/*
* 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 i915_hw_context *to);
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);
if (IS_HASWELL(dev))
ret = HSW_CXT_TOTAL_SIZE(reg) * 64;
else
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)
goto err_destroy;
ret = do_switch(ctx);
if (ret)
goto err_unpin;
DRM_DEBUG_DRIVER("Default HW context loaded\n");
return 0;
err_unpin:
i915_gem_object_unpin(ctx->obj);
err_destroy:
do_destroy(ctx);
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 i915_hw_context *to)
{
struct intel_ring_buffer *ring = to->ring;
struct drm_i915_gem_object *from_obj = ring->last_context_obj;
u32 hw_flags = 0;
int ret;
BUG_ON(from_obj != NULL && from_obj->pin_count == 0);
if (from_obj == to->obj)
return 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;
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) {
u32 seqno = i915_gem_next_request_seqno(ring);
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 != 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 i915_hw_context *to;
if (dev_priv->hw_contexts_disabled)
return 0;
if (ring != &dev_priv->ring[RCS])
return 0;
if (to_id == DEFAULT_CONTEXT_ID) {
to = ring->default_context;
} else {
if (file == NULL)
return -EINVAL;
to = i915_gem_context_get(file->driver_priv, to_id);
if (to == NULL)
return -ENOENT;
}
return do_switch(to);
}
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;
}
