Currently, the only user of vhost_log_write() is vhost-net. The 'len'
argument prevents logging of pages that are not tainted by the RX path.
Adjustments are needed since more drivers (i.e. vhost-scsi) begin using
vhost_log_write(). So far vhost-net RX path may only partially use pages
shared by the last vring descriptor. Unlike vhost-net, vhost-scsi always
logs all pages shared via vring descriptors. To accommodate this, a new
argument 'partial' is introduced. This argument works alongside 'len' to
indicate whether the driver should log all pages of a vring descriptor, or
only pages that are tainted by the driver.
In addition, removes BUG().
Suggested-by: Joao Martins <joao.m.martins@xxxxxxxxxx>
Signed-off-by: Dongli Zhang <dongli.zhang@xxxxxxxxxx>
---
drivers/vhost/net.c | 2 +-
drivers/vhost/vhost.c | 28 +++++++++++++++++-----------
drivers/vhost/vhost.h | 2 +-
3 files changed, 19 insertions(+), 13 deletions(-)
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index b9b9e9d40951..0e5d82bfde76 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -1219,7 +1219,7 @@ static void handle_rx(struct vhost_net *net)
if (nvq->done_idx > VHOST_NET_BATCH)
vhost_net_signal_used(nvq);
if (unlikely(vq_log))
- vhost_log_write(vq, vq_log, log, vhost_len,
+ vhost_log_write(vq, vq_log, log, vhost_len, true,
vq->iov, in);
total_len += vhost_len;
} while (likely(!vhost_exceeds_weight(vq, ++recv_pkts, total_len)));
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 9ac25d08f473..db3b30aba940 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -2304,8 +2304,14 @@ static int log_used(struct vhost_virtqueue *vq, u64 used_offset, u64 len)
return 0;
}
-int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
- unsigned int log_num, u64 len, struct iovec *iov, int count)
+/*
+ * 'len' is used only when 'partial' is true, to indicate whether the
+ * entire length of each descriptor is logged.
+ */
+int vhost_log_write(struct vhost_virtqueue *vq,
+ struct vhost_log *log, unsigned int log_num,
+ u64 len, bool partial,
+ struct iovec *iov, int count)
{
int i, r;
@@ -2323,19 +2329,19 @@ int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
}
for (i = 0; i < log_num; ++i) {
- u64 l = min(log[i].len, len);
+ u64 l = partial ? min(log[i].len, len) : log[i].len;
+
r = log_write(vq->log_base, log[i].addr, l);
if (r < 0)
return r;
- len -= l;
- if (!len) {
- if (vq->log_ctx)
- eventfd_signal(vq->log_ctx);
- return 0;
- }
+
+ if (partial)
+ len -= l;
}
- /* Length written exceeds what we have stored. This is a bug. */
- BUG();
+
+ if (vq->log_ctx)
+ eventfd_signal(vq->log_ctx);
+
return 0;
}
EXPORT_SYMBOL_GPL(vhost_log_write);
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index bb75a292d50c..5de5941988fe 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -224,7 +224,7 @@ bool vhost_vq_avail_empty(struct vhost_dev *, struct vhost_virtqueue *);
bool vhost_enable_notify(struct vhost_dev *, struct vhost_virtqueue *);
int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
- unsigned int log_num, u64 len,
+ unsigned int log_num, u64 len, bool partial,
struct iovec *iov, int count);
int vq_meta_prefetch(struct vhost_virtqueue *vq);
--
2.39.3
