[PATCH 2/2] gpu/i915: use HMM mirror for userptr buffer object.
jglisse at redhat.com
jglisse at redhat.com
Mon Sep 10 00:57:36 UTC 2018
From: Jérôme Glisse <jglisse at redhat.com>
This replace existing code that rely on get_user_page() aka GUP with
code that now use HMM mirror to mirror a range of virtual address as
a buffer object accessible by the GPU. There is no functional changes
from userspace point of view.
>From kernel point of view we no longer pin pages for userptr buffer
object which is a welcome change (i am assuming that everyone dislike
page pin as i do).
Another change, from kernel point of view, is that it does no longer
have a fast path with get_user_pages_fast() this can eventually added
back through HMM.
Signed-off-by: Jérôme Glisse <jglisse at redhat.com>
Cc: dri-devel at lists.freedesktop.org
Cc: David Airlie <airlied at linux.ie>
Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
Cc: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
Cc: Jani Nikula <jani.nikula at linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
Cc: intel-gfx at lists.freedesktop.org
---
drivers/gpu/drm/i915/i915_gem_userptr.c | 206 ++++++++++++------------
1 file changed, 102 insertions(+), 104 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_gem_userptr.c b/drivers/gpu/drm/i915/i915_gem_userptr.c
index 5e09b654b5ad..378aab438ebd 100644
--- a/drivers/gpu/drm/i915/i915_gem_userptr.c
+++ b/drivers/gpu/drm/i915/i915_gem_userptr.c
@@ -464,7 +464,7 @@ __i915_gem_userptr_alloc_pages(struct drm_i915_gem_object *obj,
static int
__i915_gem_userptr_set_active(struct drm_i915_gem_object *obj,
- bool value)
+ struct hmm_range *range)
{
int ret = 0;
@@ -486,86 +486,120 @@ __i915_gem_userptr_set_active(struct drm_i915_gem_object *obj,
/* In order to serialise get_pages with an outstanding
* cancel_userptr, we must drop the struct_mutex and try again.
*/
- if (!value)
+ if (range) {
+ if (!hmm_vma_range_done(range))
+ ret = -EAGAIN;
+ else
+ add_object(obj->userptr.mmu_object);
+ } else
del_object(obj->userptr.mmu_object);
- else if (!work_pending(&obj->userptr.mmu_object->work))
- add_object(obj->userptr.mmu_object);
- else
- ret = -EAGAIN;
spin_unlock(&obj->userptr.mmu_object->mirror->lock);
#endif
return ret;
}
-static void
-__i915_gem_userptr_get_pages_worker(struct work_struct *_work)
+static int
+i915_gem_userptr_map(struct drm_i915_gem_object *obj, bool try)
{
- struct get_pages_work *work = container_of(_work, typeof(*work), work);
- struct drm_i915_gem_object *obj = work->obj;
- const int npages = obj->base.size >> PAGE_SHIFT;
+#if defined(CONFIG_HMM_MIRROR)
+ static const uint64_t i915_range_flags[HMM_PFN_FLAG_MAX] = {
+ (1 << 0), /* HMM_PFN_VALID */
+ (1 << 1), /* HMM_PFN_WRITE */
+ 0 /* HMM_PFN_DEVICE_PRIVATE */
+ };
+ static const uint64_t i915_range_values[HMM_PFN_VALUE_MAX] = {
+ 0xfffffffffffffffeUL, /* HMM_PFN_ERROR */
+ 0, /* HMM_PFN_NONE */
+ 0xfffffffffffffffcUL /* HMM_PFN_SPECIAL */
+ };
+
+ const unsigned long npages = obj->base.size >> PAGE_SHIFT;
+ struct mm_struct *mm = obj->userptr.mm->mm;
+ struct sg_table *pages;
+ struct hmm_range range;
struct page **pvec;
- int pinned, ret;
-
- ret = -ENOMEM;
- pinned = 0;
-
- pvec = kvmalloc_array(npages, sizeof(struct page *), GFP_KERNEL);
- if (pvec != NULL) {
- struct mm_struct *mm = obj->userptr.mm->mm;
- unsigned int flags = 0;
-
- if (!i915_gem_object_is_readonly(obj))
- flags |= FOLL_WRITE;
-
- ret = -EFAULT;
- if (mmget_not_zero(mm)) {
- down_read(&mm->mmap_sem);
- while (pinned < npages) {
- ret = get_user_pages_remote
- (work->task, mm,
- obj->userptr.ptr + pinned * PAGE_SIZE,
- npages - pinned,
- flags,
- pvec + pinned, NULL, NULL);
- if (ret < 0)
- break;
-
- pinned += ret;
- }
- up_read(&mm->mmap_sem);
- mmput(mm);
- }
+ unsigned long i;
+ bool write = !i915_gem_object_is_readonly(obj);
+ int err;
+
+ range.pfns = kvmalloc_array(npages, sizeof(uint64_t),
+ try ? GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN : GFP_KERNEL);
+ if (range.pfns == NULL)
+ return try ? -EAGAIN : -ENOMEM;
+
+ range.pfn_shift = 12;
+ range.start = obj->userptr.ptr;
+ range.flags = i915_range_flags;
+ range.values = i915_range_values;
+ range.end = range.start + obj->base.size;
+
+ range.vma = find_vma(mm, range.start);
+ if (!range.vma || range.vma->vm_file || range.vma->vm_end < range.end) {
+ kvfree(range.pfns);
+ return -EFAULT;
}
- mutex_lock(&obj->mm.lock);
- if (obj->userptr.work == &work->work) {
- struct sg_table *pages = ERR_PTR(ret);
-
- if (pinned == npages) {
- pages = __i915_gem_userptr_alloc_pages(obj, pvec,
- npages);
- if (!IS_ERR(pages)) {
- pinned = 0;
- pages = NULL;
+again:
+ for (i = 0; i < npages; ++i) {
+ range.pfns[i] = range.flags[HMM_PFN_VALID];
+ range.pfns[i] |= write ? range.flags[HMM_PFN_WRITE] : 0;
+ }
+
+ err = hmm_vma_fault(&range, true);
+ if (err) {
+ kvfree(range.pfns);
+ return err;
+ }
+
+ for (i = 0, pvec = (void *)range.pfns; i < npages; ++i) {
+ struct page *page = hmm_pfn_to_page(&range, range.pfns[i]);
+
+ if (page == NULL) {
+ hmm_vma_range_done(&range);
+
+ if (try) {
+ kvfree(range.pfns);
+ return -EAGAIN;
}
+ goto again;
}
-
- obj->userptr.work = ERR_CAST(pages);
- if (IS_ERR(pages))
- __i915_gem_userptr_set_active(obj, false);
+ pvec[i] = page;
}
- mutex_unlock(&obj->mm.lock);
- release_pages(pvec, pinned);
- kvfree(pvec);
+ if (!try)
+ mutex_lock(&obj->mm.lock);
+ pages = __i915_gem_userptr_alloc_pages(obj, pvec, npages);
+ if (!IS_ERR(pages))
+ __i915_gem_userptr_set_active(obj, &range);
+ else
+ hmm_vma_range_done(&range);
+ if (!try)
+ mutex_unlock(&obj->mm.lock);
+
+ kvfree(range.pfns);
+ return PTR_ERR_OR_ZERO(pages);
+#else /* CONFIG_HMM_MIRROR */
+ return -EFAULT;
+#endif
+}
+
+static void
+__i915_gem_userptr_get_pages_worker(struct work_struct *_work)
+{
+ struct get_pages_work *work = container_of(_work, typeof(*work), work);
+ struct drm_i915_gem_object *obj = work->obj;
+ int ret;
+
+ ret = i915_gem_userptr_map(obj, false);
+ obj->userptr.work = ERR_PTR(ret);
i915_gem_object_put(obj);
put_task_struct(work->task);
kfree(work);
}
-static struct sg_table *
+static int
__i915_gem_userptr_get_pages_schedule(struct drm_i915_gem_object *obj)
{
struct get_pages_work *work;
@@ -591,7 +625,7 @@ __i915_gem_userptr_get_pages_schedule(struct drm_i915_gem_object *obj)
*/
work = kmalloc(sizeof(*work), GFP_KERNEL);
if (work == NULL)
- return ERR_PTR(-ENOMEM);
+ return -ENOMEM;
obj->userptr.work = &work->work;
@@ -603,17 +637,12 @@ __i915_gem_userptr_get_pages_schedule(struct drm_i915_gem_object *obj)
INIT_WORK(&work->work, __i915_gem_userptr_get_pages_worker);
queue_work(to_i915(obj->base.dev)->mm.userptr_wq, &work->work);
- return ERR_PTR(-EAGAIN);
+ return -EAGAIN;
}
static int i915_gem_userptr_get_pages(struct drm_i915_gem_object *obj)
{
- const int num_pages = obj->base.size >> PAGE_SHIFT;
- struct mm_struct *mm = obj->userptr.mm->mm;
- struct page **pvec;
- struct sg_table *pages;
- bool active;
- int pinned;
+ int ret;
/* If userspace should engineer that these pages are replaced in
* the vma between us binding this page into the GTT and completion
@@ -640,40 +669,10 @@ static int i915_gem_userptr_get_pages(struct drm_i915_gem_object *obj)
return -EAGAIN;
}
- pvec = NULL;
- pinned = 0;
-
- if (mm == current->mm) {
- pvec = kvmalloc_array(num_pages, sizeof(struct page *),
- GFP_KERNEL |
- __GFP_NORETRY |
- __GFP_NOWARN);
- if (pvec) /* defer to worker if malloc fails */
- pinned = __get_user_pages_fast(obj->userptr.ptr,
- num_pages,
- !i915_gem_object_is_readonly(obj),
- pvec);
- }
-
- active = false;
- if (pinned < 0) {
- pages = ERR_PTR(pinned);
- pinned = 0;
- } else if (pinned < num_pages) {
- pages = __i915_gem_userptr_get_pages_schedule(obj);
- active = pages == ERR_PTR(-EAGAIN);
- } else {
- pages = __i915_gem_userptr_alloc_pages(obj, pvec, num_pages);
- active = !IS_ERR(pages);
- }
- if (active)
- __i915_gem_userptr_set_active(obj, true);
-
- if (IS_ERR(pages))
- release_pages(pvec, pinned);
- kvfree(pvec);
-
- return PTR_ERR_OR_ZERO(pages);
+ ret = i915_gem_userptr_map(obj, true);
+ if (ret == -EAGAIN)
+ ret = __i915_gem_userptr_get_pages_schedule(obj);
+ return ret;
}
static void
@@ -684,7 +683,7 @@ i915_gem_userptr_put_pages(struct drm_i915_gem_object *obj,
struct page *page;
BUG_ON(obj->userptr.work != NULL);
- __i915_gem_userptr_set_active(obj, false);
+ __i915_gem_userptr_set_active(obj, NULL);
if (obj->mm.madv != I915_MADV_WILLNEED)
obj->mm.dirty = false;
@@ -696,7 +695,6 @@ i915_gem_userptr_put_pages(struct drm_i915_gem_object *obj,
set_page_dirty(page);
mark_page_accessed(page);
- put_page(page);
}
obj->mm.dirty = false;
--
2.17.1
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