[PATCH v3 0/2] Improve vhost-user VQ notifier unmap

[PATCH v3 0/2] Improve vhost-user VQ notifier unmap

[Xueming Li]

When vDPA applicaiton in client mode shutdown, unmapped VQ notifier
might being accessed by vCPU thread under high tx traffic, it will
crash VM in rare conditon. This patch try to fix it with better RCU
sychronization of new flatview.

v2: no RCU draining on vCPU thread
v3: minor fix on coding style and comments

Xueming Li (2):
  vhost-user: fix VirtQ notifier cleanup
  vhost-user: remove VirtQ notifier restore

 hw/virtio/vhost-user.c         | 41 +++++++++++++---------------------
 include/hw/virtio/vhost-user.h |  1 -
 2 files changed, 16 insertions(+), 26 deletions(-)

-- 
2.33.0

[PATCH v3 1/2] vhost-user: fix VirtQ notifier cleanup

[Xueming Li]

When vhost-user device cleanup and unmmap notifier address, VM cpu
thread that writing the notifier failed with accessing invalid address.

To avoid this concurrent issue, wait memory flatview update by draining
rcu callbacks, then unmap notifiers.

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>
---
 hw/virtio/vhost-user.c | 21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
index bf6e50223c..b2e948bdc7 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -1165,6 +1165,12 @@ static void vhost_user_host_notifier_remove(struct vhost_dev *dev,
 
     if (n->addr && n->set) {
         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. */
+            drain_call_rcu();
+        }
+        munmap(n->addr, qemu_real_host_page_size);
+        n->addr = NULL;
         n->set = false;
     }
 }
@@ -1502,12 +1508,7 @@ static int vhost_user_slave_handle_vring_host_notifier(struct vhost_dev *dev,
 
     n = &user->notifier[queue_idx];
 
-    if (n->addr) {
-        virtio_queue_set_host_notifier_mr(vdev, queue_idx, &n->mr, false);
-        object_unparent(OBJECT(&n->mr));
-        munmap(n->addr, page_size);
-        n->addr = NULL;
-    }
+    vhost_user_host_notifier_remove(dev, queue_idx);
 
     if (area->u64 & VHOST_USER_VRING_NOFD_MASK) {
         return 0;
@@ -2485,11 +2486,17 @@ void vhost_user_cleanup(VhostUserState *user)
     for (i = 0; i < VIRTIO_QUEUE_MAX; i++) {
         if (user->notifier[i].addr) {
             object_unparent(OBJECT(&user->notifier[i].mr));
+        }
+    }
+    memory_region_transaction_commit();
+    /* Wait for VM threads accessing old flatview which contains notifier. */
+    drain_call_rcu();
+    for (i = 0; i < VIRTIO_QUEUE_MAX; i++) {
+        if (user->notifier[i].addr) {
             munmap(user->notifier[i].addr, qemu_real_host_page_size);
             user->notifier[i].addr = NULL;
         }
     }
-    memory_region_transaction_commit();
     user->chr = NULL;
 }
 
-- 
2.33.0

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

[Xueming Li]

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>
---
 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

Re: [PATCH v3 1/2] vhost-user: fix VirtQ notifier cleanup

[Michael S. Tsirkin]

On Fri, Oct 08, 2021 at 03:58:04PM +0800, Xueming Li wrote:
> When vhost-user device cleanup and unmmap notifier address, VM cpu
> thread that writing the notifier failed with accessing invalid address.
> 
> To avoid this concurrent issue, wait memory flatview update by draining
> rcu callbacks, then unmap notifiers.
> 
> 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>
> ---
>  hw/virtio/vhost-user.c | 21 ++++++++++++++-------
>  1 file changed, 14 insertions(+), 7 deletions(-)
> 
> diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
> index bf6e50223c..b2e948bdc7 100644
> --- a/hw/virtio/vhost-user.c
> +++ b/hw/virtio/vhost-user.c
> @@ -1165,6 +1165,12 @@ static void vhost_user_host_notifier_remove(struct vhost_dev *dev,
>  
>      if (n->addr && n->set) {
>          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. */
> +            drain_call_rcu();
> +        }
> +        munmap(n->addr, qemu_real_host_page_size);
> +        n->addr = NULL;
>          n->set = false;
>      }
>  }


../hw/virtio/vhost-user.c: In function ‘vhost_user_host_notifier_remove’:
../hw/virtio/vhost-user.c:1168:14: error: implicit declaration of function ‘qemu_in_vcpu_thread’ [-Werror=implicit-function-declaration]
 1168 |         if (!qemu_in_vcpu_thread()) { /* Avoid vCPU dead lock. */
      |              ^~~~~~~~~~~~~~~~~~~
../hw/virtio/vhost-user.c:1168:14: error: nested extern declaration of ‘qemu_in_vcpu_thread’ [-Werror=nested-externs]
cc1: all warnings being treated as errors
ninja: build stopped: subcommand failed.
make[1]: *** [Makefile:162: run-ninja] Error 1
make[1]: Leaving directory '/scm/qemu/build'
make: *** [GNUmakefile:11: all] Error 2


Although the following patch fixes it, bisect is broken.


> @@ -1502,12 +1508,7 @@ static int vhost_user_slave_handle_vring_host_notifier(struct vhost_dev *dev,
>  
>      n = &user->notifier[queue_idx];
>  
> -    if (n->addr) {
> -        virtio_queue_set_host_notifier_mr(vdev, queue_idx, &n->mr, false);
> -        object_unparent(OBJECT(&n->mr));
> -        munmap(n->addr, page_size);
> -        n->addr = NULL;
> -    }
> +    vhost_user_host_notifier_remove(dev, queue_idx);
>  
>      if (area->u64 & VHOST_USER_VRING_NOFD_MASK) {
>          return 0;
> @@ -2485,11 +2486,17 @@ void vhost_user_cleanup(VhostUserState *user)
>      for (i = 0; i < VIRTIO_QUEUE_MAX; i++) {
>          if (user->notifier[i].addr) {
>              object_unparent(OBJECT(&user->notifier[i].mr));
> +        }
> +    }
> +    memory_region_transaction_commit();
> +    /* Wait for VM threads accessing old flatview which contains notifier. */
> +    drain_call_rcu();
> +    for (i = 0; i < VIRTIO_QUEUE_MAX; i++) {
> +        if (user->notifier[i].addr) {
>              munmap(user->notifier[i].addr, qemu_real_host_page_size);
>              user->notifier[i].addr = NULL;
>          }
>      }
> -    memory_region_transaction_commit();
>      user->chr = NULL;
>  }
>  
> -- 
> 2.33.0

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

[Michael S. Tsirkin]

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?
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.




> ---
>  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

Re: [PATCH v3 1/2] vhost-user: fix VirtQ notifier cleanup

[Xueming(Steven) Li]

On Tue, 2021-10-19 at 02:15 -0400, Michael S. Tsirkin wrote:
> On Fri, Oct 08, 2021 at 03:58:04PM +0800, Xueming Li wrote:
> > When vhost-user device cleanup and unmmap notifier address, VM cpu
> > thread that writing the notifier failed with accessing invalid address.
> > 
> > To avoid this concurrent issue, wait memory flatview update by draining
> > rcu callbacks, then unmap notifiers.
> > 
> > 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>
> > ---
> >  hw/virtio/vhost-user.c | 21 ++++++++++++++-------
> >  1 file changed, 14 insertions(+), 7 deletions(-)
> > 
> > diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
> > index bf6e50223c..b2e948bdc7 100644
> > --- a/hw/virtio/vhost-user.c
> > +++ b/hw/virtio/vhost-user.c
> > @@ -1165,6 +1165,12 @@ static void vhost_user_host_notifier_remove(struct vhost_dev *dev,
> >  
> >      if (n->addr && n->set) {
> >          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. */
> > +            drain_call_rcu();
> > +        }
> > +        munmap(n->addr, qemu_real_host_page_size);
> > +        n->addr = NULL;
> >          n->set = false;
> >      }
> >  }
> 
> 
> ../hw/virtio/vhost-user.c: In function ‘vhost_user_host_notifier_remove’:
> ../hw/virtio/vhost-user.c:1168:14: error: implicit declaration of function ‘qemu_in_vcpu_thread’ [-Werror=implicit-function-declaration]
>  1168 |         if (!qemu_in_vcpu_thread()) { /* Avoid vCPU dead lock. */
>       |              ^~~~~~~~~~~~~~~~~~~
> ../hw/virtio/vhost-user.c:1168:14: error: nested extern declaration of ‘qemu_in_vcpu_thread’ [-Werror=nested-externs]
> cc1: all warnings being treated as errors
> ninja: build stopped: subcommand failed.
> make[1]: *** [Makefile:162: run-ninja] Error 1
> make[1]: Leaving directory '/scm/qemu/build'
> make: *** [GNUmakefile:11: all] Error 2
> 
> 
> Although the following patch fixes it, bisect is broken.

Yes, really an issue, v4 posted, thanks!

> 
> 
> > @@ -1502,12 +1508,7 @@ static int vhost_user_slave_handle_vring_host_notifier(struct vhost_dev *dev,
> >  
> >      n = &user->notifier[queue_idx];
> >  
> > -    if (n->addr) {
> > -        virtio_queue_set_host_notifier_mr(vdev, queue_idx, &n->mr, false);
> > -        object_unparent(OBJECT(&n->mr));
> > -        munmap(n->addr, page_size);
> > -        n->addr = NULL;
> > -    }
> > +    vhost_user_host_notifier_remove(dev, queue_idx);
> >  
> >      if (area->u64 & VHOST_USER_VRING_NOFD_MASK) {
> >          return 0;
> > @@ -2485,11 +2486,17 @@ void vhost_user_cleanup(VhostUserState *user)
> >      for (i = 0; i < VIRTIO_QUEUE_MAX; i++) {
> >          if (user->notifier[i].addr) {
> >              object_unparent(OBJECT(&user->notifier[i].mr));
> > +        }
> > +    }
> > +    memory_region_transaction_commit();
> > +    /* Wait for VM threads accessing old flatview which contains notifier. */
> > +    drain_call_rcu();
> > +    for (i = 0; i < VIRTIO_QUEUE_MAX; i++) {
> > +        if (user->notifier[i].addr) {
> >              munmap(user->notifier[i].addr, qemu_real_host_page_size);
> >              user->notifier[i].addr = NULL;
> >          }
> >      }
> > -    memory_region_transaction_commit();
> >      user->chr = NULL;
> >  }
> >  
> > -- 
> > 2.33.0
> 

Re: [PATCH v3 1/2] vhost-user: fix VirtQ notifier cleanup

[Michael S. Tsirkin]

On Tue, Oct 19, 2021 at 06:45:19AM +0000, Xueming(Steven) Li wrote:
> On Tue, 2021-10-19 at 02:15 -0400, Michael S. Tsirkin wrote:
> > On Fri, Oct 08, 2021 at 03:58:04PM +0800, Xueming Li wrote:
> > > When vhost-user device cleanup and unmmap notifier address, VM cpu
> > > thread that writing the notifier failed with accessing invalid address.
> > > 
> > > To avoid this concurrent issue, wait memory flatview update by draining
> > > rcu callbacks, then unmap notifiers.
> > > 
> > > 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>
> > > ---
> > >  hw/virtio/vhost-user.c | 21 ++++++++++++++-------
> > >  1 file changed, 14 insertions(+), 7 deletions(-)
> > > 
> > > diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
> > > index bf6e50223c..b2e948bdc7 100644
> > > --- a/hw/virtio/vhost-user.c
> > > +++ b/hw/virtio/vhost-user.c
> > > @@ -1165,6 +1165,12 @@ static void vhost_user_host_notifier_remove(struct vhost_dev *dev,
> > >  
> > >      if (n->addr && n->set) {
> > >          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. */
> > > +            drain_call_rcu();
> > > +        }
> > > +        munmap(n->addr, qemu_real_host_page_size);
> > > +        n->addr = NULL;
> > >          n->set = false;
> > >      }
> > >  }
> > 
> > 
> > ../hw/virtio/vhost-user.c: In function ‘vhost_user_host_notifier_remove’:
> > ../hw/virtio/vhost-user.c:1168:14: error: implicit declaration of function ‘qemu_in_vcpu_thread’ [-Werror=implicit-function-declaration]
> >  1168 |         if (!qemu_in_vcpu_thread()) { /* Avoid vCPU dead lock. */
> >       |              ^~~~~~~~~~~~~~~~~~~
> > ../hw/virtio/vhost-user.c:1168:14: error: nested extern declaration of ‘qemu_in_vcpu_thread’ [-Werror=nested-externs]
> > cc1: all warnings being treated as errors
> > ninja: build stopped: subcommand failed.
> > make[1]: *** [Makefile:162: run-ninja] Error 1
> > make[1]: Leaving directory '/scm/qemu/build'
> > make: *** [GNUmakefile:11: all] Error 2
> > 
> > 
> > Although the following patch fixes it, bisect is broken.
> 
> Yes, really an issue, v4 posted, thanks!

Pls address the comment on 2/2 too.

> > 
> > 
> > > @@ -1502,12 +1508,7 @@ static int vhost_user_slave_handle_vring_host_notifier(struct vhost_dev *dev,
> > >  
> > >      n = &user->notifier[queue_idx];
> > >  
> > > -    if (n->addr) {
> > > -        virtio_queue_set_host_notifier_mr(vdev, queue_idx, &n->mr, false);
> > > -        object_unparent(OBJECT(&n->mr));
> > > -        munmap(n->addr, page_size);
> > > -        n->addr = NULL;
> > > -    }
> > > +    vhost_user_host_notifier_remove(dev, queue_idx);
> > >  
> > >      if (area->u64 & VHOST_USER_VRING_NOFD_MASK) {
> > >          return 0;
> > > @@ -2485,11 +2486,17 @@ void vhost_user_cleanup(VhostUserState *user)
> > >      for (i = 0; i < VIRTIO_QUEUE_MAX; i++) {
> > >          if (user->notifier[i].addr) {
> > >              object_unparent(OBJECT(&user->notifier[i].mr));
> > > +        }
> > > +    }
> > > +    memory_region_transaction_commit();
> > > +    /* Wait for VM threads accessing old flatview which contains notifier. */
> > > +    drain_call_rcu();
> > > +    for (i = 0; i < VIRTIO_QUEUE_MAX; i++) {
> > > +        if (user->notifier[i].addr) {
> > >              munmap(user->notifier[i].addr, qemu_real_host_page_size);
> > >              user->notifier[i].addr = NULL;
> > >          }
> > >      }
> > > -    memory_region_transaction_commit();
> > >      user->chr = NULL;
> > >  }
> > >  
> > > -- 
> > > 2.33.0
> > 
> 

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

[Xueming(Steven) Li]

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
> 

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

[Michael S. Tsirkin]

On Tue, Oct 19, 2021 at 07:21:24AM +0000, Xueming(Steven) Li wrote:
> 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.


confused even more. pls include explanation in commit log.

> > 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
> > 
> 

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

[Xueming(Steven) Li]

On Tue, 2021-10-19 at 03:24 -0400, Michael S. Tsirkin wrote:
> On Tue, Oct 19, 2021 at 07:21:24AM +0000, Xueming(Steven) Li wrote:
> > 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.
> 
> 
> confused even more. pls include explanation in commit log.

My bad, updated in v5, please check.

> 
> > > 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.

Sorry, it's a fix after another check. Will add it back.

> > 
> > > 
> > > 
> > > 
> > > 
> > > > ---
> > > >  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
> > > 
> > 
>