From: Xie Yongji <xieyongji@bytedance.com>
To: mst@redhat.com, jasowang@redhat.com, stefanha@redhat.com
Cc: amit@kernel.org, arei.gonglei@huawei.com, airlied@linux.ie,
kraxel@redhat.com, dan.j.williams@intel.com,
johannes@sipsolutions.net, ohad@wizery.com,
bjorn.andersson@linaro.org, david@redhat.com, vgoyal@redhat.com,
miklos@szeredi.hu, sgarzare@redhat.com,
virtualization@lists.linux-foundation.org,
linux-kernel@vger.kernel.org
Subject: [RFC PATCH 01/17] virtio_ring: Avoid reading unneeded used length
Date: Mon, 17 May 2021 17:08:20 +0800 [thread overview]
Message-ID: <20210517090836.533-2-xieyongji@bytedance.com> (raw)
In-Reply-To: <20210517090836.533-1-xieyongji@bytedance.com>
If device driver doesn't need used length, it can pass a NULL
len in virtqueue_get_buf()/virtqueue_get_buf_ctx(). Then
we can avoid reading and validating the len value in used
ring entries.
Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
---
drivers/virtio/virtio_ring.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 54e12dd91310..d999a1d6d271 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -772,7 +772,8 @@ static void *virtqueue_get_buf_ctx_split(struct virtqueue *_vq,
last_used = (vq->last_used_idx & (vq->split.vring.num - 1));
i = virtio32_to_cpu(_vq->vdev,
vq->split.vring.used->ring[last_used].id);
- *len = virtio32_to_cpu(_vq->vdev,
+ if (len)
+ *len = virtio32_to_cpu(_vq->vdev,
vq->split.vring.used->ring[last_used].len);
if (unlikely(i >= vq->split.vring.num)) {
@@ -1444,7 +1445,8 @@ static void *virtqueue_get_buf_ctx_packed(struct virtqueue *_vq,
last_used = vq->last_used_idx;
id = le16_to_cpu(vq->packed.vring.desc[last_used].id);
- *len = le32_to_cpu(vq->packed.vring.desc[last_used].len);
+ if (len)
+ *len = le32_to_cpu(vq->packed.vring.desc[last_used].len);
if (unlikely(id >= vq->packed.vring.num)) {
BAD_RING(vq, "id %u out of range\n", id);
--
2.11.0
next prev parent reply other threads:[~2021-05-17 9:09 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-17 9:08 [RFC PATCH 00/17] Add validation for used length Xie Yongji
2021-05-17 9:08 ` Xie Yongji [this message]
2021-05-17 9:11 ` [RFC PATCH 01/17] virtio_ring: Avoid reading unneeded " Johannes Berg
2021-05-17 9:41 ` Yongji Xie
2021-05-17 9:08 ` [RFC PATCH 02/17] virtio-blk: Remove unused " Xie Yongji
2021-05-17 9:08 ` [RFC PATCH 03/17] virtio_console: " Xie Yongji
2021-05-17 9:08 ` [RFC PATCH 04/17] crypto: virtio - " Xie Yongji
2021-05-17 9:08 ` [RFC PATCH 05/17] drm/virtio: " Xie Yongji
2021-05-17 9:08 ` [RFC PATCH 06/17] caif_virtio: " Xie Yongji
2021-05-17 9:08 ` [RFC PATCH 07/17] virtio_net: " Xie Yongji
2021-05-17 9:08 ` [RFC PATCH 08/17] mac80211_hwsim: " Xie Yongji
2021-05-17 9:08 ` [RFC PATCH 09/17] virtio_pmem: " Xie Yongji
2021-05-17 9:08 ` [RFC PATCH 10/17] rpmsg: virtio: " Xie Yongji
2021-05-17 9:08 ` [RFC PATCH 11/17] virtio_scsi: " Xie Yongji
2021-05-17 9:08 ` [RFC PATCH 12/17] virtio_balloon: " Xie Yongji
2021-05-17 9:08 ` [RFC PATCH 13/17] virtio_input: " Xie Yongji
2021-05-17 9:08 ` [RFC PATCH 14/17] virtio_mem: " Xie Yongji
2021-05-17 9:08 ` [RFC PATCH 15/17] virtiofs: " Xie Yongji
2021-05-17 9:08 ` [RFC PATCH 16/17] vsock: " Xie Yongji
2021-05-17 9:08 ` [RFC PATCH 17/17] virtio_ring: Add validation for " Xie Yongji
2021-05-17 23:39 ` Michael S. Tsirkin
2021-05-25 1:31 ` Jason Wang
2021-05-25 5:08 ` Yongji Xie
2021-05-17 23:40 ` [RFC PATCH 00/17] " Michael S. Tsirkin
2021-05-18 8:29 ` Yongji Xie
2021-05-18 9:52 ` Michael S. Tsirkin
2021-05-18 12:28 ` Yongji Xie
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