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Date: Thu, 28 Mar 2013 00:15:45 +0200
From: "Michael S. Tsirkin" <mst@redhat.com>
Message-ID: <20130327221545.GA12518@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH 3/3] vhost: Only call
 vhost_verify_ring_mappings when adding vhost memory
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To: "Nicholas A. Bellinger" <nab@linux-iscsi.org>
Cc: kvm-devel <kvm@vger.kernel.org>, qemu-devel <qemu-devel@nongnu.org>, lf-virt <virtualization@lists.linux-foundation.org>, Anthony Liguori <aliguori@linux.vnet.ibm.com>, target-devel <target-devel@vger.kernel.org>, Stefan Hajnoczi <stefanha@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>, Asias He <asias@redhat.com>

On Wed, Mar 27, 2013 at 09:59:46PM +0000, Nicholas A. Bellinger wrote:
> From: Nicholas Bellinger <nab@linux-iscsi.org>
> 
> This patch fixes a bug where vhost_verify_ring_mappings() could be
> called after vhost_dev_unassign_memory() has been called during
> vhost_set_memory(..., add=false).
> 

Sorry, I NAK'd this already.
Is a memory including the rings unassigned then?
How can this happen?
We need to debug wht's going on here.

> This appears to be fallout from when dev->started = true assignment
> occurs before vhost_set_memory(..., add=false) is called in:
> 
> commit 24f4fe345c1b80bab1ee18573914123d8028a9e6
> Author: Michael S. Tsirkin <mst@redhat.com>
> Date:   Tue Dec 25 17:41:07 2012 +0200
> 
>     vhost: set started flag while start is in progress
> 
> Cc: Michael S. Tsirkin <mst@redhat.com>
> Cc: Asias He <asias@redhat.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

-net seems to work fine with that patch.

> ---
>  hw/vhost.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/hw/vhost.c b/hw/vhost.c
> index 4d6aee3..687a689 100644
> --- a/hw/vhost.c
> +++ b/hw/vhost.c
> @@ -421,7 +421,7 @@ static void vhost_set_memory(MemoryListener *listener,
>          return;
>      }
>  
> -    if (dev->started) {
> +    if (dev->started && add) {
>          r = vhost_verify_ring_mappings(dev, start_addr, size);
>          assert(r >= 0);
>      }
> -- 
> 1.7.2.5