drm/amdgpu: Implement Enforce Isolation Handler for KGD/KFD serialization

This commit introduces the Enforce Isolation Handler designed to enforce
shader isolation on AMD GPUs, which helps to prevent data leakage
between different processes.

The handler counts the number of emitted fences for each GFX and compute
ring. If there are any fences, it schedules the `enforce_isolation_work`
to be run after a delay of `GFX_SLICE_PERIOD`. If there are no fences,
it signals the Kernel Fusion Driver (KFD) to resume the runqueue.

The function is synchronized using the `enforce_isolation_mutex`.

This commit also introduces a reference count mechanism
(kfd_sch_req_count) to keep track of the number of requests to enable
the KFD scheduler. When a request to enable the KFD scheduler is made,
the reference count is decremented. When the reference count reaches
zero, a delayed work is scheduled to enforce isolation after a delay of
GFX_SLICE_PERIOD.

When a request to disable the KFD scheduler is made, the function first
checks if the reference count is zero. If it is, it cancels the delayed
work for enforcing isolation and checks if the KFD scheduler is active.
If the KFD scheduler is active, it sends a request to stop the KFD
scheduler and sets the KFD scheduler state to inactive. Then, it
increments the reference count.

The function is synchronized using the kfd_sch_mutex to ensure that the
KFD scheduler state and reference count are updated atomically.

Cc: Christian König <christian.koenig@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam@amd.com>
Suggested-by: Christian König <christian.koenig@amd.com>
Suggested-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 16 insertions, 0 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
index 2f1bc02309fe..ad97f03f1358 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
@@ -4067,6 +4067,7 @@ int amdgpu_device_init(struct amdgpu_device *adev,
 	mutex_init(&adev->gfx.reset_sem_mutex);
 	/* Initialize the mutex for cleaner shader isolation between GFX and compute processes */
 	mutex_init(&adev->enforce_isolation_mutex);
+	mutex_init(&adev->gfx.kfd_sch_mutex);
 
 	amdgpu_device_init_apu_flags(adev);
 
@@ -4098,6 +4099,21 @@ int amdgpu_device_init(struct amdgpu_device *adev,
 			  amdgpu_device_delayed_init_work_handler);
 	INIT_DELAYED_WORK(&adev->gfx.gfx_off_delay_work,
 			  amdgpu_device_delay_enable_gfx_off);
+	/*
+	 * Initialize the enforce_isolation work structures for each XCP
+	 * partition.  This work handler is responsible for enforcing shader
+	 * isolation on AMD GPUs.  It counts the number of emitted fences for
+	 * each GFX and compute ring.  If there are any fences, it schedules
+	 * the `enforce_isolation_work` to be run after a delay.  If there are
+	 * no fences, it signals the Kernel Fusion Driver (KFD) to resume the
+	 * runqueue.
+	 */
+	for (i = 0; i < MAX_XCP; i++) {
+		INIT_DELAYED_WORK(&adev->gfx.enforce_isolation[i].work,
+				  amdgpu_gfx_enforce_isolation_handler);
+		adev->gfx.enforce_isolation[i].adev = adev;
+		adev->gfx.enforce_isolation[i].xcp_id = i;
+	}
 
 	INIT_WORK(&adev->xgmi_reset_work, amdgpu_device_xgmi_reset_func);