From: Chris Wilson <ch...@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.t...@intel.com>
Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
Cc: CQ Tang <cq.t...@intel.com>
cc: Joonas Lahtinen <joonas.lahti...@linux.intel.com>
Signed-off-by: Ramalingam C <ramalinga...@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 0a8ed4246082..b9cc89de01bf 100644
--- a/drivers/gpu/drm/i915/gt/selftest_lrc.c
+++ b/drivers/gpu/drm/i915/gt/selftest_lrc.c
@@ -1346,6 +1346,30 @@ 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)
{
u32 *sema = memset32(engine->status_page.addr + 1000, 0, 1);
@@ -1364,13 +1388,13 @@ 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;
@@ -1392,13 +1416,13 @@ 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;
--
2.20.1
