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Subject[PATCH v4 2/2] 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 | 78 +++++++++++++++++++++++---
2 files changed, 72 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/virtio/virtgpu_ioctl.c b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
index f5083c538f9c..9af1ec62434f 100644
--- a/drivers/gpu/drm/virtio/virtgpu_ioctl.c
+++ b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
@@ -143,7 +143,7 @@ static int virtio_gpu_execbuffer_ioctl(struct drm_device *dev, void *data,
goto out_unused_fd;
}

- 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;
@@ -172,7 +172,7 @@ static int virtio_gpu_execbuffer_ioctl(struct drm_device *dev, void *data,
return 0;

out_memdup:
- kfree(buf);
+ kvfree(buf);
out_unresv:
if (buflist)
virtio_gpu_array_unlock_resv(buflist);
diff --git a/drivers/gpu/drm/virtio/virtgpu_vq.c b/drivers/gpu/drm/virtio/virtgpu_vq.c
index 5a64c776138d..9f9b782dd332 100644
--- a/drivers/gpu/drm/virtio/virtgpu_vq.c
+++ b/drivers/gpu/drm/virtio/virtgpu_vq.c
@@ -155,7 +155,7 @@ 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);
}

@@ -256,13 +256,54 @@ void virtio_gpu_dequeue_cursor_func(struct work_struct *work)
wake_up(&vgdev->cursorq.ack_queue);
}

+/* Create sg_table from a vmalloc'd buffer. */
+static struct sg_table *vmalloc_to_sgt(char *data, uint32_t size, int *sg_ents)
+{
+ int ret, s, i;
+ struct sg_table *sgt;
+ struct scatterlist *sg;
+ struct page *pg;
+
+ if (WARN_ON(!PAGE_ALIGNED(data)))
+ return NULL;
+
+ sgt = kmalloc(sizeof(*sgt), GFP_KERNEL);
+ if (!sgt)
+ return NULL;
+
+ *sg_ents = DIV_ROUND_UP(size, PAGE_SIZE);
+ ret = sg_alloc_table(sgt, *sg_ents, GFP_KERNEL);
+ if (ret) {
+ kfree(sgt);
+ return NULL;
+ }
+
+ for_each_sg(sgt->sgl, sg, *sg_ents, i) {
+ pg = vmalloc_to_page(data);
+ if (!pg) {
+ sg_free_table(sgt);
+ kfree(sgt);
+ return NULL;
+ }
+
+ s = min_t(int, PAGE_SIZE, size);
+ sg_set_page(sg, pg, s, 0);
+
+ size -= s;
+ data += s;
+ }
+
+ return sgt;
+}
+
static bool virtio_gpu_queue_ctrl_buffer_locked(struct virtio_gpu_device *vgdev,
- struct virtio_gpu_vbuffer *vbuf)
+ struct virtio_gpu_vbuffer *vbuf,
+ struct scatterlist *vout)
__releases(&vgdev->ctrlq.qlock)
__acquires(&vgdev->ctrlq.qlock)
{
struct virtqueue *vq = vgdev->ctrlq.vq;
- struct scatterlist *sgs[3], vcmd, vout, vresp;
+ struct scatterlist *sgs[3], vcmd, vresp;
int outcnt = 0, incnt = 0;
bool notify = false;
int ret;
@@ -274,9 +315,8 @@ static bool virtio_gpu_queue_ctrl_buffer_locked(struct virtio_gpu_device *vgdev,
sgs[outcnt + incnt] = &vcmd;
outcnt++;

- if (vbuf->data_size) {
- sg_init_one(&vout, vbuf->data_buf, vbuf->data_size);
- sgs[outcnt + incnt] = &vout;
+ if (vout) {
+ sgs[outcnt + incnt] = vout;
outcnt++;
}

@@ -308,7 +348,24 @@ static void virtio_gpu_queue_fenced_ctrl_buffer(struct virtio_gpu_device *vgdev,
struct virtio_gpu_fence *fence)
{
struct virtqueue *vq = vgdev->ctrlq.vq;
+ struct scatterlist *vout = NULL, sg;
+ struct sg_table *sgt = NULL;
bool notify;
+ int outcnt = 0;
+
+ if (vbuf->data_size) {
+ if (is_vmalloc_addr(vbuf->data_buf)) {
+ sgt = vmalloc_to_sgt(vbuf->data_buf, vbuf->data_size,
+ &outcnt);
+ if (!sgt)
+ return -ENOMEM;
+ vout = sgt->sgl;
+ } else {
+ sg_init_one(&sg, vbuf->data_buf, vbuf->data_size);
+ vout = &sg;
+ outcnt = 1;
+ }
+ }

again:
spin_lock(&vgdev->ctrlq.qlock);
@@ -321,7 +378,7 @@ static void virtio_gpu_queue_fenced_ctrl_buffer(struct virtio_gpu_device *vgdev,
* to wait for free space, which can result in fence ids being
* submitted out-of-order.
*/
- if (vq->num_free < 3) {
+ if (vq->num_free < 2 + outcnt) {
spin_unlock(&vgdev->ctrlq.qlock);
wait_event(vgdev->ctrlq.ack_queue, vq->num_free >= 3);
goto again;
@@ -334,10 +391,15 @@ static void virtio_gpu_queue_fenced_ctrl_buffer(struct virtio_gpu_device *vgdev,
virtio_gpu_array_unlock_resv(vbuf->objs);
}
}
- notify = virtio_gpu_queue_ctrl_buffer_locked(vgdev, vbuf);
+ notify = virtio_gpu_queue_ctrl_buffer_locked(vgdev, vbuf, vout);
spin_unlock(&vgdev->ctrlq.qlock);
if (notify)
virtqueue_notify(vgdev->ctrlq.vq);
+
+ if (sgt) {
+ sg_free_table(sgt);
+ kfree(sgt);
+ }
}

static void virtio_gpu_queue_ctrl_buffer(struct virtio_gpu_device *vgdev,
--
2.23.0.162.g0b9fbb3734-goog
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