Re: [dpdk-dev] [PATCH] vhost: fix segfault as handle set_mem_table message

[Maxime Coquelin <maxime.coquelin@redhat.com>]

On 11/15/2017 12:41 PM, Jianfeng Tan wrote:
> In a running VM, operations (like device attach/detach) will
> trigger the QEMU to resend set_mem_table to vhost-user backend.
> 
> DPDK vhost-user handles this message rudely by unmap all existing
> regions and map new ones. This might lead to segfault if there
> is pmd thread just trying to touch those unmapped memory regions.
> 
> But for most cases, except VM memory hotplug, QEMU still sends the
> set_mem_table message even the memory regions are not changed as
> QEMU vhost-user filters out those not backed by file (fd > 0).
> 
> To fix this case, we add a check in the handler to see if the
> memory regions are really changed; if not, we just keep old memory
> regions.
> 
> Fixes: 8f972312b8f4 ("vhost: support vhost-user")
> 
> CC: stable@dpdk.org
> 
> CC: Yuanhan Liu <yliu@fridaylinux.org>
> CC: Maxime Coquelin <maxime.coquelin@redhat.com>
> 
> Reported-by: Yang Zhang <zy107165@alibaba-inc.com>
> Reported-by: Xin Long <longxin.xl@alibaba-inc.com>
> Signed-off-by: Yi Yang <yi.y.yang@intel.com>
> Signed-off-by: Jianfeng Tan <jianfeng.tan@intel.com>
> ---
>   lib/librte_vhost/vhost_user.c | 33 +++++++++++++++++++++++++++++++++
>   1 file changed, 33 insertions(+)

Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>

Thanks,
Maxime