drm/amdgpu: retry init if it fails due to exclusive mode timeout (v3)

The exclusive mode has real-time limitation in reality, such like being
done in 300ms. It's easy observed if running many VF/VMs in single host
with heavy CPU workload.

If we find the init fails due to exclusive mode timeout, try it again.

v2:
 - rewrite the condition for readable value.

v3:
 - fix typo, add comments for sleep
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: pding <Pixel.Ding@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -2303,6 +2303,15 @@ int amdgpu_device_init(struct amdgpu_device *adev,
 
 	r = amdgpu_init(adev);
 	if (r) {
+		/* failed in exclusive mode due to timeout */
+		if (amdgpu_sriov_vf(adev) &&
+		    !amdgpu_sriov_runtime(adev) &&
+		    amdgpu_virt_mmio_blocked(adev) &&
+		    !amdgpu_virt_wait_reset(adev)) {
+			dev_err(adev->dev, "VF exclusive mode timeout\n");
+			r = -EAGAIN;
+			goto failed;
+		}
 		dev_err(adev->dev, "amdgpu_init failed\n");
 		amdgpu_vf_error_put(adev, AMDGIM_ERROR_VF_AMDGPU_INIT_FAIL, 0, 0);
 		amdgpu_fini(adev);
@@ -2390,6 +2399,7 @@ int amdgpu_device_init(struct amdgpu_device *adev,
 	amdgpu_vf_error_trans_all(adev);
 	if (runtime)
 		vga_switcheroo_fini_domain_pm_ops(adev->dev);
+
 	return r;
 }
 

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

@@ -86,7 +86,7 @@ void amdgpu_driver_unload_kms(struct drm_device *dev)
 int amdgpu_driver_load_kms(struct drm_device *dev, unsigned long flags)
 {
 	struct amdgpu_device *adev;
-	int r, acpi_status;
+	int r, acpi_status, retry = 0;
 
 #ifdef CONFIG_DRM_AMDGPU_SI
 	if (!amdgpu_si_support) {
@@ -122,6 +122,7 @@ int amdgpu_driver_load_kms(struct drm_device *dev, unsigned long flags)
 		}
 	}
 #endif
+retry_init:
 
 	adev = kzalloc(sizeof(struct amdgpu_device), GFP_KERNEL);
 	if (adev == NULL) {
@@ -144,7 +145,17 @@ int amdgpu_driver_load_kms(struct drm_device *dev, unsigned long flags)
 	 * VRAM allocation
 	 */
 	r = amdgpu_device_init(adev, dev, dev->pdev, flags);
-	if (r) {
+	if (r == -EAGAIN && ++retry <= 3) {
+		adev->virt.caps &= ~AMDGPU_SRIOV_CAPS_RUNTIME;
+		adev->virt.ops = NULL;
+		amdgpu_device_fini(adev);
+		kfree(adev);
+		dev->dev_private = NULL;
+		/* Don't request EX mode too frequently which is attacking */
+		msleep(5000);
+		dev_err(&dev->pdev->dev, "retry init %d\n", retry);
+		goto retry_init;
+	} else if (r) {
 		dev_err(&dev->pdev->dev, "Fatal error during GPU init\n");
 		goto out;
 	}