From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eugenio Perez Martin Subject: Re: [PATCH RFC v8 05/11] vhost: format-independent API for used buffers Date: Mon, 15 Jun 2020 18:11:05 +0200 Message-ID: References: <20200611113404.17810-1-mst@redhat.com> <20200611113404.17810-6-mst@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Return-path: In-Reply-To: <20200611113404.17810-6-mst@redhat.com> Sender: kvm-owner@vger.kernel.org To: "Michael S. Tsirkin" Cc: linux-kernel@vger.kernel.org, kvm list , virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, Jason Wang List-Id: virtualization@lists.linuxfoundation.org On Thu, Jun 11, 2020 at 1:34 PM Michael S. Tsirkin wrote: > > Add a new API that doesn't assume used ring, heads, etc. > For now, we keep the old APIs around to make it easier > to convert drivers. > > Signed-off-by: Michael S. Tsirkin > --- > drivers/vhost/vhost.c | 73 +++++++++++++++++++++++++++++++++++++------ > drivers/vhost/vhost.h | 17 +++++++++- > 2 files changed, 79 insertions(+), 11 deletions(-) > > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c > index c38605b01080..03e6bca02288 100644 > --- a/drivers/vhost/vhost.c > +++ b/drivers/vhost/vhost.c > @@ -2335,13 +2335,12 @@ static void unfetch_descs(struct vhost_virtqueue *vq) > * 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 iovec iov[], unsigned int iov_size, > - unsigned int *out_num, unsigned int *in_num, > - struct vhost_log *log, unsigned int *log_num) > + * This function returns a value > 0 if a descriptor was found, or 0 if none were found. > + * A negative code is returned on error. */ > +int vhost_get_avail_buf(struct vhost_virtqueue *vq, struct vhost_buf *buf, > + struct iovec iov[], unsigned int iov_size, > + unsigned int *out_num, unsigned int *in_num, > + struct vhost_log *log, unsigned int *log_num) > { > int ret = fetch_descs(vq); > int i; > @@ -2354,6 +2353,8 @@ int vhost_get_vq_desc(struct vhost_virtqueue *vq, > *out_num = *in_num = 0; > if (unlikely(log)) > *log_num = 0; > + buf->in_len = buf->out_len = 0; > + buf->descs = 0; > > for (i = vq->first_desc; i < vq->ndescs; ++i) { > unsigned iov_count = *in_num + *out_num; > @@ -2383,6 +2384,7 @@ int (struct vhost_virtqueue *vq, > /* If this is an input descriptor, > * increment that count. */ > *in_num += ret; > + buf->in_len += desc->len; > if (unlikely(log && ret)) { > log[*log_num].addr = desc->addr; > log[*log_num].len = desc->len; > @@ -2398,9 +2400,11 @@ int vhost_get_vq_desc(struct vhost_virtqueue *vq, > goto err; > } > *out_num += ret; > + buf->out_len += desc->len; > } > > - ret = desc->id; > + buf->id = desc->id; > + ++buf->descs; > > if (!(desc->flags & VRING_DESC_F_NEXT)) > break; > @@ -2408,12 +2412,41 @@ int vhost_get_vq_desc(struct vhost_virtqueue *vq, > > vq->first_desc = i + 1; > > - return ret; > + return 1; > > err: > unfetch_descs(vq); > > - return ret ? ret : vq->num; > + return ret; > +} > +EXPORT_SYMBOL_GPL(vhost_get_avail_buf); > + > +/* Reverse the effect of vhost_get_avail_buf. Useful for error handling. */ > +void vhost_discard_avail_bufs(struct vhost_virtqueue *vq, > + struct vhost_buf *buf, unsigned count) > +{ > + vhost_discard_vq_desc(vq, count); > +} > +EXPORT_SYMBOL_GPL(vhost_discard_avail_bufs); > + > +/* 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 iovec iov[], unsigned int iov_size, > + unsigned int *out_num, unsigned int *in_num, > + struct vhost_log *log, unsigned int *log_num) > +{ > + struct vhost_buf buf; > + int ret = vhost_get_avail_buf(vq, &buf, > + iov, iov_size, out_num, in_num, > + log, log_num); > + > + if (likely(ret > 0)) > + return buf->id; This should be buf.id, isn't it? > + if (likely(!ret)) > + return vq->num; > + return ret; > } > EXPORT_SYMBOL_GPL(vhost_get_vq_desc); > > @@ -2507,6 +2540,26 @@ int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len) > } > EXPORT_SYMBOL_GPL(vhost_add_used); > > +int vhost_put_used_buf(struct vhost_virtqueue *vq, struct vhost_buf *buf) > +{ > + return vhost_add_used(vq, buf->id, buf->in_len); > +} > +EXPORT_SYMBOL_GPL(vhost_put_used_buf); > + > +int vhost_put_used_n_bufs(struct vhost_virtqueue *vq, > + struct vhost_buf *bufs, unsigned count) > +{ > + unsigned i; > + > + for (i = 0; i < count; ++i) { > + vq->heads[i].id = cpu_to_vhost32(vq, bufs[i].id); > + vq->heads[i].len = cpu_to_vhost32(vq, bufs[i].in_len); > + } > + > + return vhost_add_used_n(vq, vq->heads, count); > +} > +EXPORT_SYMBOL_GPL(vhost_put_used_n_bufs); > + > static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq) > { > __u16 old, new; > diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h > index fed36af5c444..28eea0155efb 100644 > --- a/drivers/vhost/vhost.h > +++ b/drivers/vhost/vhost.h > @@ -67,6 +67,13 @@ struct vhost_desc { > u16 id; > }; > > +struct vhost_buf { > + u32 out_len; > + u32 in_len; > + u16 descs; > + u16 id; > +}; > + > /* The virtqueue structure describes a queue attached to a device. */ > struct vhost_virtqueue { > struct vhost_dev *dev; > @@ -195,7 +202,12 @@ int vhost_get_vq_desc(struct vhost_virtqueue *, > unsigned int *out_num, unsigned int *in_num, > struct vhost_log *log, unsigned int *log_num); > void vhost_discard_vq_desc(struct vhost_virtqueue *, int n); > - > +int vhost_get_avail_buf(struct vhost_virtqueue *, struct vhost_buf *buf, > + struct iovec iov[], unsigned int iov_count, > + unsigned int *out_num, unsigned int *in_num, > + struct vhost_log *log, unsigned int *log_num); > +void vhost_discard_avail_bufs(struct vhost_virtqueue *, > + struct vhost_buf *, unsigned count); > int vhost_vq_init_access(struct vhost_virtqueue *); > int vhost_add_used(struct vhost_virtqueue *, unsigned int head, int len); > int vhost_add_used_n(struct vhost_virtqueue *, struct vring_used_elem *heads, > @@ -204,6 +216,9 @@ void vhost_add_used_and_signal(struct vhost_dev *, struct vhost_virtqueue *, > unsigned int id, int len); > void vhost_add_used_and_signal_n(struct vhost_dev *, struct vhost_virtqueue *, > struct vring_used_elem *heads, unsigned count); > +int vhost_put_used_buf(struct vhost_virtqueue *, struct vhost_buf *buf); > +int vhost_put_used_n_bufs(struct vhost_virtqueue *, > + struct vhost_buf *bufs, unsigned count); > void vhost_signal(struct vhost_dev *, struct vhost_virtqueue *); > void vhost_disable_notify(struct vhost_dev *, struct vhost_virtqueue *); > bool vhost_vq_avail_empty(struct vhost_dev *, struct vhost_virtqueue *); > -- > MST >