[PATCH 3/9] i915: Add support for drm syncobjs

Jason Ekstrand jason at jlekstrand.net
Mon Aug 14 02:58:44 UTC 2017


We now have reviewed userspace for this:

https://lists.freedesktop.org/archives/mesa-dev/2017-August/166200.html

On Fri, Aug 11, 2017 at 3:39 PM, Jason Ekstrand <jason at jlekstrand.net>
wrote:

> This commit adds support for waiting on or signaling DRM syncobjs as
> part of execbuf.  It does so by hijacking the currently unused cliprects
> pointer to instead point to an array of i915_gem_exec_fence structs
> which containe a DRM syncobj and a flags parameter which specifies
> whether to wait on it or to signal it.  This implementation
> theoretically allows for both flags to be set in which case it waits on
> the dma_fence that was in the syncobj and then immediately replaces it
> with the dma_fence from the current execbuf.
>
> v2:
>  - Rebase on new syncobj API
> v3:
>  - Pull everything out into helpers
>  - Do all allocation in gem_execbuffer2
>  - Pack the flags in the bottom 2 bits of the drm_syncobj*
> v4:
>  - Prevent a potential race on syncobj->fence
>
> Testcase: igt/gem_exec_fence/syncobj*
> Signed-off-by: Jason Ekstrand <jason at jlekstrand.net>
> Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> ---
>  drivers/gpu/drm/i915/i915_drv.c            |   3 +-
>  drivers/gpu/drm/i915/i915_gem_execbuffer.c | 146
> ++++++++++++++++++++++++++++-
>  include/uapi/drm/i915_drm.h                |  30 +++++-
>  3 files changed, 171 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_
> drv.c
> index 4c96a72..50db490 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -388,6 +388,7 @@ static int i915_getparam(struct drm_device *dev, void
> *data,
>         case I915_PARAM_HAS_EXEC_FENCE:
>         case I915_PARAM_HAS_EXEC_CAPTURE:
>         case I915_PARAM_HAS_EXEC_BATCH_FIRST:
> +       case I915_PARAM_HAS_EXEC_FENCE_ARRAY:
>                 /* For the time being all of these are always true;
>                  * if some supported hardware does not have one of these
>                  * features this value needs to be provided from
> @@ -2738,7 +2739,7 @@ static struct drm_driver driver = {
>          */
>         .driver_features =
>             DRIVER_HAVE_IRQ | DRIVER_IRQ_SHARED | DRIVER_GEM |
> DRIVER_PRIME |
> -           DRIVER_RENDER | DRIVER_MODESET | DRIVER_ATOMIC,
> +           DRIVER_RENDER | DRIVER_MODESET | DRIVER_ATOMIC |
> DRIVER_SYNCOBJ,
>         .release = i915_driver_release,
>         .open = i915_driver_open,
>         .lastclose = i915_driver_lastclose,
> diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> index 929f275..8df845b 100644
> --- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> +++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> @@ -33,6 +33,7 @@
>
>  #include <drm/drmP.h>
>  #include <drm/i915_drm.h>
> +#include <drm/drm_syncobj.h>
>
>  #include "i915_drv.h"
>  #include "i915_gem_clflush.h"
> @@ -1882,8 +1883,10 @@ static bool i915_gem_check_execbuffer(struct
> drm_i915_gem_execbuffer2 *exec)
>                 return false;
>
>         /* Kernel clipping was a DRI1 misfeature */
> -       if (exec->num_cliprects || exec->cliprects_ptr)
> -               return false;
> +       if (!(exec->flags & I915_EXEC_FENCE_ARRAY)) {
> +               if (exec->num_cliprects || exec->cliprects_ptr)
> +                       return false;
> +       }
>
>         if (exec->DR4 == 0xffffffff) {
>                 DRM_DEBUG("UXA submitting garbage DR4, fixing up\n");
> @@ -2114,11 +2117,125 @@ eb_select_engine(struct drm_i915_private
> *dev_priv,
>         return engine;
>  }
>
> +static void __free_fence_array(struct drm_syncobj **fences, unsigned int
> n)
> +{
> +       while (n--)
> +               drm_syncobj_put(ptr_mask_bits(fences[n], 2));
> +       kvfree(fences);
> +}
> +
> +static struct drm_syncobj **get_fence_array(struct
> drm_i915_gem_execbuffer2 *args,
> +                                           struct drm_file *file)
> +{
> +       const unsigned int nfences = args->num_cliprects;
> +       struct drm_i915_gem_exec_fence __user *user;
> +       struct drm_syncobj **fences;
> +       unsigned int n;
> +       int err;
> +
> +       if (!(args->flags & I915_EXEC_FENCE_ARRAY))
> +               return NULL;
> +
> +       if (nfences > SIZE_MAX / sizeof(*fences))
> +               return ERR_PTR(-EINVAL);
> +
> +       user = u64_to_user_ptr(args->cliprects_ptr);
> +       if (!access_ok(VERIFY_READ, user, nfences * 2 * sizeof(u32)))
> +               return ERR_PTR(-EFAULT);
> +
> +       fences = kvmalloc_array(args->num_cliprects, sizeof(*fences),
> +                               __GFP_NOWARN | GFP_TEMPORARY);
> +       if (!fences)
> +               return ERR_PTR(-ENOMEM);
> +
> +       for (n = 0; n < nfences; n++) {
> +               struct drm_i915_gem_exec_fence fence;
> +               struct drm_syncobj *syncobj;
> +
> +               if (__copy_from_user(&fence, user++, sizeof(fence))) {
> +                       err = -EFAULT;
> +                       goto err;
> +               }
> +
> +               syncobj = drm_syncobj_find(file, fence.handle);
> +               if (!syncobj) {
> +                       DRM_DEBUG("Invalid syncobj handle provided\n");
> +                       err = -EINVAL;
> +                       goto err;
> +               }
> +
> +               fences[n] = ptr_pack_bits(syncobj, fence.flags, 2);
> +       }
> +
> +       return fences;
> +
> +err:
> +       __free_fence_array(fences, n);
> +       return ERR_PTR(err);
> +}
> +
> +static void put_fence_array(struct drm_i915_gem_execbuffer2 *args,
> +                           struct drm_syncobj **fences)
> +{
> +       if (!fences)
> +               return;
> +       __free_fence_array(fences, args->num_cliprects);
> +}
> +
> +static int await_fence_array(struct i915_execbuffer *eb,
> +                            struct drm_syncobj **fences)
> +{
> +       const unsigned int nfences = eb->args->num_cliprects;
> +       unsigned int n;
> +       int err;
> +
> +       for (n = 0; n < nfences; n++) {
> +               struct drm_syncobj *syncobj;
> +               struct dma_fence *fence;
> +               unsigned int flags;
> +
> +               syncobj = ptr_unpack_bits(fences[n], &flags, 2);
> +               if (!(flags & I915_EXEC_FENCE_WAIT))
> +                       continue;
> +
> +               fence = drm_syncobj_fence_get(syncobj);
> +               if (!fence)
> +                   return -EINVAL;
> +
> +               err = i915_gem_request_await_dma_fence(eb->request,
> fence);
> +               dma_fence_put(fence);
> +               if (err < 0)
> +                       return err;
> +       }
> +
> +       return 0;
> +}
> +
> +static void signal_fence_array(struct i915_execbuffer *eb,
> +                              struct drm_syncobj **fences)
> +{
> +       const unsigned int nfences = eb->args->num_cliprects;
> +       struct dma_fence * const fence = &eb->request->fence;
> +       unsigned int n;
> +
> +       for (n = 0; n < nfences; n++) {
> +               struct drm_syncobj *syncobj;
> +               unsigned int flags;
> +
> +               syncobj = ptr_unpack_bits(fences[n], &flags, 2);
> +               if (!(flags & I915_EXEC_FENCE_SIGNAL))
> +                       continue;
> +
> +               drm_syncobj_replace_fence(syncobj, fence);
> +       }
> +}
> +
>  static int
>  i915_gem_do_execbuffer(struct drm_device *dev,
>                        struct drm_file *file,
>                        struct drm_i915_gem_execbuffer2 *args,
> -                      struct drm_i915_gem_exec_object2 *exec)
> +                      struct drm_i915_gem_exec_object2 *exec,
> +                      struct drm_syncobj **fences)
>  {
>         struct i915_execbuffer eb;
>         struct dma_fence *in_fence = NULL;
> @@ -2304,6 +2421,12 @@ i915_gem_do_execbuffer(struct drm_device *dev,
>                         goto err_request;
>         }
>
> +       if (fences) {
> +               err = await_fence_array(&eb, fences);
> +               if (err < 0)
> +                       goto err_request;
> +       }
> +
>         if (out_fence_fd != -1) {
>                 out_fence = sync_file_create(&eb.request->fence);
>                 if (!out_fence) {
> @@ -2327,6 +2450,9 @@ i915_gem_do_execbuffer(struct drm_device *dev,
>         __i915_add_request(eb.request, err == 0);
>         add_to_client(eb.request, file);
>
> +       if (fences)
> +               signal_fence_array(&eb, fences);
> +
>         if (out_fence) {
>                 if (err == 0) {
>                         fd_install(out_fence_fd, out_fence->file);
> @@ -2428,7 +2554,7 @@ i915_gem_execbuffer(struct drm_device *dev, void
> *data,
>                         exec2_list[i].flags = 0;
>         }
>
> -       err = i915_gem_do_execbuffer(dev, file, &exec2, exec2_list);
> +       err = i915_gem_do_execbuffer(dev, file, &exec2, exec2_list, NULL);
>         if (exec2.flags & __EXEC_HAS_RELOC) {
>                 struct drm_i915_gem_exec_object __user *user_exec_list =
>                         u64_to_user_ptr(args->buffers_ptr);
> @@ -2460,6 +2586,7 @@ i915_gem_execbuffer2(struct drm_device *dev, void
> *data,
>         const size_t sz = sizeof(struct drm_i915_gem_exec_object2);
>         struct drm_i915_gem_execbuffer2 *args = data;
>         struct drm_i915_gem_exec_object2 *exec2_list;
> +       struct drm_syncobj **fences = NULL;
>         int err;
>
>         if (args->buffer_count < 1 || args->buffer_count > SIZE_MAX / sz -
> 1) {
> @@ -2486,7 +2613,15 @@ i915_gem_execbuffer2(struct drm_device *dev, void
> *data,
>                 return -EFAULT;
>         }
>
> -       err = i915_gem_do_execbuffer(dev, file, args, exec2_list);
> +       if (args->flags & I915_EXEC_FENCE_ARRAY) {
> +               fences = get_fence_array(args, file);
> +               if (IS_ERR(fences)) {
> +                       kvfree(exec2_list);
> +                       return PTR_ERR(fences);
> +               }
> +       }
> +
> +       err = i915_gem_do_execbuffer(dev, file, args, exec2_list, fences);
>
>         /*
>          * Now that we have begun execution of the batchbuffer, we ignore
> @@ -2517,5 +2652,6 @@ i915_gem_execbuffer2(struct drm_device *dev, void
> *data,
>
>         args->flags &= ~__I915_EXEC_UNKNOWN_FLAGS;
>         kvfree(exec2_list);
> +       put_fence_array(args, fences);
>         return err;
>  }
> diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
> index 7ccbd6a..bb3fb49 100644
> --- a/include/uapi/drm/i915_drm.h
> +++ b/include/uapi/drm/i915_drm.h
> @@ -431,6 +431,11 @@ typedef struct drm_i915_irq_wait {
>   */
>  #define I915_PARAM_HAS_EXEC_BATCH_FIRST         48
>
> +/* Query whether DRM_I915_GEM_EXECBUFFER2 supports supplying an array of
> + * drm_i915_gem_exec_fence structures.  See I915_EXEC_FENCE_ARRAY.
> + */
> +#define I915_PARAM_HAS_EXEC_FENCE_ARRAY  49
> +
>  typedef struct drm_i915_getparam {
>         __s32 param;
>         /*
> @@ -812,6 +817,17 @@ struct drm_i915_gem_exec_object2 {
>         __u64 rsvd2;
>  };
>
> +struct drm_i915_gem_exec_fence {
> +       /**
> +        * User's handle for a dma-fence to wait on or signal.
> +        */
> +       __u32 handle;
> +
> +#define I915_EXEC_FENCE_WAIT            (1<<0)
> +#define I915_EXEC_FENCE_SIGNAL          (1<<1)
> +       __u32 flags;
> +};
> +
>  struct drm_i915_gem_execbuffer2 {
>         /**
>          * List of gem_exec_object2 structs
> @@ -826,7 +842,10 @@ struct drm_i915_gem_execbuffer2 {
>         __u32 DR1;
>         __u32 DR4;
>         __u32 num_cliprects;
> -       /** This is a struct drm_clip_rect *cliprects */
> +       /** This is a struct drm_clip_rect *cliprects if
> I915_EXEC_FENCE_ARRAY
> +        * is not set.  If I915_EXEC_FENCE_ARRAY is set, then this is a
> +        * struct drm_i915_gem_exec_fence *fences.
> +        */
>         __u64 cliprects_ptr;
>  #define I915_EXEC_RING_MASK              (7<<0)
>  #define I915_EXEC_DEFAULT                (0<<0)
> @@ -927,7 +946,14 @@ struct drm_i915_gem_execbuffer2 {
>   * element).
>   */
>  #define I915_EXEC_BATCH_FIRST          (1<<18)
> -#define __I915_EXEC_UNKNOWN_FLAGS (-(I915_EXEC_BATCH_FIRST<<1))
> +
> +/* Setting I915_FENCE_ARRAY implies that num_cliprects and cliprects_ptr
> + * define an array of i915_gem_exec_fence structures which specify a set
> of
> + * dma fences to wait upon or signal.
> + */
> +#define I915_EXEC_FENCE_ARRAY   (1<<19)
> +
> +#define __I915_EXEC_UNKNOWN_FLAGS (-(I915_EXEC_FENCE_ARRAY<<1))
>
>  #define I915_EXEC_CONTEXT_ID_MASK      (0xffffffff)
>  #define i915_execbuffer2_set_context_id(eb2, context) \
> --
> 2.5.0.400.gff86faf
>
>
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