[PULL 08/17] vfio/igd: emulate GGC register in mmio bar0

[Cédric Le Goater]

From: Tomita Moeko <tomitamoeko@gmail.com>

The GGC register at 0x50 of pci config space is a mirror of the same
register at 0x108040 of mmio bar0 [1]. i915 driver also reads that
register from mmio bar0 instead of config space. As GGC is programmed
and emulated by qemu, the mmio address should also be emulated, in the
same way of BDSM register.

[1] 4.1.28, 12th Generation Intel Core Processors Datasheet Volume 2
    https://www.intel.com/content/www/us/en/content-details/655259

Signed-off-by: Tomita Moeko <tomitamoeko@gmail.com>
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
Link: 20241206122749.9893-9-tomitamoeko@gmail.com">https://lore.kernel.org/r/20241206122749.9893-9-tomitamoeko@gmail.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>
---
 hw/vfio/igd.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/hw/vfio/igd.c b/hw/vfio/igd.c
index 
18d159aa8ecde3bb384dd6d3bd90e2110434335b..12e0553e830aab31980586ebf572070186ac38ad
 100644
--- a/hw/vfio/igd.c
+++ b/hw/vfio/igd.c
@@ -488,8 +488,10 @@ static const MemoryRegionOps vfio_igd_quirk_mirror_##name 
= {           \
     .endianness = DEVICE_LITTLE_ENDIAN,                                 \
 };
 
+VFIO_IGD_QUIRK_MIRROR_REG(IGD_GMCH, ggc)
 VFIO_IGD_QUIRK_MIRROR_REG(IGD_BDSM_GEN11, bdsm)
 
+#define IGD_GGC_MMIO_OFFSET     0x108040
 #define IGD_BDSM_MMIO_OFFSET    0x1080C0
 
 void vfio_probe_igd_bar0_quirk(VFIOPCIDevice *vdev, int nr)
@@ -518,14 +520,21 @@ void vfio_probe_igd_bar0_quirk(VFIOPCIDevice *vdev, int 
nr)
         return;
     }
 
-    quirk = vfio_quirk_alloc(1);
+    quirk = vfio_quirk_alloc(2);
     quirk->data = vdev;
 
     memory_region_init_io(&quirk->mem[0], OBJECT(vdev),
+                          &vfio_igd_quirk_mirror_ggc, vdev,
+                          "vfio-igd-ggc-quirk", 2);
+    memory_region_add_subregion_overlap(vdev->bars[0].region.mem,
+                                        IGD_GGC_MMIO_OFFSET, &quirk->mem[0],
+                                        1);
+
+    memory_region_init_io(&quirk->mem[1], OBJECT(vdev),
                           &vfio_igd_quirk_mirror_bdsm, vdev,
                           "vfio-igd-bdsm-quirk", 8);
     memory_region_add_subregion_overlap(vdev->bars[0].region.mem,
-                                        IGD_BDSM_MMIO_OFFSET, &quirk->mem[0],
+                                        IGD_BDSM_MMIO_OFFSET, &quirk->mem[1],
                                         1);
 
     QLIST_INSERT_HEAD(&vdev->bars[nr].quirks, quirk, next);
-- 
2.47.1