From: Maxime Coquelin <maxime.coquelin@redhat.com>
To: Hao Chen <chenh@yusur.tech>, dev@dpdk.org
Cc: david.marchand@redhat.com, zy@yusur.tech, huangml@yusur.tech,
stable@dpdk.org, Chenbo Xia <chenbox@nvidia.com>,
Xiao Wang <xiao.w.wang@intel.com>
Subject: Re: [PATCH v2] vhost: fix deadlock during software live migration of VDPA in a nested virtualization environment
Date: Tue, 6 Feb 2024 15:57:26 +0100 [thread overview]
Message-ID: <2724a1ed-0f25-4e0d-a9a4-e1baf3906bee@redhat.com> (raw)
In-Reply-To: <20240122032746.2749586-1-chenh@yusur.tech>
On 1/22/24 04:27, Hao Chen wrote:
> In a nested virtualization environment, running dpdk-vdpa in QEMU-L1 for
> software live migration will result in a deadlock between dpdke-vdpa and
> QEMU-L2 processes.
> 'rte_vdpa_relay_vring_used'->
> '__vhost_iova_to_vva'->
> 'vhost_user_iotlb_rd_unlock(vq)'->
> 'vhost_user_iotlb_miss'-> send vhost message 'VHOST_USER_SLAVE_IOTLB_MSG'
> to QEMU-L2's vdpa socket,
> then call 'vhost_user_iotlb_rd_lock(vq)' to hold the read lock `iotlb_lock`.
> But there is no place to release this read lock.
>
> QEMU-L2 get the 'VHOST_USER_SLAVE_IOTLB_MSG',
> then call 'vhost_user_send_device_iotlb_msg' to send 'VHOST_USER_IOTLB_MSG'
> messages to dpdk-vdpa.
> Dpdk-vdpa will call vhost_user_iotlb_msg->
> vhost_user_iotlb_cache_insert, here, will obtain the write lock
> `iotlb_lock`, but the read lock `iotlb_lock` has not been released and
> will block here.
>
> This patch add lock and unlock function to fix the deadlock.
>
> Fixes: b13ad2decc83 ("vhost: provide helpers for virtio ring relay")
> Cc: stable@dpdk.org
>
> Signed-off-by: Hao Chen <chenh@yusur.tech>
> ---
> Changes v1 ... v2:
> - protect the vhost_alloc_copy_ind_table() call too.
>
Applied to next-virtio tree with reworked commit message.
Thanks,
Maxime
prev parent reply other threads:[~2024-02-06 14:57 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20240118103344.50739-1-chenh@yusur.tech>
2024-01-22 3:27 ` Hao Chen
2024-02-05 10:00 ` Maxime Coquelin
2024-02-06 14:57 ` Maxime Coquelin [this message]
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