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From: michael.christie@oracle.com
To: Stefan Hajnoczi <stefanha@redhat.com>
Cc: target-devel@vger.kernel.org, linux-scsi@vger.kernel.org,
	pbonzini@redhat.com, jasowang@redhat.com, mst@redhat.com,
	sgarzare@redhat.com, virtualization@lists.linux-foundation.org
Subject: Re: vhost: multiple worker support
Date: Sat, 5 Jun 2021 17:40:17 -0500	[thread overview]
Message-ID: <faa6085b-dfd8-9ddf-8b52-20053ac182ef@oracle.com> (raw)
In-Reply-To: <523e6207-c380-9a9d-7a5d-7b7ee554d7f2@oracle.com>

On 6/3/21 5:16 PM, Mike Christie wrote:
> On 6/3/21 9:37 AM, Stefan Hajnoczi wrote:
>> On Tue, May 25, 2021 at 01:05:51PM -0500, Mike Christie wrote:
>>> The following patches apply over linus's tree or mst's vhost branch
>>> and my cleanup patchset:
>>>
>>> https://urldefense.com/v3/__https://lists.linuxfoundation.org/pipermail/virtualization/2021-May/054354.html__;!!GqivPVa7Brio!P55eslnMW_iZkoTUZckwhnSw_9Z35JBScgtSYRh4CMFTRkSsWwKOYqY0huUfBfIPM8BV$ 
>>>
>>> These patches allow us to support multiple vhost workers per device. I
>>> ended up just doing Stefan's original idea where userspace has the
>>> kernel create a worker and we pass back the pid. This has the benefit
>>> over the workqueue and userspace thread approach where we only have
>>> one'ish code path in the kernel during setup to detect old tools. The
>>> main IO paths and device/vq setup/teardown paths all use common code.
>>>
>>> The kernel patches here allow us to then do N workers device and also
>>> share workers across devices.
>>>
>>> I've also included a patch for qemu so you can get an idea of how it
>>> works. If we are ok with the kernel code then I'll break that up into
>>> a patchset and send to qemu-devel.
>>
>> It seems risky to allow userspace process A to "share" a vhost worker
>> thread with userspace process B based on a matching pid alone. Should
>> they have ptrace_may_access() or similar?
>>
> 
> I'm not sure. I already made it a little restrictive in this posting, but

Made a mistake here. In this posting I did not make it restrictive and
I was allowing any old 2 processes to share. So we would need something
like ptrace_may_access if go this route.

If we restrict sharing workers with the same owner, then I'm not sure if
need anything.

WARNING: multiple messages have this Message-ID (diff)
From: michael.christie@oracle.com
To: Stefan Hajnoczi <stefanha@redhat.com>
Cc: linux-scsi@vger.kernel.org, mst@redhat.com,
	virtualization@lists.linux-foundation.org,
	target-devel@vger.kernel.org, pbonzini@redhat.com
Subject: Re: vhost: multiple worker support
Date: Sat, 5 Jun 2021 17:40:17 -0500	[thread overview]
Message-ID: <faa6085b-dfd8-9ddf-8b52-20053ac182ef@oracle.com> (raw)
In-Reply-To: <523e6207-c380-9a9d-7a5d-7b7ee554d7f2@oracle.com>

On 6/3/21 5:16 PM, Mike Christie wrote:
> On 6/3/21 9:37 AM, Stefan Hajnoczi wrote:
>> On Tue, May 25, 2021 at 01:05:51PM -0500, Mike Christie wrote:
>>> The following patches apply over linus's tree or mst's vhost branch
>>> and my cleanup patchset:
>>>
>>> https://urldefense.com/v3/__https://lists.linuxfoundation.org/pipermail/virtualization/2021-May/054354.html__;!!GqivPVa7Brio!P55eslnMW_iZkoTUZckwhnSw_9Z35JBScgtSYRh4CMFTRkSsWwKOYqY0huUfBfIPM8BV$ 
>>>
>>> These patches allow us to support multiple vhost workers per device. I
>>> ended up just doing Stefan's original idea where userspace has the
>>> kernel create a worker and we pass back the pid. This has the benefit
>>> over the workqueue and userspace thread approach where we only have
>>> one'ish code path in the kernel during setup to detect old tools. The
>>> main IO paths and device/vq setup/teardown paths all use common code.
>>>
>>> The kernel patches here allow us to then do N workers device and also
>>> share workers across devices.
>>>
>>> I've also included a patch for qemu so you can get an idea of how it
>>> works. If we are ok with the kernel code then I'll break that up into
>>> a patchset and send to qemu-devel.
>>
>> It seems risky to allow userspace process A to "share" a vhost worker
>> thread with userspace process B based on a matching pid alone. Should
>> they have ptrace_may_access() or similar?
>>
> 
> I'm not sure. I already made it a little restrictive in this posting, but

Made a mistake here. In this posting I did not make it restrictive and
I was allowing any old 2 processes to share. So we would need something
like ptrace_may_access if go this route.

If we restrict sharing workers with the same owner, then I'm not sure if
need anything.
_______________________________________________
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization

  reply	other threads:[~2021-06-05 22:40 UTC|newest]

Thread overview: 64+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-25 18:05 vhost: multiple worker support Mike Christie
2021-05-25 18:05 ` Mike Christie
2021-05-25 18:05 ` [PATCH 1/9] vhost: move worker thread fields to new struct Mike Christie
2021-05-25 18:05   ` Mike Christie
2021-06-03 10:16   ` Stefan Hajnoczi
2021-06-03 10:16     ` Stefan Hajnoczi
2021-05-25 18:05 ` [PATCH 2/9] vhost: move vhost worker creation to kick setup Mike Christie
2021-05-25 18:05   ` Mike Christie
2021-06-03 10:28   ` Stefan Hajnoczi
2021-06-03 10:28     ` Stefan Hajnoczi
2021-05-25 18:05 ` [PATCH 3/9] vhost: modify internal functions to take a vhost_worker Mike Christie
2021-05-25 18:05   ` Mike Christie
2021-06-03 10:45   ` Stefan Hajnoczi
2021-06-03 10:45     ` Stefan Hajnoczi
2021-05-25 18:05 ` [PATCH 4/9] vhost: allow vhost_polls to use different vhost_workers Mike Christie
2021-05-25 18:05   ` Mike Christie
2021-06-03 13:51   ` Stefan Hajnoczi
2021-06-03 13:51     ` Stefan Hajnoczi
2021-05-25 18:05 ` [PATCH 5/9] vhost-scsi: flush IO vqs then send TMF rsp Mike Christie
2021-05-25 18:05   ` Mike Christie
2021-06-03 13:54   ` Stefan Hajnoczi
2021-06-03 13:54     ` Stefan Hajnoczi
2021-05-25 18:05 ` [PATCH 6/9] vhost-scsi: make SCSI cmd completion per vq Mike Christie
2021-05-25 18:05   ` Mike Christie
2021-06-03 13:57   ` Stefan Hajnoczi
2021-06-03 13:57     ` Stefan Hajnoczi
2021-05-25 18:05 ` [PATCH 7/9] vhost: allow userspace to create workers Mike Christie
2021-05-25 18:05   ` Mike Christie
2021-06-03 14:30   ` Stefan Hajnoczi
2021-06-03 14:30     ` Stefan Hajnoczi
2021-06-05 23:53     ` michael.christie
2021-06-05 23:53       ` michael.christie
2021-06-07 15:19       ` Stefan Hajnoczi
2021-06-07 15:19         ` Stefan Hajnoczi
2021-06-09 21:03         ` Mike Christie
2021-06-09 21:03           ` Mike Christie
2021-06-10  8:06           ` Stefan Hajnoczi
2021-06-10  8:06             ` Stefan Hajnoczi
2021-06-18  2:49             ` Mike Christie
2021-06-18  2:49               ` Mike Christie
2021-06-21 13:41               ` Stefan Hajnoczi
2021-06-21 13:41                 ` Stefan Hajnoczi
2021-05-25 18:05 ` [PATCH 8/9] vhost: add vhost_dev pointer to vhost_work Mike Christie
2021-05-25 18:05   ` Mike Christie
2021-06-03 14:31   ` Stefan Hajnoczi
2021-06-03 14:31     ` Stefan Hajnoczi
2021-05-25 18:06 ` [PATCH 9/9] vhost: support sharing workers across devs Mike Christie
2021-05-25 18:06   ` Mike Christie
2021-06-03 14:32   ` Stefan Hajnoczi
2021-06-03 14:32     ` Stefan Hajnoczi
2021-06-07  2:18     ` Jason Wang
2021-06-07  2:18       ` Jason Wang
2021-06-03 10:13 ` vhost: multiple worker support Stefan Hajnoczi
2021-06-03 10:13   ` Stefan Hajnoczi
2021-06-03 18:45   ` Mike Christie
2021-06-03 18:45     ` Mike Christie
2021-06-03 14:37 ` Stefan Hajnoczi
2021-06-03 14:37   ` Stefan Hajnoczi
2021-06-03 22:16   ` Mike Christie
2021-06-03 22:16     ` Mike Christie
2021-06-05 22:40     ` michael.christie [this message]
2021-06-05 22:40       ` michael.christie
2021-06-07 15:23       ` Stefan Hajnoczi
2021-06-07 15:23         ` Stefan Hajnoczi

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