[PATCH] drm/amdgpu: ensure no_hw_access is visible before MMIO

[Perry Yuan <perry.yuan@amd.com>]

Add a full memory barrier after clearing no_hw_access in
amdgpu_device_mode1_reset() so subsequent PCI state restore
access cannot observe stale state on other CPUs.

Fixes: 91ae0045130b ("drm/amd/pm: Disable MMIO access during SMU Mode 1 reset")
Signed-off-by: Perry Yuan <perry.yuan@amd.com>
Reviewed-by: Yifan Zhang <yifan1.zhang@amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
index b2deb6a74eb2..e69ab8a923e3 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
@@ -5735,6 +5735,9 @@ int amdgpu_device_mode1_reset(struct amdgpu_device *adev)
 	/* enable mmio access after mode 1 reset completed */
 	adev->no_hw_access = false;
 
+	/* ensure no_hw_access is updated before we access hw */
+	smp_mb();
+
 	amdgpu_device_load_pci_state(adev->pdev);
 	ret = amdgpu_psp_wait_for_bootloader(adev);
 	if (ret)
-- 
2.34.1