linux-stable/drivers/gpu/drm/i915/i915_gem_render_state.c
Chris Wilson a679f58d05 drm/i915: Flush pages on acquisition
When we return pages to the system, we ensure that they are marked as
being in the CPU domain since any external access is uncontrolled and we
must assume the worst. This means that we need to always flush the pages
on acquisition if we need to use them on the GPU, and from the beginning
have used set-domain. Set-domain is overkill for the purpose as it is a
general synchronisation barrier, but our intent is to only flush the
pages being swapped in. If we move that flush into the pages acquisition
phase, we know then that when we have obj->mm.pages, they are coherent
with the GPU and need only maintain that status without resorting to
heavy handed use of set-domain.

The principle knock-on effect for userspace is through mmap-gtt
pagefaulting. Our uAPI has always implied that the GTT mmap was async
(especially as when any pagefault occurs is unpredicatable to userspace)
and so userspace had to apply explicit domain control itself
(set-domain). However, swapping is transparent to the kernel, and so on
first fault we need to acquire the pages and make them coherent for
access through the GTT. Our use of set-domain here leaks into the uABI
that the first pagefault was synchronous. This is unintentional and
baring a few igt should be unoticed, nevertheless we bump the uABI
version for mmap-gtt to reflect the change in behaviour.

Another implication of the change is that gem_create() is presumed to
create an object that is coherent with the CPU and is in the CPU write
domain, so a set-domain(CPU) following a gem_create() would be a minor
operation that merely checked whether we could allocate all pages for
the object. On applying this change, a set-domain(CPU) causes a clflush
as we acquire the pages. This will have a small impact on mesa as we move
the clflush here on !llc from execbuf time to create, but that should
have minimal performance impact as the same clflush exists but is now
done early and because of the clflush issue, userspace recycles bo and
so should resist allocating fresh objects.

Internally, the presumption that objects are created in the CPU
write-domain and remain so through writes to obj->mm.mapping is more
prevalent than I expected; but easy enough to catch and apply a manual
flush.

For the future, we should push the page flush from the central
set_pages() into the callers so that we can more finely control when it
is applied, but for now doing it one location is easier to validate, at
the cost of sometimes flushing when there is no need.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Matthew Auld <matthew.william.auld@gmail.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Antonio Argenziano <antonio.argenziano@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Matthew Auld <matthew.william.auld@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190321161908.8007-1-chris@chris-wilson.co.uk
2019-03-21 17:28:12 +00:00

233 lines
6.1 KiB
C

/*
* Copyright © 2014 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:
* Mika Kuoppala <mika.kuoppala@intel.com>
*
*/
#include "i915_drv.h"
#include "i915_gem_render_state.h"
#include "intel_renderstate.h"
struct intel_render_state {
const struct intel_renderstate_rodata *rodata;
struct drm_i915_gem_object *obj;
struct i915_vma *vma;
u32 batch_offset;
u32 batch_size;
u32 aux_offset;
u32 aux_size;
};
static const struct intel_renderstate_rodata *
render_state_get_rodata(const struct intel_engine_cs *engine)
{
if (engine->id != RCS0)
return NULL;
switch (INTEL_GEN(engine->i915)) {
case 6:
return &gen6_null_state;
case 7:
return &gen7_null_state;
case 8:
return &gen8_null_state;
case 9:
return &gen9_null_state;
}
return NULL;
}
/*
* Macro to add commands to auxiliary batch.
* This macro only checks for page overflow before inserting the commands,
* this is sufficient as the null state generator makes the final batch
* with two passes to build command and state separately. At this point
* the size of both are known and it compacts them by relocating the state
* right after the commands taking care of alignment so we should sufficient
* space below them for adding new commands.
*/
#define OUT_BATCH(batch, i, val) \
do { \
if ((i) >= PAGE_SIZE / sizeof(u32)) \
goto err; \
(batch)[(i)++] = (val); \
} while(0)
static int render_state_setup(struct intel_render_state *so,
struct drm_i915_private *i915)
{
const struct intel_renderstate_rodata *rodata = so->rodata;
unsigned int i = 0, reloc_index = 0;
unsigned int needs_clflush;
u32 *d;
int ret;
ret = i915_gem_obj_prepare_shmem_write(so->obj, &needs_clflush);
if (ret)
return ret;
d = kmap_atomic(i915_gem_object_get_dirty_page(so->obj, 0));
while (i < rodata->batch_items) {
u32 s = rodata->batch[i];
if (i * 4 == rodata->reloc[reloc_index]) {
u64 r = s + so->vma->node.start;
s = lower_32_bits(r);
if (HAS_64BIT_RELOC(i915)) {
if (i + 1 >= rodata->batch_items ||
rodata->batch[i + 1] != 0)
goto err;
d[i++] = s;
s = upper_32_bits(r);
}
reloc_index++;
}
d[i++] = s;
}
if (rodata->reloc[reloc_index] != -1) {
DRM_ERROR("only %d relocs resolved\n", reloc_index);
goto err;
}
so->batch_offset = i915_ggtt_offset(so->vma);
so->batch_size = rodata->batch_items * sizeof(u32);
while (i % CACHELINE_DWORDS)
OUT_BATCH(d, i, MI_NOOP);
so->aux_offset = i * sizeof(u32);
if (HAS_POOLED_EU(i915)) {
/*
* We always program 3x6 pool config but depending upon which
* subslice is disabled HW drops down to appropriate config
* shown below.
*
* In the below table 2x6 config always refers to
* fused-down version, native 2x6 is not available and can
* be ignored
*
* SNo subslices config eu pool configuration
* -----------------------------------------------------------
* 1 3 subslices enabled (3x6) - 0x00777000 (9+9)
* 2 ss0 disabled (2x6) - 0x00777000 (3+9)
* 3 ss1 disabled (2x6) - 0x00770000 (6+6)
* 4 ss2 disabled (2x6) - 0x00007000 (9+3)
*/
u32 eu_pool_config = 0x00777000;
OUT_BATCH(d, i, GEN9_MEDIA_POOL_STATE);
OUT_BATCH(d, i, GEN9_MEDIA_POOL_ENABLE);
OUT_BATCH(d, i, eu_pool_config);
OUT_BATCH(d, i, 0);
OUT_BATCH(d, i, 0);
OUT_BATCH(d, i, 0);
}
OUT_BATCH(d, i, MI_BATCH_BUFFER_END);
so->aux_size = i * sizeof(u32) - so->aux_offset;
so->aux_offset += so->batch_offset;
/*
* Since we are sending length, we need to strictly conform to
* all requirements. For Gen2 this must be a multiple of 8.
*/
so->aux_size = ALIGN(so->aux_size, 8);
if (needs_clflush)
drm_clflush_virt_range(d, i * sizeof(u32));
kunmap_atomic(d);
ret = 0;
out:
i915_gem_obj_finish_shmem_access(so->obj);
return ret;
err:
kunmap_atomic(d);
ret = -EINVAL;
goto out;
}
#undef OUT_BATCH
int i915_gem_render_state_emit(struct i915_request *rq)
{
struct intel_engine_cs *engine = rq->engine;
struct intel_render_state so = {}; /* keep the compiler happy */
int err;
so.rodata = render_state_get_rodata(engine);
if (!so.rodata)
return 0;
if (so.rodata->batch_items * 4 > PAGE_SIZE)
return -EINVAL;
so.obj = i915_gem_object_create_internal(engine->i915, PAGE_SIZE);
if (IS_ERR(so.obj))
return PTR_ERR(so.obj);
so.vma = i915_vma_instance(so.obj, &engine->i915->ggtt.vm, NULL);
if (IS_ERR(so.vma)) {
err = PTR_ERR(so.vma);
goto err_obj;
}
err = i915_vma_pin(so.vma, 0, 0, PIN_GLOBAL | PIN_HIGH);
if (err)
goto err_vma;
err = render_state_setup(&so, rq->i915);
if (err)
goto err_unpin;
err = engine->emit_bb_start(rq,
so.batch_offset, so.batch_size,
I915_DISPATCH_SECURE);
if (err)
goto err_unpin;
if (so.aux_size > 8) {
err = engine->emit_bb_start(rq,
so.aux_offset, so.aux_size,
I915_DISPATCH_SECURE);
if (err)
goto err_unpin;
}
err = i915_vma_move_to_active(so.vma, rq, 0);
err_unpin:
i915_vma_unpin(so.vma);
err_vma:
i915_vma_close(so.vma);
err_obj:
__i915_gem_object_release_unless_active(so.obj);
return err;
}