drm/amdgpu: implement per-process MES context

MES process context is a process-level page
where process specific context is saved for
MES scheduler.

However, current user-queue code path assigns
fw_obj of a queue to MES process_context_addr
when adding the queue to MES.

This means every new queue from the same process
would replace the previous process context address
with that queue's fw_obj address.
What's worse is, when user space frees a queue,
its fw_obj will be freed as well, causing MES
working on a NULL page pointer.

This issue leads to inconsistency and crash
in the scheduler.

This commit allocates a process-level page for
MES process contexts for a process other than queue-level

Signed-off-by: Zhu Lingshan <lingshan.zhu@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

3 files changed, 47 insertions, 12 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
index 3bcde67aa092..3644e9193f58 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
@@ -1165,6 +1165,7 @@ int amdgpu_userq_mgr_init(struct amdgpu_userq_mgr *userq_mgr, struct drm_file *f
 	xa_init_flags(&userq_mgr->userq_xa, XA_FLAGS_ALLOC);
 	userq_mgr->adev = adev;
 	userq_mgr->file = file_priv;
+	mutex_init(&userq_mgr->proc_ctx_lock);
 
 	INIT_DELAYED_WORK(&userq_mgr->resume_work, amdgpu_userq_restore_worker);
 	INIT_WORK(&userq_mgr->reset_work, amdgpu_userq_mgr_reset_work);
@@ -1218,6 +1219,11 @@ void amdgpu_userq_mgr_fini(struct amdgpu_userq_mgr *userq_mgr)
 	 */
 	cancel_work_sync(&userq_mgr->reset_work);
 
+	amdgpu_bo_free_kernel(&userq_mgr->proc_ctx_obj.obj,
+			      &userq_mgr->proc_ctx_obj.gpu_addr,
+			      &userq_mgr->proc_ctx_obj.cpu_ptr);
+
+	mutex_destroy(&userq_mgr->proc_ctx_lock);
 	mutex_destroy(&userq_mgr->userq_mutex);
 }
 
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.h
index 9df1b78407f5..7a5f8ed794b8 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.h
@@ -126,6 +126,8 @@ struct amdgpu_userq_mgr {
 	struct amdgpu_device		*adev;
 	struct delayed_work		resume_work;
 	struct drm_file			*file;
+	struct mutex			proc_ctx_lock;
+	struct amdgpu_userq_obj		proc_ctx_obj;
 
 	/**
 	 * @reset_work:
diff --git a/drivers/gpu/drm/amd/amdgpu/mes_userqueue.c b/drivers/gpu/drm/amd/amdgpu/mes_userqueue.c
index e9bd5ad98265..dba3707c2659 100644
--- a/drivers/gpu/drm/amd/amdgpu/mes_userqueue.c
+++ b/drivers/gpu/drm/amd/amdgpu/mes_userqueue.c
@@ -133,8 +133,8 @@ static int mes_userq_map(struct amdgpu_usermode_queue *queue)
 	queue_input.gang_quantum = 10000;
 	queue_input.paging = false;
 
-	queue_input.process_context_addr = ctx->gpu_addr;
-	queue_input.gang_context_addr = ctx->gpu_addr + AMDGPU_USERQ_PROC_CTX_SZ;
+	queue_input.process_context_addr = uq_mgr->proc_ctx_obj.gpu_addr;
+	queue_input.gang_context_addr = ctx->gpu_addr;
 	queue_input.inprocess_gang_priority = AMDGPU_MES_PRIORITY_LEVEL_NORMAL;
 	queue_input.gang_global_priority_level = convert_to_mes_priority(queue->priority);
 
@@ -169,7 +169,7 @@ static int mes_userq_unmap(struct amdgpu_usermode_queue *queue)
 
 	memset(&queue_input, 0x0, sizeof(struct mes_remove_queue_input));
 	queue_input.doorbell_offset = queue->doorbell_index;
-	queue_input.gang_context_addr = ctx->gpu_addr + AMDGPU_USERQ_PROC_CTX_SZ;
+	queue_input.gang_context_addr = ctx->gpu_addr;
 
 	amdgpu_mes_lock(&adev->mes);
 	r = adev->mes.funcs->remove_hw_queue(&adev->mes, &queue_input);
@@ -243,12 +243,8 @@ static int mes_userq_create_ctx_space(struct amdgpu_userq_mgr *uq_mgr,
 	struct amdgpu_userq_obj *ctx = &queue->fw_obj;
 	int r, size;
 
-	/*
-	 * The FW expects at least one page space allocated for
-	 * process ctx and gang ctx each. Create an object
-	 * for the same.
-	 */
-	size = AMDGPU_USERQ_PROC_CTX_SZ + AMDGPU_USERQ_GANG_CTX_SZ;
+	/* The FW expects at least one page space allocated for gang ctx. */
+	size = AMDGPU_USERQ_GANG_CTX_SZ;
 	r = amdgpu_bo_create_kernel(uq_mgr->adev, size, 0,
 				    AMDGPU_GEM_DOMAIN_GTT,
 				    &ctx->obj, &ctx->gpu_addr,
@@ -262,6 +258,30 @@ static int mes_userq_create_ctx_space(struct amdgpu_userq_mgr *uq_mgr,
 	return 0;
 }
 
+static int mes_userq_create_proc_ctx_space(struct amdgpu_userq_mgr *uq_mgr)
+{
+	int r = 0;
+
+	mutex_lock(&uq_mgr->proc_ctx_lock);
+	/* This check is a necessary because amdgpu_bo_create_kernel()
+	 * calls helpers like amdgpu_bo_pin() and memset() unconditionally
+	 */
+	if (!uq_mgr->proc_ctx_obj.obj) {
+		r = amdgpu_bo_create_kernel(uq_mgr->adev, AMDGPU_USERQ_PROC_CTX_SZ,
+					    0, AMDGPU_GEM_DOMAIN_GTT,
+					    &uq_mgr->proc_ctx_obj.obj,
+					    &uq_mgr->proc_ctx_obj.gpu_addr,
+					    &uq_mgr->proc_ctx_obj.cpu_ptr);
+
+		if (!r)
+			memset(uq_mgr->proc_ctx_obj.cpu_ptr, 0, AMDGPU_USERQ_PROC_CTX_SZ);
+	}
+
+	mutex_unlock(&uq_mgr->proc_ctx_lock);
+
+	return r;
+}
+
 static int mes_userq_mqd_create(struct amdgpu_usermode_queue *queue,
 				struct drm_amdgpu_userq_in *args_in)
 {
@@ -434,7 +454,14 @@ static int mes_userq_mqd_create(struct amdgpu_usermode_queue *queue,
 		goto free_mqd;
 	}
 
-	/* Create BO for FW operations */
+	/* Create per-process MES process context BO */
+	r = mes_userq_create_proc_ctx_space(uq_mgr);
+	if (r) {
+		DRM_ERROR("Failed to allocate MES process context space bo, error: %d\n", r);
+		goto free_mqd;
+	}
+
+	/* Create BO of a gang for FW operations */
 	r = mes_userq_create_ctx_space(uq_mgr, queue, mqd_user);
 	if (r) {
 		DRM_ERROR("Failed to allocate BO for userqueue (%d)", r);
@@ -502,7 +529,7 @@ static int mes_userq_preempt(struct amdgpu_usermode_queue *queue)
 	*fence_ptr = 0;
 
 	memset(&queue_input, 0x0, sizeof(struct mes_suspend_gang_input));
-	queue_input.gang_context_addr = ctx->gpu_addr + AMDGPU_USERQ_PROC_CTX_SZ;
+	queue_input.gang_context_addr = ctx->gpu_addr;
 	queue_input.suspend_fence_addr = fence_gpu_addr;
 	queue_input.suspend_fence_value = 1;
 	amdgpu_mes_lock(&adev->mes);
@@ -539,7 +566,7 @@ static int mes_userq_restore(struct amdgpu_usermode_queue *queue)
 		return 0;
 
 	memset(&queue_input, 0x0, sizeof(struct mes_resume_gang_input));
-	queue_input.gang_context_addr = ctx->gpu_addr + AMDGPU_USERQ_PROC_CTX_SZ;
+	queue_input.gang_context_addr = ctx->gpu_addr;
 
 	amdgpu_mes_lock(&adev->mes);
 	r = adev->mes.funcs->resume_gang(&adev->mes, &queue_input);