From: Maxime Coquelin <maxime.coquelin@redhat.com>
To: Yuanhan Liu <yliu@fridaylinux.org>,
Jianfeng Tan <jianfeng.tan@intel.com>,
Victor Kaplansky <vkaplans@redhat.com>
Cc: dev@dpdk.org, stable@dpdk.org, Yi Yang <yi.y.yang@intel.com>
Subject: Re: [dpdk-stable] [PATCH] vhost: fix segfault as handle set_mem_table message
Date: Tue, 5 Dec 2017 15:28:07 +0100 [thread overview]
Message-ID: <cd734b70-1532-b591-63d4-63e2d6b1ec97@redhat.com> (raw)
In-Reply-To: <20171205141954.GF9111@yliu-dev>
On 12/05/2017 03:19 PM, Yuanhan Liu wrote:
> On Tue, Nov 28, 2017 at 01:09:29PM +0100, Maxime Coquelin wrote:
>>
>>
>> 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,
FYI, Victor is working on implementing a lock-less protection mechanism
to prevent crashes in such cases. It is intended first to protect
log_base in case of multiqueue + live-migration, but would solve thi
issue too.
>>>> 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>
>
> Applied to dpdk-next-virtio.
>
> Thanks.
>
> --yliu
>
Maxime
next prev parent reply other threads:[~2017-12-05 14:28 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-15 11:41 Jianfeng Tan
2017-11-28 12:09 ` Maxime Coquelin
2017-12-05 14:19 ` Yuanhan Liu
2017-12-05 14:28 ` Maxime Coquelin [this message]
2018-03-29 7:01 ` Tan, Jianfeng
2018-03-29 7:35 ` Maxime Coquelin
2018-03-29 12:57 ` Wodkowski, PawelX
2018-03-29 13:20 ` Tan, Jianfeng
2018-03-29 16:37 ` Maxime Coquelin
2018-03-29 18:09 ` Wodkowski, PawelX
2018-03-29 12:59 ` Tan, Jianfeng
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