From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave McCracken Subject: Re: [PATCH] Allow PV superpages to work with live migration Date: Tue, 18 May 2010 11:21:12 -0500 Message-ID: <201005181121.12846.dcm@mccr.org> References: <201005171410.47235.dcm@mccr.org> <201005180920.18349.dcm@mccr.org> <20100518143205.GH4164@whitby.uk.xensource.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20100518143205.GH4164@whitby.uk.xensource.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Tim Deegan Cc: Jeremy Fitzhardinge , Xen Developers List , Keir Fraser List-Id: xen-devel@lists.xenproject.org On Tuesday, May 18, 2010, Tim Deegan wrote: > At 15:20 +0100 on 18 May (1274196018), Dave McCracken wrote: > > I'm confused. As far as I know, opt_allow_hugeage only affects PV > > guests. All I did in the macro was add a test for it. I didn't touch > > any of the HVM logic. Are you saying the HVM logic is wrong or that > > opt_allow_hugepage affects HVM guests in some fashion? > > It would affect them after your change: > > + return (opt_allow_hugepage || > + (is_hvm_vcpu(v) && > + (GUEST_PAGING_LEVELS != 2 > + || !hvm_paging_enabled(v) > + || (v->arch.hvm_vcpu.guest_cr[4] & X86_CR4_PSE)))); > > This makes the whole predicate true _even_for_hvm_guests_ whenever > opt_allow_hugepage is true. It should not be true for HVM guests that > have disabled PSE, regardless of the setting of opt_allow_hugepage. Ahh, right. It didn't occur to me that people might set that parameter on machines with HVM guests. I suppose it would be reasonable if they had a mix of PV and HVM on the same machine. On Tuesday, May 18, 2010, Keir wrote: > I already fixed this when I applied the patch this morning. Thanks. Dave