From: Chris Wilson chris@chris-wilson.co.uk
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.
Reported-by: CQ Tang cq.tang@intel.com Signed-off-by: Chris Wilson chris@chris-wilson.co.uk cc: Joonas Lahtinen joonas.lahtinen@linux.intel.com Signed-off-by: Ramalingam C ramalingam.c@intel.com --- drivers/gpu/drm/i915/gt/selftest_lrc.c | 32 ++++++++++++++++++++++---- 1 file changed, 28 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/i915/gt/selftest_lrc.c b/drivers/gpu/drm/i915/gt/selftest_lrc.c index 6717ecaed178..d8face764ee4 100644 --- a/drivers/gpu/drm/i915/gt/selftest_lrc.c +++ b/drivers/gpu/drm/i915/gt/selftest_lrc.c @@ -1430,6 +1430,30 @@ 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(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, bool relative) { @@ -1449,13 +1473,13 @@ __lrc_isolation(struct intel_engine_cs *engine, u32 poison, bool relative) 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; @@ -1476,13 +1500,13 @@ __lrc_isolation(struct intel_engine_cs *engine, u32 poison, bool relative) } 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;