[PATCH 5.4 27/61] drm/nouveau/svm: fail NOUVEAU_SVM_INIT ioctl on unsupported devices

[Greg Kroah-Hartman]

From: Karol Herbst <kher...@redhat.com>

commit dcd602cc5fe2803bf532d407cde24ba0b7808ff3 upstream.

Fixes a crash when trying to create a channel on e.g. Turing GPUs when
NOUVEAU_SVM_INIT was called before.

Fixes: eeaf06ac1a558 ("drm/nouveau/svm: initial support for shared virtual 
memory")
Signed-off-by: Karol Herbst <kher...@redhat.com>
Signed-off-by: Ben Skeggs <bske...@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 drivers/gpu/drm/nouveau/nouveau_svm.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/drivers/gpu/drm/nouveau/nouveau_svm.c
+++ b/drivers/gpu/drm/nouveau/nouveau_svm.c
@@ -306,6 +306,10 @@ nouveau_svmm_init(struct drm_device *dev
        struct drm_nouveau_svm_init *args = data;
        int ret;
 
+       /* We need to fail if svm is disabled */
+       if (!cli->drm->svm)
+               return -ENOSYS;
+
        /* Allocate tracking for SVM-enabled VMM. */
        if (!(svmm = kzalloc(sizeof(*svmm), GFP_KERNEL)))
                return -ENOMEM;