drm/i915/gvt: Fix GDRST vreg state after reset

Emulating the GDRST read behavior correctly to ack the
guest reset request.

v2:
- split the original patch into two:
  GDRST read handler and virtual gpu reset. (Zhenyu)
v3:
- emulate the GDRST read right after write. (Zhenyu)

Cc: Zhenyu Wang <[email protected]>
Cc: Zhang Yulei <[email protected]>
Signed-off-by: fred gao <[email protected]>
Signed-off-by: Zhenyu Wang <[email protected]>

diff --git a/drivers/gpu/drm/i915/gvt/handlers.c b/drivers/gpu/drm/i915/gvt/handlers.c
index eb3dc15254047b674f36353fc66515428bdf800f..372421ba0259e145f81145c5e2aecc05f1abc552 100644 (file)
--- a/drivers/gpu/drm/i915/gvt/handlers.c
+++ b/drivers/gpu/drm/i915/gvt/handlers.c
@@ -298,6 +298,9 @@ static int gdrst_mmio_write(struct intel_vgpu *vgpu, unsigned int offset,
 
        intel_gvt_reset_vgpu_locked(vgpu, false, engine_mask);
 
+       /* sw will wait for the device to ack the reset request */
+        vgpu_vreg(vgpu, offset) = 0;
+
        return 0;
 }