[PATCH AUTOSEL 5.4 032/130] drm/amd/amdgpu: Add rev_id workaround logic for SRIOV setup

[Sasha Levin]

From: Bokun Zhang <Bokun.Zhang at amd.com>

[ Upstream commit de21e4aeb2b26128dcc5be1bcb2fafa73d041e51 ]

- When we are under SRIOV setup, the rev_id cannot be read
  properly. Therefore, we will return default value for it

Signed-off-by: Bokun Zhang <Bokun.Zhang at amd.com>
Reviewed-by: Monk Liu <monk.liu at amd.com>
Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
Signed-off-by: Sasha Levin <sashal at kernel.org>
---
 drivers/gpu/drm/amd/amdgpu/nbio_v2_3.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/nbio_v2_3.c b/drivers/gpu/drm/amd/amdgpu/nbio_v2_3.c
index c05d78d4efc66..56887affc13be 100644
--- a/drivers/gpu/drm/amd/amdgpu/nbio_v2_3.c
+++ b/drivers/gpu/drm/amd/amdgpu/nbio_v2_3.c
@@ -34,8 +34,17 @@
 
 static u32 nbio_v2_3_get_rev_id(struct amdgpu_device *adev)
 {
-	u32 tmp = RREG32_SOC15(NBIO, 0, mmRCC_DEV0_EPF0_STRAP0);
+	u32 tmp;
 
+	/*
+	 * guest vm gets 0xffffffff when reading RCC_DEV0_EPF0_STRAP0,
+	 * therefore we force rev_id to 0 (which is the default value)
+	 */
+	if (amdgpu_sriov_vf(adev)) {
+		return 0;
+	}
+
+	tmp = RREG32_SOC15(NBIO, 0, mmRCC_DEV0_EPF0_STRAP0);
 	tmp &= RCC_DEV0_EPF0_STRAP0__STRAP_ATI_REV_ID_DEV0_F0_MASK;
 	tmp >>= RCC_DEV0_EPF0_STRAP0__STRAP_ATI_REV_ID_DEV0_F0__SHIFT;
 
-- 
2.27.0