[Intel-gfx] [PATCH i-g-t] i915/perf_pmu: Exercise mixing perf reads into i915 mmaps

[Chris Wilson]

Quoting Chris Wilson (2020-04-02 15:00:57)
> Feed a fresh i915 mmap into a read(perf_fd) to teach lockdep about the
> potential lock chains should we take a pagefault into our vm_fault
> handlers from within perf.
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> ---
>  tests/perf_pmu.c | 39 +++++++++++++++++++++++++++++++++++++++
>  1 file changed, 39 insertions(+)
> 
> diff --git a/tests/perf_pmu.c b/tests/perf_pmu.c
> index 259670f4b..1d6681d80 100644
> --- a/tests/perf_pmu.c
> +++ b/tests/perf_pmu.c
> @@ -1827,6 +1827,35 @@ accuracy(int gem_fd, const struct intel_execution_engine2 *e,
>         assert_within(100.0 * busy_r, 100.0 * expected, 2);
>  }
>  
> +static void *create_mmap(int gem_fd, const struct mmap_offset *t, int sz)
> +{
> +       uint32_t handle;
> +       void *ptr;
> +
> +       handle = gem_create(gem_fd, sz);
> +       ptr = __gem_mmap_offset(gem_fd, handle, 0, sz, PROT_WRITE, t->type);
> +       gem_close(gem_fd, handle);
> +
> +       return ptr;
> +}
> +
> +static void
> +faulting_read(int gem_fd, const struct mmap_offset *t)
> +{
> +       void *ptr;
> +       int fd;
> +
> +       ptr = create_mmap(gem_fd, t, 4096);
> +       igt_require(ptr != NULL);
> +
> +       fd = open_pmu(gem_fd, I915_PMU_ENGINE_BUSY(0, 0));
> +       igt_require(fd != -1);
> +       igt_assert_eq(read(fd, ptr, 4096), 2 * sizeof(uint64_t));
> +       close(fd);
> +
> +       munmap(ptr, 4096);
> +}
> +
>  #define test_each_engine(T, i915, e) \
>         igt_subtest_with_dynamic(T) __for_each_physical_engine(i915, e) \
>                 igt_dynamic_f("%s", e->name)
> @@ -1860,6 +1889,16 @@ igt_main
>         igt_subtest("invalid-init")
>                 invalid_init(fd);
>  
> +       igt_subtest_with_dynamic("faulting-read") {
> +               for_each_mmap_offset_type(fd, t) {
> +                       if (!gem_has_mmap_offset_type(fd, t))
> +                               continue;

Redundant, for_each_mmap_offset_type() includes the skip.
-Chris