On 10/28/19 3:13 AM, Liu, Yong wrote:
>
>
>> -----Original Message-----
>> From: Adrian Moreno [mailto:amore...@redhat.com]
>> Sent: Friday, October 25, 2019 8:21 PM
>> To: Liu, Yong <yong....@intel.com>; maxime.coque...@redhat.com; Bie, Tiwei
>> <tiwei....@intel.com>; Wang, Zhihong <zhihong.w...@intel.com>
>> Cc: dev@dpdk.org
>> Subject: Re: [PATCH] vhost: fix vhost user virtqueue not accessable
>>
>> Hi Marvin,
>>
>> On 10/25/19 6:20 PM, Marvin Liu wrote:
>>> Log feature is disabled in vhost user, so that log address was invalid
>>> when checking. Add feature bit check can skip useless address check.
>>>
>> Just so I understand, what conditions is the log address invalid?
>>
>>> Fixes: 04cfc7fdbfca ("vhost: translate incoming log address to gpa")
>>>
>>> Signed-off-by: Marvin Liu <yong....@intel.com>
>>> ---
>>> lib/librte_vhost/vhost_user.c | 16 +++++++++-------
>>> 1 file changed, 9 insertions(+), 7 deletions(-)
>>>
>>> diff --git a/lib/librte_vhost/vhost_user.c
>> b/lib/librte_vhost/vhost_user.c
>>> index 61ef699ac..0407fdc29 100644
>>> --- a/lib/librte_vhost/vhost_user.c
>>> +++ b/lib/librte_vhost/vhost_user.c
>>> @@ -741,13 +741,15 @@ translate_ring_addresses(struct virtio_net *dev,
>> int vq_index)
>>> vq->last_avail_idx = vq->used->idx;
>>> }
>>>
>>> - vq->log_guest_addr =
>>> - translate_log_addr(dev, vq, addr->log_guest_addr);
>>> - if (vq->log_guest_addr == 0) {
>>> - RTE_LOG(DEBUG, VHOST_CONFIG,
>>> - "(%d) failed to map log_guest_addr .\n",
>>> - dev->vid);
>>> - return dev;
>>> + if (dev->features & (1ULL << VHOST_F_LOG_ALL)) {
>>> + vq->log_guest_addr =
>>> + translate_log_addr(dev, vq, addr->log_guest_addr);
>>
>> VHOST_F_LOG_ALL is only negotiated once the migration has started (at least
>> from
>> qemu's perspective).
>> That means that we will postponing the translation of the log address to
>> the
>> vhost_user_set_vring_addr() call that follows the VHOST_F_LOG_ALL enabling.
>> In
>> that call there are (at least) two things that could go wrong and lead to a
>> migration failure:
>> - If VHOST_USER_F_PROTOCOL_FEATURES is not enabled, the address won't be
>> translated:
>>
>> vhost_user:795
>> if ((vq->enabled && (dev->features &
>> (1ULL << VHOST_USER_F_PROTOCOL_FEATURES))) ||
>> access_ok) {
>> dev = translate_ring_addresses(dev, msg->payload.addr.index);
>> if (!dev)
>> return RTE_VHOST_MSG_RESULT_ERR;
>>
>> *pdev = dev;
>> }
>>
>> - If the IOMMU is enabled and there's a miss, we would have to wait for the
>> IOTLB_UPDATE and during that time, there would be failed accesses to the
>> (still
>> untranslated) log address.
>>
>>
>
> Thanks, Adrian.
> Log address can be zero when logging is not enabled.
> How about add other criteria after translation? Log address will be
> translated anyway and not affect vq status.
>
> vq->log_guest_addr =
> translate_log_addr(dev, vq, addr->log_guest_addr);
> - if (vq->log_guest_addr == 0) {
> + if (vq->log_guest_addr == 0 && addr->flags) {
> RTE_LOG(DEBUG, VHOST_CONFIG,
> "(%d) failed to map log_guest_addr .\n",
> dev->vid);
> return dev;
> }
>
That makes perfect sense IMHO. Thank you.
> Meanwhile, log address of packed ring is fixed to zero. Is any special reason
> to do that?
>
No idea to be honest.
Thanks.
Adrian
> Regards,
> Marvin
>
>>
>>> + if (vq->log_guest_addr == 0) {
>>> + RTE_LOG(DEBUG, VHOST_CONFIG,
>>> + "(%d) failed to map log_guest_addr .\n",
>>> + dev->vid);
>>> + return dev;
>>> + }
>>> }
>>> vq->access_ok = 1;
>>>
>>>
>> Thanks,
>> Adrian
