[Intel-gfx] [PATCH i-g-t 1/2] lib/i915: Add helper for copying engine maps from one context to another

[Chris Wilson]

Quoting Tvrtko Ursulin (2020-01-24 12:26:31)
> 
> On 24/01/2020 12:23, Chris Wilson wrote:
> > Quoting Tvrtko Ursulin (2020-01-24 12:17:58)
> >> From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> >>
> >> We also need to support copying across file descriptors.
> >>
> >> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> >> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> >> Cc: Sreedhar Telukuntla <sreedhar.telukuntla at intel.com>
> >> ---
> >>   lib/i915/gem_context.c | 30 ++++++++++++++++++++++++++++++
> >>   lib/i915/gem_context.h |  2 ++
> >>   2 files changed, 32 insertions(+)
> >>
> >> diff --git a/lib/i915/gem_context.c b/lib/i915/gem_context.c
> >> index 0b6a554dfe27..41957b66ca52 100644
> >> --- a/lib/i915/gem_context.c
> >> +++ b/lib/i915/gem_context.c
> >> @@ -462,3 +462,33 @@ bool gem_context_has_engine(int fd, uint32_t ctx, uint64_t engine)
> >>   
> >>          return __gem_execbuf(fd, &execbuf) == -ENOENT;
> >>   }
> >> +
> >> +/**
> >> + * gem_context_copy_engines:
> >> + * @src_fd: open i915 drm file descriptor where @src context belongs to
> >> + * @src: source engine map context id
> >> + * @dst_fd: open i915 drm file descriptor where @dst context belongs to
> >> + * @dst: destination engine map context id
> >> + *
> >> + * Special purpose wrapper for copying engine map from one context to another.
> >> + *
> >> + * In can be called regardless of whether the kernel supports context engine
> >> + * maps and is a no-op if not supported.
> >> + */
> >> +void
> >> +gem_context_copy_engines(int src_fd, uint32_t src, int dst_fd, uint32_t dst)
> >> +{
> >> +       I915_DEFINE_CONTEXT_PARAM_ENGINES(engines, I915_EXEC_RING_MASK + 1);
> >> +       struct drm_i915_gem_context_param param = {
> >> +               .param = I915_CONTEXT_PARAM_ENGINES,
> >> +               .ctx_id = src,
> >> +               .size = sizeof(engines),
> >> +               .value = to_user_pointer(&engines),
> >> +       };
> >> +
> >> +       if (__gem_context_get_param(src_fd, &param) || !param.size)
> >> +               return;
> >> +
> >> +       param.ctx_id = dst;
> >> +       gem_context_set_param(dst_fd, &param);
> > 
> > You don't want to copy across the use-default set? You presume dst is
> > already using defaults?
> 
> Hm hm.. not sure. I guess it would be most in-line with what the helper 
> say on the tin to copy as is. I'll respin.

In which case, a preemptive
Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
-Chris