[PATCH] drm/amd/powerplay: Protect backend resource when unload driver

[Jesse Zhang]

From: Jesse Zhang <Zhexi.Zhang at amd.com>

Guest driver can be unloaded while engines still using some
backend resources. That would lead to use after free and then
cause guest driver failed.

Need to add mutex lock before backend resources free to make
sure nobody is using it.

Need to check backend data availablility before VCE/UVD enter
powergating mode, if backend resources have been free, then
skip entering powergating.

Change-Id: If7f93221ddecc578884dc9e99a52f22a43e16b07
Signed-off-by: Jesse Zhang <zhexi.zhang at amd.com>
---
 drivers/gpu/drm/amd/powerplay/amd_powerplay.c      | 2 ++
 drivers/gpu/drm/amd/powerplay/hwmgr/vega10_hwmgr.c | 6 ++++++
 2 files changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/amd/powerplay/amd_powerplay.c b/drivers/gpu/drm/amd/powerplay/amd_powerplay.c
index fa8ad7d..c32b2dd 100644
--- a/drivers/gpu/drm/amd/powerplay/amd_powerplay.c
+++ b/drivers/gpu/drm/amd/powerplay/amd_powerplay.c
@@ -134,7 +134,9 @@ static int pp_hw_fini(void *handle)
 	struct amdgpu_device *adev = handle;
 	struct pp_hwmgr *hwmgr = adev->powerplay.pp_handle;
 
+	mutex_lock(&hwmgr->smu_lock);
 	hwmgr_hw_fini(hwmgr);
+	mutex_unlock(&pp_hwmgr->smu_lock);
 
 	return 0;
 }
diff --git a/drivers/gpu/drm/amd/powerplay/hwmgr/vega10_hwmgr.c b/drivers/gpu/drm/amd/powerplay/hwmgr/vega10_hwmgr.c
index d08493b..e51ffdd 100644
--- a/drivers/gpu/drm/amd/powerplay/hwmgr/vega10_hwmgr.c
+++ b/drivers/gpu/drm/amd/powerplay/hwmgr/vega10_hwmgr.c
@@ -4619,6 +4619,9 @@ static void vega10_power_gate_vce(struct pp_hwmgr *hwmgr, bool bgate)
 {
 	struct vega10_hwmgr *data = hwmgr->backend;
 
+	if (!data)
+		return;
+
 	data->vce_power_gated = bgate;
 	vega10_enable_disable_vce_dpm(hwmgr, !bgate);
 }
@@ -4627,6 +4630,9 @@ static void vega10_power_gate_uvd(struct pp_hwmgr *hwmgr, bool bgate)
 {
 	struct vega10_hwmgr *data = hwmgr->backend;
 
+	if (!data)
+		return;
+
 	data->uvd_power_gated = bgate;
 	vega10_enable_disable_uvd_dpm(hwmgr, !bgate);
 }
-- 
2.7.4