[PATCH v2 2/4] drm/xe/vm: Implement userptr page pinning
Thomas Hellström
thomas.hellstrom at linux.intel.com
Tue Aug 22 16:21:34 UTC 2023
Implement pinning of userptrs between VM_BIND and VM_UNBIND, which will
facilitate avoiding long hangs on non-preemptible workloads. But don't
hook it up to userspace just yet.
v2:
- Avoid marking userptr VMAs as invalid in the mmu invalidation notifier.
(Matthew Brost)
- Add an WARN that we don't try to repin userptr pages (Matthew Brost)
Signed-off-by: Thomas Hellström <thomas.hellstrom at linux.intel.com>
---
drivers/gpu/drm/xe/xe_vm.c | 80 +++++++++++++++++++++++---------
drivers/gpu/drm/xe/xe_vm.h | 9 ++++
drivers/gpu/drm/xe/xe_vm_types.h | 12 +++++
3 files changed, 79 insertions(+), 22 deletions(-)
diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c
index 8bf7f62e6548..037ac42f74a5 100644
--- a/drivers/gpu/drm/xe/xe_vm.c
+++ b/drivers/gpu/drm/xe/xe_vm.c
@@ -74,10 +74,6 @@ int xe_vma_userptr_pin_pages(struct xe_vma *vma)
if (notifier_seq == vma->userptr.notifier_seq)
return 0;
- pages = kvmalloc_array(num_pages, sizeof(*pages), GFP_KERNEL);
- if (!pages)
- return -ENOMEM;
-
if (vma->userptr.sg) {
dma_unmap_sgtable(xe->drm.dev,
vma->userptr.sg,
@@ -87,6 +83,18 @@ int xe_vma_userptr_pin_pages(struct xe_vma *vma)
vma->userptr.sg = NULL;
}
+ /* TODO: Convert to xe_assert() */
+ if (XE_WARN_ON(vma->userptr.pinned_pages)) {
+ unpin_user_pages_dirty_lock(vma->userptr.pinned_pages,
+ vma->userptr.num_pinned,
+ !read_only);
+ pages = vma->userptr.pinned_pages;
+ } else {
+ pages = kvmalloc_array(num_pages, sizeof(*pages), GFP_KERNEL);
+ if (!pages)
+ return -ENOMEM;
+ }
+
pinned = ret = 0;
if (in_kthread) {
if (!mmget_not_zero(vma->userptr.notifier.mm)) {
@@ -97,11 +105,18 @@ int xe_vma_userptr_pin_pages(struct xe_vma *vma)
}
while (pinned < num_pages) {
- ret = get_user_pages_fast(xe_vma_userptr(vma) +
- pinned * PAGE_SIZE,
- num_pages - pinned,
- read_only ? 0 : FOLL_WRITE,
- &pages[pinned]);
+ if (xe_vma_is_pinned(vma))
+ ret = pin_user_pages_fast(xe_vma_userptr(vma) +
+ pinned * PAGE_SIZE,
+ num_pages - pinned,
+ read_only ? 0 : FOLL_WRITE,
+ &pages[pinned]);
+ else
+ ret = get_user_pages_fast(xe_vma_userptr(vma) +
+ pinned * PAGE_SIZE,
+ num_pages - pinned,
+ read_only ? 0 : FOLL_WRITE,
+ &pages[pinned]);
if (ret < 0) {
if (in_kthread)
ret = 0;
@@ -137,19 +152,24 @@ int xe_vma_userptr_pin_pages(struct xe_vma *vma)
if (ret)
goto out_free_sg;
- for (i = 0; i < pinned; ++i) {
- if (!read_only) {
- lock_page(pages[i]);
- set_page_dirty(pages[i]);
- unlock_page(pages[i]);
+ if (!xe_vma_is_pinned(vma)) {
+ for (i = 0; i < pinned; ++i) {
+ if (!read_only) {
+ lock_page(pages[i]);
+ set_page_dirty(pages[i]);
+ unlock_page(pages[i]);
+ }
+
+ mark_page_accessed(pages[i]);
}
- mark_page_accessed(pages[i]);
+ release_pages(pages, pinned);
+ kvfree(pages);
+ } else {
+ vma->userptr.pinned_pages = pages;
+ vma->userptr.num_pinned = pinned;
}
- release_pages(pages, pinned);
- kvfree(pages);
-
vma->userptr.notifier_seq = notifier_seq;
if (xe_vma_userptr_check_repin(vma) == -EAGAIN)
goto retry;
@@ -160,9 +180,14 @@ int xe_vma_userptr_pin_pages(struct xe_vma *vma)
sg_free_table(vma->userptr.sg);
vma->userptr.sg = NULL;
out_release_pages:
- release_pages(pages, pinned);
+ if (!xe_vma_is_pinned(vma))
+ release_pages(pages, pinned);
+ else
+ unpin_user_pages(pages, pinned);
+ vma->userptr.num_pinned = 0;
mm_closed:
kvfree(pages);
+ vma->userptr.pinned_pages = NULL;
return ret;
}
@@ -718,6 +743,11 @@ static bool vma_userptr_invalidate(struct mmu_interval_notifier *mni,
return false;
down_write(&vm->userptr.notifier_lock);
+ if (xe_vma_is_pinned(vma)) {
+ up_write(&vm->userptr.notifier_lock);
+ return true;
+ }
+
mmu_interval_set_seq(mni, cur_seq);
/* No need to stop gpu access if the userptr is not yet bound. */
@@ -976,10 +1006,16 @@ static void xe_vma_destroy_late(struct xe_vma *vma)
vma->userptr.sg = NULL;
}
+ if (vma->userptr.pinned_pages) {
+ unpin_user_pages_dirty_lock(vma->userptr.pinned_pages,
+ vma->userptr.num_pinned,
+ !read_only);
+ kvfree(vma->userptr.pinned_pages);
+ }
+
/*
- * Since userptr pages are not pinned, we can't remove
- * the notifer until we're sure the GPU is not accessing
- * them anymore
+ * We can't remove the notifer until we're sure the GPU is
+ * not accessing the pages anymore
*/
mmu_interval_notifier_remove(&vma->userptr.notifier);
xe_vm_put(vm);
diff --git a/drivers/gpu/drm/xe/xe_vm.h b/drivers/gpu/drm/xe/xe_vm.h
index 6de6e3edb24a..913544d7d995 100644
--- a/drivers/gpu/drm/xe/xe_vm.h
+++ b/drivers/gpu/drm/xe/xe_vm.h
@@ -139,6 +139,15 @@ static inline bool xe_vma_is_userptr(struct xe_vma *vma)
return xe_vma_has_no_bo(vma) && !xe_vma_is_null(vma);
}
+/**
+ * xe_vma_is_pinned() - User has requested the backing store of this vma
+ * to be pinned.
+ */
+static inline bool xe_vma_is_pinned(struct xe_vma *vma)
+{
+ return xe_vma_is_userptr(vma) && (vma->gpuva.flags & XE_VMA_PINNED);
+}
+
#define xe_vm_assert_held(vm) dma_resv_assert_held(&(vm)->resv)
u64 xe_vm_pdp4_descriptor(struct xe_vm *vm, struct xe_tile *tile);
diff --git a/drivers/gpu/drm/xe/xe_vm_types.h b/drivers/gpu/drm/xe/xe_vm_types.h
index 3681a5ff588b..9b90e649cd69 100644
--- a/drivers/gpu/drm/xe/xe_vm_types.h
+++ b/drivers/gpu/drm/xe/xe_vm_types.h
@@ -33,6 +33,8 @@ struct xe_vm;
#define XE_VMA_PTE_4K (DRM_GPUVA_USERBITS << 5)
#define XE_VMA_PTE_2M (DRM_GPUVA_USERBITS << 6)
#define XE_VMA_PTE_1G (DRM_GPUVA_USERBITS << 7)
+/* User requested backing store to be pinned */
+#define XE_VMA_PINNED (DRM_GPUVA_USERBITS << 8)
/** struct xe_userptr - User pointer */
struct xe_userptr {
@@ -54,6 +56,16 @@ struct xe_userptr {
* read: vm->userptr.notifier_lock in write mode or vm->resv held.
*/
bool initial_bind;
+ /**
+ * @pinned_pages: List of pinned pages if xe_vma_pinned(),
+ * NULL otherwise. protected by the vm lock.
+ */
+ struct page **pinned_pages;
+ /**
+ * @num_pinned: Number of pointers to pinned pages in @pinned_pages.
+ * protected by the vm lock.
+ */
+ unsigned long num_pinned;
#if IS_ENABLED(CONFIG_DRM_XE_USERPTR_INVAL_INJECT)
u32 divisor;
#endif
--
2.41.0
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