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Subject[PATCH] drm/virtio: Use vmalloc for command buffer allocations.
Date
Userspace requested command buffer allocations could be too large
to make as a contiguous allocation. Use vmalloc if necessary to
satisfy those allocations.

Signed-off-by: David Riley <davidriley@chromium.org>
---
drivers/gpu/drm/virtio/virtgpu_ioctl.c | 4 +-
drivers/gpu/drm/virtio/virtgpu_vq.c | 74 ++++++++++++++++++++++++--
2 files changed, 73 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/virtio/virtgpu_ioctl.c b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
index ac60be9b5c19..a8732a8af766 100644
--- a/drivers/gpu/drm/virtio/virtgpu_ioctl.c
+++ b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
@@ -195,7 +195,7 @@ static int virtio_gpu_execbuffer_ioctl(struct drm_device *dev, void *data,
if (ret)
goto out_free;

- buf = memdup_user(u64_to_user_ptr(exbuf->command), exbuf->size);
+ buf = vmemdup_user(u64_to_user_ptr(exbuf->command), exbuf->size);
if (IS_ERR(buf)) {
ret = PTR_ERR(buf);
goto out_unresv;
@@ -230,7 +230,7 @@ static int virtio_gpu_execbuffer_ioctl(struct drm_device *dev, void *data,
return 0;

out_memdup:
- kfree(buf);
+ kvfree(buf);
out_unresv:
ttm_eu_backoff_reservation(&ticket, &validate_list);
out_free:
diff --git a/drivers/gpu/drm/virtio/virtgpu_vq.c b/drivers/gpu/drm/virtio/virtgpu_vq.c
index 981ee16e3ee9..bcbc48b7284f 100644
--- a/drivers/gpu/drm/virtio/virtgpu_vq.c
+++ b/drivers/gpu/drm/virtio/virtgpu_vq.c
@@ -154,7 +154,7 @@ static void free_vbuf(struct virtio_gpu_device *vgdev,
{
if (vbuf->resp_size > MAX_INLINE_RESP_SIZE)
kfree(vbuf->resp_buf);
- kfree(vbuf->data_buf);
+ kvfree(vbuf->data_buf);
kmem_cache_free(vgdev->vbufs, vbuf);
}

@@ -251,6 +251,59 @@ void virtio_gpu_dequeue_cursor_func(struct work_struct *work)
wake_up(&vgdev->cursorq.ack_queue);
}

+/* How many bytes left in this page. */
+static unsigned int rest_of_page(void *data)
+{
+ return PAGE_SIZE - offset_in_page(data);
+}
+
+/* Create sg_table from a vmalloc'd buffer. */
+static struct sg_table *vmalloc_to_sgt(char *data, uint32_t size)
+{
+ int nents, ret, s, i;
+ struct sg_table *sgt;
+ struct scatterlist *sg;
+ struct page *pg;
+
+ sgt = kmalloc(sizeof(*sgt), GFP_KERNEL);
+ if (!sgt)
+ return NULL;
+
+ nents = DIV_ROUND_UP(size, PAGE_SIZE) + 1;
+ ret = sg_alloc_table(sgt, nents, GFP_KERNEL);
+ if (ret) {
+ kfree(sgt);
+ return NULL;
+ }
+
+ for_each_sg(sgt->sgl, sg, nents, i) {
+ pg = vmalloc_to_page(data);
+ if (!pg) {
+ sg_free_table(sgt);
+ kfree(sgt);
+ return NULL;
+ }
+
+ s = rest_of_page(data);
+ if (s > size)
+ s = size;
+
+ sg_set_page(sg, pg, s, offset_in_page(data));
+
+ size -= s;
+ data += s;
+
+ if (size) {
+ sg_unmark_end(sg);
+ } else {
+ sg_mark_end(sg);
+ break;
+ }
+ }
+
+ return sgt;
+}
+
static int virtio_gpu_queue_ctrl_buffer_locked(struct virtio_gpu_device *vgdev,
struct virtio_gpu_vbuffer *vbuf)
__releases(&vgdev->ctrlq.qlock)
@@ -260,6 +313,7 @@ static int virtio_gpu_queue_ctrl_buffer_locked(struct virtio_gpu_device *vgdev,
struct scatterlist *sgs[3], vcmd, vout, vresp;
int outcnt = 0, incnt = 0;
int ret;
+ struct sg_table *sgt = NULL;

if (!vgdev->vqs_ready)
return -ENODEV;
@@ -269,8 +323,17 @@ static int virtio_gpu_queue_ctrl_buffer_locked(struct virtio_gpu_device *vgdev,
outcnt++;

if (vbuf->data_size) {
- sg_init_one(&vout, vbuf->data_buf, vbuf->data_size);
- sgs[outcnt + incnt] = &vout;
+ if (is_vmalloc_addr(vbuf->data_buf)) {
+ spin_unlock(&vgdev->ctrlq.qlock);
+ sgt = vmalloc_to_sgt(vbuf->data_buf, vbuf->data_size);
+ spin_lock(&vgdev->ctrlq.qlock);
+ if (!sgt)
+ return -ENOMEM;
+ sgs[outcnt + incnt] = sgt->sgl;
+ } else {
+ sg_init_one(&vout, vbuf->data_buf, vbuf->data_size);
+ sgs[outcnt + incnt] = &vout;
+ }
outcnt++;
}

@@ -294,6 +357,11 @@ static int virtio_gpu_queue_ctrl_buffer_locked(struct virtio_gpu_device *vgdev,
virtqueue_kick(vq);
}

+ if (sgt) {
+ sg_free_table(sgt);
+ kfree(sgt);
+ }
+
if (!ret)
ret = vq->num_free;
return ret;
--
2.23.0.187.g17f5b7556c-goog
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