Re: [PATCH v4 00/10] vfio/igd: Enable legacy mode on more devices

[Alex Williamson <alex.williamson@redhat.com>]

On Fri,  6 Dec 2024 20:27:38 +0800
Tomita Moeko <tomitamoeko@gmail.com> wrote:

> This patchset extends the support of legacy mode igd passthrough to
> all Intel Gen 11 and 12 devices (including Ice Lake, Jasper Lake,
> Rocket Lake, Alder Lake and Raptor Lake), and emulates GGC register
> in MMIO BAR0 for better compatibiltiy (It is tested Windows and GOP
> driver will read this MMIO register).
> 
> It also replaces magic numbers with macros to improve readability,
> and aligns behavior (BDSM registor mirroring and GGMS calculation for
> gen7) with i915 driver to avoid possible issues.
> 
> The x-igd-gms option removed in 971ca22f041b ("vfio/igd: don't set
> stolen memory size to zero") is also added back so that data stolen
> memory size can be specified for guest. It is tested that GMS may
> related to framebuffer size, a small GMS value may cause display issues
> like blackscreen. It can be changed by DVMT Pre-allocated option in
> host BIOS, but not all BIOS comes with this option. Having it in QEMU
> helps resolves such issues.
> 
> This patchset was verified on Intel i9-12900K CPU(UHD 770, 8086:4680)
> with custom OVMF firmware [1] and IntelGopDriver extracted from host
> bios. IGD device works well in both Windows and Linux guests, and
> scored 726 in 3DMark Time Spy Graphics on Windows guest.
> 
> [1] https://github.com/tomitamoeko/edk2/commits/igd-pt-adl/
> 
> Btw, IO BAR4 seems never be used by guest, and it the IO BAR itself
> is not working on Gen11+ devices in my experiments. There is no hints
> about that in old commit message and mailing list. It would be greatly
> appreciated if someone shares the background.
> 
> Changelog:
> v4:
> * Move "vfio/igd: fix GTT stolen memory size calculation for gen 8+" to
>   the first.
> Link: https://lore.kernel.org/qemu-devel/20241205105535.30498-1-tomitamoeko@gmail.com/

Series:

Reviewed-by: Alex Williamson <alex.williamson@redhat.com>