The vq->is_le field is used to fix endianness when accessing the vring via the cpu_to_vhost16() and vhost16_to_cpu() helpers in the following cases: 1) host is big endian and device is modern virtio 2) host has cross-endian support and device is legacy virtio with a different endianness than the host Both cases rely on the VHOST_SET_FEATURES ioctl, but 2) also needs the VHOST_SET_VRING_ENDIAN ioctl to be called by userspace. Since vq->is_le is only needed when the backend is active, it was decided to set it at backend start. This is currently done in vhost_init_used()->vhost_init_is_le() but it obfuscates the core vhost code. This patch moves the is_le setup to a dedicated function that is called from the backend code. Note vhost_net is the only backend that can pass vq->private_data == NULL to vhost_init_used(), hence the "if (sock)" branch. No behaviour change. Reviewed-by: Cornelia Huck <cornelia.huck@xxxxxxxxxx> Signed-off-by: Greg Kurz <gkurz@xxxxxxxxxxxxxxxxxx> --- Hi Michael, This is a cleanup patch I had posted last year: http://patchwork.ozlabs.org/patch/538277/ I am just reposting with Cornelia's R-b. Cheers. -- Greg drivers/vhost/net.c | 6 ++++++ drivers/vhost/scsi.c | 3 +++ drivers/vhost/test.c | 2 ++ drivers/vhost/vhost.c | 12 +++++++----- drivers/vhost/vhost.h | 1 + 5 files changed, 19 insertions(+), 5 deletions(-) diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c index 9eda69e40678..d6319cb2664c 100644 --- a/drivers/vhost/net.c +++ b/drivers/vhost/net.c @@ -917,6 +917,12 @@ static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd) vhost_net_disable_vq(n, vq); vq->private_data = sock; + + if (sock) + vhost_set_is_le(vq); + else + vq->is_le = virtio_legacy_is_little_endian(); + r = vhost_init_used(vq); if (r) goto err_used; diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c index 29cfc57d496e..1f4f405ebba8 100644 --- a/drivers/vhost/scsi.c +++ b/drivers/vhost/scsi.c @@ -1274,6 +1274,9 @@ vhost_scsi_set_endpoint(struct vhost_scsi *vs, vq = &vs->vqs[i].vq; mutex_lock(&vq->mutex); vq->private_data = vs_tpg; + + vhost_set_is_le(vq); + vhost_init_used(vq); mutex_unlock(&vq->mutex); } diff --git a/drivers/vhost/test.c b/drivers/vhost/test.c index f2882ac98726..b1c7df502211 100644 --- a/drivers/vhost/test.c +++ b/drivers/vhost/test.c @@ -196,6 +196,8 @@ static long vhost_test_run(struct vhost_test *n, int test) oldpriv = vq->private_data; vq->private_data = priv; + vhost_set_is_le(vq); + r = vhost_init_used(&n->vqs[index]); mutex_unlock(&vq->mutex); diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index ad2146a9ab2d..e688eb801d43 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -113,6 +113,12 @@ static void vhost_init_is_le(struct vhost_virtqueue *vq) } #endif /* CONFIG_VHOST_CROSS_ENDIAN_LEGACY */ +void vhost_set_is_le(struct vhost_virtqueue *vq) +{ + vhost_init_is_le(vq); +} +EXPORT_SYMBOL_GPL(vhost_set_is_le); + static void vhost_poll_func(struct file *file, wait_queue_head_t *wqh, poll_table *pt) { @@ -1156,12 +1162,8 @@ int vhost_init_used(struct vhost_virtqueue *vq) { __virtio16 last_used_idx; int r; - if (!vq->private_data) { - vq->is_le = virtio_legacy_is_little_endian(); + if (!vq->private_data) return 0; - } - - vhost_init_is_le(vq); r = vhost_update_used_flags(vq); if (r) diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h index d3f767448a72..af5d33797937 100644 --- a/drivers/vhost/vhost.h +++ b/drivers/vhost/vhost.h @@ -162,6 +162,7 @@ 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); +void vhost_set_is_le(struct vhost_virtqueue *vq); #define vq_err(vq, fmt, ...) do { \ pr_debug(pr_fmt(fmt), ##__VA_ARGS__); \ _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
