diff options
Diffstat (limited to 'drivers/gpu/drm/i915/i915_gem_context.c')
| -rw-r--r-- | drivers/gpu/drm/i915/i915_gem_context.c | 536 |
1 files changed, 536 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c new file mode 100644 index 000000000000..da8b01fb1bf8 --- /dev/null +++ b/drivers/gpu/drm/i915/i915_gem_context.c @@ -0,0 +1,536 @@ +/* + * Copyright © 2011-2012 Intel Corporation + * + * Permission is hereby granted, free of charge, to any person obtaining a + * copy of this software and associated documentation files (the "Software"), + * to deal in the Software without restriction, including without limitation + * the rights to use, copy, modify, merge, publish, distribute, sublicense, + * and/or sell copies of the Software, and to permit persons to whom the + * Software is furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice (including the next + * paragraph) shall be included in all copies or substantial portions of the + * Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS + * IN THE SOFTWARE. + * + * Authors: + * Ben Widawsky <ben@bwidawsk.net> + * + */ + +/* + * This file implements HW context support. On gen5+ a HW context consists of an + * opaque GPU object which is referenced at times of context saves and restores. + * With RC6 enabled, the context is also referenced as the GPU enters and exists + * from RC6 (GPU has it's own internal power context, except on gen5). Though + * something like a context does exist for the media ring, the code only + * supports contexts for the render ring. + * + * In software, there is a distinction between contexts created by the user, + * and the default HW context. The default HW context is used by GPU clients + * that do not request setup of their own hardware context. The default + * context's state is never restored to help prevent programming errors. This + * would happen if a client ran and piggy-backed off another clients GPU state. + * The default context only exists to give the GPU some offset to load as the + * current to invoke a save of the context we actually care about. In fact, the + * code could likely be constructed, albeit in a more complicated fashion, to + * never use the default context, though that limits the driver's ability to + * swap out, and/or destroy other contexts. + * + * All other contexts are created as a request by the GPU client. These contexts + * store GPU state, and thus allow GPU clients to not re-emit state (and + * potentially query certain state) at any time. The kernel driver makes + * certain that the appropriate commands are inserted. + * + * The context life cycle is semi-complicated in that context BOs may live + * longer than the context itself because of the way the hardware, and object + * tracking works. Below is a very crude representation of the state machine + * describing the context life. + * refcount pincount active + * S0: initial state 0 0 0 + * S1: context created 1 0 0 + * S2: context is currently running 2 1 X + * S3: GPU referenced, but not current 2 0 1 + * S4: context is current, but destroyed 1 1 0 + * S5: like S3, but destroyed 1 0 1 + * + * The most common (but not all) transitions: + * S0->S1: client creates a context + * S1->S2: client submits execbuf with context + * S2->S3: other clients submits execbuf with context + * S3->S1: context object was retired + * S3->S2: clients submits another execbuf + * S2->S4: context destroy called with current context + * S3->S5->S0: destroy path + * S4->S5->S0: destroy path on current context + * + * There are two confusing terms used above: + * The "current context" means the context which is currently running on the + * GPU. The GPU has loaded it's state already and has stored away the gtt + * offset of the BO. The GPU is not actively referencing the data at this + * offset, but it will on the next context switch. The only way to avoid this + * is to do a GPU reset. + * + * An "active context' is one which was previously the "current context" and is + * on the active list waiting for the next context switch to occur. Until this + * happens, the object must remain at the same gtt offset. It is therefore + * possible to destroy a context, but it is still active. + * + */ + +#include "drmP.h" +#include "i915_drm.h" +#include "i915_drv.h" + +/* This is a HW constraint. The value below is the largest known requirement + * I've seen in a spec to date, and that was a workaround for a non-shipping + * part. It should be safe to decrease this, but it's more future proof as is. + */ +#define CONTEXT_ALIGN (64<<10) + +static struct i915_hw_context * +i915_gem_context_get(struct drm_i915_file_private *file_priv, u32 id); +static int do_switch(struct drm_i915_gem_object *from_obj, + struct i915_hw_context *to, u32 seqno); + +static int get_context_size(struct drm_device *dev) +{ + struct drm_i915_private *dev_priv = dev->dev_private; + int ret; + u32 reg; + + switch (INTEL_INFO(dev)->gen) { + case 6: + reg = I915_READ(CXT_SIZE); + ret = GEN6_CXT_TOTAL_SIZE(reg) * 64; + break; + case 7: + reg = I915_READ(GEN7_CXT_SIZE); + ret = GEN7_CXT_TOTAL_SIZE(reg) * 64; + break; + default: + BUG(); + } + + return ret; +} + +static void do_destroy(struct i915_hw_context *ctx) +{ + struct drm_device *dev = ctx->obj->base.dev; + struct drm_i915_private *dev_priv = dev->dev_private; + + if (ctx->file_priv) + idr_remove(&ctx->file_priv->context_idr, ctx->id); + else + BUG_ON(ctx != dev_priv->ring[RCS].default_context); + + drm_gem_object_unreference(&ctx->obj->base); + kfree(ctx); +} + +static struct i915_hw_context * +create_hw_context(struct drm_device *dev, + struct drm_i915_file_private *file_priv) +{ + struct drm_i915_private *dev_priv = dev->dev_private; + struct i915_hw_context *ctx; + int ret, id; + + ctx = kzalloc(sizeof(struct drm_i915_file_private), GFP_KERNEL); + if (ctx == NULL) + return ERR_PTR(-ENOMEM); + + ctx->obj = i915_gem_alloc_object(dev, dev_priv->hw_context_size); + if (ctx->obj == NULL) { + kfree(ctx); + DRM_DEBUG_DRIVER("Context object allocated failed\n"); + return ERR_PTR(-ENOMEM); + } + + /* The ring associated with the context object is handled by the normal + * object tracking code. We give an initial ring value simple to pass an + * assertion in the context switch code. + */ + ctx->ring = &dev_priv->ring[RCS]; + + /* Default context will never have a file_priv */ + if (file_priv == NULL) + return ctx; + + ctx->file_priv = file_priv; + +again: + if (idr_pre_get(&file_priv->context_idr, GFP_KERNEL) == 0) { + ret = -ENOMEM; + DRM_DEBUG_DRIVER("idr allocation failed\n"); + goto err_out; + } + + ret = idr_get_new_above(&file_priv->context_idr, ctx, + DEFAULT_CONTEXT_ID + 1, &id); + if (ret == 0) + ctx->id = id; + + if (ret == -EAGAIN) + goto again; + else if (ret) + goto err_out; + + return ctx; + +err_out: + do_destroy(ctx); + return ERR_PTR(ret); +} + +static inline bool is_default_context(struct i915_hw_context *ctx) +{ + return (ctx == ctx->ring->default_context); +} + +/** + * The default context needs to exist per ring that uses contexts. It stores the + * context state of the GPU for applications that don't utilize HW contexts, as + * well as an idle case. + */ +static int create_default_context(struct drm_i915_private *dev_priv) +{ + struct i915_hw_context *ctx; + int ret; + + BUG_ON(!mutex_is_locked(&dev_priv->dev->struct_mutex)); + + ctx = create_hw_context(dev_priv->dev, NULL); + if (IS_ERR(ctx)) + return PTR_ERR(ctx); + + /* We may need to do things with the shrinker which require us to + * immediately switch back to the default context. This can cause a + * problem as pinning the default context also requires GTT space which + * may not be available. To avoid this we always pin the + * default context. + */ + dev_priv->ring[RCS].default_context = ctx; + ret = i915_gem_object_pin(ctx->obj, CONTEXT_ALIGN, false); + if (ret) { + do_destroy(ctx); + return ret; + } + + ret = do_switch(NULL, ctx, 0); + if (ret) { + i915_gem_object_unpin(ctx->obj); + do_destroy(ctx); + } else { + DRM_DEBUG_DRIVER("Default HW context loaded\n"); + } + + return ret; +} + +void i915_gem_context_init(struct drm_device *dev) +{ + struct drm_i915_private *dev_priv = dev->dev_private; + uint32_t ctx_size; + + if (!HAS_HW_CONTEXTS(dev)) { + dev_priv->hw_contexts_disabled = true; + return; + } + + /* If called from reset, or thaw... we've been here already */ + if (dev_priv->hw_contexts_disabled || + dev_priv->ring[RCS].default_context) + return; + + ctx_size = get_context_size(dev); + dev_priv->hw_context_size = get_context_size(dev); + dev_priv->hw_context_size = round_up(dev_priv->hw_context_size, 4096); + + if (ctx_size <= 0 || ctx_size > (1<<20)) { + dev_priv->hw_contexts_disabled = true; + return; + } + + if (create_default_context(dev_priv)) { + dev_priv->hw_contexts_disabled = true; + return; + } + + DRM_DEBUG_DRIVER("HW context support initialized\n"); +} + +void i915_gem_context_fini(struct drm_device *dev) +{ + struct drm_i915_private *dev_priv = dev->dev_private; + + if (dev_priv->hw_contexts_disabled) + return; + + /* The only known way to stop the gpu from accessing the hw context is + * to reset it. Do this as the very last operation to avoid confusing + * other code, leading to spurious errors. */ + intel_gpu_reset(dev); + + i915_gem_object_unpin(dev_priv->ring[RCS].default_context->obj); + + do_destroy(dev_priv->ring[RCS].default_context); +} + +static int context_idr_cleanup(int id, void *p, void *data) +{ + struct i915_hw_context *ctx = p; + + BUG_ON(id == DEFAULT_CONTEXT_ID); + + do_destroy(ctx); + + return 0; +} + +void i915_gem_context_close(struct drm_device *dev, struct drm_file *file) +{ + struct drm_i915_file_private *file_priv = file->driver_priv; + + mutex_lock(&dev->struct_mutex); + idr_for_each(&file_priv->context_idr, context_idr_cleanup, NULL); + idr_destroy(&file_priv->context_idr); + mutex_unlock(&dev->struct_mutex); +} + +static struct i915_hw_context * +i915_gem_context_get(struct drm_i915_file_private *file_priv, u32 id) +{ + return (struct i915_hw_context *)idr_find(&file_priv->context_idr, id); +} + +static inline int +mi_set_context(struct intel_ring_buffer *ring, + struct i915_hw_context *new_context, + u32 hw_flags) +{ + int ret; + + /* w/a: If Flush TLB Invalidation Mode is enabled, driver must do a TLB + * invalidation prior to MI_SET_CONTEXT. On GEN6 we don't set the value + * explicitly, so we rely on the value at ring init, stored in + * itlb_before_ctx_switch. + */ + if (IS_GEN6(ring->dev) && ring->itlb_before_ctx_switch) { + ret = ring->flush(ring, 0, 0); + if (ret) + return ret; + } + + ret = intel_ring_begin(ring, 6); + if (ret) + return ret; + + if (IS_GEN7(ring->dev)) + intel_ring_emit(ring, MI_ARB_ON_OFF | MI_ARB_DISABLE); + else + intel_ring_emit(ring, MI_NOOP); + + intel_ring_emit(ring, MI_NOOP); + intel_ring_emit(ring, MI_SET_CONTEXT); + intel_ring_emit(ring, new_context->obj->gtt_offset | + MI_MM_SPACE_GTT | + MI_SAVE_EXT_STATE_EN | + MI_RESTORE_EXT_STATE_EN | + hw_flags); + /* w/a: MI_SET_CONTEXT must always be followed by MI_NOOP */ + intel_ring_emit(ring, MI_NOOP); + + if (IS_GEN7(ring->dev)) + intel_ring_emit(ring, MI_ARB_ON_OFF | MI_ARB_ENABLE); + else + intel_ring_emit(ring, MI_NOOP); + + intel_ring_advance(ring); + + return ret; +} + +static int do_switch(struct drm_i915_gem_object *from_obj, + struct i915_hw_context *to, + u32 seqno) +{ + struct intel_ring_buffer *ring = NULL; + u32 hw_flags = 0; + int ret; + + BUG_ON(to == NULL); + BUG_ON(from_obj != NULL && from_obj->pin_count == 0); + + ret = i915_gem_object_pin(to->obj, CONTEXT_ALIGN, false); + if (ret) + return ret; + + /* Clear this page out of any CPU caches for coherent swap-in/out. Note + * that thanks to write = false in this call and us not setting any gpu + * write domains when putting a context object onto the active list + * (when switching away from it), this won't block. + * XXX: We need a real interface to do this instead of trickery. */ + ret = i915_gem_object_set_to_gtt_domain(to->obj, false); + if (ret) { + i915_gem_object_unpin(to->obj); + return ret; + } + + if (!to->obj->has_global_gtt_mapping) + i915_gem_gtt_bind_object(to->obj, to->obj->cache_level); + + if (!to->is_initialized || is_default_context(to)) + hw_flags |= MI_RESTORE_INHIBIT; + else if (WARN_ON_ONCE(from_obj == to->obj)) /* not yet expected */ + hw_flags |= MI_FORCE_RESTORE; + + ring = to->ring; + ret = mi_set_context(ring, to, hw_flags); + if (ret) { + i915_gem_object_unpin(to->obj); + return ret; + } + + /* The backing object for the context is done after switching to the + * *next* context. Therefore we cannot retire the previous context until + * the next context has already started running. In fact, the below code + * is a bit suboptimal because the retiring can occur simply after the + * MI_SET_CONTEXT instead of when the next seqno has completed. + */ + if (from_obj != NULL) { + from_obj->base.read_domains = I915_GEM_DOMAIN_INSTRUCTION; + i915_gem_object_move_to_active(from_obj, ring, seqno); + /* As long as MI_SET_CONTEXT is serializing, ie. it flushes the + * whole damn pipeline, we don't need to explicitly mark the + * object dirty. The only exception is that the context must be + * correct in case the object gets swapped out. Ideally we'd be + * able to defer doing this until we know the object would be + * swapped, but there is no way to do that yet. + */ + from_obj->dirty = 1; + BUG_ON(from_obj->ring != to->ring); + i915_gem_object_unpin(from_obj); + + drm_gem_object_unreference(&from_obj->base); + } + + drm_gem_object_reference(&to->obj->base); + ring->last_context_obj = to->obj; + to->is_initialized = true; + + return 0; +} + +/** + * i915_switch_context() - perform a GPU context switch. + * @ring: ring for which we'll execute the context switch + * @file_priv: file_priv associated with the context, may be NULL + * @id: context id number + * @seqno: sequence number by which the new context will be switched to + * @flags: + * + * The context life cycle is simple. The context refcount is incremented and + * decremented by 1 and create and destroy. If the context is in use by the GPU, + * it will have a refoucnt > 1. This allows us to destroy the context abstract + * object while letting the normal object tracking destroy the backing BO. + */ +int i915_switch_context(struct intel_ring_buffer *ring, + struct drm_file *file, + int to_id) +{ + struct drm_i915_private *dev_priv = ring->dev->dev_private; + struct drm_i915_file_private *file_priv = NULL; + struct i915_hw_context *to; + struct drm_i915_gem_object *from_obj = ring->last_context_obj; + int ret; + + if (dev_priv->hw_contexts_disabled) + return 0; + + if (ring != &dev_priv->ring[RCS]) + return 0; + + if (file) + file_priv = file->driver_priv; + + if (to_id == DEFAULT_CONTEXT_ID) { + to = ring->default_context; + } else { + to = i915_gem_context_get(file_priv, to_id); + if (to == NULL) + return -ENOENT; + } + + if (from_obj == to->obj) + return 0; + + return do_switch(from_obj, to, i915_gem_next_request_seqno(to->ring)); +} + +int i915_gem_context_create_ioctl(struct drm_device *dev, void *data, + struct drm_file *file) +{ + struct drm_i915_private *dev_priv = dev->dev_private; + struct drm_i915_gem_context_create *args = data; + struct drm_i915_file_private *file_priv = file->driver_priv; + struct i915_hw_context *ctx; + int ret; + + if (!(dev->driver->driver_features & DRIVER_GEM)) + return -ENODEV; + + if (dev_priv->hw_contexts_disabled) + return -ENODEV; + + ret = i915_mutex_lock_interruptible(dev); + if (ret) + return ret; + + ctx = create_hw_context(dev, file_priv); + mutex_unlock(&dev->struct_mutex); + if (IS_ERR(ctx)) + return PTR_ERR(ctx); + + args->ctx_id = ctx->id; + DRM_DEBUG_DRIVER("HW context %d created\n", args->ctx_id); + + return 0; +} + +int i915_gem_context_destroy_ioctl(struct drm_device *dev, void *data, + struct drm_file *file) +{ + struct drm_i915_gem_context_destroy *args = data; + struct drm_i915_file_private *file_priv = file->driver_priv; + struct i915_hw_context *ctx; + int ret; + + if (!(dev->driver->driver_features & DRIVER_GEM)) + return -ENODEV; + + ret = i915_mutex_lock_interruptible(dev); + if (ret) + return ret; + + ctx = i915_gem_context_get(file_priv, args->ctx_id); + if (!ctx) { + mutex_unlock(&dev->struct_mutex); + return -ENOENT; + } + + do_destroy(ctx); + + mutex_unlock(&dev->struct_mutex); + + DRM_DEBUG_DRIVER("HW context %d destroyed\n", args->ctx_id); + return 0; +} |