RE: [PATCH] drm/amdgpu: Add lock around VF RLCG interface

["Luo, Zhigang" <Zhigang.Luo@xxxxxxx>]

[AMD Official Use Only - AMD Internal Distribution Only]

Reviewed-by: Zhigang Luo <zhigang.luo@xxxxxxx>

-----Original Message-----
From: Skvortsov, Victor <Victor.Skvortsov@xxxxxxx>
Sent: Monday, May 27, 2024 4:19 PM
To: amd-gfx@xxxxxxxxxxxxxxxxxxxxx; Zhang, Hawking <Hawking.Zhang@xxxxxxx>; Lazar, Lijo <Lijo.Lazar@xxxxxxx>; Luo, Zhigang <Zhigang.Luo@xxxxxxx>
Cc: Skvortsov, Victor <Victor.Skvortsov@xxxxxxx>
Subject: [PATCH] drm/amdgpu: Add lock around VF RLCG interface

flush_gpu_tlb may be called from another thread while device_gpu_recover is running.

Both of these threads access registers through the VF RLCG interface during VF Full Access. Add a lock around this interface to prevent race conditions between these threads.

Signed-off-by: Victor Skvortsov <victor.skvortsov@xxxxxxx>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 1 +
 drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c   | 6 ++++++
 drivers/gpu/drm/amd/amdgpu/amdgpu_virt.h   | 2 ++
 3 files changed, 9 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
index f5168b4c3b03..6711836054f9 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
@@ -4049,6 +4049,7 @@ int amdgpu_device_init(struct amdgpu_device *adev,
        mutex_init(&adev->grbm_idx_mutex);
        mutex_init(&adev->mn_lock);
        mutex_init(&adev->virt.vf_errors.lock);
+       mutex_init(&adev->virt.rlcg_reg_lock);
        hash_init(adev->mn_hash);
        mutex_init(&adev->psp.mutex);
        mutex_init(&adev->notifier_lock);
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c
index 3d5f58e76f2d..a72683f83390 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c
@@ -982,6 +982,9 @@ u32 amdgpu_virt_rlcg_reg_rw(struct amdgpu_device *adev, u32 offset, u32 v, u32 f
        scratch_reg1 = (void __iomem *)adev->rmmio + 4 * reg_access_ctrl->scratch_reg1;
        scratch_reg2 = (void __iomem *)adev->rmmio + 4 * reg_access_ctrl->scratch_reg2;
        scratch_reg3 = (void __iomem *)adev->rmmio + 4 * reg_access_ctrl->scratch_reg3;
+
+       mutex_lock(&adev->virt.rlcg_reg_lock);
+
        if (reg_access_ctrl->spare_int)
                spare_int = (void __iomem *)adev->rmmio + 4 * reg_access_ctrl->spare_int;

@@ -1038,6 +1041,9 @@ u32 amdgpu_virt_rlcg_reg_rw(struct amdgpu_device *adev, u32 offset, u32 v, u32 f
        }

        ret = readl(scratch_reg0);
+
+       mutex_unlock(&adev->virt.rlcg_reg_lock);
+
        return ret;
 }

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.h
index 642f1fd287d8..0ec246c74570 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.h
@@ -272,6 +272,8 @@ struct amdgpu_virt {

        /* the ucode id to signal the autoload */
        uint32_t autoload_ucode_id;
+
+       struct mutex rlcg_reg_lock;
 };

 struct amdgpu_video_codec_info;
--
2.34.1