[PATCH 3/3] vdpa_sim_blk: call vringh_complete_iotlb() also in the error path

From: Stefano Garzarella
Date: Tue Jun 21 2022 - 12:13:15 EST


Call vringh_complete_iotlb() even when we encounter a serious error
that prevents us from writing the status in the "in" header
(e.g. the header length is incorrect, etc.).

The guest is misbehaving, so maybe the ring is in a bad state, but
let's avoid making things worse.

Signed-off-by: Stefano Garzarella <sgarzare@xxxxxxxxxx>
---
drivers/vdpa/vdpa_sim/vdpa_sim_blk.c | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim_blk.c b/drivers/vdpa/vdpa_sim/vdpa_sim_blk.c
index ac86478845b6..de9cd9843143 100644
--- a/drivers/vdpa/vdpa_sim/vdpa_sim_blk.c
+++ b/drivers/vdpa/vdpa_sim/vdpa_sim_blk.c
@@ -63,6 +63,7 @@ static bool vdpasim_blk_handle_req(struct vdpasim *vdpasim,
{
size_t pushed = 0, to_pull, to_push;
struct virtio_blk_outhdr hdr;
+ bool handled = false;
ssize_t bytes;
loff_t offset;
u64 sector;
@@ -78,12 +79,12 @@ static bool vdpasim_blk_handle_req(struct vdpasim *vdpasim,
if (vq->out_iov.used < 1 || vq->in_iov.used < 1) {
dev_dbg(&vdpasim->vdpa.dev, "missing headers - out_iov: %u in_iov %u\n",
vq->out_iov.used, vq->in_iov.used);
- return false;
+ goto err;
}

if (vq->in_iov.iov[vq->in_iov.used - 1].iov_len < 1) {
dev_dbg(&vdpasim->vdpa.dev, "request in header too short\n");
- return false;
+ goto err;
}

/* The last byte is the status and we checked if the last iov has
@@ -97,7 +98,7 @@ static bool vdpasim_blk_handle_req(struct vdpasim *vdpasim,
sizeof(hdr));
if (bytes != sizeof(hdr)) {
dev_dbg(&vdpasim->vdpa.dev, "request out header too short\n");
- return false;
+ goto err;
}

to_pull -= bytes;
@@ -182,16 +183,19 @@ static bool vdpasim_blk_handle_req(struct vdpasim *vdpasim,
/* Last byte is the status */
bytes = vringh_iov_push_iotlb(&vq->vring, &vq->in_iov, &status, 1);
if (bytes != 1)
- return false;
+ goto err;

pushed += bytes;

/* Make sure data is wrote before advancing index */
smp_wmb();

+ handled = true;
+
+err:
vringh_complete_iotlb(&vq->vring, vq->head, pushed);

- return true;
+ return handled;
}

static void vdpasim_blk_work(struct work_struct *work)
--
2.36.1