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From: Mike Christie <michael.christie@oracle.com>
To: Jason Wang <jasowang@redhat.com>,
	martin.petersen@oracle.com, linux-scsi@vger.kernel.org,
	target-devel@vger.kernel.org, mst@redhat.com,
	pbonzini@redhat.com, stefanha@redhat.com,
	virtualization@lists.linux-foundation.org
Subject: Re: [PATCH 2/8] vhost: add helper to check if a vq has been setup
Date: Wed, 23 Sep 2020 14:12:51 -0500
Message-ID: <63094bae-1f26-c21e-9b3c-3a6aa99a7e24@oracle.com> (raw)
In-Reply-To: <e2d16333-d5ed-4c5c-58b3-7b5d0a9da47a@redhat.com>

On 9/21/20 9:02 PM, Jason Wang wrote:
> 
> On 2020/9/22 上午2:23, Mike Christie wrote:
>> This adds a helper check if a vq has been setup. The next patches
>> will use this when we move the vhost scsi cmd preallocation from per
>> session to per vq. In the per vq case, we only want to allocate cmds
>> for vqs that have actually been setup and not for all the possible
>> vqs.
>>
>> Signed-off-by: Mike Christie <michael.christie@oracle.com>
>> ---
>>   drivers/vhost/vhost.c | 9 +++++++++
>>   drivers/vhost/vhost.h | 1 +
>>   2 files changed, 10 insertions(+)
>>
>> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
>> index b45519c..5dd9eb1 100644
>> --- a/drivers/vhost/vhost.c
>> +++ b/drivers/vhost/vhost.c
>> @@ -305,6 +305,15 @@ static void vhost_vring_call_reset(struct vhost_vring_call *call_ctx)
>>       spin_lock_init(&call_ctx->ctx_lock);
>>   }
>>   +bool vhost_vq_is_setup(struct vhost_virtqueue *vq)
>> +{
>> +    if (vq->avail && vq->desc && vq->used && vhost_vq_access_ok(vq))
>> +        return true;
>> +    else
>> +        return false;
>> +}
>> +EXPORT_SYMBOL_GPL(vhost_vq_is_setup);
> 
> 
> This is probably ok but I wonder maybe we should have something like what vDPA did (VHOST_SET_VRING_ENABLE) to match virtio 1.0 device definition.

It looks like I can make that work. Some questions:

1. Do you mean a generic VHOST_SET_VRING_ENABLE or a SCSI specific one VHOST_SCSI_SET_VRING_ENABLE?

2. I can see the VHOST_VDPA_SET_VRING_ENABLE kernel code and the vhost_set_vring_enable qemu code, so I have an idea of how it should work for vhost scsi. However, I'm not sure the requirements for a generic VHOST_SET_VRING_ENABLE if that is what you meant. I could not find it in the spec either. Could you send me a pointer to the section?

For example, for vhost-net we seem to enable a device in the VHOST_NET_SET_BACKEND ioctl, so I'm not sure what behavior should be or needs to be implemented for net and vsock.



  reply index

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-21 18:23 [PATCH 0/8] vhost scsi: fixes and cleanups Mike Christie
2020-09-21 18:23 ` [PATCH 1/8] vhost vdpa: fix vhost_vdpa_open error handling Mike Christie
2020-09-22  1:58   ` Jason Wang
2020-09-21 18:23 ` [PATCH 2/8] vhost: add helper to check if a vq has been setup Mike Christie
2020-09-22  2:02   ` Jason Wang
2020-09-23 19:12     ` Mike Christie [this message]
2020-09-24  7:22       ` Jason Wang
2020-09-22  2:45   ` Bart Van Assche
2020-09-22 15:34     ` Michael Christie
2020-09-21 18:23 ` [PATCH 3/8] vhost scsi: alloc cmds per vq instead of session Mike Christie
2020-09-22  1:32   ` kernel test robot
2020-09-23  7:53   ` Dan Carpenter
2020-09-24  6:22   ` Michael S. Tsirkin
2020-09-24 15:31     ` Michael Christie
2020-09-21 18:23 ` [PATCH 4/8] vhost scsi: fix cmd completion race Mike Christie
2020-09-22  2:48   ` Bart Van Assche
2020-09-22  2:51     ` Bart Van Assche
2020-09-21 18:23 ` [PATCH 5/8] vhost scsi: add lun parser helper Mike Christie
2020-09-23 10:23   ` Paolo Bonzini
2020-09-21 18:23 ` [PATCH 6/8] vhost scsi: Add support for LUN resets Mike Christie
2020-09-21 18:23 ` [PATCH 7/8] vhost: remove work arg from vhost_work_flush Mike Christie
2020-09-22  2:01   ` Jason Wang
2020-09-21 18:23 ` [PATCH 8/8] vhost scsi: remove extra flushes Mike Christie

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