On Mon, 2 Dec 2024 00:09:31 +0800 Tomita Moeko <tomitamo...@gmail.com> wrote:
> Both intel documentation [1][2] and i915 driver shows GGMS represents > GTT stolen memory size in multiple of 1MB, not 2MB starting from gen 8. > > [1] > https://www.intel.com/content/dam/www/public/us/en/documents/datasheets/3rd-gen-core-desktop-vol-2-datasheet.pdf > [2] > https://www.intel.com/content/dam/www/public/us/en/documents/datasheets/4th-gen-core-family-desktop-vol-2-datasheet.pdf > > Signed-off-by: Tomita Moeko <tomitamo...@gmail.com> > --- > hw/vfio/igd.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/hw/vfio/igd.c b/hw/vfio/igd.c > index 4047f4f071..e40e601026 100644 > --- a/hw/vfio/igd.c > +++ b/hw/vfio/igd.c > @@ -268,7 +268,7 @@ static int vfio_igd_gtt_max(VFIOPCIDevice *vdev) > > gmch = vfio_pci_read_config(&vdev->pdev, IGD_GMCH, sizeof(gmch)); > ggms = (gmch >> (gen < 8 ? 8 : 6)) & 0x3; > - if (gen > 6) { > + if (gen > 7) { > ggms = 1 << ggms; > } > > @@ -678,7 +678,7 @@ void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int > nr) > > /* Determine the size of stolen memory needed for GTT */ > ggms_mb = (gmch >> (gen < 8 ? 8 : 6)) & 0x3; > - if (gen > 6) { > + if (gen > 7) { > ggms_mb = 1 << ggms_mb; > } > I'd argue this should be rolled into patch 4. It's not really fixing anything because igd_gen() can't return anything between 6 and 8. This only allows for several device versions that we currently consider to be gen 6 to align with i915 kernel driver generation by calling them generation 7. We'd previously lumped them into generation 6 because there's no functional difference we care about here between 6 & 7. In the next patch you replace this '1 << ggms_mb' with '*= 2', which would be equivalent to 'ggms_mb << 1' and matches your description that the increment is doubled. Is there a separate bug fix that needs to be pulled out here? Also, please send a cover letter for any series longer than a single patch and please configure your tools to thread the series. Thanks, Alex
