[PATCH i-g-t v2 2/4] lib/intel_bufops: Provide pread/pwrite based fallback when we don't have WC

[Juha-Pekka Heikkilä]

Reviewed-by: Juha-Pekka Heikkila <juhapekka.heikkila at gmail.com>

On Fri, Nov 22, 2024 at 10:48 AM Ville Syrjala
<ville.syrjala at linux.intel.com> 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.
>
> v2: Add missing *malloced=true (Kamil)
>
> Cc: Kamil Konieczny <kamil.konieczny at linux.intel.com>
> 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..15f23d0e1375 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 +593,31 @@ static void *mmap_write(int fd, struct intel_buf *buf)
>                                I915_GEM_DOMAIN_WC, I915_GEM_DOMAIN_WC);
>         }
>
> +       if (!map) {
> +               map = malloc(buf->surface[0].size);
> +               igt_assert(map);
> +               *malloced = true;
> +       }
> +
>         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 +642,7 @@ 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 +652,25 @@ 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);
> +               *malloced = true;
> +
> +               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
>