From: "Wu, Feng" <feng.wu@intel.com>
To: George Dunlap <George.Dunlap@eu.citrix.com>
Cc: "Tian, Kevin" <kevin.tian@intel.com>,
"keir@xen.org" <keir@xen.org>,
"andrew.cooper3@citrix.com" <andrew.cooper3@citrix.com>,
"dario.faggioli@citrix.com" <dario.faggioli@citrix.com>,
"xen-devel@lists.xen.org" <xen-devel@lists.xen.org>,
Jan Beulich <JBeulich@suse.com>, "Wu, Feng" <feng.wu@intel.com>
Subject: Re: [PATCH v2 4/4] VMX: fixup PI descritpor when cpu is offline
Date: Fri, 24 Jun 2016 06:34:58 +0000 [thread overview]
Message-ID: <E959C4978C3B6342920538CF579893F01972E2D3@SHSMSX103.ccr.corp.intel.com> (raw)
In-Reply-To: <CAFLBxZYQQxku7Wq0oVA=KGw1heYqXvMHdbduYuKwdwKsddK-5g@mail.gmail.com>
> >> > @@ -122,10 +124,25 @@ static void vmx_vcpu_block(struct vcpu *v)
> >> > * new vCPU to the list.
> >> > */
> >> > spin_unlock_irqrestore(&v->arch.hvm_vmx.pi_hotplug_lock, flags);
> >> > - return;
> >> > + return 1;
> >> > }
> >> >
> >> > spin_lock(pi_blocking_list_lock);
> >> > + if ( unlikely(per_cpu(vmx_pi_blocking, v->processor).down) )
> >>
> >> Is this something that can actually happen? vmx_pi_desc_fixup()
> >> runs in stop-machine context, i.e. no CPU can actively be here (or
> >> anywhere near the arch_vcpu_block() call sites).
> >
> > This is related to scheduler, maybe Dario can give some input about
> > this. Dario?
>
> Yeah, I was going to say just looking through this -- there's no way
> that vmx_cpu_dead() will be called while there are vcpus *still
> running* on that pcpu. vcpus will be migrated to other pcpus before
> that happens. All of your changes around vmx_vcpu_block() are
> unnecessary.
Thanks for the clarification, George!
Thanks,
Feng
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next prev parent reply other threads:[~2016-06-24 6:34 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-26 13:39 [PATCH v2 0/4] VMX: Properly handle pi descriptor and per-cpu blocking list Feng Wu
2016-05-26 13:39 ` [PATCH v2 1/4] VMX: Properly handle pi when all the assigned devices are removed Feng Wu
2016-05-27 13:43 ` Jan Beulich
2016-05-31 10:22 ` Wu, Feng
2016-05-31 11:52 ` Jan Beulich
2016-06-03 5:12 ` Wu, Feng
2016-06-03 9:45 ` Jan Beulich
2016-05-26 13:39 ` [PATCH v2 2/4] VMX: Cleanup PI per-cpu blocking list when vcpu is destroyed Feng Wu
2016-05-27 13:49 ` Jan Beulich
2016-05-31 10:22 ` Wu, Feng
2016-05-31 11:54 ` Jan Beulich
2016-05-26 13:39 ` [PATCH v2 3/4] VMX: Assign the right value to 'NDST' field in a concern case Feng Wu
2016-05-27 14:00 ` Jan Beulich
2016-05-31 10:27 ` Wu, Feng
2016-05-31 11:58 ` Jan Beulich
2016-06-03 5:23 ` Wu, Feng
2016-06-03 9:57 ` Jan Beulich
2016-06-22 18:00 ` George Dunlap
2016-06-24 9:08 ` Wu, Feng
2016-05-26 13:39 ` [PATCH v2 4/4] VMX: fixup PI descritpor when cpu is offline Feng Wu
2016-05-27 14:56 ` Jan Beulich
2016-05-31 10:31 ` Wu, Feng
2016-06-22 18:33 ` George Dunlap
2016-06-24 6:34 ` Wu, Feng [this message]
2016-05-26 17:20 ` [PATCH v2 0/4] VMX: Properly handle pi descriptor and per-cpu blocking list Dario Faggioli
2016-05-31 10:19 ` Wu, Feng
2016-06-22 21:33 ` Dario Faggioli
2016-06-24 6:33 ` Wu, Feng
2016-06-24 10:29 ` Dario Faggioli
2016-06-24 13:42 ` Wu, Feng
2016-06-24 13:49 ` George Dunlap
2016-06-24 14:36 ` Dario Faggioli
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