From: Jason Wang <jasowang@redhat.com>
To: mst@redhat.com, jasowang@redhat.com,
virtualization@lists.linux-foundation.org,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: kvm@vger.kernel.org
Subject: [PATCH net-next RFC 3/5] vhost: introduce vhost_add_used_idx()
Date: Fri, 22 Sep 2017 16:02:33 +0800 [thread overview]
Message-ID: <1506067355-5771-4-git-send-email-jasowang@redhat.com> (raw)
In-Reply-To: <1506067355-5771-1-git-send-email-jasowang@redhat.com>
This patch introduces a helper which just increase the used idx. This
will be used in pair with vhost_prefetch_desc_indices() by batching
code.
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
drivers/vhost/vhost.c | 33 +++++++++++++++++++++++++++++++++
drivers/vhost/vhost.h | 1 +
2 files changed, 34 insertions(+)
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 8424166d..6532cda 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -2178,6 +2178,39 @@ int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len)
}
EXPORT_SYMBOL_GPL(vhost_add_used);
+int vhost_add_used_idx(struct vhost_virtqueue *vq, int n)
+{
+ u16 old, new;
+
+ old = vq->last_used_idx;
+ new = (vq->last_used_idx += n);
+ /* If the driver never bothers to signal in a very long while,
+ * used index might wrap around. If that happens, invalidate
+ * signalled_used index we stored. TODO: make sure driver
+ * signals at least once in 2^16 and remove this.
+ */
+ if (unlikely((u16)(new - vq->signalled_used) < (u16)(new - old)))
+ vq->signalled_used_valid = false;
+
+ /* Make sure buffer is written before we update index. */
+ smp_wmb();
+ if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->last_used_idx),
+ &vq->used->idx)) {
+ vq_err(vq, "Failed to increment used idx");
+ return -EFAULT;
+ }
+ if (unlikely(vq->log_used)) {
+ /* Log used index update. */
+ log_write(vq->log_base,
+ vq->log_addr + offsetof(struct vring_used, idx),
+ sizeof(vq->used->idx));
+ if (vq->log_ctx)
+ eventfd_signal(vq->log_ctx, 1);
+ }
+ return 0;
+}
+EXPORT_SYMBOL_GPL(vhost_add_used_idx);
+
static int __vhost_add_used_n(struct vhost_virtqueue *vq,
struct vring_used_elem *heads,
unsigned count)
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index 16c2cb6..5dd6c05 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -199,6 +199,7 @@ int __vhost_get_vq_desc(struct vhost_virtqueue *vq,
void vhost_discard_vq_desc(struct vhost_virtqueue *, int n);
int vhost_vq_init_access(struct vhost_virtqueue *);
+int vhost_add_used_idx(struct vhost_virtqueue *vq, int n);
int vhost_add_used(struct vhost_virtqueue *, unsigned int head, int len);
int vhost_add_used_n(struct vhost_virtqueue *, struct vring_used_elem *heads,
unsigned count);
--
2.7.4
next prev parent reply other threads:[~2017-09-22 8:04 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-22 8:02 [PATCH net-next RFC 0/5] batched tx processing in vhost_net Jason Wang
2017-09-22 8:02 ` [PATCH net-next RFC 1/5] vhost: split out ring head fetching logic Jason Wang
2017-09-22 8:31 ` Stefan Hajnoczi
2017-09-25 2:03 ` Jason Wang
2017-09-22 8:02 ` [PATCH net-next RFC 2/5] vhost: introduce helper to prefetch desc index Jason Wang
2017-09-22 9:02 ` Stefan Hajnoczi
2017-09-25 2:04 ` Jason Wang
2017-09-26 19:19 ` Michael S. Tsirkin
2017-09-27 0:35 ` Jason Wang
2017-09-27 22:57 ` Michael S. Tsirkin
2017-09-28 7:18 ` Jason Wang
2017-09-28 0:47 ` Willem de Bruijn
2017-09-28 7:44 ` Jason Wang
2017-09-22 8:02 ` Jason Wang [this message]
2017-09-22 9:07 ` [PATCH net-next RFC 3/5] vhost: introduce vhost_add_used_idx() Stefan Hajnoczi
2017-09-26 19:13 ` Michael S. Tsirkin
2017-09-27 0:38 ` Jason Wang
2017-09-27 22:58 ` Michael S. Tsirkin
2017-09-28 0:59 ` Willem de Bruijn
2017-09-28 7:19 ` Jason Wang
2017-09-22 8:02 ` [PATCH net-next RFC 4/5] vhost_net: rename VHOST_RX_BATCH to VHOST_NET_BATCH Jason Wang
2017-09-22 8:02 ` [PATCH net-next RFC 5/5] vhost_net: basic tx virtqueue batched processing Jason Wang
2017-09-26 19:25 ` Michael S. Tsirkin
2017-09-27 2:04 ` Jason Wang
2017-09-27 22:19 ` Michael S. Tsirkin
2017-09-28 7:02 ` Jason Wang
2017-09-28 7:52 ` Jason Wang
2017-09-28 0:55 ` Willem de Bruijn
2017-09-28 7:50 ` Jason Wang
2017-09-26 13:45 ` [PATCH net-next RFC 0/5] batched tx processing in vhost_net Michael S. Tsirkin
2017-09-27 0:27 ` Jason Wang
2017-09-27 22:28 ` Michael S. Tsirkin
2017-09-28 7:16 ` Jason Wang
2017-09-26 19:26 ` Michael S. Tsirkin
2017-09-27 2:06 ` Jason Wang
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