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From: Maxime Coquelin <maxime.coquelin@redhat.com>
To: Matan Azrad <matan@mellanox.com>,
	"xiaolong.ye@intel.com" <xiaolong.ye@intel.com>,
	Shahaf Shuler <shahafs@mellanox.com>,
	"amorenoz@redhat.com" <amorenoz@redhat.com>,
	"xiao.w.wang@intel.com" <xiao.w.wang@intel.com>,
	Slava Ovsiienko <viacheslavo@mellanox.com>,
	"dev@dpdk.org" <dev@dpdk.org>
Cc: "jasowang@redhat.com" <jasowang@redhat.com>,
	"lulu@redhat.com" <lulu@redhat.com>
Subject: Re: [dpdk-dev] [PATCH 9/9] vhost: only use vDPA config workaround if needed
Date: Mon, 8 Jun 2020 10:34:53 +0200	[thread overview]
Message-ID: <0216165f-aedd-06c7-5a90-2cd0d238b143@redhat.com> (raw)
In-Reply-To: <AM0PR0502MB4019EE6ECDB66AD2D0D22925D2840@AM0PR0502MB4019.eurprd05.prod.outlook.com>

Hi Matan,

On 6/7/20 12:38 PM, Matan Azrad wrote:
> Hi Maxime
> 
> Thanks for the huge work.
> Please see a suggestion inline.
> 
> From: Maxime Coquelin:
>> Sent: Thursday, May 14, 2020 11:02 AM
>> To: xiaolong.ye@intel.com; Shahaf Shuler <shahafs@mellanox.com>; Matan
>> Azrad <matan@mellanox.com>; amorenoz@redhat.com;
>> xiao.w.wang@intel.com; Slava Ovsiienko <viacheslavo@mellanox.com>;
>> dev@dpdk.org
>> Cc: jasowang@redhat.com; lulu@redhat.com; Maxime Coquelin
>> <maxime.coquelin@redhat.com>
>> Subject: [PATCH 9/9] vhost: only use vDPA config workaround if needed
>>
>> Now that we have Virtio device status support, let's only use the vDPA
>> workaround if it is not supported.
>>
>> This patch also document why Virtio device status protocol feature support is
>> strongly advised.
>>
>> Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
>> ---
>>  lib/librte_vhost/vhost_user.c | 16 ++++++++++++++--
>>  1 file changed, 14 insertions(+), 2 deletions(-)
>>
>> diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
>> index e5a44be58d..67e96a872a 100644
>> --- a/lib/librte_vhost/vhost_user.c
>> +++ b/lib/librte_vhost/vhost_user.c
>> @@ -2847,8 +2847,20 @@ vhost_user_msg_handler(int vid, int fd)
>>  	if (!vdpa_dev)
>>  		goto out;
>>
>> -	if (!(dev->flags & VIRTIO_DEV_VDPA_CONFIGURED) &&
>> -			request == VHOST_USER_SET_VRING_CALL) {
>> +	if (!(dev->flags & VIRTIO_DEV_VDPA_CONFIGURED)) {
>> +		/*
>> +		 * Workaround when Virtio device status protocol
>> +		 * feature is not supported, wait for SET_VRING_CALL
>> +		 * request. This is not ideal as some frontends like
>> +		 * Virtio-user may not send this request, so vDPA device
>> +		 * may never be configured. Virtio device status support
>> +		 * on frontend side is strongly advised.
>> +		 */
>> +		if (!(dev->protocol_features &
>> +				(1ULL <<
>> VHOST_USER_PROTOCOL_F_STATUS)) &&
>> +				(request !=
>> VHOST_USER_SET_VRING_CALL))
>> +			goto out;
>> +
> 
> 
> When status protocol feature is not supported, in the current code, the vDPA configuration triggering depends in:
> 1. Device is ready - all the queues are configured (datapath addresses, callfd and kickfd) .
> 2. last command is callfd.
> 
> 
> The code doesn't take into account that some queues may stay disabled.
> Maybe the correct timing is:
> 1. Device is ready - all the enabled queues are configured and MEM table is configured.

I think current virtio_is_ready() already assumes the mem table is
configured, otherwise we would not have vq->desc, vq->used and vq->avail
being set as it needs to be translated using the mem table.

> 2. no need callfd to be last.
> 
> Queues that will be configured later will be configured to the HW when the virtq becoming enabled.
> 
> 
> What do think? 

Maybe I did not understood what you mean, so please correct me if
needed.

If I understood correctly, then your suggestion is just to remove the
workaround, but it has been introduced by Intel because the callfd gets
set a second time in some cases.


Thanks,
Maxime
> 
>>  		if (vdpa_dev->ops->dev_conf(dev->vid))
>>  			VHOST_LOG_CONFIG(ERR,
>>  					"Failed to configure vDPA device\n");
>> --
>> 2.25.4
> 


  reply	other threads:[~2020-06-08  8:35 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-14  8:02 [dpdk-dev] [PATCH (v20.08) 0/9] vhost: improve Vhost/vDPA device init Maxime Coquelin
2020-05-14  8:02 ` [dpdk-dev] [PATCH 1/9] vhost: fix virtio ready flag check Maxime Coquelin
2020-05-14  8:02 ` [dpdk-dev] [PATCH 2/9] vhost: refactor Virtio ready check Maxime Coquelin
2020-05-14  8:02 ` [dpdk-dev] [PATCH 3/9] vdpa/ifc: add support to vDPA queue enable Maxime Coquelin
2020-05-15  8:45   ` Ye Xiaolong
2020-05-15  9:09   ` Jason Wang
2020-05-15  9:42     ` Wang, Xiao W
2020-05-15 10:06       ` Jason Wang
2020-05-15 10:08       ` Jason Wang
2020-05-18  3:09         ` Wang, Xiao W
2020-05-18  3:17           ` Jason Wang
2020-05-14  8:02 ` [dpdk-dev] [PATCH 4/9] vhost: make some vDPA callbacks mandatory Maxime Coquelin
2020-05-14  8:02 ` [dpdk-dev] [PATCH 5/9] vhost: check vDPA configuration succeed Maxime Coquelin
2020-05-14  8:02 ` [dpdk-dev] [PATCH 6/9] vhost: add support for virtio status Maxime Coquelin
2020-06-11  2:45   ` Xia, Chenbo
2020-06-16  4:29   ` Xia, Chenbo
2020-06-22 10:18     ` Adrian Moreno
2020-06-22 11:00       ` Xia, Chenbo
2020-05-14  8:02 ` [dpdk-dev] [PATCH 7/9] vdpa/ifc: enable status protocol feature Maxime Coquelin
2020-05-14  8:02 ` [dpdk-dev] [PATCH 8/9] vdpa/mlx5: " Maxime Coquelin
2020-05-14  8:02 ` [dpdk-dev] [PATCH 9/9] vhost: only use vDPA config workaround if needed Maxime Coquelin
2020-06-07 10:38   ` Matan Azrad
2020-06-08  8:34     ` Maxime Coquelin [this message]
2020-06-08  9:19       ` Matan Azrad
2020-06-09  9:04         ` Maxime Coquelin
2020-06-09 11:09           ` Matan Azrad
2020-06-09 11:26             ` Maxime Coquelin
2020-06-09 17:23             ` Maxime Coquelin
2020-06-14  6:08               ` Matan Azrad
2020-06-17  9:39                 ` Maxime Coquelin
2020-06-17 11:04                   ` Matan Azrad
2020-06-17 12:29                     ` Maxime Coquelin
2020-06-18  6:39                       ` Matan Azrad
2020-06-18  7:30                         ` Maxime Coquelin
2020-06-23 10:42                           ` Wang, Xiao W

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