From: Chris Wilson Date: Tue, 21 May 2019 21:11:29 +0000 (+0100) Subject: drm/i915: Allow userspace to clone contexts on creation X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=b81dde719439c8f09bb61e742ed95bfc4b33946b;p=openwrt%2Fstaging%2Fblogic.git drm/i915: Allow userspace to clone contexts on creation 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. The ideal here is that we don't expose control over anything more than can be obtained via CONTEXT_PARAM. That is userspace retains explicit control over all features, and this api is just convenience. For example, you could replace struct context_param p = { .param = CONTEXT_PARAM_VM }; param.ctx_id = old_id; gem_context_get_param(&p.param); new_id = gem_context_create(); param.ctx_id = new_id; gem_context_set_param(&p.param); gem_vm_destroy(param.value); /* drop the ref to VM_ID handle */ with struct create_ext_param p = { { .name = CONTEXT_CREATE_CLONE }, .clone_id = old_id, .flags = CLONE_FLAGS_VM } new_id = gem_context_create_ext(&p); and not have to worry about stray namespace pollution etc. Signed-off-by: Chris Wilson Reviewed-by: Tvrtko Ursulin Link: https://patchwork.freedesktop.org/patch/msgid/20190521211134.16117-5-chris@chris-wilson.co.uk --- diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c index d391d474820f..24736fcd463d 100644 --- a/drivers/gpu/drm/i915/i915_gem_context.c +++ b/drivers/gpu/drm/i915/i915_gem_context.c @@ -1723,8 +1723,214 @@ static int create_setparam(struct i915_user_extension __user *ext, void *data) return ctx_setparam(arg->fpriv, arg->ctx, &local.param); } +static int clone_engines(struct i915_gem_context *dst, + struct i915_gem_context *src) +{ + struct i915_gem_engines *e = i915_gem_context_lock_engines(src); + struct i915_gem_engines *clone; + bool user_engines; + unsigned long n; + + clone = kmalloc(struct_size(e, engines, e->num_engines), GFP_KERNEL); + if (!clone) + goto err_unlock; + + clone->i915 = dst->i915; + for (n = 0; n < e->num_engines; n++) { + if (!e->engines[n]) { + clone->engines[n] = NULL; + continue; + } + + clone->engines[n] = + intel_context_create(dst, e->engines[n]->engine); + if (!clone->engines[n]) { + __free_engines(clone, n); + goto err_unlock; + } + } + clone->num_engines = n; + + user_engines = i915_gem_context_user_engines(src); + i915_gem_context_unlock_engines(src); + + free_engines(dst->engines); + RCU_INIT_POINTER(dst->engines, clone); + if (user_engines) + i915_gem_context_set_user_engines(dst); + else + i915_gem_context_clear_user_engines(dst); + return 0; + +err_unlock: + i915_gem_context_unlock_engines(src); + return -ENOMEM; +} + +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) +{ + struct i915_gem_engines *e = i915_gem_context_lock_engines(src); + struct i915_gem_engines *clone; + unsigned long n; + int err; + + clone = dst->engines; /* no locking required; sole access */ + if (e->num_engines != clone->num_engines) { + err = -EINVAL; + goto unlock; + } + + for (n = 0; n < e->num_engines; n++) { + struct intel_context *ce = e->engines[n]; + + if (clone->engines[n]->engine->class != ce->engine->class) { + /* Must have compatible engine maps! */ + err = -EINVAL; + goto unlock; + } + + /* serialises with set_sseu */ + err = intel_context_lock_pinned(ce); + if (err) + goto unlock; + + clone->engines[n]->sseu = ce->sseu; + intel_context_unlock_pinned(ce); + } + + err = 0; +unlock: + i915_gem_context_unlock_engines(src); + return err; +} + +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(ENGINES, clone_engines), + 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 957ba8e60e02..62396d575e28 100644 --- a/include/uapi/drm/i915_drm.h +++ b/include/uapi/drm/i915_drm.h @@ -1624,6 +1624,21 @@ 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_ENGINES (1u << 0) +#define I915_CONTEXT_CLONE_FLAGS (1u << 1) +#define I915_CONTEXT_CLONE_SCHEDATTR (1u << 2) +#define I915_CONTEXT_CLONE_SSEU (1u << 3) +#define I915_CONTEXT_CLONE_TIMELINE (1u << 4) +#define I915_CONTEXT_CLONE_VM (1u << 5) +#define I915_CONTEXT_CLONE_UNKNOWN -(I915_CONTEXT_CLONE_VM << 1) + __u64 rsvd; +}; + struct drm_i915_gem_context_destroy { __u32 ctx_id; __u32 pad;