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drm/i915/gem: Only call eb_lookup_vma once during execbuf ioctl
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As we no longer stash anything inside i915_vma under the exclusive
protection of struct_mutex, we do not need to revoke the i915_vma
stashes before dropping struct_mutex to handle pagefaults. Knowing that
we must drop the struct_mutex while keeping the eb->vma around, means
that we are required to hold onto to the object reference until we have
marked the vma as active.

Fixes: 155ab88 ("drm/i915: Move object close under its own lock")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200303204345.1859734-3-chris@chris-wilson.co.uk
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Chris Wilson committed Mar 3, 2020
1 parent 7d6236b commit 003d8b9
Showing 1 changed file with 42 additions and 65 deletions.
107 changes: 42 additions & 65 deletions drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
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Original file line number Diff line number Diff line change
Expand Up @@ -47,17 +47,15 @@ enum {
#define DBG_FORCE_RELOC 0 /* choose one of the above! */
};

#define __EXEC_OBJECT_HAS_REF BIT(31)
#define __EXEC_OBJECT_HAS_PIN BIT(30)
#define __EXEC_OBJECT_HAS_FENCE BIT(29)
#define __EXEC_OBJECT_NEEDS_MAP BIT(28)
#define __EXEC_OBJECT_NEEDS_BIAS BIT(27)
#define __EXEC_OBJECT_INTERNAL_FLAGS (~0u << 27) /* all of the above */
#define __EXEC_OBJECT_HAS_PIN BIT(31)
#define __EXEC_OBJECT_HAS_FENCE BIT(30)
#define __EXEC_OBJECT_NEEDS_MAP BIT(29)
#define __EXEC_OBJECT_NEEDS_BIAS BIT(28)
#define __EXEC_OBJECT_INTERNAL_FLAGS (~0u << 28) /* all of the above */
#define __EXEC_OBJECT_RESERVED (__EXEC_OBJECT_HAS_PIN | __EXEC_OBJECT_HAS_FENCE)

#define __EXEC_HAS_RELOC BIT(31)
#define __EXEC_VALIDATED BIT(30)
#define __EXEC_INTERNAL_FLAGS (~0u << 30)
#define __EXEC_INTERNAL_FLAGS (~0u << 31)
#define UPDATE PIN_OFFSET_FIXED

#define BATCH_OFFSET_BIAS (256*1024)
Expand Down Expand Up @@ -472,24 +470,17 @@ eb_validate_vma(struct i915_execbuffer *eb,
return 0;
}

static int
static void
eb_add_vma(struct i915_execbuffer *eb,
unsigned int i, unsigned batch_idx,
struct i915_vma *vma)
{
struct drm_i915_gem_exec_object2 *entry = &eb->exec[i];
struct eb_vma *ev = &eb->vma[i];
int err;

GEM_BUG_ON(i915_vma_is_closed(vma));

if (!(eb->args->flags & __EXEC_VALIDATED)) {
err = eb_validate_vma(eb, entry, vma);
if (unlikely(err))
return err;
}

ev->vma = vma;
ev->vma = i915_vma_get(vma);
ev->exec = entry;
ev->flags = entry->flags;

Expand Down Expand Up @@ -522,20 +513,15 @@ eb_add_vma(struct i915_execbuffer *eb,
eb->batch = ev;
}

err = 0;
if (eb_pin_vma(eb, entry, ev)) {
if (entry->offset != vma->node.start) {
entry->offset = vma->node.start | UPDATE;
eb->args->flags |= __EXEC_HAS_RELOC;
}
} else {
eb_unreserve_vma(ev);

list_add_tail(&ev->bind_link, &eb->unbound);
if (drm_mm_node_allocated(&vma->node))
err = i915_vma_unbind(vma);
}
return err;
}

static inline int use_cpu_reloc(const struct reloc_cache *cache,
Expand Down Expand Up @@ -582,6 +568,13 @@ static int eb_reserve_vma(const struct i915_execbuffer *eb,
else if (exec_flags & __EXEC_OBJECT_NEEDS_BIAS)
pin_flags |= BATCH_OFFSET_BIAS | PIN_OFFSET_BIAS;

if (drm_mm_node_allocated(&vma->node) &&
eb_vma_misplaced(entry, vma, ev->flags)) {
err = i915_vma_unbind(vma);
if (err)
return err;
}

err = i915_vma_pin(vma,
entry->pad_to_size, entry->alignment,
pin_flags);
Expand Down Expand Up @@ -641,7 +634,7 @@ static int eb_reserve(struct i915_execbuffer *eb)
if (err)
break;
}
if (err != -ENOSPC)
if (!(err == -ENOSPC || err == -EAGAIN))
return err;

/* Resort *all* the objects into priority order */
Expand Down Expand Up @@ -672,6 +665,11 @@ static int eb_reserve(struct i915_execbuffer *eb)
}
list_splice_tail(&last, &eb->unbound);

if (err == -EAGAIN) {
flush_workqueue(eb->i915->mm.userptr_wq);
continue;
}

switch (pass++) {
case 0:
break;
Expand Down Expand Up @@ -727,17 +725,14 @@ static int eb_lookup_vmas(struct i915_execbuffer *eb)
unsigned int i, batch;
int err;

if (unlikely(i915_gem_context_is_closed(eb->gem_context)))
return -ENOENT;

INIT_LIST_HEAD(&eb->relocs);
INIT_LIST_HEAD(&eb->unbound);

batch = eb_batch_index(eb);

mutex_lock(&eb->gem_context->mutex);
if (unlikely(i915_gem_context_is_closed(eb->gem_context))) {
err = -ENOENT;
goto err_ctx;
}

for (i = 0; i < eb->buffer_count; i++) {
u32 handle = eb->exec[i].handle;
struct i915_lut_handle *lut;
Expand Down Expand Up @@ -782,25 +777,19 @@ static int eb_lookup_vmas(struct i915_execbuffer *eb)
i915_gem_object_unlock(obj);

add_vma:
err = eb_add_vma(eb, i, batch, vma);
err = eb_validate_vma(eb, &eb->exec[i], vma);
if (unlikely(err))
goto err_vma;

GEM_BUG_ON(drm_mm_node_allocated(&vma->node) &&
eb_vma_misplaced(&eb->exec[i], vma, eb->vma[i].flags));
eb_add_vma(eb, i, batch, vma);
}

mutex_unlock(&eb->gem_context->mutex);

eb->args->flags |= __EXEC_VALIDATED;
return eb_reserve(eb);
return 0;

err_obj:
i915_gem_object_put(obj);
err_vma:
eb->vma[i].vma = NULL;
err_ctx:
mutex_unlock(&eb->gem_context->mutex);
return err;
}

Expand Down Expand Up @@ -841,19 +830,10 @@ static void eb_release_vmas(const struct i915_execbuffer *eb)
if (ev->flags & __EXEC_OBJECT_HAS_PIN)
__eb_unreserve_vma(vma, ev->flags);

if (ev->flags & __EXEC_OBJECT_HAS_REF)
i915_vma_put(vma);
i915_vma_put(vma);
}
}

static void eb_reset_vmas(const struct i915_execbuffer *eb)
{
eb_release_vmas(eb);
if (eb->lut_size > 0)
memset(eb->buckets, 0,
sizeof(struct hlist_head) << eb->lut_size);
}

static void eb_destroy(const struct i915_execbuffer *eb)
{
GEM_BUG_ON(eb->reloc_cache.rq);
Expand Down Expand Up @@ -1662,8 +1642,6 @@ static noinline int eb_relocate_slow(struct i915_execbuffer *eb)
goto out;
}

/* We may process another execbuffer during the unlock... */
eb_reset_vmas(eb);
mutex_unlock(&dev->struct_mutex);

/*
Expand Down Expand Up @@ -1702,11 +1680,6 @@ static noinline int eb_relocate_slow(struct i915_execbuffer *eb)
goto out;
}

/* reacquire the objects */
err = eb_lookup_vmas(eb);
if (err)
goto err;

GEM_BUG_ON(!eb->batch);

list_for_each_entry(ev, &eb->relocs, reloc_link) {
Expand Down Expand Up @@ -1757,23 +1730,29 @@ static noinline int eb_relocate_slow(struct i915_execbuffer *eb)

static int eb_relocate(struct i915_execbuffer *eb)
{
if (eb_lookup_vmas(eb))
goto slow;
int err;

mutex_lock(&eb->gem_context->mutex);
err = eb_lookup_vmas(eb);
mutex_unlock(&eb->gem_context->mutex);
if (err)
return err;

err = eb_reserve(eb);
if (err)
return err;

/* The objects are in their final locations, apply the relocations. */
if (eb->args->flags & __EXEC_HAS_RELOC) {
struct eb_vma *ev;

list_for_each_entry(ev, &eb->relocs, reloc_link) {
if (eb_relocate_vma(eb, ev))
goto slow;
return eb_relocate_slow(eb);
}
}

return 0;

slow:
return eb_relocate_slow(eb);
}

static int eb_move_to_gpu(struct i915_execbuffer *eb)
Expand Down Expand Up @@ -1855,8 +1834,7 @@ static int eb_move_to_gpu(struct i915_execbuffer *eb)
i915_vma_unlock(vma);

__eb_unreserve_vma(vma, flags);
if (unlikely(flags & __EXEC_OBJECT_HAS_REF))
i915_vma_put(vma);
i915_vma_put(vma);

ev->vma = NULL;
}
Expand Down Expand Up @@ -2116,8 +2094,7 @@ static int eb_parse(struct i915_execbuffer *eb)
goto err_trampoline;

eb->vma[eb->buffer_count].vma = i915_vma_get(shadow);
eb->vma[eb->buffer_count].flags =
__EXEC_OBJECT_HAS_PIN | __EXEC_OBJECT_HAS_REF;
eb->vma[eb->buffer_count].flags = __EXEC_OBJECT_HAS_PIN;
eb->batch = &eb->vma[eb->buffer_count++];

eb->trampoline = trampoline;
Expand Down

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