drm/radeon: move IB pool to 1MB offset

Even GPUs can have a null pointer dereference, so move
the IB pool to another offset to catch those.
Signed-off-by: Christian König <deathsimple@vodafone.de>
Reviewed-by: Jerome Glisse <jglisse@redhat.com>

drivers/gpu/drm/radeon/radeon.h

@@ -123,6 +123,7 @@ extern int radeon_lockup_timeout;
 #define CAYMAN_RING_TYPE_CP2_INDEX		2
 
 /* hardcode those limit for now */
+#define RADEON_VA_IB_OFFSET			(1 << 20)
 #define RADEON_VA_RESERVED_SIZE			(8 << 20)
 #define RADEON_IB_VM_MAX_SIZE			(64 << 10)
 

drivers/gpu/drm/radeon/radeon_gart.c

@@ -980,7 +980,7 @@ int radeon_vm_init(struct radeon_device *rdev, struct radeon_vm *vm)
 	/* map the ib pool buffer at 0 in virtual address space, set
 	 * read only
 	 */
-	r = radeon_vm_bo_add(rdev, vm, rdev->ring_tmp_bo.bo, 0,
+	r = radeon_vm_bo_add(rdev, vm, rdev->ring_tmp_bo.bo, RADEON_VA_IB_OFFSET,
 			     RADEON_VM_PAGE_READABLE | RADEON_VM_PAGE_SNOOPED);
 	return r;
 }

drivers/gpu/drm/radeon/radeon_ring.c

@@ -79,10 +79,10 @@ int radeon_ib_get(struct radeon_device *rdev, int ring,
 	ib->ptr = radeon_sa_bo_cpu_addr(ib->sa_bo);
 	ib->vm = vm;
 	if (vm) {
-		/* ib pool is bind at 0 in virtual address space,
-		 * so gpu_addr is the offset inside the pool bo
+		/* ib pool is bound at RADEON_VA_IB_OFFSET in virtual address
+		 * space and soffset is the offset inside the pool bo
 		 */
-		ib->gpu_addr = ib->sa_bo->soffset;
+		ib->gpu_addr = ib->sa_bo->soffset + RADEON_VA_IB_OFFSET;
 	} else {
 		ib->gpu_addr = radeon_sa_bo_gpu_addr(ib->sa_bo);
 	}