From mboxrd@z Thu Jan 1 00:00:00 1970 From: Keir Fraser Subject: Re: [PATCH] Xen/MCE: adjust for future new vMCE model Date: Thu, 05 Jul 2012 09:55:49 +0100 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: "Liu, Jinsong" , Jan Beulich , Ian Campbell Cc: "Auld, Will" , "Luck, Tony" , xen-devel , "Jiang, Yunhong" List-Id: xen-devel@lists.xenproject.org On 05/07/2012 08:50, "Liu, Jinsong" wrote: >> >> We're currently saving MCG_CAP, with the bank count in it >> reflecting the host bank count, and with other bits in there also >> matching the host's. That's what we'd like to simplify, _but_ as >> said we're already shipping the current interface, so backward >> compatibility will be needed anyway. >> >> The main issue really was with MCi_CTL, which if not saved by >> 4.2 wouldn't be restorable in 4.3. Now that we decided that they >> will get fixed values anyway, simply enforcing these fixed values >> (to not surprise the guest) would seem sufficient for 4.2. MCi_CTL2 >> are different in that afaiu setting them to 0 for a guest with no >> saved values (i.e. 4.2, where their presence isn't being advertised, >> since CMCI doesn't get surfaced) would be correct. >> >> Jan > > So Jan and Ian, do we really care migrate N -> N-1 ? > If yes, I will save/restore MCi_CTL2, but that would involve more code change. We categorically do not care about migration N -> N-1. N-1 -> N is the only thing that really gets much test (N-k -> N should work by design though), and it's the most useful one, for rolling fairly-seamless upgrades. -- Keir