On 10/07/2020 00:53, Chris Wilson wrote:
Perf implements a GPU delay (noa_wait) by looping until the CS timestamp
has passed a certain point. This use MI_MATH and the general purpose
registers of the user's context, and since it is clobbering the user
state it must carefully save and restore the user's data around the
noa_wait. We can verify this by loading some values in the GPR that we
know will be clobbered the noa_wait, and then inspecting the GPR after
the noa_wait completes and confirming that have been restored.
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@xxxxxxxxx>
Cc: Lionel Landwerlin <lionel.g.landwerlin@xxxxxxxxx>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@xxxxxxxxx>
Thanks a lot!
-Lionel
---
drivers/gpu/drm/i915/selftests/i915_perf.c | 124 +++++++++++++++++++++
1 file changed, 124 insertions(+)
diff --git a/drivers/gpu/drm/i915/selftests/i915_perf.c b/drivers/gpu/drm/i915/selftests/i915_perf.c
index be54570c407c..be63cfe82feb 100644
--- a/drivers/gpu/drm/i915/selftests/i915_perf.c
+++ b/drivers/gpu/drm/i915/selftests/i915_perf.c
@@ -280,11 +280,135 @@ static int live_noa_delay(void *arg)
return err;
}
+static int live_noa_gpr(void *arg)
+{
+ struct drm_i915_private *i915 = arg;
+ struct i915_perf_stream *stream;
+ struct intel_context *ce;
+ struct i915_request *rq;
+ u32 *cs, *store;
+ void *scratch;
+ u32 gpr0;
+ int err;
+ int i;
+
+ /* Check that the delay does not clobber user context state (GPR) */
+
+ stream = test_stream(&i915->perf);
+ if (!stream)
+ return -ENOMEM;
+
+ gpr0 = i915_mmio_reg_offset(GEN8_RING_CS_GPR(stream->engine->mmio_base, 0));
+
+ ce = intel_context_create(stream->engine);
+ if (IS_ERR(ce)) {
+ err = PTR_ERR(ce);
+ goto out;
+ }
+
+ scratch = kmap(ce->vm->scratch[0].base.page);
+ memset(scratch, POISON_FREE, PAGE_SIZE);
+
+ rq = intel_context_create_request(ce);
+ if (IS_ERR(rq)) {
+ err = PTR_ERR(rq);
+ goto out_ce;
+ }
+ i915_request_get(rq);
+
+ if (rq->engine->emit_init_breadcrumb) {
+ err = rq->engine->emit_init_breadcrumb(rq);
+ if (err) {
+ i915_request_add(rq);
+ goto out_rq;
+ }
+ }
+
+ cs = intel_ring_begin(rq, 2 * 32 + 2);
+ if (IS_ERR(cs)) {
+ i915_request_add(rq);
+ goto out_rq;
+ }
+
+ *cs++ = MI_LOAD_REGISTER_IMM(32);
+ for (i = 0; i < 32; i++) {
+ *cs++ = gpr0 + i * sizeof(u32);
+ *cs++ = STACK_MAGIC;
+ }
+ *cs++ = MI_NOOP;
+ intel_ring_advance(rq, cs);
+
+ err = rq->engine->emit_bb_start(rq,
+ i915_ggtt_offset(stream->noa_wait), 0,
+ I915_DISPATCH_SECURE);
+ if (err) {
+ i915_request_add(rq);
+ goto out_rq;
+ }
+
+ store = memset32(rq->engine->status_page.addr + 512, 0, 32);
+ for (i = 0; i < 32; i++) {
+ u32 cmd;
+
+ cs = intel_ring_begin(rq, 4);
+ if (IS_ERR(cs)) {
+ i915_request_add(rq);
+ goto out_rq;
+ }
+
+ cmd = MI_STORE_REGISTER_MEM;
+ if (INTEL_GEN(i915) >= 8)
+ cmd++;
+ cmd |= MI_USE_GGTT;
+
+ *cs++ = cmd;
+ *cs++ = gpr0 + i * sizeof(u32);
+ *cs++ = i915_ggtt_offset(rq->engine->status_page.vma) +
+ offset_in_page(store) +
+ i * sizeof(u32);
+ *cs++ = 0;
+ intel_ring_advance(rq, cs);
+ }
+
+ i915_request_add(rq);
+
+ if (i915_request_wait(rq, I915_WAIT_INTERRUPTIBLE, HZ / 2) < 0) {
+ intel_gt_set_wedged(stream->engine->gt);
+ err = -EIO;
+ goto out_rq;
+ }
+
+ for (i = 0; i < 32; i++) {
+ if (store[i] == STACK_MAGIC)
+ continue;
+
+ pr_err("GPR[%d] lost, found:%08x, expected:%08x!\n",
+ i, store[i], STACK_MAGIC);
+ err = -EINVAL;
+ }
+
+ if (memchr_inv(scratch, POISON_FREE, PAGE_SIZE)) {
+ pr_err("scratch page overwritten!\n");
+ igt_hexdump(scratch, 4096);
+ err = -EINVAL;
+ }
+
+out_rq:
+ i915_request_put(rq);
+out_ce:
+ kunmap(ce->vm->scratch[0].base.page);
+ intel_context_put(ce);
+out:
+ stream_destroy(stream);
+ return err;
+}
+
int i915_perf_live_selftests(struct drm_i915_private *i915)
{
static const struct i915_subtest tests[] = {
SUBTEST(live_sanitycheck),
SUBTEST(live_noa_delay),
+ SUBTEST(live_noa_gpr),
};
struct i915_perf *perf = &i915->perf;
int err;
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