[Intel-gfx] [PATCH 2/3] drm/i915/gtt: Read-only pages for insert_entries on bdw+
Chris Wilson
chris at chris-wilson.co.uk
Thu May 31 09:19:22 UTC 2018
From: Jon Bloomfield <jon.bloomfield at intel.com>
Hook up the flags to allow read-only ppGTT mappings for gen8+
Signed-off-by: Jon Bloomfield <jon.bloomfield at intel.com>
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
Cc: Matthew Auld <matthew.william.auld at gmail.com>
---
drivers/gpu/drm/i915/i915_gem_gtt.c | 45 ++++++++++++++++---------
drivers/gpu/drm/i915/i915_gem_gtt.h | 7 +++-
drivers/gpu/drm/i915/intel_ringbuffer.c | 11 ++++--
3 files changed, 44 insertions(+), 19 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index 5936f0bfdd19..1ac626cacc8d 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -204,7 +204,7 @@ static int ppgtt_bind_vma(struct i915_vma *vma,
return ret;
}
- /* Currently applicable only to VLV */
+ /* Applicable to VLV, and gen8+ */
pte_flags = 0;
if (vma->obj->gt_ro)
pte_flags |= PTE_READ_ONLY;
@@ -1008,10 +1008,11 @@ gen8_ppgtt_insert_pte_entries(struct i915_hw_ppgtt *ppgtt,
struct i915_page_directory_pointer *pdp,
struct sgt_dma *iter,
struct gen8_insert_pte *idx,
- enum i915_cache_level cache_level)
+ enum i915_cache_level cache_level,
+ u32 flags)
{
struct i915_page_directory *pd;
- const gen8_pte_t pte_encode = gen8_pte_encode(0, cache_level, 0);
+ const gen8_pte_t pte_encode = gen8_pte_encode(0, cache_level, flags);
gen8_pte_t *vaddr;
bool ret;
@@ -1062,14 +1063,14 @@ gen8_ppgtt_insert_pte_entries(struct i915_hw_ppgtt *ppgtt,
static void gen8_ppgtt_insert_3lvl(struct i915_address_space *vm,
struct i915_vma *vma,
enum i915_cache_level cache_level,
- u32 unused)
+ u32 flags)
{
struct i915_hw_ppgtt *ppgtt = i915_vm_to_ppgtt(vm);
struct sgt_dma iter = sgt_dma(vma);
struct gen8_insert_pte idx = gen8_insert_pte(vma->node.start);
gen8_ppgtt_insert_pte_entries(ppgtt, &ppgtt->pdp, &iter, &idx,
- cache_level);
+ cache_level, flags);
vma->page_sizes.gtt = I915_GTT_PAGE_SIZE;
}
@@ -1077,9 +1078,10 @@ static void gen8_ppgtt_insert_3lvl(struct i915_address_space *vm,
static void gen8_ppgtt_insert_huge_entries(struct i915_vma *vma,
struct i915_page_directory_pointer **pdps,
struct sgt_dma *iter,
- enum i915_cache_level cache_level)
+ enum i915_cache_level cache_level,
+ u32 flags)
{
- const gen8_pte_t pte_encode = gen8_pte_encode(0, cache_level, 0);
+ const gen8_pte_t pte_encode = gen8_pte_encode(0, cache_level, flags);
u64 start = vma->node.start;
dma_addr_t rem = iter->sg->length;
@@ -1195,19 +1197,21 @@ static void gen8_ppgtt_insert_huge_entries(struct i915_vma *vma,
static void gen8_ppgtt_insert_4lvl(struct i915_address_space *vm,
struct i915_vma *vma,
enum i915_cache_level cache_level,
- u32 unused)
+ u32 flags)
{
struct i915_hw_ppgtt *ppgtt = i915_vm_to_ppgtt(vm);
struct sgt_dma iter = sgt_dma(vma);
struct i915_page_directory_pointer **pdps = ppgtt->pml4.pdps;
if (vma->page_sizes.sg > I915_GTT_PAGE_SIZE) {
- gen8_ppgtt_insert_huge_entries(vma, pdps, &iter, cache_level);
+ gen8_ppgtt_insert_huge_entries(vma, pdps, &iter, cache_level,
+ flags);
} else {
struct gen8_insert_pte idx = gen8_insert_pte(vma->node.start);
while (gen8_ppgtt_insert_pte_entries(ppgtt, pdps[idx.pml4e++],
- &iter, &idx, cache_level))
+ &iter, &idx, cache_level,
+ flags))
GEM_BUG_ON(idx.pml4e >= GEN8_PML4ES_PER_PML4);
vma->page_sizes.gtt = I915_GTT_PAGE_SIZE;
@@ -1614,6 +1618,9 @@ static int gen8_ppgtt_init(struct i915_hw_ppgtt *ppgtt)
1ULL << 48 :
1ULL << 32;
+ /* From bdw, there is support for read-only pages in the PPGTT */
+ ppgtt->base.has_read_only = true;
+
/* There are only few exceptions for gen >=6. chv and bxt.
* And we are not sure about the latter so play safe for now.
*/
@@ -2430,7 +2437,7 @@ static void gen8_ggtt_insert_page(struct i915_address_space *vm,
static void gen8_ggtt_insert_entries(struct i915_address_space *vm,
struct i915_vma *vma,
enum i915_cache_level level,
- u32 unused)
+ u32 flags)
{
struct i915_ggtt *ggtt = i915_vm_to_ggtt(vm);
struct sgt_iter sgt_iter;
@@ -2438,6 +2445,9 @@ static void gen8_ggtt_insert_entries(struct i915_address_space *vm,
const gen8_pte_t pte_encode = gen8_pte_encode(0, level, 0);
dma_addr_t addr;
+ /* The GTT does not support read-only mappings */
+ GEM_BUG_ON(flags & PTE_READ_ONLY);
+
gtt_entries = (gen8_pte_t __iomem *)ggtt->gsm;
gtt_entries += vma->node.start >> PAGE_SHIFT;
for_each_sgt_dma(addr, sgt_iter, vma->pages)
@@ -2564,13 +2574,14 @@ struct insert_entries {
struct i915_address_space *vm;
struct i915_vma *vma;
enum i915_cache_level level;
+ u32 flags;
};
static int bxt_vtd_ggtt_insert_entries__cb(void *_arg)
{
struct insert_entries *arg = _arg;
- gen8_ggtt_insert_entries(arg->vm, arg->vma, arg->level, 0);
+ gen8_ggtt_insert_entries(arg->vm, arg->vma, arg->level, arg->flags);
bxt_vtd_ggtt_wa(arg->vm);
return 0;
@@ -2579,9 +2590,9 @@ static int bxt_vtd_ggtt_insert_entries__cb(void *_arg)
static void bxt_vtd_ggtt_insert_entries__BKL(struct i915_address_space *vm,
struct i915_vma *vma,
enum i915_cache_level level,
- u32 unused)
+ u32 flags)
{
- struct insert_entries arg = { vm, vma, level };
+ struct insert_entries arg = { vm, vma, level, flags };
stop_machine(bxt_vtd_ggtt_insert_entries__cb, &arg, NULL);
}
@@ -2672,7 +2683,7 @@ static int ggtt_bind_vma(struct i915_vma *vma,
struct drm_i915_gem_object *obj = vma->obj;
u32 pte_flags;
- /* Currently applicable only to VLV */
+ /* Applicable to VLV (gen8+ do not support RO in the GGTT) */
pte_flags = 0;
if (obj->gt_ro)
pte_flags |= PTE_READ_ONLY;
@@ -3555,6 +3566,10 @@ int i915_ggtt_init_hw(struct drm_i915_private *dev_priv)
*/
mutex_lock(&dev_priv->drm.struct_mutex);
i915_address_space_init(&ggtt->base, dev_priv, "[global]");
+
+ /* Only VLV supports read-only GGTT mappings */
+ ggtt->base.has_read_only = IS_VALLEYVIEW(dev_priv);
+
if (!HAS_LLC(dev_priv) && !USES_PPGTT(dev_priv))
ggtt->base.mm.color_adjust = i915_gtt_color_adjust;
mutex_unlock(&dev_priv->drm.struct_mutex);
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.h b/drivers/gpu/drm/i915/i915_gem_gtt.h
index aec4f73574f4..b0929b547846 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.h
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.h
@@ -309,7 +309,12 @@ struct i915_address_space {
struct list_head unbound_list;
struct pagevec free_pages;
- bool pt_kmap_wc;
+
+ /* Some systems require uncached updates of the page directories */
+ bool pt_kmap_wc:1;
+
+ /* Some systems support read-only mappings for GGTT and/or PPGTT */
+ bool has_read_only:1;
/* FIXME: Need a more generic return type */
gen6_pte_t (*pte_encode)(dma_addr_t addr,
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 97b38bbb7ce2..6cac4ce59438 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -1111,6 +1111,7 @@ void intel_ring_unpin(struct intel_ring *ring)
static struct i915_vma *
intel_ring_create_vma(struct drm_i915_private *dev_priv, int size)
{
+ struct i915_address_space *vm = &dev_priv->ggtt.base;
struct drm_i915_gem_object *obj;
struct i915_vma *vma;
@@ -1120,10 +1121,14 @@ intel_ring_create_vma(struct drm_i915_private *dev_priv, int size)
if (IS_ERR(obj))
return ERR_CAST(obj);
- /* mark ring buffers as read-only from GPU side by default */
- obj->gt_ro = 1;
+ /*
+ * Mark ring buffers as read-only from GPU side (so no stray overwrites)
+ * if supported by the platform's GGTT.
+ */
+ if (vm->has_read_only)
+ obj->gt_ro = 1;
- vma = i915_vma_instance(obj, &dev_priv->ggtt.base, NULL);
+ vma = i915_vma_instance(obj, vm, NULL);
if (IS_ERR(vma))
goto err;
--
2.17.0
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