From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Cooper Subject: Re: [PATCH v2] x86: Fixup IRQs when CPUs go down during shutdown Date: Fri, 4 Dec 2015 10:46:41 +0000 Message-ID: <56616F11.1080803@citrix.com> References: <1449063981-31486-1-git-send-email-ross.lagerwall@citrix.com> <565F081502000078000BB4A1@prv-mh.provo.novell.com> <565F09A9.9000408@citrix.com> <565F1C9202000078000BB534@prv-mh.provo.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <565F1C9202000078000BB534@prv-mh.provo.novell.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Jan Beulich , Ross Lagerwall Cc: xen-devel@lists.xen.org List-Id: xen-devel@lists.xenproject.org On 02/12/15 15:30, Jan Beulich wrote: >>>> On 02.12.15 at 16:09, wrote: >> On 12/02/2015 02:02 PM, Jan Beulich wrote: >>>>>> On 02.12.15 at 14:46, wrote: >>>> --- a/xen/arch/x86/smp.c >>>> +++ b/xen/arch/x86/smp.c >>>> @@ -286,6 +286,7 @@ void __stop_this_cpu(void) >>>> >>>> static void stop_this_cpu(void *dummy) >>>> { >>>> + fixup_eoi(); >>>> __stop_this_cpu(); >>> Is this really needed during shutdown? >> Possibly not, but I think it's cleaner to do the same as what is used >> for CPU down. > I'm not convinced. Andrew? Suppose there is an oustanding line interrupt on the pending eoi stack. Without this fixup_eoi(), it could stay permanently attached to a cpu which isn't processing anything further. With the current use of smp_send_stop(), all cpus will end up in a state where they can only be recovered with an #INIT, so I suppose it doesn't actually matter. Therefore, not performing redundant work is probably the best course of action. ~Andrew