Re: [PATCH v3 2/2] vhost-user: remove VirtQ notifier restore

["Xueming(Steven) Li" <xuemingl@nvidia.com>]

On Tue, 2021-10-19 at 02:37 -0400, Michael S. Tsirkin wrote:
> On Fri, Oct 08, 2021 at 03:58:05PM +0800, Xueming Li wrote:
> > When vhost-user vdpa client restart, VQ notifier resources become
> > invalid, no need to keep mmap, vdpa client will set VQ notifier after
> > reconnect.
> > 
> > Removes VQ notifier restore and related flags.
> > 
> > Fixes: 44866521bd6e ("vhost-user: support registering external host notifiers")
> > Cc: tiwei.bie@intel.com
> > Cc: qemu-stable@nongnu.org
> > Cc: Yuwei Zhang <zhangyuwei.9149@bytedance.com>
> > Signed-off-by: Xueming Li <xuemingl@nvidia.com>
> 
> Pls fix up bisect and repost.
> Also, can you please clarify what does "no need" mean?

mmap becomes invalid, need to unmap it.

> You include a Fixes tag but is there a bug? What behaviour
> are you trying to fix? A resource leak?
> Or are you just simplifying code?
> If the later then no need for a Fixes tag.

Yes, just simplifying code, will remove it.

> 
> 
> 
> 
> > ---
> >  hw/virtio/vhost-user.c         | 20 ++------------------
> >  include/hw/virtio/vhost-user.h |  1 -
> >  2 files changed, 2 insertions(+), 19 deletions(-)
> > 
> > diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
> > index b2e948bdc7..d127aa478a 100644
> > --- a/hw/virtio/vhost-user.c
> > +++ b/hw/virtio/vhost-user.c
> > @@ -22,6 +22,7 @@
> >  #include "qemu/main-loop.h"
> >  #include "qemu/sockets.h"
> >  #include "sysemu/cryptodev.h"
> > +#include "sysemu/cpus.h"
> >  #include "migration/migration.h"
> >  #include "migration/postcopy-ram.h"
> >  #include "trace.h"
> > @@ -1143,19 +1144,6 @@ static int vhost_user_set_vring_num(struct vhost_dev *dev,
> >      return vhost_set_vring(dev, VHOST_USER_SET_VRING_NUM, ring);
> >  }
> >  
> > -static void vhost_user_host_notifier_restore(struct vhost_dev *dev,
> > -                                             int queue_idx)
> > -{
> > -    struct vhost_user *u = dev->opaque;
> > -    VhostUserHostNotifier *n = &u->user->notifier[queue_idx];
> > -    VirtIODevice *vdev = dev->vdev;
> > -
> > -    if (n->addr && !n->set) {
> > -        virtio_queue_set_host_notifier_mr(vdev, queue_idx, &n->mr, true);
> > -        n->set = true;
> > -    }
> > -}
> > -
> >  static void vhost_user_host_notifier_remove(struct vhost_dev *dev,
> >                                              int queue_idx)
> >  {
> > @@ -1163,7 +1151,7 @@ static void vhost_user_host_notifier_remove(struct vhost_dev *dev,
> >      VhostUserHostNotifier *n = &u->user->notifier[queue_idx];
> >      VirtIODevice *vdev = dev->vdev;
> >  
> > -    if (n->addr && n->set) {
> > +    if (n->addr) {
> >          virtio_queue_set_host_notifier_mr(vdev, queue_idx, &n->mr, false);
> >          if (!qemu_in_vcpu_thread()) { /* Avoid vCPU dead lock. */
> >              /* Wait for VM threads accessing old flatview which contains notifier. */
> > @@ -1171,15 +1159,12 @@ static void vhost_user_host_notifier_remove(struct vhost_dev *dev,
> >          }
> >          munmap(n->addr, qemu_real_host_page_size);
> >          n->addr = NULL;
> > -        n->set = false;
> >      }
> >  }
> >  
> >  static int vhost_user_set_vring_base(struct vhost_dev *dev,
> >                                       struct vhost_vring_state *ring)
> >  {
> > -    vhost_user_host_notifier_restore(dev, ring->index);
> > -
> >      return vhost_set_vring(dev, VHOST_USER_SET_VRING_BASE, ring);
> >  }
> >  
> > @@ -1539,7 +1524,6 @@ static int vhost_user_slave_handle_vring_host_notifier(struct vhost_dev *dev,
> >      }
> >  
> >      n->addr = addr;
> > -    n->set = true;
> >  
> >      return 0;
> >  }
> > diff --git a/include/hw/virtio/vhost-user.h b/include/hw/virtio/vhost-user.h
> > index a9abca3288..f6012b2078 100644
> > --- a/include/hw/virtio/vhost-user.h
> > +++ b/include/hw/virtio/vhost-user.h
> > @@ -14,7 +14,6 @@
> >  typedef struct VhostUserHostNotifier {
> >      MemoryRegion mr;
> >      void *addr;
> > -    bool set;
> >  } VhostUserHostNotifier;
> >  
> >  typedef struct VhostUserState {
> > -- 
> > 2.33.0
>