[RFC V5 PATCH 7/8] vhost: packed ring support

Jason Wang
2018-05-29T02:10:29Z

drivers/vhost/net.c | 13 +-
drivers/vhost/vhost.c | 585 ++++++++++++++++++++++++++++++++++++++++++++++----
drivers/vhost/vhost.h | 13 +-
3 files changed, 566 insertions(+), 45 deletions(-)

diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 30273ad..4991aa4 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -71,7 +71,8 @@ enum {
VHOST_NET_FEATURES = VHOST_FEATURES |
(1ULL << VHOST_NET_F_VIRTIO_NET_HDR) |
(1ULL << VIRTIO_NET_F_MRG_RXBUF) |
- (1ULL << VIRTIO_F_IOMMU_PLATFORM)
+ (1ULL << VIRTIO_F_IOMMU_PLATFORM) |
+ (1ULL << VIRTIO_F_RING_PACKED)
};

enum {
@@ -576,7 +577,7 @@ static void handle_tx(struct vhost_net *net)
nvq->upend_idx = ((unsigned)nvq->upend_idx - 1)
% UIO_MAXIOV;
}
- vhost_discard_vq_desc(vq, 1);
+ vhost_discard_vq_desc(vq, &used, 1);
vhost_net_enable_vq(net, vq);
break;
}
@@ -714,9 +715,11 @@ static void handle_rx(struct vhost_net *net)
mergeable = vhost_has_feature(vq, VIRTIO_NET_F_MRG_RXBUF);

while ((sock_len = vhost_net_rx_peek_head_len(net, sock->sk))) {
+ struct vhost_used_elem *used = vq->heads + nheads;
+
sock_len += sock_hlen;
vhost_len = sock_len + vhost_hlen;
- err = vhost_get_bufs(vq, vq->heads + nheads, vhost_len,
+ err = vhost_get_bufs(vq, used, vhost_len,
&in, vq_log, &log,
likely(mergeable) ? UIO_MAXIOV : 1,
&headcount);
@@ -762,7 +765,7 @@ static void handle_rx(struct vhost_net *net)
if (unlikely(err != sock_len)) {
pr_debug("Discarded rx packet: "
" len %d, expected %zd\n", err, sock_len);
- vhost_discard_vq_desc(vq, headcount);
+ vhost_discard_vq_desc(vq, used, 1);
continue;
}
/* Supply virtio_net_hdr if VHOST_NET_F_VIRTIO_NET_HDR */
@@ -786,7 +789,7 @@ static void handle_rx(struct vhost_net *net)
copy_to_iter(&num_buffers, sizeof num_buffers,
&fixup) != sizeof num_buffers) {
vq_err(vq, "Failed num_buffers write");
- vhost_discard_vq_desc(vq, headcount);
+ vhost_discard_vq_desc(vq, used, 1);
goto out;
}
nheads += headcount;
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 4031a8f..a36e5ad2 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -323,6 +323,9 @@ static void vhost_vq_reset(struct vhost_dev *dev,
vhost_reset_is_le(vq);
vhost_disable_cross_endian(vq);
vq->busyloop_timeout = 0;
+ vq->used_wrap_counter = true;
+ vq->last_avail_wrap_counter = true;
+ vq->avail_wrap_counter = true;
vq->umem = NULL;
vq->iotlb = NULL;
__vhost_vq_meta_reset(vq);
@@ -1103,11 +1106,22 @@ static int vhost_iotlb_miss(struct vhost_virtqueue *vq, u64 iova, int access)
return 0;
}

-static bool vq_access_ok(struct vhost_virtqueue *vq, unsigned int num,
- struct vring_desc __user *desc,
- struct vring_avail __user *avail,
- struct vring_used __user *used)
+static int vq_access_ok_packed(struct vhost_virtqueue *vq, unsigned int num,
+ struct vring_desc __user *desc,
+ struct vring_avail __user *avail,
+ struct vring_used __user *used)
+{
+ struct vring_desc_packed *packed = (struct vring_desc_packed *)desc;
+
+ /* FIXME: check device area and driver area */
+ return access_ok(VERIFY_READ, packed, num * sizeof(*packed)) &&
+ access_ok(VERIFY_WRITE, packed, num * sizeof(*packed));
+}

+static int vq_access_ok_split(struct vhost_virtqueue *vq, unsigned int num,
+ struct vring_desc __user *desc,
+ struct vring_avail __user *avail,
+ struct vring_used __user *used)
{
size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;

@@ -1118,6 +1132,17 @@ static bool vq_access_ok(struct vhost_virtqueue *vq, unsigned int num,
sizeof *used + num * sizeof *used->ring + s);
}

+static int vq_access_ok(struct vhost_virtqueue *vq, unsigned int num,
+ struct vring_desc __user *desc,
+ struct vring_avail __user *avail,
+ struct vring_used __user *used)
+{
+ if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED))
+ return vq_access_ok_packed(vq, num, desc, avail, used);
+ else
+ return vq_access_ok_split(vq, num, desc, avail, used);
+}
+
static void vhost_vq_meta_update(struct vhost_virtqueue *vq,
const struct vhost_umem_node *node,
int type)
@@ -1361,6 +1386,10 @@ long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *arg
break;
}
vq->last_avail_idx = s.num;
+ if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED)) {
+ vq->last_avail_wrap_counter = s.num >> 31;
+ vq->avail_wrap_counter = vq->last_avail_wrap_counter;
+ }
/* Forget the cached index value. */
vq->avail_idx = vq->last_avail_idx;
break;
@@ -1369,6 +1398,8 @@ long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *arg
s.num = vq->last_avail_idx;
if (copy_to_user(argp, &s, sizeof s))
r = -EFAULT;
+ if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED))
+ s.num |= vq->last_avail_wrap_counter << 31;
break;
case VHOST_SET_VRING_ADDR:
if (copy_from_user(&a, argp, sizeof a)) {
@@ -1730,6 +1761,9 @@ int vhost_vq_init_access(struct vhost_virtqueue *vq)

vhost_init_is_le(vq);

+ if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED))
+ return 0;
+
r = vhost_update_used_flags(vq);
if (r)
goto err;
@@ -1803,7 +1837,8 @@ static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
/* Each buffer in the virtqueues is actually a chain of descriptors. This
* function returns the next descriptor in the chain,
* or -1U if we're at the end. */
-static unsigned next_desc(struct vhost_virtqueue *vq, struct vring_desc *desc)
+static unsigned next_desc_split(struct vhost_virtqueue *vq,
+ struct vring_desc *desc)
{
unsigned int next;

@@ -1816,11 +1851,17 @@ static unsigned next_desc(struct vhost_virtqueue *vq, struct vring_desc *desc)
return next;
}

-static int get_indirect(struct vhost_virtqueue *vq,
- struct iovec iov[], unsigned int iov_size,
- unsigned int *out_num, unsigned int *in_num,
- struct vhost_log *log, unsigned int *log_num,
- struct vring_desc *indirect)
+static unsigned next_desc_packed(struct vhost_virtqueue *vq,
+ struct vring_desc_packed *desc)
+{
+ return desc->flags & cpu_to_vhost16(vq, VRING_DESC_F_NEXT);
+}
+
+static int get_indirect_split(struct vhost_virtqueue *vq,
+ struct iovec iov[], unsigned int iov_size,
+ unsigned int *out_num, unsigned int *in_num,
+ struct vhost_log *log, unsigned int *log_num,
+ struct vring_desc *indirect)
{
struct vring_desc desc;
unsigned int i = 0, count, found = 0;
@@ -1910,23 +1951,301 @@ static int get_indirect(struct vhost_virtqueue *vq,
}
*out_num += ret;
}
- } while ((i = next_desc(vq, &desc)) != -1);
+ } while ((i = next_desc_split(vq, &desc)) != -1);
return 0;
}

-/* This looks in the virtqueue and for the first available buffer, and converts
- * it to an iovec for convenient access. Since descriptors consist of some
- * number of output then some number of input descriptors, it's actually two
- * iovecs, but we pack them into one and note how many of each there were.
- *
- * This function returns the descriptor number found, or vq->num (which is
- * never a valid descriptor number) if none was found. A negative code is
- * returned on error. */
-int vhost_get_vq_desc(struct vhost_virtqueue *vq,
- struct vhost_used_elem *used,
- struct iovec iov[], unsigned int iov_size,
- unsigned int *out_num, unsigned int *in_num,
- struct vhost_log *log, unsigned int *log_num)
+static int get_indirect_packed(struct vhost_virtqueue *vq,
+ struct iovec iov[], unsigned int iov_size,
+ unsigned int *out_num, unsigned int *in_num,
+ struct vhost_log *log, unsigned int *log_num,
+ struct vring_desc_packed *indirect)
+{
+ struct vring_desc_packed desc;
+ unsigned int i = 0, count, found = 0;
+ u32 len = vhost32_to_cpu(vq, indirect->len);
+ struct iov_iter from;
+ int ret, access;
+
+ /* Sanity check */
+ if (unlikely(len % sizeof(desc))) {
+ vq_err(vq, "Invalid length in indirect descriptor: "
+ "len 0x%llx not multiple of 0x%zx\n",
+ (unsigned long long)len,
+ sizeof desc);
+ return -EINVAL;
+ }
+
+ ret = translate_desc(vq, vhost64_to_cpu(vq, indirect->addr),
+ len, vq->indirect,
+ UIO_MAXIOV, VHOST_ACCESS_RO);
+ if (unlikely(ret < 0)) {
+ if (ret != -EAGAIN)
+ vq_err(vq, "Translation failure %d in indirect.\n",
+ ret);
+ return ret;
+ }
+ iov_iter_init(&from, READ, vq->indirect, ret, len);
+
+ /* We will use the result as an address to read from, so most
+ * architectures only need a compiler barrier here. */
+ read_barrier_depends();
+
+ count = len / sizeof desc;
+ /* Buffers are chained via a 16 bit next field, so
+ * we can have at most 2^16 of these. */
+ if (unlikely(count > USHRT_MAX + 1)) {
+ vq_err(vq, "Indirect buffer length too big: %d\n",
+ indirect->len);
+ return -E2BIG;
+ }
+
+ do {
+ unsigned iov_count = *in_num + *out_num;
+ if (unlikely(++found > count)) {
+ vq_err(vq, "Loop detected: last one at %u "
+ "indirect size %u\n",
+ i, count);
+ return -EINVAL;
+ }
+ if (unlikely(!copy_from_iter_full(&desc, sizeof(desc),
+ &from))) {
+ vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n",
+ i, (size_t)vhost64_to_cpu(vq, indirect->addr)
+ + i * sizeof desc);
+ return -EINVAL;
+ }
+ if (unlikely(desc.flags &
+ cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT))) {
+ vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n",
+ i, (size_t)vhost64_to_cpu(vq, indirect->addr)
+ + i * sizeof desc);
+ return -EINVAL;
+ }
+
+ if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE))
+ access = VHOST_ACCESS_WO;
+ else
+ access = VHOST_ACCESS_RO;
+
+ ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
+ vhost32_to_cpu(vq, desc.len),
+ iov + iov_count,
+ iov_size - iov_count, access);
+ if (unlikely(ret < 0)) {
+ if (ret != -EAGAIN)
+ vq_err(vq, "Translation failure %d "
+ "indirect idx %d\n",
+ ret, i);
+ return ret;
+ }
+ /* If this is an input descriptor, increment that count. */
+ if (access == VHOST_ACCESS_WO) {
+ *in_num += ret;
+ if (unlikely(log)) {
+ log[*log_num].addr =
+ vhost64_to_cpu(vq, desc.addr);
+ log[*log_num].len =
+ vhost32_to_cpu(vq, desc.len);
+ ++*log_num;
+ }
+ } else {
+ /* If it's an output descriptor, they're all supposed
+ * to come before any input descriptors. */
+ if (unlikely(*in_num)) {
+ vq_err(vq, "Indirect descriptor "
+ "has out after in: idx %d\n", i);
+ return -EINVAL;
+ }
+ *out_num += ret;
+ }
+ i++;
+ } while (next_desc_packed(vq, &desc));
+ return 0;
+}
+
+#define DESC_AVAIL (1 << VRING_DESC_F_AVAIL)
+#define DESC_USED (1 << VRING_DESC_F_USED)
+static bool desc_is_avail(struct vhost_virtqueue *vq, bool wrap_counter,
+ __virtio16 flags)
+{
+ bool avail = flags & cpu_to_vhost16(vq, DESC_AVAIL);
+
+ return avail == wrap_counter;
+}
+
+static __virtio16 get_desc_flags(struct vhost_virtqueue *vq, bool write)
+{
+ __virtio16 flags = 0;
+
+ if (vq->used_wrap_counter) {
+ flags |= cpu_to_vhost16(vq, DESC_AVAIL);
+ flags |= cpu_to_vhost16(vq, DESC_USED);
+ } else {
+ flags &= ~cpu_to_vhost16(vq, DESC_AVAIL);
+ flags &= ~cpu_to_vhost16(vq, DESC_USED);
+ }
+
+ if (write)
+ flags |= cpu_to_vhost16(vq, VRING_DESC_F_WRITE);
+
+ return flags;
+}
+
+static bool vhost_vring_packed_need_event(struct vhost_virtqueue *vq,
+ bool wrap, __u16 off_wrap, __u16 new,
+ __u16 old)
+{
+ int off = off_wrap & ~(1 << 15);
+
+ if (new < old) {
+ new += vq->num;
+ wrap ^= 1;
+ }
+
+ if (wrap != off_wrap >> 15)
+ off += vq->num;
+
+ return vring_need_event(off, new, old);
+}
+
+static int vhost_get_vq_desc_packed(struct vhost_virtqueue *vq,
+ struct vhost_used_elem *used,
+ struct iovec iov[], unsigned int iov_size,
+ unsigned int *out_num, unsigned int *in_num,
+ struct vhost_log *log,
+ unsigned int *log_num)
+{
+ struct vring_desc_packed desc;
+ int ret, access, i;
+ u16 last_avail_idx = vq->last_avail_idx;
+ u16 off_wrap = vq->avail_idx | (vq->avail_wrap_counter << 15);
+
+ /* When we start there are none of either input nor output. */
+ *out_num = *in_num = 0;
+ if (unlikely(log))
+ *log_num = 0;
+
+ used->count = 0;
+
+ do {
+ struct vring_desc_packed *d = vq->desc_packed +
+ vq->last_avail_idx;
+ unsigned int iov_count = *in_num + *out_num;
+
+ ret = vhost_get_user(vq, desc.flags, &d->flags,
+ VHOST_ADDR_DESC);
+ if (unlikely(ret)) {
+ vq_err(vq, "Failed to get flags: idx %d addr %p\n",
+ vq->last_avail_idx, &d->flags);
+ return -EFAULT;
+ }
+
+ if (!desc_is_avail(vq, vq->last_avail_wrap_counter, desc.flags)) {
+ /* If there's nothing new since last we looked, return
+ * invalid.
+ */
+ if (!used->count)
+ return -ENOSPC;
+ vq_err(vq, "Unexpected unavail descriptor: idx %d\n",
+ vq->last_avail_idx);
+ return -EFAULT;
+ }
+
+ /* Read desc content after we're sure it was available. */
+ smp_rmb();
+
+ ret = vhost_copy_from_user(vq, &desc, d, sizeof(desc));
+ if (unlikely(ret)) {
+ vq_err(vq, "Failed to get descriptor: idx %d addr %p\n",
+ vq->last_avail_idx, d);
+ return -EFAULT;
+ }
+
+ used->elem.id = desc.id;
+
+ if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT)) {
+ ret = get_indirect_packed(vq, iov, iov_size,
+ out_num, in_num, log,
+ log_num, &desc);
+ if (unlikely(ret < 0)) {
+ if (ret != -EAGAIN)
+ vq_err(vq, "Failure detected "
+ "in indirect descriptor "
+ "at idx %d\n", i);
+ return ret;
+ }
+ goto next;
+ }
+
+ if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE))
+ access = VHOST_ACCESS_WO;
+ else
+ access = VHOST_ACCESS_RO;
+ ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
+ vhost32_to_cpu(vq, desc.len),
+ iov + iov_count, iov_size - iov_count,
+ access);
+ if (unlikely(ret < 0)) {
+ if (ret != -EAGAIN)
+ vq_err(vq, "Translation failure %d idx %d\n",
+ ret, i);
+ return ret;
+ }
+
+ if (access == VHOST_ACCESS_WO) {
+ /* If this is an input descriptor,
+ * increment that count.
+ */
+ *in_num += ret;
+ if (unlikely(log)) {
+ log[*log_num].addr =
+ vhost64_to_cpu(vq, desc.addr);
+ log[*log_num].len =
+ vhost32_to_cpu(vq, desc.len);
+ ++*log_num;
+ }
+ } else {
+ /* If it's an output descriptor, they're all supposed
+ * to come before any input descriptors.
+ */
+ if (unlikely(*in_num)) {
+ vq_err(vq, "Desc out after in: idx %d\n",
+ i);
+ return -EINVAL;
+ }
+ *out_num += ret;
+ }
+
+next:
+ if (unlikely(++used->count > vq->num)) {
+ vq_err(vq, "Loop detected: last one at %u "
+ "vq size %u head %u\n",
+ i, vq->num, used->elem.id);
+ return -EINVAL;
+ }
+ if (++vq->last_avail_idx >= vq->num) {
+ vq->last_avail_idx = 0;
+ vq->last_avail_wrap_counter ^= 1;
+ }
+ /* If this descriptor says it doesn't chain, we're done. */
+ } while (next_desc_packed(vq, &desc));
+
+ if (vhost_vring_packed_need_event(vq, vq->last_avail_wrap_counter,
+ off_wrap, vq->last_avail_idx,
+ last_avail_idx)) {
+ vq->avail_idx = vq->last_avail_idx;
+ vq->avail_wrap_counter = vq->last_avail_wrap_counter;
+ }
+
+ return 0;
+}
+
+static int vhost_get_vq_desc_split(struct vhost_virtqueue *vq,
+ struct vhost_used_elem *used,
+ struct iovec iov[], unsigned int iov_size,
+ unsigned int *out_num, unsigned int *in_num,
+ struct vhost_log *log, unsigned int *log_num)
{
struct vring_desc desc;
unsigned int i, head, found = 0;
@@ -2011,9 +2330,9 @@ int vhost_get_vq_desc(struct vhost_virtqueue *vq,
return -EFAULT;
}
if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT)) {
- ret = get_indirect(vq, iov, iov_size,
- out_num, in_num,
- log, log_num, &desc);
+ ret = get_indirect_split(vq, iov, iov_size,
+ out_num, in_num,
+ log, log_num, &desc);
if (unlikely(ret < 0)) {
if (ret != -EAGAIN)
vq_err(vq, "Failure detected "
@@ -2055,7 +2374,7 @@ int vhost_get_vq_desc(struct vhost_virtqueue *vq,
}
*out_num += ret;
}
- } while ((i = next_desc(vq, &desc)) != -1);
+ } while ((i = next_desc_split(vq, &desc)) != -1);

/* On success, increment avail index. */
vq->last_avail_idx++;
@@ -2065,6 +2384,31 @@ int vhost_get_vq_desc(struct vhost_virtqueue *vq,
BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY));
return 0;
}
+
+/* This looks in the virtqueue and for the first available buffer, and converts
+ * it to an iovec for convenient access. Since descriptors consist of some
+ * number of output then some number of input descriptors, it's actually two
+ * iovecs, but we pack them into one and note how many of each there were.
+ *
+ * This function returns the descriptor number found, or vq->num (which is
+ * never a valid descriptor number) if none was found. A negative code is
+ * returned on error.
+ */
+int vhost_get_vq_desc(struct vhost_virtqueue *vq,
+ struct vhost_used_elem *used,
+ struct iovec iov[], unsigned int iov_size,
+ unsigned int *out_num, unsigned int *in_num,
+ struct vhost_log *log, unsigned int *log_num)
+{
+ if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED))
+ return vhost_get_vq_desc_packed(vq, used, iov, iov_size,
+ out_num, in_num,
+ log, log_num);
+ else
+ return vhost_get_vq_desc_split(vq, used, iov, iov_size,
+ out_num, in_num,
+ log, log_num);
+}
EXPORT_SYMBOL_GPL(vhost_get_vq_desc);

void vhost_set_used_len(struct vhost_virtqueue *vq,
@@ -2151,15 +2495,30 @@ int vhost_get_bufs(struct vhost_virtqueue *vq,
*count = headcount;
return 0;
err:
- vhost_discard_vq_desc(vq, headcount);
+ vhost_discard_vq_desc(vq, heads, headcount);
return r;
}
EXPORT_SYMBOL_GPL(vhost_get_bufs);

/* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */
-void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n)
+void vhost_discard_vq_desc(struct vhost_virtqueue *vq,
+ struct vhost_used_elem *heads,
+ int headcount)
{
- vq->last_avail_idx -= n;
+ int i;
+
+ if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED)) {
+ for (i = 0; i < headcount; i++) {
+ vq->last_avail_idx -= heads[i].count;
+ if (vq->last_avail_idx >= vq->num) {
+ vq->last_avail_wrap_counter ^= 1;
+ vq->last_avail_idx += vq->num;
+ }
+ }
+ } else {
+ vq->last_avail_idx -= headcount;
+ }
+
}
EXPORT_SYMBOL_GPL(vhost_discard_vq_desc);

@@ -2215,10 +2574,69 @@ static int __vhost_add_used_n(struct vhost_virtqueue *vq,
return 0;
}

+static int vhost_add_used_n_packed(struct vhost_virtqueue *vq,
+ struct vhost_used_elem *heads,
+ unsigned int count)
+{
+ struct vring_desc_packed __user *desc;
+ int i, ret;
+
+ for (i = 0; i < count; i++) {
+ desc = vq->desc_packed + vq->last_used_idx;
+
+ ret = vhost_put_user(vq, heads[i].elem.id, &desc->id,
+ VHOST_ADDR_DESC);
+ if (unlikely(ret)) {
+ vq_err(vq, "Failed to update id: idx %d addr %p\n",
+ vq->last_used_idx, desc);
+ return -EFAULT;
+ }
+ ret = vhost_put_user(vq, heads[i].elem.len, &desc->len,
+ VHOST_ADDR_DESC);
+ if (unlikely(ret)) {
+ vq_err(vq, "Failed to update len: idx %d addr %p\n",
+ vq->last_used_idx, desc);
+ return -EFAULT;
+ }
+
+ /* Update flags after descriptor id and len is wrote,
+ * TODO: Update head flags at last for saving barriers */
+ smp_wmb();
+
+ ret = vhost_put_user(vq, get_desc_flags(vq, heads[i].elem.len),
+ &desc->flags, VHOST_ADDR_DESC);
+ if (unlikely(ret)) {
+ vq_err(vq, "Failed to update flags: idx %d addr %p\n",
+ vq->last_used_idx, desc);
+ return -EFAULT;
+ }
+
+ if (unlikely(vq->log_used)) {
+ /* Make sure desc is written before update log. */
+ smp_wmb();
+ log_write(vq->log_base, vq->log_addr +
+ vq->last_used_idx * sizeof(*desc),
+ sizeof(*desc));
+ if (vq->log_ctx)
+ eventfd_signal(vq->log_ctx, 1);
+ }
+
+ vq->last_used_idx += heads[i].count;
+ if (vq->last_used_idx >= vq->num) {
+ vq->used_wrap_counter ^= 1;
+ vq->last_used_idx -= vq->num;
+ }
+ }
+
+ return 0;
+}
+
/* After we've used one of their buffers, we tell them about it. We'll then
* want to notify the guest, using eventfd. */
-int vhost_add_used_n(struct vhost_virtqueue *vq, struct vhost_used_elem *heads,
- unsigned count)
+static int vhost_add_used_n_split(struct vhost_virtqueue *vq,
+ struct vhost_used_elem *heads,
+ unsigned count)
+
{
int start, n, r;

@@ -2250,6 +2668,19 @@ int vhost_add_used_n(struct vhost_virtqueue *vq, struct vhost_used_elem *heads,
}
return r;
}
+
+/* After we've used one of their buffers, we tell them about it. We'll then
+ * want to notify the guest, using eventfd.
+ */
+int vhost_add_used_n(struct vhost_virtqueue *vq,
+ struct vhost_used_elem *heads,
+ unsigned int count)
+{
+ if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED))
+ return vhost_add_used_n_packed(vq, heads, count);
+ else
+ return vhost_add_used_n_split(vq, heads, count);
+}
EXPORT_SYMBOL_GPL(vhost_add_used_n);

static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
@@ -2257,6 +2688,11 @@ static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
__u16 old, new;
__virtio16 event;
bool v;
+
+ /* FIXME: check driver area */
+ if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED))
+ return true;
+
/* Flush out used index updates. This is paired
* with the barrier that the Guest executes when enabling
* interrupts. */
@@ -2319,7 +2755,8 @@ void vhost_add_used_and_signal_n(struct vhost_dev *dev,
EXPORT_SYMBOL_GPL(vhost_add_used_and_signal_n);

/* return true if we're sure that avaiable ring is empty */
-bool vhost_vq_avail_empty(struct vhost_dev *dev, struct vhost_virtqueue *vq)
+static bool vhost_vq_avail_empty_split(struct vhost_dev *dev,
+ struct vhost_virtqueue *vq)
{
__virtio16 avail_idx;
int r;
@@ -2334,10 +2771,58 @@ bool vhost_vq_avail_empty(struct vhost_dev *dev, struct vhost_virtqueue *vq)

return vq->avail_idx == vq->last_avail_idx;
}
+
+static bool vhost_vq_avail_empty_packed(struct vhost_dev *dev,
+ struct vhost_virtqueue *vq)
+{
+ struct vring_desc_packed *d = vq->desc_packed + vq->avail_idx;
+ __virtio16 flags;
+ int ret;
+
+ ret = vhost_get_user(vq, flags, &d->flags, VHOST_ADDR_DESC);
+ if (unlikely(ret)) {
+ vq_err(vq, "Failed to get flags: idx %d addr %p\n",
+ vq->last_avail_idx, d);
+ return -EFAULT;
+ }
+
+ return !desc_is_avail(vq, vq->avail_wrap_counter, flags);
+}
+
+bool vhost_vq_avail_empty(struct vhost_dev *dev, struct vhost_virtqueue *vq)
+{
+ if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED))
+ return vhost_vq_avail_empty_packed(dev, vq);
+ else
+ return vhost_vq_avail_empty_split(dev, vq);
+}
EXPORT_SYMBOL_GPL(vhost_vq_avail_empty);

-/* OK, now we need to know about added descriptors. */
-bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
+static bool vhost_enable_notify_packed(struct vhost_dev *dev,
+ struct vhost_virtqueue *vq)
+{
+ struct vring_desc_packed *d = vq->desc_packed + vq->avail_idx;
+ __virtio16 flags;
+ int ret;
+
+ /* FIXME: disable notification through device area */
+
+ /* They could have slipped one in as we were doing that: make
+ * sure it's written, then check again. */
+ smp_mb();
+
+ ret = vhost_get_user(vq, flags, &d->flags, VHOST_ADDR_DESC);
+ if (unlikely(ret)) {
+ vq_err(vq, "Failed to get descriptor: idx %d addr %p\n",
+ vq->last_avail_idx, &d->flags);
+ return -EFAULT;
+ }
+
+ return desc_is_avail(vq, vq->avail_wrap_counter, flags);
+}
+
+static bool vhost_enable_notify_split(struct vhost_dev *dev,
+ struct vhost_virtqueue *vq)
{
__virtio16 avail_idx;
int r;
@@ -2372,10 +2857,25 @@ bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)

return vhost16_to_cpu(vq, avail_idx) != vq->avail_idx;
}
+
+/* OK, now we need to know about added descriptors. */
+bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
+{
+ if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED))
+ return vhost_enable_notify_packed(dev, vq);
+ else
+ return vhost_enable_notify_split(dev, vq);
+}
EXPORT_SYMBOL_GPL(vhost_enable_notify);

-/* We don't need to be notified again. */
-void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
+static void vhost_disable_notify_packed(struct vhost_dev *dev,
+ struct vhost_virtqueue *vq)
+{
+ /* FIXME: disable notification through device area */
+}
+
+static void vhost_disable_notify_split(struct vhost_dev *dev,
+ struct vhost_virtqueue *vq)
{
int r;

@@ -2389,6 +2889,15 @@ void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
&vq->used->flags, r);
}
}
+
+/* We don't need to be notified again. */
+void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
+{
+ if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED))
+ return vhost_disable_notify_packed(dev, vq);
+ else
+ return vhost_disable_notify_split(dev, vq);
+}
EXPORT_SYMBOL_GPL(vhost_disable_notify);

/* Create a new message. */
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index 604821b..7543a46 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -36,6 +36,7 @@ struct vhost_poll {

struct vhost_used_elem {
struct vring_used_elem elem;
+ int count;
};

void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn);
@@ -91,7 +92,10 @@ struct vhost_virtqueue {
/* The actual ring of buffers. */
struct mutex mutex;
unsigned int num;
- struct vring_desc __user *desc;
+ union {
+ struct vring_desc __user *desc;
+ struct vring_desc_packed __user *desc_packed;
+ };
struct vring_avail __user *avail;
struct vring_used __user *used;
const struct vhost_umem_node *meta_iotlb[VHOST_NUM_ADDRS];
@@ -148,6 +152,9 @@ struct vhost_virtqueue {
bool user_be;
#endif
u32 busyloop_timeout;
+ bool used_wrap_counter;
+ bool avail_wrap_counter;
+ bool last_avail_wrap_counter;
};

struct vhost_msg_node {
@@ -203,7 +210,9 @@ void vhost_set_used_len(struct vhost_virtqueue *vq,
int len);
int vhost_get_used_len(struct vhost_virtqueue *vq,
struct vhost_used_elem *used);
-void vhost_discard_vq_desc(struct vhost_virtqueue *, int n);
+void vhost_discard_vq_desc(struct vhost_virtqueue *,
+ struct vhost_used_elem *,
+ int n);

int vhost_vq_init_access(struct vhost_virtqueue *);
int vhost_add_used(struct vhost_virtqueue *vq,
--
2.7.4