drm/amdgpu: Redo XGMI reset synchronization.

Use task barrier in XGMI hive to synchronize ASIC resets
across devices in XGMI hive.

v2: Return right away with a warning if no xgmi hive, update doc.
Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
Reviewed-by: Le Ma <Le.Ma@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_device.c

@@ -66,6 +66,7 @@
 #include "amdgpu_pmu.h"
 
 #include <linux/suspend.h>
+#include <drm/task_barrier.h>
 
 MODULE_FIRMWARE("amdgpu/vega10_gpu_info.bin");
 MODULE_FIRMWARE("amdgpu/vega12_gpu_info.bin");
@@ -2664,14 +2665,38 @@ static void amdgpu_device_xgmi_reset_func(struct work_struct *__work)
 {
 	struct amdgpu_device *adev =
 		container_of(__work, struct amdgpu_device, xgmi_reset_work);
+	struct amdgpu_hive_info *hive = amdgpu_get_xgmi_hive(adev, 0);
 
-	if (amdgpu_asic_reset_method(adev) == AMD_RESET_METHOD_BACO)
-		adev->asic_reset_res = (adev->in_baco == false) ?
-				amdgpu_device_baco_enter(adev->ddev) :
-				amdgpu_device_baco_exit(adev->ddev);
-	else
-		adev->asic_reset_res = amdgpu_asic_reset(adev);
+	/* It's a bug to not have a hive within this function */
+	if (WARN_ON(!hive))
+		return;
+
+	/*
+	 * Use task barrier to synchronize all xgmi reset works across the
+	 * hive. task_barrier_enter and task_barrier_exit will block
+	 * until all the threads running the xgmi reset works reach
+	 * those points. task_barrier_full will do both blocks.
+	 */
+	if (amdgpu_asic_reset_method(adev) == AMD_RESET_METHOD_BACO) {
+
+		task_barrier_enter(&hive->tb);
+		adev->asic_reset_res = amdgpu_device_baco_enter(adev->ddev);
+
+		if (adev->asic_reset_res)
+			goto fail;
+
+		task_barrier_exit(&hive->tb);
+		adev->asic_reset_res = amdgpu_device_baco_exit(adev->ddev);
+
+		if (adev->asic_reset_res)
+			goto fail;
+	} else {
+
+		task_barrier_full(&hive->tb);
+		adev->asic_reset_res =  amdgpu_asic_reset(adev);
+	}
 
+fail:
 	if (adev->asic_reset_res)
 		DRM_WARN("ASIC reset failed with error, %d for drm dev, %s",
 			 adev->asic_reset_res, adev->ddev->unique);