Nouveau - Apr 2020 - [PATCH AUTOSEL 5.6 077/129] drm/nouveau/svm: check for SVM initialized before migrating

From: Ralph Campbell <rcampbell at nvidia.com>

[ Upstream commit 822cab6150d3002952407a8297ff5a0d32bb7b54 ]

When migrating system memory to GPU memory, check that SVM has been
enabled. Even though most errors can be ignored since migration is
a performance optimization, return an error because this is a violation
of the API.

Signed-off-by: Ralph Campbell <rcampbell at nvidia.com>
Signed-off-by: Ben Skeggs <bskeggs at redhat.com>
Signed-off-by: Sasha Levin <sashal at kernel.org>
---
 drivers/gpu/drm/nouveau/nouveau_svm.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/gpu/drm/nouveau/nouveau_svm.c
b/drivers/gpu/drm/nouveau/nouveau_svm.c
index df9bf1fd1bc0b..3ec5da025bea7 100644
--- a/drivers/gpu/drm/nouveau/nouveau_svm.c
+++ b/drivers/gpu/drm/nouveau/nouveau_svm.c
@@ -171,6 +171,11 @@ nouveau_svmm_bind(struct drm_device *dev, void *data,
 	mm = get_task_mm(current);
 	down_read(&mm->mmap_sem);
 
+	if (!cli->svm.svmm) {
+		up_read(&mm->mmap_sem);
+		return -EINVAL;
+	}
+
 	for (addr = args->va_start, end = args->va_start + size; addr < end;)
{
 		struct vm_area_struct *vma;
 		unsigned long next;
-- 
2.20.1