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drm/i915/gtt: Pull global wc page stash under its own locking 

Currently, the wc-stash used for providing flushed WC pages ready for
constructing the page directories is assumed to be protected by the
struct_mutex. However, we want to remove this global lock and so must
install a replacement global lock for accessing the global wc-stash (the
per-vm stash continues to be guarded by the vm).

We need to push ahead on this patch due to an oversight in hastily
removing the struct_mutex guard around the igt_ppgtt_alloc selftest. No
matter, it will prove very useful (i.e. will be required) in the near
future.

v2: Restore the onstack stash so that we can drop the vm->mutex in
future across the allocation.
v3: Restore the lost pagevec_init of the onstack allocation, and repaint
function names.
v4: Reorder init so that we don't try and use i915_address_space before
it is ininitialised.

Fixes: 1f6f00238a ("drm/i915/selftests: Drop struct_mutex around lowlevel pggtt allocation")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180704185518.4193-1-chris@chris-wilson.co.uk
This commit is contained in:
Chris Wilson 2018-07-04 19:55:18 +01:00
parent 16659bc53a
commit 63fd659fb1
7 changed files with 143 additions and 85 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
drivers/gpu/drm/i915/i915_drv.h
View File

@ -952,7 +952,7 @@ struct i915_gem_mm {
/**
* Small stash of WC pages
*/
struct pagevec wc_stash;
struct pagestash wc_stash;
/**
* tmpfs instance used for shmem backed objects

2
drivers/gpu/drm/i915/i915_gem_context.c
View File

@ -374,7 +374,7 @@ i915_gem_create_context(struct drm_i915_private *dev_priv,
if (USES_FULL_PPGTT(dev_priv)) {
struct i915_hw_ppgtt *ppgtt;
ppgtt = i915_ppgtt_create(dev_priv, file_priv, ctx->name);
ppgtt = i915_ppgtt_create(dev_priv, file_priv);
if (IS_ERR(ppgtt)) {
DRM_DEBUG_DRIVER("PPGTT setup failed (%ld)\n",
PTR_ERR(ppgtt));

208
drivers/gpu/drm/i915/i915_gem_gtt.c
View File

@ -375,37 +375,70 @@ static gen6_pte_t iris_pte_encode(dma_addr_t addr,
return pte;
}
static void stash_init(struct pagestash *stash)
{
pagevec_init(&stash->pvec);
spin_lock_init(&stash->lock);
}
static struct page *stash_pop_page(struct pagestash *stash)
{
struct page *page = NULL;
spin_lock(&stash->lock);
if (likely(stash->pvec.nr))
page = stash->pvec.pages[--stash->pvec.nr];
spin_unlock(&stash->lock);
return page;
}
static void stash_push_pagevec(struct pagestash *stash, struct pagevec *pvec)
{
int nr;
spin_lock_nested(&stash->lock, SINGLE_DEPTH_NESTING);
nr = min_t(int, pvec->nr, pagevec_space(&stash->pvec));
memcpy(stash->pvec.pages + stash->pvec.nr,
pvec->pages + pvec->nr - nr,
sizeof(pvec->pages[0]) * nr);
stash->pvec.nr += nr;
spin_unlock(&stash->lock);
pvec->nr -= nr;
}
static struct page *vm_alloc_page(struct i915_address_space *vm, gfp_t gfp)
{
struct pagevec *pvec = &vm->free_pages;
struct pagevec stash;
struct pagevec stack;
struct page *page;
if (I915_SELFTEST_ONLY(should_fail(&vm->fault_attr, 1)))
i915_gem_shrink_all(vm->i915);
if (likely(pvec->nr))
return pvec->pages[--pvec->nr];
page = stash_pop_page(&vm->free_pages);
if (page)
return page;
if (!vm->pt_kmap_wc)
return alloc_page(gfp);
/* A placeholder for a specific mutex to guard the WC stash */
lockdep_assert_held(&vm->i915->drm.struct_mutex);
/* Look in our global stash of WC pages... */
pvec = &vm->i915->mm.wc_stash;
if (likely(pvec->nr))
return pvec->pages[--pvec->nr];
page = stash_pop_page(&vm->i915->mm.wc_stash);
if (page)
return page;
/*
* Otherwise batch allocate pages to amoritize cost of set_pages_wc.
* Otherwise batch allocate pages to amortize cost of set_pages_wc.
*
* We have to be careful as page allocation may trigger the shrinker
* (via direct reclaim) which will fill up the WC stash underneath us.
* So we add our WB pages into a temporary pvec on the stack and merge
* them into the WC stash after all the allocations are complete.
*/
pagevec_init(&stash);
pagevec_init(&stack);
do {
struct page *page;
@ -413,59 +446,67 @@ static struct page *vm_alloc_page(struct i915_address_space *vm, gfp_t gfp)
if (unlikely(!page))
break;
stash.pages[stash.nr++] = page;
} while (stash.nr < pagevec_space(pvec));
stack.pages[stack.nr++] = page;
} while (pagevec_space(&stack));
if (stash.nr) {
int nr = min_t(int, stash.nr, pagevec_space(pvec));
struct page **pages = stash.pages + stash.nr - nr;
if (stack.nr && !set_pages_array_wc(stack.pages, stack.nr)) {
page = stack.pages[--stack.nr];
if (nr && !set_pages_array_wc(pages, nr)) {
memcpy(pvec->pages + pvec->nr,
pages, sizeof(pages[0]) * nr);
pvec->nr += nr;
stash.nr -= nr;
}
/* Merge spare WC pages to the global stash */
stash_push_pagevec(&vm->i915->mm.wc_stash, &stack);
pagevec_release(&stash);
/* Push any surplus WC pages onto the local VM stash */
if (stack.nr)
stash_push_pagevec(&vm->free_pages, &stack);
}
return likely(pvec->nr) ? pvec->pages[--pvec->nr] : NULL;
/* Return unwanted leftovers */
if (unlikely(stack.nr)) {
WARN_ON_ONCE(set_pages_array_wb(stack.pages, stack.nr));
__pagevec_release(&stack);
}
return page;
}
static void vm_free_pages_release(struct i915_address_space *vm,
bool immediate)
{
struct pagevec *pvec = &vm->free_pages;
struct pagevec *pvec = &vm->free_pages.pvec;
struct pagevec stack;
lockdep_assert_held(&vm->free_pages.lock);
GEM_BUG_ON(!pagevec_count(pvec));
if (vm->pt_kmap_wc) {
struct pagevec *stash = &vm->i915->mm.wc_stash;
/* When we use WC, first fill up the global stash and then
/*
* When we use WC, first fill up the global stash and then
* only if full immediately free the overflow.
*/
stash_push_pagevec(&vm->i915->mm.wc_stash, pvec);
lockdep_assert_held(&vm->i915->drm.struct_mutex);
if (pagevec_space(stash)) {
do {
stash->pages[stash->nr++] =
pvec->pages[--pvec->nr];
if (!pvec->nr)
return;
} while (pagevec_space(stash));
/*
* As we have made some room in the VM's free_pages,
* we can wait for it to fill again. Unless we are
* inside i915_address_space_fini() and must
* immediately release the pages!
*/
if (pvec->nr <= (immediate ? 0 : PAGEVEC_SIZE - 1))
return;
/* As we have made some room in the VM's free_pages,
* we can wait for it to fill again. Unless we are
* inside i915_address_space_fini() and must
* immediately release the pages!
*/
if (!immediate)
return;
}
/*
* We have to drop the lock to allow ourselves to sleep,
* so take a copy of the pvec and clear the stash for
* others to use it as we sleep.
*/
stack = *pvec;
pagevec_reinit(pvec);
spin_unlock(&vm->free_pages.lock);
pvec = &stack;
set_pages_array_wb(pvec->pages, pvec->nr);
spin_lock(&vm->free_pages.lock);
}
__pagevec_release(pvec);
@ -481,8 +522,38 @@ static void vm_free_page(struct i915_address_space *vm, struct page *page)
* unconditional might_sleep() for everybody.
*/
might_sleep();
if (!pagevec_add(&vm->free_pages, page))
spin_lock(&vm->free_pages.lock);
if (!pagevec_add(&vm->free_pages.pvec, page))
vm_free_pages_release(vm, false);
spin_unlock(&vm->free_pages.lock);
}
static void i915_address_space_init(struct i915_address_space *vm,
struct drm_i915_private *dev_priv)
{
GEM_BUG_ON(!vm->total);
drm_mm_init(&vm->mm, 0, vm->total);
vm->mm.head_node.color = I915_COLOR_UNEVICTABLE;
stash_init(&vm->free_pages);
INIT_LIST_HEAD(&vm->active_list);
INIT_LIST_HEAD(&vm->inactive_list);
INIT_LIST_HEAD(&vm->unbound_list);
list_add_tail(&vm->global_link, &dev_priv->vm_list);
}
static void i915_address_space_fini(struct i915_address_space *vm)
{
spin_lock(&vm->free_pages.lock);
if (pagevec_count(&vm->free_pages.pvec))
vm_free_pages_release(vm, true);
GEM_BUG_ON(pagevec_count(&vm->free_pages.pvec));
spin_unlock(&vm->free_pages.lock);
drm_mm_takedown(&vm->mm);
list_del(&vm->global_link);
}
static int __setup_page_dma(struct i915_address_space *vm,
@ -1562,6 +1633,8 @@ static struct i915_hw_ppgtt *gen8_ppgtt_create(struct drm_i915_private *i915)
if (!ppgtt)
return ERR_PTR(-ENOMEM);
kref_init(&ppgtt->ref);
ppgtt->vm.i915 = i915;
ppgtt->vm.dma = &i915->drm.pdev->dev;
@ -1569,6 +1642,8 @@ static struct i915_hw_ppgtt *gen8_ppgtt_create(struct drm_i915_private *i915)
1ULL << 48 :
1ULL << 32;
i915_address_space_init(&ppgtt->vm, i915);
/* There are only few exceptions for gen >=6. chv and bxt.
* And we are not sure about the latter so play safe for now.
*/
@ -2068,11 +2143,15 @@ static struct i915_hw_ppgtt *gen6_ppgtt_create(struct drm_i915_private *i915)
if (!ppgtt)
return ERR_PTR(-ENOMEM);
kref_init(&ppgtt->base.ref);
ppgtt->base.vm.i915 = i915;
ppgtt->base.vm.dma = &i915->drm.pdev->dev;
ppgtt->base.vm.total = I915_PDES * GEN6_PTES * PAGE_SIZE;
i915_address_space_init(&ppgtt->base.vm, i915);
ppgtt->base.vm.allocate_va_range = gen6_alloc_va_range;
ppgtt->base.vm.clear_range = gen6_ppgtt_clear_range;
ppgtt->base.vm.insert_entries = gen6_ppgtt_insert_entries;
@ -2105,30 +2184,6 @@ err_free:
return ERR_PTR(err);
}
static void i915_address_space_init(struct i915_address_space *vm,
struct drm_i915_private *dev_priv,
const char *name)
{
drm_mm_init(&vm->mm, 0, vm->total);
vm->mm.head_node.color = I915_COLOR_UNEVICTABLE;
INIT_LIST_HEAD(&vm->active_list);
INIT_LIST_HEAD(&vm->inactive_list);
INIT_LIST_HEAD(&vm->unbound_list);
list_add_tail(&vm->global_link, &dev_priv->vm_list);
pagevec_init(&vm->free_pages);
}
static void i915_address_space_fini(struct i915_address_space *vm)
{
if (pagevec_count(&vm->free_pages))
vm_free_pages_release(vm, true);
drm_mm_takedown(&vm->mm);
list_del(&vm->global_link);
}
static void gtt_write_workarounds(struct drm_i915_private *dev_priv)
{
/* This function is for gtt related workarounds. This function is
@ -2199,8 +2254,7 @@ __hw_ppgtt_create(struct drm_i915_private *i915)
struct i915_hw_ppgtt *
i915_ppgtt_create(struct drm_i915_private *i915,
struct drm_i915_file_private *fpriv,
const char *name)
struct drm_i915_file_private *fpriv)
{
struct i915_hw_ppgtt *ppgtt;
@ -2208,8 +2262,6 @@ i915_ppgtt_create(struct drm_i915_private *i915,
if (IS_ERR(ppgtt))
return ppgtt;
kref_init(&ppgtt->ref);
i915_address_space_init(&ppgtt->vm, i915, name);
ppgtt->vm.file = fpriv;
trace_i915_ppgtt_create(&ppgtt->vm);
@ -2788,7 +2840,7 @@ int i915_gem_init_aliasing_ppgtt(struct drm_i915_private *i915)
struct i915_hw_ppgtt *ppgtt;
int err;
ppgtt = i915_ppgtt_create(i915, ERR_PTR(-EPERM), "[alias]");
ppgtt = i915_ppgtt_create(i915, ERR_PTR(-EPERM));
if (IS_ERR(ppgtt))
return PTR_ERR(ppgtt);
@ -2918,7 +2970,7 @@ void i915_ggtt_cleanup_hw(struct drm_i915_private *dev_priv)
ggtt->vm.cleanup(&ggtt->vm);
pvec = &dev_priv->mm.wc_stash;
pvec = &dev_priv->mm.wc_stash.pvec;
if (pvec->nr) {
set_pages_array_wb(pvec->pages, pvec->nr);
__pagevec_release(pvec);
@ -3518,6 +3570,8 @@ int i915_ggtt_init_hw(struct drm_i915_private *dev_priv)
struct i915_ggtt *ggtt = &dev_priv->ggtt;
int ret;
stash_init(&dev_priv->mm.wc_stash);
INIT_LIST_HEAD(&dev_priv->vm_list);
/* Note that we use page colouring to enforce a guard page at the
@ -3526,7 +3580,7 @@ int i915_ggtt_init_hw(struct drm_i915_private *dev_priv)
* and beyond the end of the GTT if we do not provide a guard.
*/
mutex_lock(&dev_priv->drm.struct_mutex);
i915_address_space_init(&ggtt->vm, dev_priv, "[global]");
i915_address_space_init(&ggtt->vm, dev_priv);
if (!HAS_LLC(dev_priv) && !USES_PPGTT(dev_priv))
ggtt->vm.mm.color_adjust = i915_gtt_color_adjust;
mutex_unlock(&dev_priv->drm.struct_mutex);

10
drivers/gpu/drm/i915/i915_gem_gtt.h
View File

@ -270,6 +270,11 @@ struct i915_vma_ops {
void (*clear_pages)(struct i915_vma *vma);
};
struct pagestash {
spinlock_t lock;
struct pagevec pvec;
};
struct i915_address_space {
struct drm_mm mm;
struct drm_i915_private *i915;
@ -324,7 +329,7 @@ struct i915_address_space {
*/
struct list_head unbound_list;
struct pagevec free_pages;
struct pagestash free_pages;
bool pt_kmap_wc;
/* FIXME: Need a more generic return type */
@ -615,8 +620,7 @@ void i915_ggtt_cleanup_hw(struct drm_i915_private *dev_priv);
int i915_ppgtt_init_hw(struct drm_i915_private *dev_priv);
void i915_ppgtt_release(struct kref *kref);
struct i915_hw_ppgtt *i915_ppgtt_create(struct drm_i915_private *dev_priv,
struct drm_i915_file_private *fpriv,
const char *name);
struct drm_i915_file_private *fpriv);
void i915_ppgtt_close(struct i915_address_space *vm);
static inline void i915_ppgtt_get(struct i915_hw_ppgtt *ppgtt)
{

2
drivers/gpu/drm/i915/selftests/huge_pages.c
View File

@ -1694,7 +1694,7 @@ int i915_gem_huge_page_mock_selftests(void)
dma_coerce_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(39));
mutex_lock(&dev_priv->drm.struct_mutex);
ppgtt = i915_ppgtt_create(dev_priv, ERR_PTR(-ENODEV), "mock");
ppgtt = i915_ppgtt_create(dev_priv, ERR_PTR(-ENODEV));
if (IS_ERR(ppgtt)) {
err = PTR_ERR(ppgtt);
goto out_unlock;

2
drivers/gpu/drm/i915/selftests/i915_gem_gtt.c
View File

@ -1004,7 +1004,7 @@ static int exercise_ppgtt(struct drm_i915_private *dev_priv,
return PTR_ERR(file);
mutex_lock(&dev_priv->drm.struct_mutex);
ppgtt = i915_ppgtt_create(dev_priv, file->driver_priv, "mock");
ppgtt = i915_ppgtt_create(dev_priv, file->driver_priv);
if (IS_ERR(ppgtt)) {
err = PTR_ERR(ppgtt);
goto out_unlock;

2
drivers/gpu/drm/i915/selftests/mock_gtt.c
View File

@ -124,7 +124,7 @@ void mock_init_ggtt(struct drm_i915_private *i915)
ggtt->vm.vma_ops.set_pages = ggtt_set_pages;
ggtt->vm.vma_ops.clear_pages = clear_pages;
i915_address_space_init(&ggtt->vm, i915, "global");
i915_address_space_init(&ggtt->vm, i915);
}
void mock_fini_ggtt(struct drm_i915_private *i915)