Re: [PATCH V2 1/6] vhost: introduce vhost_call_ctx

["Zhu, Lingshan" <lingshan.zhu@xxxxxxxxx>]

On 7/17/2020 11:32 AM, Jason Wang wrote:
> On 2020/7/16 下午7:23, Zhu Lingshan wrote:
> > This commit introduces struct vhost_call_ctx which replaced
> > raw struct eventfd_ctx *call_ctx in struct vhost_virtqueue.
> > Besides eventfd_ctx, it contains a spin lock and an
> > irq_bypass_producer in its structure.
> >
> > Signed-off-by: Zhu Lingshan <lingshan.zhu@xxxxxxxxx>
> > Suggested-by: Jason Wang <jasowang@xxxxxxxxxx>
> > ---
> >   drivers/vhost/vdpa.c  |  4 ++--
> >   drivers/vhost/vhost.c | 22 ++++++++++++++++------
> >   drivers/vhost/vhost.h |  9 ++++++++-
> >   3 files changed, 26 insertions(+), 9 deletions(-)
> >
> > diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
> > index 7580e34..2fcc422 100644
> > --- a/drivers/vhost/vdpa.c
> > +++ b/drivers/vhost/vdpa.c
> > @@ -96,7 +96,7 @@ static void handle_vq_kick(struct vhost_work *work)
> >   static irqreturn_t vhost_vdpa_virtqueue_cb(void *private)
> >   {
> >       struct vhost_virtqueue *vq = private;
> > -    struct eventfd_ctx *call_ctx = vq->call_ctx;
> > +    struct eventfd_ctx *call_ctx = vq->call_ctx.ctx;
> >         if (call_ctx)
> >           eventfd_signal(call_ctx, 1);
> > @@ -382,7 +382,7 @@ static long vhost_vdpa_vring_ioctl(struct 
> > vhost_vdpa *v, unsigned int cmd,
> >           break;
> >         case VHOST_SET_VRING_CALL:
> > -        if (vq->call_ctx) {
> > +        if (vq->call_ctx.ctx) {
> >               cb.callback = vhost_vdpa_virtqueue_cb;
> >               cb.private = vq;
> >           } else {
> > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> > index d7b8df3..4004e94 100644
> > --- a/drivers/vhost/vhost.c
> > +++ b/drivers/vhost/vhost.c
> > @@ -298,6 +298,13 @@ static void vhost_vq_meta_reset(struct vhost_dev 
> > *d)
> >           __vhost_vq_meta_reset(d->vqs[i]);
> >   }
> >   +static void vhost_call_ctx_reset(struct vhost_call_ctx *call_ctx)
> > +{
> > +    call_ctx->ctx = NULL;
> > +    memset(&call_ctx->producer, 0x0, sizeof(struct 
> > irq_bypass_producer));
> > +    spin_lock_init(&call_ctx->ctx_lock);
> > +}
> > +
> >   static void vhost_vq_reset(struct vhost_dev *dev,
> >                  struct vhost_virtqueue *vq)
> >   {
> > @@ -319,13 +326,13 @@ static void vhost_vq_reset(struct vhost_dev *dev,
> >       vq->log_base = NULL;
> >       vq->error_ctx = NULL;
> >       vq->kick = NULL;
> > -    vq->call_ctx = NULL;
> >       vq->log_ctx = NULL;
> >       vhost_reset_is_le(vq);
> >       vhost_disable_cross_endian(vq);
> >       vq->busyloop_timeout = 0;
> >       vq->umem = NULL;
> >       vq->iotlb = NULL;
> > +    vhost_call_ctx_reset(&vq->call_ctx);
> >       __vhost_vq_meta_reset(vq);
> >   }
> >   @@ -685,8 +692,8 @@ void vhost_dev_cleanup(struct vhost_dev *dev)
> > eventfd_ctx_put(dev->vqs[i]->error_ctx);
> >           if (dev->vqs[i]->kick)
> >               fput(dev->vqs[i]->kick);
> > -        if (dev->vqs[i]->call_ctx)
> > - eventfd_ctx_put(dev->vqs[i]->call_ctx);
> > +        if (dev->vqs[i]->call_ctx.ctx)
> > + eventfd_ctx_put(dev->vqs[i]->call_ctx.ctx);
> >           vhost_vq_reset(dev, dev->vqs[i]);
> >       }
> >       vhost_dev_free_iovecs(dev);
> > @@ -1629,7 +1636,10 @@ long vhost_vring_ioctl(struct vhost_dev *d, 
> > unsigned int ioctl, void __user *arg
> >               r = PTR_ERR(ctx);
> >               break;
> >           }
> > -        swap(ctx, vq->call_ctx);
> > +
> > +        spin_lock(&vq->call_ctx.ctx_lock);
> > +        swap(ctx, vq->call_ctx.ctx);
> > +        spin_unlock(&vq->call_ctx.ctx_lock);
> >           break;
> >       case VHOST_SET_VRING_ERR:
> >           if (copy_from_user(&f, argp, sizeof f)) {
> > @@ -2440,8 +2450,8 @@ static bool vhost_notify(struct vhost_dev *dev, 
> > struct vhost_virtqueue *vq)
> >   void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq)
> >   {
> >       /* Signal the Guest tell them we used something up. */
> > -    if (vq->call_ctx && vhost_notify(dev, vq))
> > -        eventfd_signal(vq->call_ctx, 1);
> > +    if (vq->call_ctx.ctx && vhost_notify(dev, vq))
> > +        eventfd_signal(vq->call_ctx.ctx, 1);
> >   }
> >   EXPORT_SYMBOL_GPL(vhost_signal);
> >   diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
> > index c8e96a0..402c62e 100644
> > --- a/drivers/vhost/vhost.h
> > +++ b/drivers/vhost/vhost.h
> > @@ -13,6 +13,7 @@
> >   #include <linux/virtio_ring.h>
> >   #include <linux/atomic.h>
> >   #include <linux/vhost_iotlb.h>
> > +#include <linux/irqbypass.h>
> >     struct vhost_work;
> >   typedef void (*vhost_work_fn_t)(struct vhost_work *work);
> > @@ -60,6 +61,12 @@ enum vhost_uaddr_type {
> >       VHOST_NUM_ADDRS = 3,
> >   };
> >   +struct vhost_call_ctx {
>
>
> I think maybe "vhost_vring_call" is a better name since it contains 
> not only the eventfd_ctx now.
>
> Thanks
Sure
> > +    struct eventfd_ctx *ctx;
> > +    struct irq_bypass_producer producer;
> > +    spinlock_t ctx_lock;
> > +};
> > +
> >   /* The virtqueue structure describes a queue attached to a device. */
> >   struct vhost_virtqueue {
> >       struct vhost_dev *dev;
> > @@ -72,7 +79,7 @@ struct vhost_virtqueue {
> >       vring_used_t __user *used;
> >       const struct vhost_iotlb_map *meta_iotlb[VHOST_NUM_ADDRS];
> >       struct file *kick;
> > -    struct eventfd_ctx *call_ctx;
> > +    struct vhost_call_ctx call_ctx;
> >       struct eventfd_ctx *error_ctx;
> >       struct eventfd_ctx *log_ctx;