vfio-next.

Thanks,

C.