From ed2690a9ca896882a124ee0bd4eaff9678ed1162 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Thu, 9 Jul 2020 23:45:04 +0100 Subject: [PATCH] drm/i915/selftest: Check that GPR are restored across noa_wait 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 by the noa_wait, and then inspecting the GPR after the noa_wait completes and confirming that they have been restored. Signed-off-by: Chris Wilson Cc: Umesh Nerlige Ramappa Cc: Lionel Landwerlin Reviewed-by: Lionel Landwerlin Link: https://patchwork.freedesktop.org/patch/msgid/20200709224504.11345-2-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/selftests/i915_perf.c | 131 +++++++++++++++++++++++++++++ 1 file changed, 131 insertions(+) diff --git a/drivers/gpu/drm/i915/selftests/i915_perf.c b/drivers/gpu/drm/i915/selftests/i915_perf.c index be54570..deb6dec 100644 --- a/drivers/gpu/drm/i915/selftests/i915_perf.c +++ b/drivers/gpu/drm/i915/selftests/i915_perf.c @@ -280,11 +280,142 @@ out: 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; + } + + /* Poison the ce->vm so we detect writes not to the GGTT gt->scratch */ + 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; + } + } + + /* Fill the 16 qword [32 dword] GPR with a known unlikely value */ + 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); + + /* Execute the GPU delay */ + 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; + } + + /* Read the GPR back, using the pinned global HWSP for convenience */ + 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) { + pr_err("noa_wait timed out\n"); + intel_gt_set_wedged(stream->engine->gt); + err = -EIO; + goto out_rq; + } + + /* Verify that the GPR contain our expected values */ + 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; + } + + /* Verify that the user's scratch page was not used for GPR storage */ + 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; -- 2.7.4