From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ian Campbell Subject: Re: [PATCH] Xen/MCE: adjust for future new vMCE model Date: Thu, 5 Jul 2012 08:02:45 +0100 Message-ID: <1341471765.14447.17.camel@dagon.hellion.org.uk> References: <4FF46407020000780008DAB2@nat28.tlf.novell.com> <4FF552D8020000780008DC3A@nat28.tlf.novell.com> <1341470649.14447.12.camel@dagon.hellion.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1341470649.14447.12.camel@dagon.hellion.org.uk> 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 Cc: Jinsong Liu , Tony Luck , "Keir (Xen.org)" , Yunhong Jiang , xen-devel , Will Auld List-Id: xen-devel@lists.xenproject.org On Thu, 2012-07-05 at 07:44 +0100, Ian Campbell wrote: > On Thu, 2012-07-05 at 07:39 +0100, Jan Beulich wrote: > > >>> On 05.07.12 at 05:03, "Liu, Jinsong" wrote: > > > Jan Beulich wrote: > > >> Also I seem to recall that there was going to be a need to > > >> save/restore MCi_CTL2, but there's nothing being done in that > > >> direction. > > > > > > Yes, but that would be done at new vMCE. > > > Current vMCE didn't enable MCG_CMCI_P, and MCi_CTL2 are not used, so we > > > don't save/restore MCi_CTL2 at this version. > > > > But _that_ is the major save/restore related issue to be > > addressed, at least if backward migration (4.2 -> 4.1) is also > > to be working reasonably. If such compatibility is entirely > > unneeded, then I agree that it likely doesn't need any > > consideration at this point. > > We don't generally worry about N->N-1 migration, just N->N+1. If there's nothing to save in 4.2 (and therefore to restore in 4.3) what is it we are giving a freeze exception to again? If there's no save/restore can you even migrate a guest with vMCE enabled at all? (these aren't rhetorical questions, I have absolutely no idea how this stuff works ;-)) Ian.