Re: [PATCH 1/2] vhost: move acked_features to VQs

From: Michael S. Tsirkin
Date: Thu Jun 05 2014 - 08:15:56 EST

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In reply to: Michael S. Tsirkin: "[PATCH 2/2] vhost: move memory pointer to VQs"
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On Thu, Jun 05, 2014 at 01:44:14PM +0300, Michael S. Tsirkin wrote:
> Refactor code to make sure features are only accessed
> under VQ mutex. This makes everything simpler, no need
> for RCU here anymore.
>
> Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>

Ouch, I sent out wrong version of the patch.
Self-NACK, will repost.
Sorry about the noise.

> ---
>
> This is on top of the recent pull request that I sent.
>
> drivers/vhost/vhost.h | 11 +++--------
> drivers/vhost/net.c | 8 +++-----
> drivers/vhost/scsi.c | 22 +++++++++++++---------
> drivers/vhost/test.c | 9 ++++++---
> drivers/vhost/vhost.c | 31 ++++++++++++++++---------------
> 5 files changed, 41 insertions(+), 40 deletions(-)
>
> diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
> index 35eeb2a..ff454a0 100644
> --- a/drivers/vhost/vhost.h
> +++ b/drivers/vhost/vhost.h
> @@ -105,6 +105,7 @@ struct vhost_virtqueue {
> struct vring_used_elem *heads;
> /* Protected by virtqueue mutex. */
> void *private_data;
> + unsigned acked_features;
> /* Log write descriptors */
> void __user *log_base;
> struct vhost_log *log;
> @@ -117,7 +118,6 @@ struct vhost_dev {
> struct vhost_memory __rcu *memory;
> struct mm_struct *mm;
> struct mutex mutex;
> - unsigned acked_features;
> struct vhost_virtqueue **vqs;
> int nvqs;
> struct file *log_file;
> @@ -174,13 +174,8 @@ enum {
> (1ULL << VHOST_F_LOG_ALL),
> };
>
> -static inline int vhost_has_feature(struct vhost_dev *dev, int bit)
> +static inline int vhost_has_feature(struct vhost_virtqueue *vq, int bit)
> {
> - unsigned acked_features;
> -
> - /* TODO: check that we are running from vhost_worker or dev mutex is
> - * held? */
> - acked_features = rcu_dereference_index_check(dev->acked_features, 1);
> - return acked_features & (1 << bit);
> + return vq->acked_features & (1 << bit);
> }
> #endif
> diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
> index e489161..7635b59 100644
> --- a/drivers/vhost/net.c
> +++ b/drivers/vhost/net.c
> @@ -585,9 +585,9 @@ static void handle_rx(struct vhost_net *net)
> vhost_hlen = nvq->vhost_hlen;
> sock_hlen = nvq->sock_hlen;
>
> - vq_log = unlikely(vhost_has_feature(&net->dev, VHOST_F_LOG_ALL)) ?
> + vq_log = unlikely(vhost_has_feature(vq, VHOST_F_LOG_ALL)) ?
> vq->log : NULL;
> - mergeable = vhost_has_feature(&net->dev, VIRTIO_NET_F_MRG_RXBUF);
> + mergeable = vhost_has_feature(vq, VIRTIO_NET_F_MRG_RXBUF);
>
> while ((sock_len = peek_head_len(sock->sk))) {
> sock_len += sock_hlen;
> @@ -1051,15 +1051,13 @@ static int vhost_net_set_features(struct vhost_net *n, u64 features)
> mutex_unlock(&n->dev.mutex);
> return -EFAULT;
> }
> - n->dev.acked_features = features;
> - smp_wmb();
> for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
> mutex_lock(&n->vqs[i].vq.mutex);
> + n->vqs[i].acked_features = features;
> n->vqs[i].vhost_hlen = vhost_hlen;
> n->vqs[i].sock_hlen = sock_hlen;
> mutex_unlock(&n->vqs[i].vq.mutex);
> }
> - vhost_net_flush(n);
> mutex_unlock(&n->dev.mutex);
> return 0;
> }
> diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
> index cf50ce9..f1f284f 100644
> --- a/drivers/vhost/scsi.c
> +++ b/drivers/vhost/scsi.c
> @@ -1373,6 +1373,9 @@ err_dev:
>
> static int vhost_scsi_set_features(struct vhost_scsi *vs, u64 features)
> {
> + struct vhost_virtqueue *vq;
> + int i;
> +
> if (features & ~VHOST_SCSI_FEATURES)
> return -EOPNOTSUPP;
>
> @@ -1382,9 +1385,13 @@ static int vhost_scsi_set_features(struct vhost_scsi *vs, u64 features)
> mutex_unlock(&vs->dev.mutex);
> return -EFAULT;
> }
> - vs->dev.acked_features = features;
> - smp_wmb();
> - vhost_scsi_flush(vs);
> +
> + for (i = 0; i < VHOST_SCSI_MAX_VQ; i++) {
> + vq = &vs->vqs[i].vq;
> + mutex_lock(&vq->mutex);
> + vq->acked_features = features;
> + mutex_unlock(&vq->mutex);
> + }
> mutex_unlock(&vs->dev.mutex);
> return 0;
> }
> @@ -1591,10 +1598,6 @@ tcm_vhost_do_plug(struct tcm_vhost_tpg *tpg,
> return;
>
> mutex_lock(&vs->dev.mutex);
> - if (!vhost_has_feature(&vs->dev, VIRTIO_SCSI_F_HOTPLUG)) {
> - mutex_unlock(&vs->dev.mutex);
> - return;
> - }
>
> if (plug)
> reason = VIRTIO_SCSI_EVT_RESET_RESCAN;
> @@ -1603,8 +1606,9 @@ tcm_vhost_do_plug(struct tcm_vhost_tpg *tpg,
>
> vq = &vs->vqs[VHOST_SCSI_VQ_EVT].vq;
> mutex_lock(&vq->mutex);
> - tcm_vhost_send_evt(vs, tpg, lun,
> - VIRTIO_SCSI_T_TRANSPORT_RESET, reason);
> + if (vhost_has_feature(vq, VIRTIO_SCSI_F_HOTPLUG))
> + tcm_vhost_send_evt(vs, tpg, lun,
> + VIRTIO_SCSI_T_TRANSPORT_RESET, reason);
> mutex_unlock(&vq->mutex);
> mutex_unlock(&vs->dev.mutex);
> }
> diff --git a/drivers/vhost/test.c b/drivers/vhost/test.c
> index c2a54fb..6fa3bf8 100644
> --- a/drivers/vhost/test.c
> +++ b/drivers/vhost/test.c
> @@ -241,15 +241,18 @@ done:
>
> static int vhost_test_set_features(struct vhost_test *n, u64 features)
> {
> + struct vhost_virtqueue *vq;
> +
> mutex_lock(&n->dev.mutex);
> if ((features & (1 << VHOST_F_LOG_ALL)) &&
> !vhost_log_access_ok(&n->dev)) {
> mutex_unlock(&n->dev.mutex);
> return -EFAULT;
> }
> - n->dev.acked_features = features;
> - smp_wmb();
> - vhost_test_flush(n);
> + vq = &n->vqs[VHOST_TEST_VQ];
> + mutex_lock(&vq->mutex);
> + vq->acked_features = features;
> + mutex_unlock(&vq->mutex);
> mutex_unlock(&n->dev.mutex);
> return 0;
> }
> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> index 1c05e60..9183f0b 100644
> --- a/drivers/vhost/vhost.c
> +++ b/drivers/vhost/vhost.c
> @@ -524,11 +524,13 @@ static int memory_access_ok(struct vhost_dev *d, struct vhost_memory *mem,
>
> for (i = 0; i < d->nvqs; ++i) {
> int ok;
> + bool log;
> +
> mutex_lock(&d->vqs[i]->mutex);
> + log = log_all || vhost_has_feature(d->vqs[i], VHOST_F_LOG_ALL);
> /* If ring is inactive, will check when it's enabled. */
> if (d->vqs[i]->private_data)
> - ok = vq_memory_access_ok(d->vqs[i]->log_base, mem,
> - log_all);
> + ok = vq_memory_access_ok(d->vqs[i]->log_base, mem, log);
> else
> ok = 1;
> mutex_unlock(&d->vqs[i]->mutex);
> @@ -538,12 +540,12 @@ static int memory_access_ok(struct vhost_dev *d, struct vhost_memory *mem,
> return 1;
> }
>
> -static int vq_access_ok(struct vhost_dev *d, unsigned int num,
> +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)
> {
> - size_t s = vhost_has_feature(d, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
> + size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
> return access_ok(VERIFY_READ, desc, num * sizeof *desc) &&
> access_ok(VERIFY_READ, avail,
> sizeof *avail + num * sizeof *avail->ring + s) &&
> @@ -565,16 +567,16 @@ EXPORT_SYMBOL_GPL(vhost_log_access_ok);
>
> /* Verify access for write logging. */
> /* Caller should have vq mutex and device mutex */
> -static int vq_log_access_ok(struct vhost_dev *d, struct vhost_virtqueue *vq,
> +static int vq_log_access_ok(struct vhost_virtqueue *vq,
> void __user *log_base)
> {
> struct vhost_memory *mp;
> - size_t s = vhost_has_feature(d, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
> + size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
>
> mp = rcu_dereference_protected(vq->dev->memory,
> lockdep_is_held(&vq->mutex));
> return vq_memory_access_ok(log_base, mp,
> - vhost_has_feature(vq->dev, VHOST_F_LOG_ALL)) &&
> + vhost_has_feature(vq, VHOST_F_LOG_ALL)) &&
> (!vq->log_used || log_access_ok(log_base, vq->log_addr,
> sizeof *vq->used +
> vq->num * sizeof *vq->used->ring + s));
> @@ -584,8 +586,8 @@ static int vq_log_access_ok(struct vhost_dev *d, struct vhost_virtqueue *vq,
> /* Caller should have vq mutex and device mutex */
> int vhost_vq_access_ok(struct vhost_virtqueue *vq)
> {
> - return vq_access_ok(vq->dev, vq->num, vq->desc, vq->avail, vq->used) &&
> - vq_log_access_ok(vq->dev, vq, vq->log_base);
> + return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used) &&
> + vq_log_access_ok(vq, vq->log_base);
> }
> EXPORT_SYMBOL_GPL(vhost_vq_access_ok);
>
> @@ -612,8 +614,7 @@ static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
> return -EFAULT;
> }
>
> - if (!memory_access_ok(d, newmem,
> - vhost_has_feature(d, VHOST_F_LOG_ALL))) {
> + if (!memory_access_ok(d, newmem, 0)) {
> kfree(newmem);
> return -EFAULT;
> }
> @@ -1434,11 +1435,11 @@ static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
> * interrupts. */
> smp_mb();
>
> - if (vhost_has_feature(dev, VIRTIO_F_NOTIFY_ON_EMPTY) &&
> + if (vhost_has_feature(vq, VIRTIO_F_NOTIFY_ON_EMPTY) &&
> unlikely(vq->avail_idx == vq->last_avail_idx))
> return true;
>
> - if (!vhost_has_feature(dev, VIRTIO_RING_F_EVENT_IDX)) {
> + if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
> __u16 flags;
> if (__get_user(flags, &vq->avail->flags)) {
> vq_err(vq, "Failed to get flags");
> @@ -1499,7 +1500,7 @@ bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
> if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY))
> return false;
> vq->used_flags &= ~VRING_USED_F_NO_NOTIFY;
> - if (!vhost_has_feature(dev, VIRTIO_RING_F_EVENT_IDX)) {
> + if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
> r = vhost_update_used_flags(vq);
> if (r) {
> vq_err(vq, "Failed to enable notification at %p: %d\n",
> @@ -1536,7 +1537,7 @@ void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
> if (vq->used_flags & VRING_USED_F_NO_NOTIFY)
> return;
> vq->used_flags |= VRING_USED_F_NO_NOTIFY;
> - if (!vhost_has_feature(dev, VIRTIO_RING_F_EVENT_IDX)) {
> + if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
> r = vhost_update_used_flags(vq);
> if (r)
> vq_err(vq, "Failed to enable notification at %p: %d\n",
> --
> MST
>
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In reply to: Michael S. Tsirkin: "[PATCH 2/2] vhost: move memory pointer to VQs"
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