On Tue, Jun 08, 2021 at 11:35:58PM -0500, Jason Ekstrand wrote: > The current context uAPI allows for two methods of setting context > parameters: SET_CONTEXT_PARAM and CONTEXT_CREATE_EXT_SETPARAM. The > former is allowed to be called at any time while the later happens as > part of GEM_CONTEXT_CREATE. Currently, everything settable via one is > settable via the other. While some params are fairly simple and setting > them on a live context is harmless such the context priority, others are > far trickier such as the VM or the set of engines. In order to swap out > the VM, for instance, we have to delay until all current in-flight work > is complete, swap in the new VM, and then continue. This leads to a > plethora of potential race conditions we'd really rather avoid. > > Unfortunately, both methods of setting the VM and the engine set are in > active use today so we can't simply disallow setting the VM or engine > set vial SET_CONTEXT_PARAM. In order to work around this wart, this > commit adds a proto-context struct which contains all the context create > parameters. > > v2 (Daniel Vetter): > - Better commit message > - Use __set/clear_bit instead of set/clear_bit because there's no race > and we don't need the atomics > > v3 (Daniel Vetter): > - Use manual bitops and BIT() instead of __set_bit > > v4 (Daniel Vetter): > - Add a changelog to the commit message > - Better hyperlinking in docs > - Create the default PPGTT in i915_gem_create_context > > Signed-off-by: Jason Ekstrand <[email protected]> > --- > drivers/gpu/drm/i915/gem/i915_gem_context.c | 124 +++++++++++++++--- > .../gpu/drm/i915/gem/i915_gem_context_types.h | 22 ++++ > .../gpu/drm/i915/gem/selftests/mock_context.c | 16 ++- > 3 files changed, 145 insertions(+), 17 deletions(-) > > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c > b/drivers/gpu/drm/i915/gem/i915_gem_context.c > index f9a6eac78c0ae..b5d8c1ff5d7b3 100644 > --- a/drivers/gpu/drm/i915/gem/i915_gem_context.c > +++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c > @@ -191,6 +191,83 @@ static int validate_priority(struct drm_i915_private > *i915, > return 0; > } > > +static void proto_context_close(struct i915_gem_proto_context *pc) > +{ > + if (pc->vm) > + i915_vm_put(pc->vm); > + kfree(pc); > +} > + > +static int proto_context_set_persistence(struct drm_i915_private *i915, > + struct i915_gem_proto_context *pc, > + bool persist) > +{ > + if (persist) { > + /* > + * Only contexts that are short-lived [that will expire or be > + * reset] are allowed to survive past termination. We require > + * hangcheck to ensure that the persistent requests are healthy. > + */ > + if (!i915->params.enable_hangcheck) > + return -EINVAL; > + > + pc->user_flags |= BIT(UCONTEXT_PERSISTENCE); > + } else { > + /* To cancel a context we use "preempt-to-idle" */ > + if (!(i915->caps.scheduler & I915_SCHEDULER_CAP_PREEMPTION)) > + return -ENODEV; > + > + /* > + * If the cancel fails, we then need to reset, cleanly! > + * > + * If the per-engine reset fails, all hope is lost! We resort > + * to a full GPU reset in that unlikely case, but realistically > + * if the engine could not reset, the full reset does not fare > + * much better. The damage has been done. > + * > + * However, if we cannot reset an engine by itself, we cannot > + * cleanup a hanging persistent context without causing > + * colateral damage, and we should not pretend we can by > + * exposing the interface. > + */ > + if (!intel_has_reset_engine(&i915->gt)) > + return -ENODEV; > + > + pc->user_flags &= ~BIT(UCONTEXT_PERSISTENCE); > + } > + > + return 0; > +} > + > +static struct i915_gem_proto_context * > +proto_context_create(struct drm_i915_private *i915, unsigned int flags) > +{ > + struct i915_gem_proto_context *pc, *err; > + > + pc = kzalloc(sizeof(*pc), GFP_KERNEL); > + if (!pc) > + return ERR_PTR(-ENOMEM); > + > + pc->user_flags = BIT(UCONTEXT_BANNABLE) | > + BIT(UCONTEXT_RECOVERABLE); > + proto_context_set_persistence(i915, pc, true);
I think we're down to the bikeshed here that I think should be open-coded for clarity of what exactly is going on. But maybe better in a distinct patch. Reviewed-by: Daniel Vetter <[email protected]> > + pc->sched.priority = I915_PRIORITY_NORMAL; > + > + if (flags & I915_CONTEXT_CREATE_FLAGS_SINGLE_TIMELINE) { > + if (!HAS_EXECLISTS(i915)) { > + err = ERR_PTR(-EINVAL); > + goto proto_close; > + } > + pc->single_timeline = true; > + } > + > + return pc; > + > +proto_close: > + proto_context_close(pc); > + return err; > +} > + > static struct i915_address_space * > context_get_vm_rcu(struct i915_gem_context *ctx) > { > @@ -660,7 +737,8 @@ static int __context_set_persistence(struct > i915_gem_context *ctx, bool state) > } > > static struct i915_gem_context * > -__create_context(struct drm_i915_private *i915) > +__create_context(struct drm_i915_private *i915, > + const struct i915_gem_proto_context *pc) > { > struct i915_gem_context *ctx; > struct i915_gem_engines *e; > @@ -673,7 +751,7 @@ __create_context(struct drm_i915_private *i915) > > kref_init(&ctx->ref); > ctx->i915 = i915; > - ctx->sched.priority = I915_PRIORITY_NORMAL; > + ctx->sched = pc->sched; > mutex_init(&ctx->mutex); > INIT_LIST_HEAD(&ctx->link); > > @@ -696,9 +774,7 @@ __create_context(struct drm_i915_private *i915) > * is no remap info, it will be a NOP. */ > ctx->remap_slice = ALL_L3_SLICES(i915); > > - i915_gem_context_set_bannable(ctx); > - i915_gem_context_set_recoverable(ctx); > - __context_set_persistence(ctx, true /* cgroup hook? */); > + ctx->user_flags = pc->user_flags; > > for (i = 0; i < ARRAY_SIZE(ctx->hang_timestamp); i++) > ctx->hang_timestamp[i] = jiffies - CONTEXT_FAST_HANG_JIFFIES; > @@ -786,20 +862,22 @@ static void __assign_ppgtt(struct i915_gem_context *ctx, > } > > static struct i915_gem_context * > -i915_gem_create_context(struct drm_i915_private *i915, unsigned int flags) > +i915_gem_create_context(struct drm_i915_private *i915, > + const struct i915_gem_proto_context *pc) > { > struct i915_gem_context *ctx; > int ret; > > - if (flags & I915_CONTEXT_CREATE_FLAGS_SINGLE_TIMELINE && > - !HAS_EXECLISTS(i915)) > - return ERR_PTR(-EINVAL); > - > - ctx = __create_context(i915); > + ctx = __create_context(i915, pc); > if (IS_ERR(ctx)) > return ctx; > > - if (HAS_FULL_PPGTT(i915)) { > + if (pc->vm) { > + /* __assign_ppgtt() requires this mutex to be held */ > + mutex_lock(&ctx->mutex); > + __assign_ppgtt(ctx, pc->vm); > + mutex_unlock(&ctx->mutex); > + } else if (HAS_FULL_PPGTT(i915)) { > struct i915_ppgtt *ppgtt; > > ppgtt = i915_ppgtt_create(&i915->gt); > @@ -810,14 +888,16 @@ i915_gem_create_context(struct drm_i915_private *i915, > unsigned int flags) > return ERR_CAST(ppgtt); > } > > + /* __assign_ppgtt() requires this mutex to be held */ > mutex_lock(&ctx->mutex); > __assign_ppgtt(ctx, &ppgtt->vm); > mutex_unlock(&ctx->mutex); > > + /* __assign_ppgtt() takes another reference for us */ > i915_vm_put(&ppgtt->vm); > } > > - if (flags & I915_CONTEXT_CREATE_FLAGS_SINGLE_TIMELINE) { > + if (pc->single_timeline) { > ret = drm_syncobj_create(&ctx->syncobj, > DRM_SYNCOBJ_CREATE_SIGNALED, > NULL); > @@ -883,6 +963,7 @@ int i915_gem_context_open(struct drm_i915_private *i915, > struct drm_file *file) > { > struct drm_i915_file_private *file_priv = file->driver_priv; > + struct i915_gem_proto_context *pc; > struct i915_gem_context *ctx; > int err; > u32 id; > @@ -892,7 +973,14 @@ int i915_gem_context_open(struct drm_i915_private *i915, > /* 0 reserved for invalid/unassigned ppgtt */ > xa_init_flags(&file_priv->vm_xa, XA_FLAGS_ALLOC1); > > - ctx = i915_gem_create_context(i915, 0); > + pc = proto_context_create(i915, 0); > + if (IS_ERR(pc)) { > + err = PTR_ERR(pc); > + goto err; > + } > + > + ctx = i915_gem_create_context(i915, pc); > + proto_context_close(pc); > if (IS_ERR(ctx)) { > err = PTR_ERR(ctx); > goto err; > @@ -1884,6 +1972,7 @@ int i915_gem_context_create_ioctl(struct drm_device > *dev, void *data, > { > struct drm_i915_private *i915 = to_i915(dev); > struct drm_i915_gem_context_create_ext *args = data; > + struct i915_gem_proto_context *pc; > struct create_ext ext_data; > int ret; > u32 id; > @@ -1906,7 +1995,12 @@ int i915_gem_context_create_ioctl(struct drm_device > *dev, void *data, > return -EIO; > } > > - ext_data.ctx = i915_gem_create_context(i915, args->flags); > + pc = proto_context_create(i915, args->flags); > + if (IS_ERR(pc)) > + return PTR_ERR(pc); > + > + ext_data.ctx = i915_gem_create_context(i915, pc); > + proto_context_close(pc); > if (IS_ERR(ext_data.ctx)) > return PTR_ERR(ext_data.ctx); > > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context_types.h > b/drivers/gpu/drm/i915/gem/i915_gem_context_types.h > index 5f0673a2129f9..e0bdf3e298a6a 100644 > --- a/drivers/gpu/drm/i915/gem/i915_gem_context_types.h > +++ b/drivers/gpu/drm/i915/gem/i915_gem_context_types.h > @@ -66,6 +66,28 @@ struct i915_gem_engines_iter { > const struct i915_gem_engines *engines; > }; > > +/** > + * struct i915_gem_proto_context - prototype context > + * > + * The struct i915_gem_proto_context represents the creation parameters for > + * a struct i915_gem_context. This is used to gather parameters provided > + * either through creation flags or via SET_CONTEXT_PARAM so that, when we > + * create the final i915_gem_context, those parameters can be immutable. > + */ > +struct i915_gem_proto_context { > + /** @vm: See &i915_gem_context.vm */ > + struct i915_address_space *vm; > + > + /** @user_flags: See &i915_gem_context.user_flags */ > + unsigned long user_flags; > + > + /** @sched: See &i915_gem_context.sched */ > + struct i915_sched_attr sched; > + > + /** @single_timeline: See See &i915_gem_context.syncobj */ > + bool single_timeline; > +}; > + > /** > * struct i915_gem_context - client state > * > diff --git a/drivers/gpu/drm/i915/gem/selftests/mock_context.c > b/drivers/gpu/drm/i915/gem/selftests/mock_context.c > index 51b5a3421b400..e0f512ef7f3c6 100644 > --- a/drivers/gpu/drm/i915/gem/selftests/mock_context.c > +++ b/drivers/gpu/drm/i915/gem/selftests/mock_context.c > @@ -80,11 +80,17 @@ void mock_init_contexts(struct drm_i915_private *i915) > struct i915_gem_context * > live_context(struct drm_i915_private *i915, struct file *file) > { > + struct i915_gem_proto_context *pc; > struct i915_gem_context *ctx; > int err; > u32 id; > > - ctx = i915_gem_create_context(i915, 0); > + pc = proto_context_create(i915, 0); > + if (IS_ERR(pc)) > + return ERR_CAST(pc); > + > + ctx = i915_gem_create_context(i915, pc); > + proto_context_close(pc); > if (IS_ERR(ctx)) > return ctx; > > @@ -142,8 +148,14 @@ struct i915_gem_context * > kernel_context(struct drm_i915_private *i915) > { > struct i915_gem_context *ctx; > + struct i915_gem_proto_context *pc; > + > + pc = proto_context_create(i915, 0); > + if (IS_ERR(pc)) > + return ERR_CAST(pc); > > - ctx = i915_gem_create_context(i915, 0); > + ctx = i915_gem_create_context(i915, pc); > + proto_context_close(pc); > if (IS_ERR(ctx)) > return ctx; > > -- > 2.31.1 > > _______________________________________________ > Intel-gfx mailing list > [email protected] > https://lists.freedesktop.org/mailman/listinfo/intel-gfx -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ Intel-gfx mailing list [email protected] https://lists.freedesktop.org/mailman/listinfo/intel-gfx
