From: Jon Derrick <jonathan.derr...@intel.com>

[ Upstream commit f10b83de1fd49216a4c657816f48001437e4bdd5 ]

If the BAR is zero size, it indicates it was never successfully mapped.
Ensure that the BAR is valid during initialization before attempting to
use it.

Signed-off-by: Jon Derrick <jonathan.derr...@intel.com>
Signed-off-by: Ben Skeggs <bske...@redhat.com>
Signed-off-by: Sasha Levin <sas...@kernel.org>
---
 drivers/gpu/drm/nouveau/nvkm/subdev/bar/nv50.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/bar/nv50.c 
b/drivers/gpu/drm/nouveau/nvkm/subdev/bar/nv50.c
index 157b076a12723..38c9c086754b6 100644
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/bar/nv50.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/bar/nv50.c
@@ -109,7 +109,7 @@ nv50_bar_oneinit(struct nvkm_bar *base)
        struct nvkm_device *device = bar->base.subdev.device;
        static struct lock_class_key bar1_lock;
        static struct lock_class_key bar2_lock;
-       u64 start, limit;
+       u64 start, limit, size;
        int ret;
 
        ret = nvkm_gpuobj_new(device, 0x20000, 0, false, NULL, &bar->mem);
@@ -127,7 +127,10 @@ nv50_bar_oneinit(struct nvkm_bar *base)
 
        /* BAR2 */
        start = 0x0100000000ULL;
-       limit = start + device->func->resource_size(device, 3);
+       size = device->func->resource_size(device, 3);
+       if (!size)
+               return -ENOMEM;
+       limit = start + size;
 
        ret = nvkm_vmm_new(device, start, limit-- - start, NULL, 0,
                           &bar2_lock, "bar2", &bar->bar2_vmm);
@@ -164,7 +167,10 @@ nv50_bar_oneinit(struct nvkm_bar *base)
 
        /* BAR1 */
        start = 0x0000000000ULL;
-       limit = start + device->func->resource_size(device, 1);
+       size = device->func->resource_size(device, 1);
+       if (!size)
+               return -ENOMEM;
+       limit = start + size;
 
        ret = nvkm_vmm_new(device, start, limit-- - start, NULL, 0,
                           &bar1_lock, "bar1", &bar->bar1_vmm);
-- 
2.20.1

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