diff mbox series

[7/7] vfio/igd: correctly calculate stolen memory size for gen 9 and later

Message ID 20240822135420.58849-7-c.koehne@beckhoff.com (mailing list archive)
State New, archived
Headers show
Series vfio/igd: add passthrough support for IGDs of gen 11 and later | expand

Commit Message

Corvin Köhne Aug. 22, 2024, 1:54 p.m. UTC
We have to update the calculation of the stolen memory size because
we've seen devices using values of 0xf0 and above for the graphics mode
select field. The new calculation was taken from the linux kernel [1].

[1] https://github.com/torvalds/linux/blob/7c626ce4bae1ac14f60076d00eafe71af30450ba/arch/x86/kernel/early-quirks.c#L455-L460

Signed-off-by: Corvin Köhne <c.koehne@beckhoff.com>
---
 hw/vfio/igd.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)
diff mbox series

Patch

diff --git a/hw/vfio/igd.c b/hw/vfio/igd.c
index 122432e6a6..70c60fe7bc 100644
--- a/hw/vfio/igd.c
+++ b/hw/vfio/igd.c
@@ -487,11 +487,18 @@  static int igd_get_stolen_mb(int gen, uint32_t gmch)
         gms = (gmch >> 8) & 0xff;
     }
 
-    if (gms > 0x10) {
-        error_report("Unsupported IGD GMS value 0x%x", gms);
-        return 0;
+    if (gen < 9) {
+        if (gms > 0x10) {
+            error_report("Unsupported IGD GMS value 0x%x", gms);
+            return 0;
+        }
+        return gms * 32;
+    } else {
+        if (gms < 0xf0)
+            return gms * 32;
+        else
+            return gms * 4 + 4;
     }
-    return gms * 32;
 }
 
 void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int nr)