Hi Igor,
> -----Original Message-----
> From: Igor Mammedov [mailto:imamm...@redhat.com]
> Sent: Wednesday, January 10, 2018 9:31 PM
> To: Zhoujian (jay) <jianjay.z...@huawei.com>
> Cc: qemu-devel@nongnu.org; Huangweidong (C) <weidong.hu...@huawei.com>;
> m...@redhat.com; wangxin (U) <wangxinxin.w...@huawei.com>; qemu-
> sta...@nongnu.org; Gonglei (Arei) <arei.gong...@huawei.com>; Liuzhe (Ahriy,
> Euler) <liuzh...@huawei.com>
> Subject: Re: [Qemu-devel] [PATCH v5 1/4] vhost: remove assertion to prevent
> crash
>
> On Wed, 10 Jan 2018 00:39:35 +0800
> Jay Zhou <jianjay.z...@huawei.com> wrote:
>
> > Start QEMU with more DIMM devices than limit but without any vhost
> > backends and then hotplug a vhost user backend, the VM will be
> > crashed.
> > Instead of asserting in vhost_user_set_mem_table(), error number is
> > used to gracefully prevent device to start. This fixes the crash
> > issue.
>
> I'd rewrite commit message as following:
> --
> QEMU will assert on vhsot-user backed virtio device hotplug if QEMU is using
> more RAM regions than VHOST_MEMORY_MAX_NREGIONS (for example if it were
> started with a lot of DIMM devices).
>
> Fix it by returning error instead of asserting and let callers of
> vhost_set_mem_table() handle error condition gracefully.
> --
s/vhsot-user/vhost-user, otherwise much better than mine, will use it
in the next version, thanks!
Jay
> >
> > Cc: qemu-sta...@nongnu.org
> > Signed-off-by: Igor Mammedov <imamm...@redhat.com>
> > Signed-off-by: Jay Zhou <jianjay.z...@huawei.com>
> > ---
> > hw/virtio/vhost-user.c | 5 ++++-
> > 1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c index
> > 093675e..8500562 100644
> > --- a/hw/virtio/vhost-user.c
> > +++ b/hw/virtio/vhost-user.c
> > @@ -317,11 +317,14 @@ static int vhost_user_set_mem_table(struct vhost_dev
> *dev,
> > &offset);
> > fd = memory_region_get_fd(mr);
> > if (fd > 0) {
> > + if (fd_num == VHOST_MEMORY_MAX_NREGIONS) {
> > + error_report("Failed preparing vhost-user memory table
> msg");
> > + return -1;
> > + }
> > msg.payload.memory.regions[fd_num].userspace_addr = reg-
> >userspace_addr;
> > msg.payload.memory.regions[fd_num].memory_size = reg-
> >memory_size;
> > msg.payload.memory.regions[fd_num].guest_phys_addr = reg-
> >guest_phys_addr;
> > msg.payload.memory.regions[fd_num].mmap_offset = offset;
> > - assert(fd_num < VHOST_MEMORY_MAX_NREGIONS);
> > fds[fd_num++] = fd;
> > }
> > }
