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.
Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
---
drivers/gpu/drm/i915/i915_gem_context.c | 154 ++++++++++++++++++++++++
include/uapi/drm/i915_drm.h | 14 +++
2 files changed, 168 insertions(+)
diff --git a/drivers/gpu/drm/i915/i915_gem_context.c
b/drivers/gpu/drm/i915/i915_gem_context.c
index 57b4e760fa4b..1972f112d72b 100644
--- a/drivers/gpu/drm/i915/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/i915_gem_context.c
@@ -1513,8 +1513,162 @@ static int create_setparam(struct i915_user_extension
__user *ext, void *data)
return ctx_setparam(arg->ctx, &local.param);
}
+static int clone_flags(struct i915_gem_context *dst,
+ struct i915_gem_context *src)
+{
+ dst->user_flags = src->user_flags;
+ return 0;
+}
+
+static int clone_schedattr(struct i915_gem_context *dst,
+ struct i915_gem_context *src)
+{
+ dst->sched = src->sched;
+ return 0;
+}
+
+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 clone_timeline(struct i915_gem_context *dst,
+ struct i915_gem_context *src)
+{
+ if (src->timeline) {
+ GEM_BUG_ON(src->timeline == dst->timeline);
+
+ if (dst->timeline)
+ i915_timeline_put(dst->timeline);
+ dst->timeline = i915_timeline_get(src->timeline);
+ }
+
+ return 0;
+}
+
+static int clone_vm(struct i915_gem_context *dst,
+ struct i915_gem_context *src)
+{
+ struct i915_hw_ppgtt *ppgtt;
+
+ rcu_read_lock();
+ do {
+ ppgtt = READ_ONCE(src->ppgtt);
+ if (!ppgtt)
+ break;
+
+ if (!kref_get_unless_zero(&ppgtt->ref))
+ continue;
+
+ /*
+ * This ppgtt may have be reallocated between
+ * the read and the kref, and reassigned to a third
+ * context. In order to avoid inadvertent sharing
+ * of this ppgtt with that third context (and not
+ * src), we have to confirm that we have the same
+ * ppgtt after passing through the strong memory
+ * barrier implied by a successful
+ * kref_get_unless_zero().
+ *
+ * Once we have acquired the current ppgtt of src,
+ * we no longer care if it is released from src, as
+ * it cannot be reallocated elsewhere.
+ */
+
+ if (ppgtt == READ_ONCE(src->ppgtt))
+ break;
+
+ i915_ppgtt_put(ppgtt);
+ } while (1);
+ rcu_read_unlock();
+
+ if (ppgtt) {
+ __assign_ppgtt(dst, ppgtt);
+ i915_ppgtt_put(ppgtt);
+ }
+
+ return 0;
+}
+
+static int create_clone(struct i915_user_extension __user *ext, void *data)
+{
+ static int (* const fn[])(struct i915_gem_context *dst,
+ struct i915_gem_context *src) = {
+#define MAP(x, y) [ilog2(I915_CONTEXT_CLONE_##x)] = y
+ MAP(FLAGS, clone_flags),
+ MAP(SCHEDATTR, clone_schedattr),
+ MAP(SSEU, clone_sseu),
+ MAP(TIMELINE, clone_timeline),
+ MAP(VM, clone_vm),
+#undef MAP
+ };
+ struct drm_i915_gem_context_create_ext_clone local;
+ const struct create_ext *arg = data;
+ struct i915_gem_context *dst = arg->ctx;
+ struct i915_gem_context *src;
+ int err, bit;
+
+ if (copy_from_user(&local, ext, sizeof(local)))
+ return -EFAULT;
+
+ BUILD_BUG_ON(GENMASK(BITS_PER_TYPE(local.flags) - 1, ARRAY_SIZE(fn)) !=
+ I915_CONTEXT_CLONE_UNKNOWN);
+
+ if (local.flags & I915_CONTEXT_CLONE_UNKNOWN)
+ return -EINVAL;
+
+ if (local.rsvd)
+ return -EINVAL;
+
+ rcu_read_lock();
+ src = __i915_gem_context_lookup_rcu(arg->fpriv, local.clone_id);
+ rcu_read_unlock();
+ if (!src)
+ return -ENOENT;
+
+ GEM_BUG_ON(src == dst);
+
+ for (bit = 0; bit < ARRAY_SIZE(fn); bit++) {
+ if (!(local.flags & BIT(bit)))
+ continue;
+
+ err = fn[bit](dst, src);
+ if (err)
+ return err;
+ }
+
+ 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 9999f7d6a5a9..a5bdb86858f6 100644
--- a/include/uapi/drm/i915_drm.h
+++ b/include/uapi/drm/i915_drm.h
@@ -1581,6 +1581,20 @@ struct drm_i915_gem_context_create_ext_setparam {
struct drm_i915_gem_context_param param;
};
+struct drm_i915_gem_context_create_ext_clone {
+#define I915_CONTEXT_CREATE_EXT_CLONE 1
+ struct i915_user_extension base;
+ __u32 clone_id;
+ __u32 flags;
+#define I915_CONTEXT_CLONE_FLAGS (1u << 0)
+#define I915_CONTEXT_CLONE_SCHEDATTR (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;
--
2.20.1
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