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Subject[PATCH AUTOSEL 5.2 37/59] drm/vgem: fix cache synchronization on arm/arm64
Date
From: Rob Clark <robdclark@chromium.org>

[ Upstream commit 7e9e5ead55beacc11116b3fb90b0de6e7cf55a69 ]

drm_cflush_pages() is no-op on arm/arm64. But instead we can use
dma_sync API.

Fixes failures w/ vgem_test.

Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Rob Clark <robdclark@chromium.org>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20190717211542.30482-1-robdclark@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpu/drm/vgem/vgem_drv.c | 130 ++++++++++++++++++++------------
1 file changed, 83 insertions(+), 47 deletions(-)

diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c
index 11a8f99ba18c5..fc04803ff4035 100644
--- a/drivers/gpu/drm/vgem/vgem_drv.c
+++ b/drivers/gpu/drm/vgem/vgem_drv.c
@@ -47,10 +47,16 @@ static struct vgem_device {
struct platform_device *platform;
} *vgem_device;

+static void sync_and_unpin(struct drm_vgem_gem_object *bo);
+static struct page **pin_and_sync(struct drm_vgem_gem_object *bo);
+
static void vgem_gem_free_object(struct drm_gem_object *obj)
{
struct drm_vgem_gem_object *vgem_obj = to_vgem_bo(obj);

+ if (!obj->import_attach)
+ sync_and_unpin(vgem_obj);
+
kvfree(vgem_obj->pages);
mutex_destroy(&vgem_obj->pages_lock);

@@ -78,40 +84,15 @@ static vm_fault_t vgem_gem_fault(struct vm_fault *vmf)
return VM_FAULT_SIGBUS;

mutex_lock(&obj->pages_lock);
+ if (!obj->pages)
+ pin_and_sync(obj);
if (obj->pages) {
get_page(obj->pages[page_offset]);
vmf->page = obj->pages[page_offset];
ret = 0;
}
mutex_unlock(&obj->pages_lock);
- if (ret) {
- struct page *page;
-
- page = shmem_read_mapping_page(
- file_inode(obj->base.filp)->i_mapping,
- page_offset);
- if (!IS_ERR(page)) {
- vmf->page = page;
- ret = 0;
- } else switch (PTR_ERR(page)) {
- case -ENOSPC:
- case -ENOMEM:
- ret = VM_FAULT_OOM;
- break;
- case -EBUSY:
- ret = VM_FAULT_RETRY;
- break;
- case -EFAULT:
- case -EINVAL:
- ret = VM_FAULT_SIGBUS;
- break;
- default:
- WARN_ON(PTR_ERR(page));
- ret = VM_FAULT_SIGBUS;
- break;
- }

- }
return ret;
}

@@ -277,32 +258,93 @@ static const struct file_operations vgem_driver_fops = {
.release = drm_release,
};

-static struct page **vgem_pin_pages(struct drm_vgem_gem_object *bo)
+/* Called under pages_lock, except in free path (where it can't race): */
+static void sync_and_unpin(struct drm_vgem_gem_object *bo)
{
- mutex_lock(&bo->pages_lock);
- if (bo->pages_pin_count++ == 0) {
- struct page **pages;
+ struct drm_device *dev = bo->base.dev;
+
+ if (bo->table) {
+ dma_sync_sg_for_cpu(dev->dev, bo->table->sgl,
+ bo->table->nents, DMA_BIDIRECTIONAL);
+ sg_free_table(bo->table);
+ kfree(bo->table);
+ bo->table = NULL;
+ }
+
+ if (bo->pages) {
+ drm_gem_put_pages(&bo->base, bo->pages, true, true);
+ bo->pages = NULL;
+ }
+}
+
+static struct page **pin_and_sync(struct drm_vgem_gem_object *bo)
+{
+ struct drm_device *dev = bo->base.dev;
+ int npages = bo->base.size >> PAGE_SHIFT;
+ struct page **pages;
+ struct sg_table *sgt;
+
+ WARN_ON(!mutex_is_locked(&bo->pages_lock));
+
+ pages = drm_gem_get_pages(&bo->base);
+ if (IS_ERR(pages)) {
+ bo->pages_pin_count--;
+ mutex_unlock(&bo->pages_lock);
+ return pages;
+ }

- pages = drm_gem_get_pages(&bo->base);
- if (IS_ERR(pages)) {
- bo->pages_pin_count--;
- mutex_unlock(&bo->pages_lock);
- return pages;
- }
+ sgt = drm_prime_pages_to_sg(pages, npages);
+ if (IS_ERR(sgt)) {
+ dev_err(dev->dev,
+ "failed to allocate sgt: %ld\n",
+ PTR_ERR(bo->table));
+ drm_gem_put_pages(&bo->base, pages, false, false);
+ mutex_unlock(&bo->pages_lock);
+ return ERR_CAST(bo->table);
+ }
+
+ /*
+ * Flush the object from the CPU cache so that importers
+ * can rely on coherent indirect access via the exported
+ * dma-address.
+ */
+ dma_sync_sg_for_device(dev->dev, sgt->sgl,
+ sgt->nents, DMA_BIDIRECTIONAL);
+
+ bo->pages = pages;
+ bo->table = sgt;
+
+ return pages;
+}
+
+static struct page **vgem_pin_pages(struct drm_vgem_gem_object *bo)
+{
+ struct page **pages;

- bo->pages = pages;
+ mutex_lock(&bo->pages_lock);
+ if (bo->pages_pin_count++ == 0 && !bo->pages) {
+ pages = pin_and_sync(bo);
+ } else {
+ WARN_ON(!bo->pages);
+ pages = bo->pages;
}
mutex_unlock(&bo->pages_lock);

- return bo->pages;
+ return pages;
}

static void vgem_unpin_pages(struct drm_vgem_gem_object *bo)
{
+ /*
+ * We shouldn't hit this for imported bo's.. in the import
+ * case we don't own the scatter-table
+ */
+ WARN_ON(bo->base.import_attach);
+
mutex_lock(&bo->pages_lock);
if (--bo->pages_pin_count == 0) {
- drm_gem_put_pages(&bo->base, bo->pages, true, true);
- bo->pages = NULL;
+ WARN_ON(!bo->table);
+ sync_and_unpin(bo);
}
mutex_unlock(&bo->pages_lock);
}
@@ -310,18 +352,12 @@ static void vgem_unpin_pages(struct drm_vgem_gem_object *bo)
static int vgem_prime_pin(struct drm_gem_object *obj)
{
struct drm_vgem_gem_object *bo = to_vgem_bo(obj);
- long n_pages = obj->size >> PAGE_SHIFT;
struct page **pages;

pages = vgem_pin_pages(bo);
if (IS_ERR(pages))
return PTR_ERR(pages);

- /* Flush the object from the CPU cache so that importers can rely
- * on coherent indirect access via the exported dma-address.
- */
- drm_clflush_pages(pages, n_pages);
-
return 0;
}

--
2.20.1
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