On 08/03/2019 14:12, Chris Wilson wrote:
A usecase arose out of handling context recovery in mesa, whereby they
wish to recreate a context with fresh logical state but preserving all
other details of the original. Currently, they create a new context and
iterate over which bits they want to copy across, but it would much more
convenient if they were able to just pass in a target context to clone
during creation. This essentially extends the setparam during creation
to pull the details from a target context instead of the user supplied
parameters.
This one is not used by media so it will likely have to find a separate
route upstream.
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/i915_gem_context.c | 90 +++++++++++++++++++++++++
include/uapi/drm/i915_drm.h | 14 ++++
2 files changed, 104 insertions(+)
diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
index 310892b42b68..2cfc68b66944 100644
--- a/drivers/gpu/drm/i915/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/i915_gem_context.c
@@ -1428,8 +1428,98 @@ static int create_setparam(struct i915_user_extension __user *ext, void *data)
return ctx_setparam(data, &local.setparam);
}
+static int clone_sseu(struct i915_gem_context *dst,
+ struct i915_gem_context *src)
+{
+ const struct intel_sseu default_sseu =
+ intel_device_default_sseu(dst->i915);
+ struct intel_engine_cs *engine;
+ enum intel_engine_id id;
+
+ for_each_engine(engine, dst->i915, id) {
+ struct intel_context *ce;
+ struct intel_sseu sseu;
+
+ ce = intel_context_lookup(src, engine);
+ if (!ce)
+ continue;
+
+ sseu = ce->sseu;
+ if (!memcmp(&sseu, &default_sseu, sizeof(sseu)))
+ continue;
+
+ ce = intel_context_pin_lock(dst, engine);
+ if (IS_ERR(ce))
+ return PTR_ERR(ce);
+
+ ce->sseu = sseu;
+ intel_context_pin_unlock(ce);
+ }
+
+ return 0;
+}
+
+static int create_clone(struct i915_user_extension __user *ext, void *data)
+{
+ struct drm_i915_gem_context_create_ext_clone local;
+ struct i915_gem_context *dst = data;
+ struct i915_gem_context *src;
+ int err;
+
+ if (copy_from_user(&local, ext, sizeof(local)))
+ return -EFAULT;
+
+ if (local.flags & I915_CONTEXT_CLONE_UNKNOWN)
+ return -EINVAL;
+
+ if (local.rsvd)
+ return -EINVAL;
+
+ if (local.clone == dst->user_handle) /* good guess! denied. */
+ return -ENOENT;
:) Good one, but put a more obvious comment like "Cannot clone itself!".
+
+ rcu_read_lock();
+ src = __i915_gem_context_lookup_rcu(dst->file_priv, local.clone);
+ rcu_read_unlock();
+ if (!src)
+ return -ENOENT;
+
+ GEM_BUG_ON(src == dst);
+
+ if (local.flags & I915_CONTEXT_CLONE_FLAGS)
+ dst->user_flags = src->user_flags;
+
+ if (local.flags & I915_CONTEXT_CLONE_SCHED)
+ dst->sched = src->sched;
+
+ if (local.flags & I915_CONTEXT_CLONE_SSEU) {
+ err = clone_sseu(dst, src);
+ if (err)
+ return err;
+ }
+
+ if (local.flags & I915_CONTEXT_CLONE_TIMELINE && src->timeline) {
Do we want to error out if no timeline and cloning was requested?
+ if (dst->timeline)
+ i915_timeline_put(dst->timeline);
+ dst->timeline = i915_timeline_get(src->timeline);
What prevents a different thread from changing either context in
parallel and making reference counting go bad?
+ }
+
+ if (local.flags & I915_CONTEXT_CLONE_VM && src->ppgtt) {
Also fail if impossible was requested?
+ GEM_BUG_ON(dst->ppgtt == src->ppgtt);
Hm... what prevents this? Set_vm extension followed by clone could
trigger it I think.
+
+ if (dst->ppgtt)
+ i915_ppgtt_put(dst->ppgtt);
+
+ dst->ppgtt = i915_ppgtt_get(src->ppgtt);
+ i915_ppgtt_open(dst->ppgtt);
Also some locking is needed I think to make the exchange atomic.
Could use __assign_ppgtt?
+ }
+
+ return 0;
+}
+
static const i915_user_extension_fn create_extensions[] = {
[I915_CONTEXT_CREATE_EXT_SETPARAM] = create_setparam,
+ [I915_CONTEXT_CREATE_EXT_CLONE] = create_clone,
};
static bool client_is_banned(struct drm_i915_file_private *file_priv)
diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
index 007d77ff7295..50d154954d5f 100644
--- a/include/uapi/drm/i915_drm.h
+++ b/include/uapi/drm/i915_drm.h
@@ -1579,6 +1579,20 @@ struct drm_i915_gem_context_create_ext_setparam {
struct drm_i915_gem_context_param setparam;
};
+struct drm_i915_gem_context_create_ext_clone {
+#define I915_CONTEXT_CREATE_EXT_CLONE 1
+ struct i915_user_extension base;
+ __u32 clone;
id, clone_id, source_id?
+ __u32 flags;
+#define I915_CONTEXT_CLONE_FLAGS (1u << 0)
+#define I915_CONTEXT_CLONE_SCHED (1u << 1)
+#define I915_CONTEXT_CLONE_SSEU (1u << 2)
+#define I915_CONTEXT_CLONE_TIMELINE (1u << 3)
+#define I915_CONTEXT_CLONE_VM (1u << 4)
+#define I915_CONTEXT_CLONE_UNKNOWN -(I915_CONTEXT_CLONE_VM << 1)
+ __u64 rsvd;
+};
+
struct drm_i915_gem_context_destroy {
__u32 ctx_id;
__u32 pad;
Regards,
Tvrtko
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