Commit 42b2bdc8 authored by Chris Wilson's avatar Chris Wilson Committed by Andi Shyti
Browse files

drm/i915/selftest: Clear the output buffers before GPU writes 



When testing whether we can get the GPU to leak information about
non-privileged state, we first need to ensure that the output buffer is
set to a known value as the HW may opt to skip the write into memory for
a non-privileged read of a sensitive register. We chose POISON_INUSE (0x5a)
so that is both non-zero and distinct from the poison values used during
the test.

v2:
  Use i915_gem_object_pin_map_unlocked

Reported-by: default avatarCQ Tang <cq.tang@intel.com>
Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Cc: CQ Tang <cq.tang@intel.com>
cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: default avatarRamalingam C <ramalingam.c@intel.com>
Reviewed-by: default avatarThomas Hellstrom <thomas.hellstrom@linux.intel.com>
Signed-off-by: default avatarKarolina Drobnik <karolina.drobnik@intel.com>
Reviewed-by: default avatarAndi Shyti <andi.shyti@linux.intel.com>
Signed-off-by: default avatarAndi Shyti <andi.shyti@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/5cebab02d182c171cf40cb5b73d6c3eeb7619360.1663081418.git.karolina.drobnik@intel.com
parent 25e4b266

drivers/gpu/drm/i915/gt/selftest_lrc.c

+28 −4
Original line number Diff line number Diff line
@@ -1395,6 +1395,30 @@ static int compare_isolation(struct intel_engine_cs *engine, 
	return err;

}



static struct i915_vma *

create_result_vma(struct i915_address_space *vm, unsigned long sz)

{

	struct i915_vma *vma;

	void *ptr;



	vma = create_user_vma(vm, sz);

	if (IS_ERR(vma))

		return vma;



	/* Set the results to a known value distinct from the poison */

	ptr = i915_gem_object_pin_map_unlocked(vma->obj, I915_MAP_WC);

	if (IS_ERR(ptr)) {

		i915_vma_put(vma);

		return ERR_CAST(ptr);

	}



	memset(ptr, POISON_INUSE, vma->size);

	i915_gem_object_flush_map(vma->obj);

	i915_gem_object_unpin_map(vma->obj);



	return vma;

}



static int __lrc_isolation(struct intel_engine_cs *engine, u32 poison)

{

	u32 *sema = memset32(engine->status_page.addr + 1000, 0, 1);
@@ -1413,13 +1437,13 @@ static int __lrc_isolation(struct intel_engine_cs *engine, u32 poison) 
		goto err_A;

	}



	ref[0] = create_user_vma(A->vm, SZ_64K);

	ref[0] = create_result_vma(A->vm, SZ_64K);

	if (IS_ERR(ref[0])) {

		err = PTR_ERR(ref[0]);

		goto err_B;

	}



	ref[1] = create_user_vma(A->vm, SZ_64K);

	ref[1] = create_result_vma(A->vm, SZ_64K);

	if (IS_ERR(ref[1])) {

		err = PTR_ERR(ref[1]);

		goto err_ref0;
@@ -1441,13 +1465,13 @@ static int __lrc_isolation(struct intel_engine_cs *engine, u32 poison) 
	}

	i915_request_put(rq);



	result[0] = create_user_vma(A->vm, SZ_64K);

	result[0] = create_result_vma(A->vm, SZ_64K);

	if (IS_ERR(result[0])) {

		err = PTR_ERR(result[0]);

		goto err_ref1;

	}



	result[1] = create_user_vma(A->vm, SZ_64K);

	result[1] = create_result_vma(A->vm, SZ_64K);

	if (IS_ERR(result[1])) {

		err = PTR_ERR(result[1]);

		goto err_result0;