drm/amdgpu/virt: add function to check MMIO (v2)

MMIO space can be blocked on virtualised device. Add this
function to check if MMIO is blocked or not.

Todo: need a reliable method such like communation
with hypervisor.

v2:
 - add comments inline

Signed-off-by: pding <Pixel.Ding@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c
index 6738df836a70..0f227cf7a67c 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c
@@ -24,6 +24,14 @@
 #include "amdgpu.h"
 #define MAX_KIQ_REG_WAIT        100000000 /* in usecs */
 
+bool amdgpu_virt_mmio_blocked(struct amdgpu_device *adev)
+{
+        /* By now all MMIO pages except mailbox are blocked */
+        /* if blocking is enabled in hypervisor. Choose the */
+        /* SCRATCH_REG0 to test. */
+        return RREG32_NO_KIQ(0xc040) == 0xffffffff;
+}
+
 int amdgpu_allocate_static_csa(struct amdgpu_device *adev)
 {
         int r;