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Date: Tue, 1 Jun 2010 17:47:16 +0300
From: "Michael S. Tsirkin" <mst@...hat.com>
To: Rusty Russell <rusty@...tcorp.com.au>,
linux-kernel@...r.kernel.org,
virtualization@...ts.linux-foundation.org, kvm@...r.kernel.org,
qemu-devel@...gnu.org
Subject: [PATCHv3 2/2] virtio: publish used idx
Signed-off-by: Michael S. Tsirkin <mst@...hat.com>
---
drivers/net/virtio_net.c | 2 ++
drivers/virtio/virtio_ring.c | 15 +++++++++++++--
include/linux/virtio_ring.h | 10 ++++++++++
3 files changed, 25 insertions(+), 2 deletions(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 78eb319..30e7483 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -23,6 +23,7 @@
#include <linux/module.h>
#include <linux/virtio.h>
#include <linux/virtio_net.h>
+#include <linux/virtio_ring.h>
#include <linux/scatterlist.h>
#include <linux/if_vlan.h>
#include <linux/slab.h>
@@ -1056,6 +1057,7 @@ static unsigned int features[] = {
VIRTIO_NET_F_GUEST_ECN, VIRTIO_NET_F_GUEST_UFO,
VIRTIO_NET_F_MRG_RXBUF, VIRTIO_NET_F_STATUS, VIRTIO_NET_F_CTRL_VQ,
VIRTIO_NET_F_CTRL_RX, VIRTIO_NET_F_CTRL_VLAN,
+ VIRTIO_RING_F_PUBLISH_USED,
};
static struct virtio_driver virtio_net_driver = {
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 0f684b4..5a8c711 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -92,6 +92,9 @@ struct vring_virtqueue
/* Last used index we've seen. */
u16 last_used_idx;
+ /* Publish last used index we've seen at this location. */
+ u16 *publish_last_used_idx;
+
/* How to notify other side. FIXME: commonalize hcalls! */
void (*notify)(struct virtqueue *vq);
@@ -325,7 +328,7 @@ void *virtqueue_get_buf(struct virtqueue *_vq, unsigned int *len)
/* detach_buf clears data, so grab it now. */
ret = vq->data[i];
detach_buf(vq, i);
- vq->last_used_idx++;
+ *vq->publish_last_used_idx = ++vq->last_used_idx;
END_USE(vq);
return ret;
}
@@ -425,13 +428,19 @@ struct virtqueue *vring_new_virtqueue(unsigned int num,
if (!vq)
return NULL;
- vring_init(&vq->vring, num, pages, vring_align, false);
+ vring_init(&vq->vring, num, pages, vring_align,
+ virtio_has_feature(vdev, VIRTIO_RING_F_PUBLISH_USED));
+ if (virtio_has_feature(vdev, VIRTIO_RING_F_PUBLISH_USED))
+ vq->publish_last_used_idx = &vq->vring.avail->last_used_idx;
+ else
+ vq->publish_last_used_idx = &vq->last_used_idx;
vq->vq.callback = callback;
vq->vq.vdev = vdev;
vq->vq.name = name;
vq->notify = notify;
vq->broken = false;
vq->last_used_idx = 0;
+ *vq->publish_last_used_idx = 0;
vq->num_added = 0;
list_add_tail(&vq->vq.list, &vdev->vqs);
#ifdef DEBUG
@@ -473,6 +482,8 @@ void vring_transport_features(struct virtio_device *vdev)
switch (i) {
case VIRTIO_RING_F_INDIRECT_DESC:
break;
+ case VIRTIO_RING_F_PUBLISH_USED:
+ break;
default:
/* We don't understand this bit. */
clear_bit(i, vdev->features);
diff --git a/include/linux/virtio_ring.h b/include/linux/virtio_ring.h
index 458ce41..87f8fd3 100644
--- a/include/linux/virtio_ring.h
+++ b/include/linux/virtio_ring.h
@@ -29,6 +29,9 @@
/* We support indirect buffer descriptors */
#define VIRTIO_RING_F_INDIRECT_DESC 28
+/* The Guest publishes last-seen used index at the end of the avail ring. */
+#define VIRTIO_RING_F_PUBLISH_USED 29
+
/* Virtio ring descriptors: 16 bytes. These can chain together via "next". */
struct vring_desc {
/* Address (guest-physical). */
@@ -51,6 +54,7 @@ struct vring_avail_ctrl {
__u16 idx;
__u8 pad[254];
__u16 flags;
+ __u16 last_used_idx;
};
/* u32 is used here for ids for padding reasons. */
@@ -75,6 +79,7 @@ struct vring {
__u16 *avail_idx;
__u16 *avail_flags;
__u16 *avail_ring;
+ __u16 *last_used_idx;
struct vring_used *used;
};
@@ -100,6 +105,7 @@ struct vring {
* __u16 avail_idx;
* __u8 pad[254]; // Padding to align flags at cache line boundary.
* __u16 avail_flags;
+ * __u16 last_used_idx;
* // Padding to the next align boundary.
* char pad[];
*
@@ -120,14 +126,18 @@ static inline void vring_init(struct vring *vr, unsigned int num, void *p,
vr->avail_ring = (void*)avail;
vr->avail_idx = &ctrl->idx;
vr->avail_flags = &ctrl->flags;
+ vr->last_used_idx = &ctrl->last_used_idx;
} else {
vr->avail_idx = &avail->idx;
vr->avail_flags = &avail->flags;
+ vr->last_used_idx = NULL;
}
vr->used = (void *)ALIGN((unsigned long)&avail->ring[num], align);
/* Verify that avail fits before used. */
BUG_ON((unsigned long)(vr->avail_flags + 1) > (unsigned long)vr->used);
BUG_ON((unsigned long)(vr->avail_idx + 1) > (unsigned long)vr->used);
+ BUG_ON(vr->last_used_idx && (unsigned long)(vr->last_used_idx + 1) >
+ (unsigned long)vr->used);
BUG_ON((unsigned long)(&vr->avail_ring[num]) > (unsigned long)vr->used);
}
--
1.7.1.12.g42b7f
--
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