From eb17cc79af832ecbc9daa78c1b340280319f4523 Mon Sep 17 00:00:00 2001
From: Philip Yang <Philip.Yang@amd.com>
Date: Tue, 26 Oct 2021 11:59:28 -0400
Subject: drm/amdkfd: restore userptr ignore bad address error
Git-commit: 3b8a23ae52dfbf785ea6f7c81358b1225a6bd339
Patch-mainline: v5.16-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225

The userptr can be unmapped by application and still registered to
driver, restore userptr work return user pages will get -EFAULT bad
address error. Pretend this error as succeed. GPU access this userptr
will have VM fault later, it is better than application soft hangs with
stalled user mode queues.

v2: squash in warning fix (Alex)

Signed-off-by: Philip Yang <Philip.Yang@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 .../gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c  | 27 ++++++++++++-------
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c       |  3 +++
 2 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
index cdf46bd0d8d5..6f01c6145a87 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
@@ -2041,19 +2041,26 @@ static int update_invalid_user_pages(struct amdkfd_process_info *process_info,
 		/* Get updated user pages */
 		ret = amdgpu_ttm_tt_get_user_pages(bo, bo->tbo.ttm->pages);
 		if (ret) {
-			pr_debug("%s: Failed to get user pages: %d\n",
-				__func__, ret);
+			pr_debug("Failed %d to get user pages\n", ret);
+
+			/* Return -EFAULT bad address error as success. It will
+			 * fail later with a VM fault if the GPU tries to access
+			 * it. Better than hanging indefinitely with stalled
+			 * user mode queues.
+			 *
+			 * Return other error -EBUSY or -ENOMEM to retry restore
+			 */
+			if (ret != -EFAULT)
+				return ret;
+		} else {
 
-			/* Return error -EBUSY or -ENOMEM, retry restore */
-			return ret;
+			/*
+			 * FIXME: Cannot ignore the return code, must hold
+			 * notifier_lock
+			 */
+			amdgpu_ttm_tt_get_user_pages_done(bo->tbo.ttm);
 		}
 
-		/*
-		 * FIXME: Cannot ignore the return code, must hold
-		 * notifier_lock
-		 */
-		amdgpu_ttm_tt_get_user_pages_done(bo->tbo.ttm);
-
 		/* Mark the BO as valid unless it was invalidated
 		 * again concurrently.
 		 */
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index 590537b62a0a..17b5dd6adf8c 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -696,6 +696,9 @@ int amdgpu_ttm_tt_get_user_pages(struct amdgpu_bo *bo, struct page **pages)
 				       true, NULL);
 out_unlock:
 	mmap_read_unlock(mm);
+	if (r)
+		pr_debug("failed %d to get user pages 0x%lx\n", r, start);
+
 	mmput(mm);
 
 	return r;
-- 
2.38.1