[igt-dev] [i-g-t] lib/ioctl_wrappers: Keep IGT working without pread/pwrite ioctls

Dave Airlie airlied at linux.ie
Mon Jan 11 20:46:55 UTC 2021


> The general direction at this time is to phase out pread/write ioctls
> and not support them in future products. This means IGT must handle
> the absence of these ioctls. This patch does this by modifying
> gem_read() and gem_write() to do the read/write using the pread/pwrite
> ioctls first but when these ioctls are unavailable fall back to doing
> the read/write using a combination of mmap and memcpy.
> 
> Callers who must absolutely use the pread/pwrite ioctls (such as tests
> which test these ioctls or must otherwise only use the pread/pwrite
> ioctls) must use gem_require_pread_pwrite() to skip when these ioctls
> are not available.
> 
> v1: Removed __gem_pread, gem_pread, __gem_pwrite and gem_pwrite
>     introduced previously since they are not necessary,
>     gem_require_pread_pwrite is sufficient
> v2: Fix CI failures in gem_advise and gen9_exec_parse by introducing
>     gem_require_pread_pwrite
> v3: Skip mmap for 0 length read/write's
> v4: Remove redundant igt_assert's
> v5: Re-run
> v6: s/EOPNOTSUPP/-EOPNOTSUPP/

There appears to be some push back on landing this,

Acked-by: Dave Airlie <airlied at redhat.com>

If there are testing reasons for keeping pread/pwrite then they should
be done with a test interface via debugfs or hidden behind a big
unstable testing trapdoor, not a uAPI for other userpsace to use.

Dave.

> 
> Reviewed-by: Zbigniew Kempczyński <zbigniew.kempczynski at intel.com>
> Signed-off-by: Ashutosh Dixit <ashutosh.dixit at intel.com>
> ---
>  lib/ioctl_wrappers.c                        | 135 +++++++++++++++++++-
>  lib/ioctl_wrappers.h                        |   3 +
>  tests/i915/gem_madvise.c                    |   2 +
>  tests/i915/gem_partial_pwrite_pread.c       |   1 +
>  tests/i915/gem_pread.c                      |   1 +
>  tests/i915/gem_pread_after_blit.c           |   1 +
>  tests/i915/gem_pwrite.c                     |   1 +
>  tests/i915/gem_pwrite_snooped.c             |   1 +
>  tests/i915/gem_readwrite.c                  |   1 +
>  tests/i915/gem_set_tiling_vs_pwrite.c       |   1 +
>  tests/i915/gem_tiled_partial_pwrite_pread.c |   1 +
>  tests/i915/gem_tiled_pread_basic.c          |   1 +
>  tests/i915/gem_tiled_pread_pwrite.c         |   1 +
>  tests/i915/gem_userptr_blits.c              |   2 +
>  tests/i915/gen9_exec_parse.c                |   4 +-
>  15 files changed, 149 insertions(+), 7 deletions(-)
> 
> diff --git a/lib/ioctl_wrappers.c b/lib/ioctl_wrappers.c
> index edac50f0f..ac77b3eb6 100644
> --- a/lib/ioctl_wrappers.c
> +++ b/lib/ioctl_wrappers.c
> @@ -55,6 +55,7 @@
>  #include "igt_debugfs.h"
>  #include "igt_sysfs.h"
>  #include "config.h"
> +#include "i915/gem_mman.h"
>  
>  #ifdef HAVE_VALGRIND
>  #include <valgrind/valgrind.h>
> @@ -323,6 +324,70 @@ void gem_close(int fd, uint32_t handle)
>  	do_ioctl(fd, DRM_IOCTL_GEM_CLOSE, &close_bo);
>  }
>  
> +static bool is_cache_coherent(int fd, uint32_t handle)
> +{
> +	return gem_get_caching(fd, handle) != I915_CACHING_NONE;
> +}
> +
> +static void mmap_write(int fd, uint32_t handle, uint64_t offset,
> +		       const void *buf, uint64_t length)
> +{
> +	void *map = NULL;
> +
> +	if (!length)
> +		return;
> +
> +	if (is_cache_coherent(fd, handle)) {
> +		/* offset arg for mmap functions must be 0 */
> +		map = __gem_mmap__cpu_coherent(fd, handle, 0, offset + length,
> +					       PROT_READ | PROT_WRITE);
> +		if (map)
> +			gem_set_domain(fd, handle,
> +				       I915_GEM_DOMAIN_CPU, I915_GEM_DOMAIN_CPU);
> +	}
> +
> +	if (!map) {
> +		map = __gem_mmap_offset__wc(fd, handle, 0, offset + length,
> +					    PROT_READ | PROT_WRITE);
> +		if (!map)
> +			map = gem_mmap__wc(fd, handle, 0, offset + length,
> +					   PROT_READ | PROT_WRITE);
> +		gem_set_domain(fd, handle,
> +			       I915_GEM_DOMAIN_WC, I915_GEM_DOMAIN_WC);
> +	}
> +
> +	memcpy(map + offset, buf, length);
> +	munmap(map, offset + length);
> +}
> +
> +static void mmap_read(int fd, uint32_t handle, uint64_t offset, void *buf, uint64_t length)
> +{
> +	void *map = NULL;
> +
> +	if (!length)
> +		return;
> +
> +	if (gem_has_llc(fd) || is_cache_coherent(fd, handle)) {
> +		/* offset arg for mmap functions must be 0 */
> +		map = __gem_mmap__cpu_coherent(fd, handle, 0,
> +					       offset + length, PROT_READ);
> +		if (map)
> +			gem_set_domain(fd, handle, I915_GEM_DOMAIN_CPU, 0);
> +	}
> +
> +	if (!map) {
> +		map = __gem_mmap_offset__wc(fd, handle, 0, offset + length,
> +					    PROT_READ);
> +		if (!map)
> +			map = gem_mmap__wc(fd, handle, 0, offset + length,
> +					   PROT_READ);
> +		gem_set_domain(fd, handle, I915_GEM_DOMAIN_WC, 0);
> +	}
> +
> +	memcpy(buf, map + offset, length);
> +	munmap(map, offset + length);
> +}
> +
>  int __gem_write(int fd, uint32_t handle, uint64_t offset, const void *buf, uint64_t length)
>  {
>  	struct drm_i915_gem_pwrite gem_pwrite;
> @@ -348,12 +413,18 @@ int __gem_write(int fd, uint32_t handle, uint64_t offset, const void *buf, uint6
>   * @buf: pointer to the data to write into the buffer
>   * @length: size of the subrange
>   *
> - * This wraps the PWRITE ioctl, which is to upload a linear data to a subrange
> - * of a gem buffer object.
> + * Method to write to a gem object. Uses the PWRITE ioctl when it is
> + * available, else it uses mmap + memcpy to upload linear data to a
> + * subrange of a gem buffer object.
>   */
>  void gem_write(int fd, uint32_t handle, uint64_t offset, const void *buf, uint64_t length)
>  {
> -	igt_assert_eq(__gem_write(fd, handle, offset, buf, length), 0);
> +	int ret = __gem_write(fd, handle, offset, buf, length);
> +
> +	igt_assert(ret == 0 || ret == -EOPNOTSUPP);
> +
> +	if (ret == -EOPNOTSUPP)
> +		mmap_write(fd, handle, offset, buf, length);
>  }
>  
>  int __gem_read(int fd, uint32_t handle, uint64_t offset, void *buf, uint64_t length)
> @@ -380,12 +451,64 @@ int __gem_read(int fd, uint32_t handle, uint64_t offset, void *buf, uint64_t len
>   * @buf: pointer to the data to read into
>   * @length: size of the subrange
>   *
> - * This wraps the PREAD ioctl, which is to download a linear data to a subrange
> - * of a gem buffer object.
> + * Method to read from a gem object. Uses the PREAD ioctl when it is
> + * available, else it uses mmap + memcpy to download linear data from a
> + * subrange of a gem buffer object.
>   */
>  void gem_read(int fd, uint32_t handle, uint64_t offset, void *buf, uint64_t length)
>  {
> -	igt_assert_eq(__gem_read(fd, handle, offset, buf, length), 0);
> +	int ret = __gem_read(fd, handle, offset, buf, length);
> +
> +	igt_assert(ret == 0 || ret == -EOPNOTSUPP);
> +
> +	if (ret == -EOPNOTSUPP)
> +		mmap_read(fd, handle, offset, buf, length);
> +}
> +
> +/**
> + * gem_has_pwrite
> + * @fd: open i915 drm file descriptor
> + *
> + * Feature test macro to query whether pwrite ioctl is supported
> + */
> +bool gem_has_pwrite(int fd)
> +{
> +	uint32_t handle = gem_create(fd, 4096);
> +	int buf, ret;
> +
> +	ret = __gem_write(fd, handle, 0, &buf, sizeof(buf));
> +	gem_close(fd, handle);
> +
> +	return ret != -EOPNOTSUPP;
> +}
> +
> +/**
> + * gem_has_pread
> + * @fd: open i915 drm file descriptor
> + *
> + * Feature test macro to query whether pread ioctl is supported
> + */
> +bool gem_has_pread(int fd)
> +{
> +	uint32_t handle = gem_create(fd, 4096);
> +	int buf, ret;
> +
> +	ret = __gem_read(fd, handle, 0, &buf, sizeof(buf));
> +	gem_close(fd, handle);
> +
> +	return ret != -EOPNOTSUPP;
> +}
> +
> +/**
> + * gem_require_pread_pwrite
> + * @fd: open i915 drm file descriptor
> + *
> + * Feature test macro to query whether pread/pwrite ioctls are supported
> + * and skip if they are not
> + */
> +void gem_require_pread_pwrite(int fd)
> +{
> +	igt_require(gem_has_pread(fd) && gem_has_pwrite(fd));
>  }
>  
>  int __gem_set_domain(int fd, uint32_t handle, uint32_t read, uint32_t write)
> diff --git a/lib/ioctl_wrappers.h b/lib/ioctl_wrappers.h
> index b76bea564..81166000a 100644
> --- a/lib/ioctl_wrappers.h
> +++ b/lib/ioctl_wrappers.h
> @@ -71,6 +71,9 @@ int __gem_write(int fd, uint32_t handle, uint64_t offset, const void *buf, uint6
>  void gem_write(int fd, uint32_t handle, uint64_t offset,  const void *buf, uint64_t length);
>  int __gem_read(int fd, uint32_t handle, uint64_t offset, void *buf, uint64_t length);
>  void gem_read(int fd, uint32_t handle, uint64_t offset, void *buf, uint64_t length);
> +bool gem_has_pwrite(int fd);
> +bool gem_has_pread(int fd);
> +void gem_require_pread_pwrite(int fd);
>  int __gem_set_domain(int fd, uint32_t handle, uint32_t read, uint32_t write);
>  void gem_set_domain(int fd, uint32_t handle, uint32_t read, uint32_t write);
>  int gem_wait(int fd, uint32_t handle, int64_t *timeout_ns);
> diff --git a/tests/i915/gem_madvise.c b/tests/i915/gem_madvise.c
> index 54c9befff..92e1c5192 100644
> --- a/tests/i915/gem_madvise.c
> +++ b/tests/i915/gem_madvise.c
> @@ -154,6 +154,7 @@ dontneed_before_pwrite(void)
>  	uint32_t bbe = MI_BATCH_BUFFER_END;
>  	uint32_t handle;
>  
> +	gem_require_pread_pwrite(fd);
>  	handle = gem_create(fd, OBJECT_SIZE);
>  	gem_madvise(fd, handle, I915_MADV_DONTNEED);
>  
> @@ -170,6 +171,7 @@ dontneed_before_exec(void)
>  	struct drm_i915_gem_exec_object2 exec;
>  	uint32_t buf[] = { MI_BATCH_BUFFER_END, 0 };
>  
> +	gem_require_pread_pwrite(fd);
>  	memset(&execbuf, 0, sizeof(execbuf));
>  	memset(&exec, 0, sizeof(exec));
>  
> diff --git a/tests/i915/gem_partial_pwrite_pread.c b/tests/i915/gem_partial_pwrite_pread.c
> index b10284721..fd7b19f31 100644
> --- a/tests/i915/gem_partial_pwrite_pread.c
> +++ b/tests/i915/gem_partial_pwrite_pread.c
> @@ -281,6 +281,7 @@ igt_main
>  		data.drm_fd = drm_open_driver(DRIVER_INTEL);
>  		igt_require_gem(data.drm_fd);
>  		gem_require_blitter(data.drm_fd);
> +		gem_require_pread_pwrite(data.drm_fd);
>  
>  		data.devid = intel_get_drm_devid(data.drm_fd);
>  		data.bops = buf_ops_create(data.drm_fd);
> diff --git a/tests/i915/gem_pread.c b/tests/i915/gem_pread.c
> index 6d12b8e9f..db1eacedc 100644
> --- a/tests/i915/gem_pread.c
> +++ b/tests/i915/gem_pread.c
> @@ -149,6 +149,7 @@ igt_main_args("s:", NULL, help_str, opt_handler, NULL)
>  
>  	igt_fixture {
>  		fd = drm_open_driver(DRIVER_INTEL);
> +		gem_require_pread_pwrite(fd);
>  
>  		dst = gem_create(fd, object_size);
>  		src = malloc(object_size);
> diff --git a/tests/i915/gem_pread_after_blit.c b/tests/i915/gem_pread_after_blit.c
> index 81454c930..5c99d0887 100644
> --- a/tests/i915/gem_pread_after_blit.c
> +++ b/tests/i915/gem_pread_after_blit.c
> @@ -212,6 +212,7 @@ igt_main
>  	igt_fixture {
>  		fd = drm_open_driver(DRIVER_INTEL);
>  		igt_require_gem(fd);
> +		gem_require_pread_pwrite(fd);
>  
>  		bufmgr = drm_intel_bufmgr_gem_init(fd, 4096);
>  		drm_intel_bufmgr_gem_enable_reuse(bufmgr);
> diff --git a/tests/i915/gem_pwrite.c b/tests/i915/gem_pwrite.c
> index e491263fd..eea51f978 100644
> --- a/tests/i915/gem_pwrite.c
> +++ b/tests/i915/gem_pwrite.c
> @@ -317,6 +317,7 @@ igt_main_args("s:", NULL, help_str, opt_handler, NULL)
>  
>  	igt_fixture {
>  		fd = drm_open_driver(DRIVER_INTEL);
> +		gem_require_pread_pwrite(fd);
>  
>  		dst = gem_create(fd, object_size);
>  		src = malloc(object_size);
> diff --git a/tests/i915/gem_pwrite_snooped.c b/tests/i915/gem_pwrite_snooped.c
> index 4a3395241..a2eca6afc 100644
> --- a/tests/i915/gem_pwrite_snooped.c
> +++ b/tests/i915/gem_pwrite_snooped.c
> @@ -132,6 +132,7 @@ igt_simple_main
>  	fd = drm_open_driver(DRIVER_INTEL);
>  	igt_require_gem(fd);
>  	gem_require_blitter(fd);
> +	gem_require_pread_pwrite(fd);
>  
>  	devid = intel_get_drm_devid(fd);
>  	bufmgr = drm_intel_bufmgr_gem_init(fd, 4096);
> diff --git a/tests/i915/gem_readwrite.c b/tests/i915/gem_readwrite.c
> index 6b2977c1c..ca31741c6 100644
> --- a/tests/i915/gem_readwrite.c
> +++ b/tests/i915/gem_readwrite.c
> @@ -83,6 +83,7 @@ igt_main
>  
>  	igt_fixture {
>  		fd = drm_open_driver(DRIVER_INTEL);
> +		gem_require_pread_pwrite(fd);
>  
>  		handle = gem_create(fd, OBJECT_SIZE);
>  	}
> diff --git a/tests/i915/gem_set_tiling_vs_pwrite.c b/tests/i915/gem_set_tiling_vs_pwrite.c
> index 302ea24b6..8f38c9b9b 100644
> --- a/tests/i915/gem_set_tiling_vs_pwrite.c
> +++ b/tests/i915/gem_set_tiling_vs_pwrite.c
> @@ -55,6 +55,7 @@ igt_simple_main
>  
>  	fd = drm_open_driver(DRIVER_INTEL);
>  	igt_require(gem_available_fences(fd) > 0);
> +	gem_require_pread_pwrite(fd);
>  
>  	for (int i = 0; i < OBJECT_SIZE/4; i++)
>  		data[i] = i;
> diff --git a/tests/i915/gem_tiled_partial_pwrite_pread.c b/tests/i915/gem_tiled_partial_pwrite_pread.c
> index 7de5358b2..0c4545990 100644
> --- a/tests/i915/gem_tiled_partial_pwrite_pread.c
> +++ b/tests/i915/gem_tiled_partial_pwrite_pread.c
> @@ -270,6 +270,7 @@ igt_main
>  		igt_require_gem(fd);
>  		gem_require_mappable_ggtt(fd);
>  		gem_require_blitter(fd);
> +		gem_require_pread_pwrite(fd);
>  
>  		bufmgr = drm_intel_bufmgr_gem_init(fd, 4096);
>  		//drm_intel_bufmgr_gem_enable_reuse(bufmgr);
> diff --git a/tests/i915/gem_tiled_pread_basic.c b/tests/i915/gem_tiled_pread_basic.c
> index 7cb644104..f8f73c03a 100644
> --- a/tests/i915/gem_tiled_pread_basic.c
> +++ b/tests/i915/gem_tiled_pread_basic.c
> @@ -127,6 +127,7 @@ igt_simple_main
>  	igt_require(gem_available_fences(fd) > 0);
>  	handle = create_bo(fd);
>  	igt_require(gem_get_tiling(fd, handle, &tiling, &swizzle));
> +	gem_require_pread_pwrite(fd);
>  
>  	devid = intel_get_drm_devid(fd);
>  
> diff --git a/tests/i915/gem_tiled_pread_pwrite.c b/tests/i915/gem_tiled_pread_pwrite.c
> index f58048faa..28490840f 100644
> --- a/tests/i915/gem_tiled_pread_pwrite.c
> +++ b/tests/i915/gem_tiled_pread_pwrite.c
> @@ -114,6 +114,7 @@ igt_simple_main
>  	
>  	fd = drm_open_driver(DRIVER_INTEL);
>  	igt_require(gem_available_fences(fd) > 0);
> +	gem_require_pread_pwrite(fd);
>  
>  	count = gem_available_fences(fd) + 1;
>  	intel_require_memory(2 * count, sizeof(linear), CHECK_RAM);
> diff --git a/tests/i915/gem_userptr_blits.c b/tests/i915/gem_userptr_blits.c
> index 268423dcd..0ccfdbd9c 100644
> --- a/tests/i915/gem_userptr_blits.c
> +++ b/tests/i915/gem_userptr_blits.c
> @@ -890,6 +890,7 @@ static int test_forbidden_ops(int fd)
>  	uint32_t handle;
>  	void *ptr;
>  
> +	gem_require_pread_pwrite(fd);
>  	igt_assert(posix_memalign(&ptr, PAGE_SIZE, PAGE_SIZE) == 0);
>  	gem_userptr(fd, ptr, PAGE_SIZE, 0, userptr_flags, &handle);
>  
> @@ -1416,6 +1417,7 @@ static void test_readonly_pwrite(int i915)
>  	 */
>  
>  	igt_require(igt_setup_clflush());
> +	gem_require_pread_pwrite(i915);
>  
>  	sz = 16 << 12;
>  	pages = mmap(NULL, sz, PROT_WRITE, MAP_ANON | MAP_PRIVATE, -1, 0);
> diff --git a/tests/i915/gen9_exec_parse.c b/tests/i915/gen9_exec_parse.c
> index 7ddb5bf2b..cfb6de080 100644
> --- a/tests/i915/gen9_exec_parse.c
> +++ b/tests/i915/gen9_exec_parse.c
> @@ -1104,8 +1104,10 @@ igt_main
>  			   -EINVAL);
>  	}
>  
> -	igt_subtest("batch-invalid-length")
> +	igt_subtest("batch-invalid-length") {
> +		gem_require_pread_pwrite(i915);
>  		test_invalid_length(i915, handle);
> +	}
>  
>  	igt_subtest("basic-rejected")
>  		test_rejected(i915, handle, false);
> 


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