[PATCH i-g-t 10/14] lib/intel_bufops: Provide pread/pwrite based fallback when we don't have WC

[Kamil Konieczny]

Hi Ville,
On 2024-10-04 at 13:41:17 +0300, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> The linear<->tiled conversion code currently assume that we may
> be able to use either cpu or wc mmaps. That is not true on all
> systems. As a last resort provide a pread/pwrite based fallback.
> 
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> ---
>  lib/intel_bufops.c | 68 ++++++++++++++++++++++++++++++++++++++--------
>  1 file changed, 56 insertions(+), 12 deletions(-)
> 
> diff --git a/lib/intel_bufops.c b/lib/intel_bufops.c
> index 619222019fd8..641f1dae91b5 100644
> --- a/lib/intel_bufops.c
> +++ b/lib/intel_bufops.c
> @@ -549,10 +549,12 @@ static void __copy_ccs(struct buf_ops *bops, struct intel_buf *buf,
>  	munmap(map, size);
>  }
>  
> -static void *mmap_write(int fd, struct intel_buf *buf)
> +static void *mmap_write(int fd, const struct intel_buf *buf, bool *malloced)
>  {
>  	void *map = NULL;
>  
> +	*malloced = false;
> +
>  	if (buf->bops->driver == INTEL_DRIVER_XE)
>  		return xe_bo_map(fd, buf->handle, buf->surface[0].size);
>  
> @@ -580,7 +582,7 @@ static void *mmap_write(int fd, struct intel_buf *buf)
>  				       I915_GEM_DOMAIN_CPU);
>  	}
>  
> -	if (!map) {
> +	if (!map && gem_mmap__has_wc(fd)) {
>  		map = __gem_mmap_offset__wc(fd, buf->handle, 0, buf->surface[0].size,
>  					    PROT_READ | PROT_WRITE);
>  		if (!map)
> @@ -591,13 +593,32 @@ static void *mmap_write(int fd, struct intel_buf *buf)
>  			       I915_GEM_DOMAIN_WC, I915_GEM_DOMAIN_WC);
>  	}
>  
> +	if (!map) {
> +		*malloced = true;

I would move that after igt_assert.

> +
> +		map = malloc(buf->surface[0].size);
> +		igt_assert(map);
> +	}
> +
>  	return map;
>  }
>  
> -static void *mmap_read(int fd, struct intel_buf *buf)
> +static void munmap_write(void *map, int fd, const struct intel_buf *buf, bool malloced)
> +{
> +	if (malloced) {
> +		igt_assert(__gem_write(fd, buf->handle, 0, map, buf->surface[0].size) == 0);
> +		free(map);
> +	} else {
> +		munmap(map, buf->surface[0].size);
> +	}
> +}
> +
> +static void *mmap_read(int fd, struct intel_buf *buf, bool *malloced)
>  {
>  	void *map = NULL;
>  
> +	*malloced = false;
> +
>  	if (buf->bops->driver == INTEL_DRIVER_XE)
>  		return xe_bo_map(fd, buf->handle, buf->surface[0].size);
>  
> @@ -622,7 +643,7 @@ static void *mmap_read(int fd, struct intel_buf *buf)
>  			gem_set_domain(fd, buf->handle, I915_GEM_DOMAIN_CPU, 0);
>  	}
>  
> -	if (!map) {
> +	if (!map && gem_mmap__has_wc(fd)) {
>  		map = __gem_mmap_offset__wc(fd, buf->handle, 0, buf->surface[0].size,
>  					    PROT_READ);
>  		if (!map)
> @@ -632,9 +653,24 @@ static void *mmap_read(int fd, struct intel_buf *buf)
>  		gem_set_domain(fd, buf->handle, I915_GEM_DOMAIN_WC, 0);
>  	}
>  
> +	if (!map) {
> +		map = malloc(buf->surface[0].size);
> +		igt_assert(map);

Add here:
		*malloced = true;

Regards,
Kamil

> +
> +		igt_assert(__gem_read(fd, buf->handle, 0, map, buf->surface[0].size) == 0);
> +	}
> +
>  	return map;
>  }
>  
> +static void munmap_read(void *map, int fd, const struct intel_buf *buf, bool malloced)
> +{
> +	if (malloced)
> +		free(map);
> +	else
> +		munmap(map, buf->surface[0].size);
> +}
> +
>  static void __copy_linear_to(int fd, struct intel_buf *buf,
>  			     const uint32_t *linear,
>  			     int tiling, uint32_t swizzle)
> @@ -642,7 +678,10 @@ static void __copy_linear_to(int fd, struct intel_buf *buf,
>  	const tile_fn fn = __get_tile_fn_ptr(fd, tiling);
>  	int height = intel_buf_height(buf);
>  	int width = intel_buf_width(buf);
> -	void *map = mmap_write(fd, buf);
> +	bool malloced;
> +	void *map;
> +
> +	map = mmap_write(fd, buf, &malloced);
>  
>  	for (int y = 0; y < height; y++) {
>  		for (int x = 0; x < width; x++) {
> @@ -655,7 +694,7 @@ static void __copy_linear_to(int fd, struct intel_buf *buf,
>  		}
>  	}
>  
> -	munmap(map, buf->surface[0].size);
> +	munmap_write(map, fd, buf, malloced);
>  }
>  
>  static void copy_linear_to_none(struct buf_ops *bops, struct intel_buf *buf,
> @@ -706,7 +745,10 @@ static void __copy_to_linear(int fd, struct intel_buf *buf,
>  	const tile_fn fn = __get_tile_fn_ptr(fd, tiling);
>  	int height = intel_buf_height(buf);
>  	int width = intel_buf_width(buf);
> -	void *map = mmap_write(fd, buf);
> +	bool malloced;
> +	void *map;
> +
> +	map = mmap_write(fd, buf, &malloced);
>  
>  	for (int y = 0; y < height; y++) {
>  		for (int x = 0; x < width; x++) {
> @@ -719,7 +761,7 @@ static void __copy_to_linear(int fd, struct intel_buf *buf,
>  		}
>  	}
>  
> -	munmap(map, buf->surface[0].size);
> +	munmap_write(map, fd, buf, malloced);
>  }
>  
>  static void copy_none_to_linear(struct buf_ops *bops, struct intel_buf *buf,
> @@ -803,25 +845,27 @@ static void copy_gtt_to_linear(struct buf_ops *bops, struct intel_buf *buf,
>  static void copy_linear_to_wc(struct buf_ops *bops, struct intel_buf *buf,
>  			      uint32_t *linear)
>  {
> +	bool malloced;
>  	void *map;
>  
>  	DEBUGFN();
>  
> -	map = mmap_write(bops->fd, buf);
> +	map = mmap_write(bops->fd, buf, &malloced);
>  	memcpy(map, linear, buf->surface[0].size);
> -	munmap(map, buf->surface[0].size);
> +	munmap_write(map, bops->fd, buf, malloced);
>  }
>  
>  static void copy_wc_to_linear(struct buf_ops *bops, struct intel_buf *buf,
>  			      uint32_t *linear)
>  {
> +	bool malloced;
>  	void *map;
>  
>  	DEBUGFN();
>  
> -	map = mmap_read(bops->fd, buf);
> +	map = mmap_read(bops->fd, buf, &malloced);
>  	igt_memcpy_from_wc(linear, map, buf->surface[0].size);
> -	munmap(map, buf->surface[0].size);
> +	munmap_read(map, bops->fd, buf, malloced);
>  }
>  
>  void intel_buf_to_linear(struct buf_ops *bops, struct intel_buf *buf,
> -- 
> 2.45.2
>