[igt-dev] [PATCH i-g-t] i915/gem_workarounds: Verify regs directly

[Chris Wilson]

It seems like the HW validator is getting better at preventing our
snooping of system registers from non-privileged batches! If we can't
use SRM, let's probe the register directly through mmio, making sure we
have the context spinning on the GPU first.

v2: Hold forcewake just in case the spinning batch isn't enough to
justify our register access.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=110544
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Matthew Auld <matthew.william.auld at gmail.com>
---
 tests/i915/gem_workarounds.c | 88 +++++++-----------------------------
 1 file changed, 17 insertions(+), 71 deletions(-)

diff --git a/tests/i915/gem_workarounds.c b/tests/i915/gem_workarounds.c
index 44e3dce8a..2767b04d7 100644
--- a/tests/i915/gem_workarounds.c
+++ b/tests/i915/gem_workarounds.c
@@ -80,70 +80,27 @@ static bool write_only(const uint32_t addr)
 	return false;
 }
 
-#define MI_STORE_REGISTER_MEM (0x24 << 23)
-
-static int workaround_fail_count(int fd, uint32_t ctx)
+static int workaround_fail_count(int i915, uint32_t ctx)
 {
-	struct drm_i915_gem_exec_object2 obj[2];
-	struct drm_i915_gem_relocation_entry *reloc;
-	struct drm_i915_gem_execbuffer2 execbuf;
-	uint32_t result_sz, batch_sz;
-	uint32_t *base, *out;
-	int fail_count = 0;
-
-	reloc = calloc(num_wa_regs, sizeof(*reloc));
-	igt_assert(reloc);
-
-	result_sz = 4 * num_wa_regs;
-	result_sz = PAGE_ALIGN(result_sz);
-
-	batch_sz = 16 * num_wa_regs + 4;
-	batch_sz = PAGE_ALIGN(batch_sz);
-
-	memset(obj, 0, sizeof(obj));
-	obj[0].handle = gem_create(fd, result_sz);
-	gem_set_caching(fd, obj[0].handle, I915_CACHING_CACHED);
-	obj[1].handle = gem_create(fd, batch_sz);
-	obj[1].relocs_ptr = to_user_pointer(reloc);
-	obj[1].relocation_count = num_wa_regs;
-
-	out = base = gem_mmap__cpu(fd, obj[1].handle, 0, batch_sz, PROT_WRITE);
-	for (int i = 0; i < num_wa_regs; i++) {
-		*out++ = MI_STORE_REGISTER_MEM | ((gen >= 8 ? 4 : 2) - 2);
-		*out++ = wa_regs[i].addr;
-		reloc[i].target_handle = obj[0].handle;
-		reloc[i].offset = (out - base) * sizeof(*out);
-		reloc[i].delta = i * sizeof(uint32_t);
-		reloc[i].read_domains = I915_GEM_DOMAIN_INSTRUCTION;
-		reloc[i].write_domain = I915_GEM_DOMAIN_INSTRUCTION;
-		*out++ = reloc[i].delta;
-		if (gen >= 8)
-			*out++ = 0;
-	}
-	*out++ = MI_BATCH_BUFFER_END;
-	munmap(base, batch_sz);
+	igt_spin_t *spin;
+	int fw, fail = 0;
 
-	memset(&execbuf, 0, sizeof(execbuf));
-	execbuf.buffers_ptr = to_user_pointer(obj);
-	execbuf.buffer_count = 2;
-	execbuf.rsvd1 = ctx;
-	gem_execbuf(fd, &execbuf);
+	spin = igt_spin_new(i915, .ctx = ctx, .flags = IGT_SPIN_POLL_RUN);
+	igt_spin_busywait_until_started(spin);
 
-	gem_set_domain(fd, obj[0].handle, I915_GEM_DOMAIN_CPU, 0);
-
-	igt_debug("Address\tval\t\tmask\t\tread\t\tresult\n");
-
-	out = gem_mmap__cpu(fd, obj[0].handle, 0, result_sz, PROT_READ);
+	fw = igt_open_forcewake_handle(i915);
 	for (int i = 0; i < num_wa_regs; i++) {
+		uint32_t value =
+			*(uint32_t *)(igt_global_mmio + wa_regs[i].addr);
 		const bool ok =
 			(wa_regs[i].value & wa_regs[i].mask) ==
-			(out[i] & wa_regs[i].mask);
+			(value & wa_regs[i].mask);
 		char buf[80];
 
 		snprintf(buf, sizeof(buf),
 			 "0x%05X\t0x%08X\t0x%08X\t0x%08X",
 			 wa_regs[i].addr, wa_regs[i].value, wa_regs[i].mask,
-			 out[i]);
+			 value);
 
 		if (ok) {
 			igt_debug("%s\tOK\n", buf);
@@ -151,27 +108,14 @@ static int workaround_fail_count(int fd, uint32_t ctx)
 			igt_debug("%s\tIGNORED (w/o)\n", buf);
 		} else {
 			igt_warn("%s\tFAIL\n", buf);
-			fail_count++;
+			fail++;
 		}
 	}
-	munmap(out, result_sz);
+	close(fw);
 
-	gem_close(fd, obj[1].handle);
-	gem_close(fd, obj[0].handle);
-	free(reloc);
+	igt_spin_free(i915, spin);
 
-	return fail_count;
-}
-
-static int reopen(int fd)
-{
-	char path[256];
-
-	snprintf(path, sizeof(path), "/proc/self/fd/%d", fd);
-	fd = open(path, O_RDWR);
-	igt_assert_lte(0, fd);
-
-	return fd;
+	return fail;
 }
 
 #define CONTEXT 0x1
@@ -181,7 +125,7 @@ static void check_workarounds(int fd, enum operation op, unsigned int flags)
 	uint32_t ctx = 0;
 
 	if (flags & FD)
-		fd = reopen(fd);
+		fd = gem_reopen_driver(fd);
 
 	if (flags & CONTEXT) {
 		gem_require_contexts(fd);
@@ -252,6 +196,8 @@ igt_main
 		device = drm_open_driver(DRIVER_INTEL);
 		igt_require_gem(device);
 
+		intel_mmio_use_pci_bar(intel_get_pci_device());
+
 		gen = intel_gen(intel_get_drm_devid(device));
 
 		fd = igt_debugfs_open(device, "i915_wa_registers", O_RDONLY);
-- 
2.20.1