Re: [hypervisor deadlock] Re: [PATCH v9 for Xen 4.7 1/4] xen: enable per-VCPU parameter for RTDS

From: Chong Li <lichong659@gmail.com>
To: Wei Liu <wei.liu2@citrix.com>
Cc: Chong Li <chong.li@wustl.edu>, Sisu Xi <xisisu@gmail.com>,
	George Dunlap <george.dunlap@eu.citrix.com>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	Dario Faggioli <dario.faggioli@citrix.com>,
	George Dunlap <george.dunlap@citrix.com>,
	xen-devel <xen-devel@lists.xen.org>,
	Meng Xu <mengxu@cis.upenn.edu>, Jan Beulich <jbeulich@suse.com>,
	Dagaen Golomb <dgolomb@seas.upenn.edu>
Subject: Re: [hypervisor deadlock] Re: [PATCH v9 for Xen 4.7 1/4] xen: enable per-VCPU parameter for RTDS
Date: Mon, 4 Apr 2016 12:22:04 -0500	[thread overview]
Message-ID: <CAGHO-iopzYnc7i_kBu9gon99Y7u6k9Fj+QBRJHhGwyWV5gpKEg@mail.gmail.com> (raw)
In-Reply-To: <20160404164710.GQ25710@citrix.com>

On Mon, Apr 4, 2016 at 11:47 AM, Wei Liu <wei.liu2@citrix.com> wrote:
> On Mon, Apr 04, 2016 at 06:32:48PM +0200, Dario Faggioli wrote:
>> On Mon, 2016-04-04 at 17:05 +0100, George Dunlap wrote:
>> > On 04/04/16 16:58, Chong Li wrote:
>> > > On Mon, Apr 4, 2016 at 10:14 AM, Andrew Cooper
>> > > <andrew.cooper3@citrix.com> wrote:
>> > > > On 01/04/16 05:59, Chong Li wrote:
>> > > > >
>> > > > > --- a/xen/common/sched_credit2.c
>> > > > > +++ b/xen/common/sched_credit2.c
>> > > > > @@ -1421,14 +1421,12 @@ csched2_dom_cntl(
>> > > > >       * runq lock to update csvcs. */
>> > > > >      spin_lock_irqsave(&prv->lock, flags);
>> > > > >
>> > > > > -    if ( op->cmd == XEN_DOMCTL_SCHEDOP_getinfo )
>> > > > > +    switch ( op->cmd )
>> > > > >      {
>> > > > > +    case XEN_DOMCTL_SCHEDOP_getinfo:
>> > > > >          op->u.credit2.weight = sdom->weight;
>> > > > > -    }
>> > > > > -    else
>> > > > > -    {
>> > > > > -        ASSERT(op->cmd == XEN_DOMCTL_SCHEDOP_putinfo);
>> > > > > -
>> > > > > +        break;
>> > > > > +    case XEN_DOMCTL_SCHEDOP_putinfo:
>> > > > >          if ( op->u.credit2.weight != 0 )
>> > > > >          {
>> > > > >              struct vcpu *v;
>> > > > > @@ -1457,6 +1455,9 @@ csched2_dom_cntl(
>> > > > >                  vcpu_schedule_unlock(lock, svc->vcpu);
>> > > > >              }
>> > > > >          }
>> > > > > +        break;
>> > > > > +    default:
>> > > > > +        return -EINVAL;
>> > > > As does this.
>> > > >
>> > > > Please submit a bugfix ASAP.  This will become a security
>> > > > vulnerability
>> > > > if Xen 4.7 is shipped without it being fixed.
>> > > >
>> > > > >
>> > > > >      }
>> > > > >
>> > > > >      spin_unlock_irqrestore(&prv->lock, flags);
>> > > Thanks for pointing this out.
>> > >
>> > > Dario, do you want to include this bugfix in your cleanup patch, or
>> > > let me submit this?
>> > If you're around and can test it, it's probably better if you can
>> > send a
>> > patch right a way.
>> >
>> Exactly. In fact:
>>  - we don't fold bugfixes in clanups,
>>  - I think I mentioned wanting to cleanup some code duplication in
>>    libxl, this is in xen,
>>  - cleanups are delayed to 4.8, while this must be fixed before
>>    release (or the patch/the whole feature be reverted).
>>
>> So, if you can't work out a fix today or, at most, tomorrow, let me
>> know and I'll do it myself.
>>
>
> Yes, please fix this by tomorrow. I think it is quite straightforward to
> fix anyway.
>
> Wei.
>

Will do.

-- 
Chong Li
Department of Computer Science and Engineering
Washington University in St.louis

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