Re: [PATCH i-g-t V2 2/2] tests/intel: Add xe_pci_membarrier test

[Matthew Auld <matthew.auld@intel.com>]

On 23/10/2024 10:43, Tejas Upadhyay wrote:
> We want to make sure that direct mmap mapping of physical
> page at doorbell space and whole page is accessible in order
> to use pci memory barrier effect effectively.
> 
> This is basic pci memory barrier test to showcase xe driver
> support for feature. In follow up patches we will have more
> of corner and negative tests added later.
> 
> Signed-off-by: Tejas Upadhyay <tejas.upadhyay@intel.com>
> ---
>   tests/intel/xe_pci_membarrier.c | 80 +++++++++++++++++++++++++++++++++

Could probably just plonk this in the existing mmap offset tests file?

>   tests/meson.build               |  1 +
>   2 files changed, 81 insertions(+)
>   create mode 100644 tests/intel/xe_pci_membarrier.c
> 
> diff --git a/tests/intel/xe_pci_membarrier.c b/tests/intel/xe_pci_membarrier.c
> new file mode 100644
> index 000000000..d0bf447b6
> --- /dev/null
> +++ b/tests/intel/xe_pci_membarrier.c
> @@ -0,0 +1,80 @@
> +// SPDX-License-Identifier: MIT
> +/*
> + * Copyright(c) 2024 Intel Corporation. All rights reserved.
> + */
> +
> +#include "xe_drm.h"
> +#include "igt.h"
> +
> +/**
> + * TEST: Test if the driver is capable of putting pci memory barrier using mmap
> + * Category: Core
> + * Mega feature: General Core features
> + * Sub-category: Memory management tests
> + * Functionality: mmap with pre-defined offset
> + */
> +
> +IGT_TEST_DESCRIPTION("Basic MMAP tests pci memory barrier effect with special offset");
> +#define PAGE_SHIFT 12
> +#define PAGE_SIZE 4096
> +
> +/**
> + * SUBTEST: basic
> + * Description: create pci memory barrier with write on defined mmap offset.
> + * Test category: functionality test
> + *
> + */
> +
> +static void pci_membarrier(int xe)
> +{
> +	uint64_t flags = MAP_SHARED;
> +	unsigned int prot = PROT_WRITE;
> +	uint32_t *ptr;
> +	uint64_t size = PAGE_SIZE;
> +	struct timespec tv;
> +        struct drm_xe_gem_mmap_offset mmo = {
> +                .handle = 0,
> +                .flags = DRM_XE_MMAP_OFFSET_FLAG_PCI_BARRIER,
> +        };
> +
> +        igt_assert_eq(igt_ioctl(xe, DRM_IOCTL_XE_GEM_MMAP_OFFSET, &mmo), 0);
> +        ptr = mmap(NULL, size, prot, flags, xe, mmo.offset);
> +	igt_assert(ptr != MAP_FAILED);

nit: formatting

> +
> +	/* Check whole page for any errors, also check as
> +	 * we should not read written values back
> +	 */
> +	for (int i = 0; i < size / sizeof(*ptr); i++) {
> +		/* It is expected unconfigured doorbell space
> +		 * will return read value 0xdeadbeef
> +		 */
> +		igt_assert_eq_u32(READ_ONCE(ptr[i]), 0xdeadbeef);
> +
> +		igt_gettime(&tv);
> +		ptr[i] = i;
> +		if (READ_ONCE(ptr[i]) == i) {

Can this actually happen where the value is written?

I think also consider adding some negative testcases. For example:

- Try to mmap something larger than 4K. Ensure we get an error.
- Try BARRIER mmap_offset, and also supply a BO. Ensure we get an error.

> +			while (READ_ONCE(ptr[i]) == i)
> +				;
> +			igt_info("fd:%d value retained for %"PRId64"ns pos:%d\n",
> +				 xe, igt_nsec_elapsed(&tv), i);
> +		}
> +		igt_assert_neq(READ_ONCE(ptr[i]), i);
> +	}
> +
> +	munmap(ptr, size);
> +}
> +
> +igt_main
> +{
> +	int xe;
> +
> +	igt_fixture {
> +		xe = drm_open_driver(DRIVER_XE);
> +	}
> +
> +	igt_subtest_f("basic")
> +		pci_membarrier(xe);
> +
> +	igt_fixture
> +		drm_close_driver(xe);
> +}
> diff --git a/tests/meson.build b/tests/meson.build
> index 34b87b125..15131d812 100644
> --- a/tests/meson.build
> +++ b/tests/meson.build
> @@ -306,6 +306,7 @@ intel_xe_progs = [
>   	'xe_noexec_ping_pong',
>   	'xe_oa',
>   	'xe_pat',
> +        'xe_pci_membarrier',
>   	'xe_peer2peer',
>   	'xe_pm',
>   	'xe_pm_residency',