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 09:20:18 -0500 Message-ID: <201005180920.18349.dcm@mccr.org> References: <201005171410.47235.dcm@mccr.org> <20100518123553.GG4164@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: <20100518123553.GG4164@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: > > PV superpages currently do not work with live migration. They fall over > > dead when the shadow page table is enabled for dirty tracking. The HVM > > support for superpages in this code has been tested and found to work > > just fine for PV superpages. This patch modifies the test macro to > > allow the code to work with PV superpages. > > It rather overshoots. :) This enables PSE even for HVM guests which > have explicitly disabled it. I think you want > > return (is_hvm_vcpu(v) ? (GUEST_PAGING_LEVELS != 2 > || !hvm_paging_enabled(v) > || (v->arch.hvm_vcpu.guest_cr[4] & > X86_CR4_PSE)) : opt_allow_hugepage); 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? Dave McCracken Oracle Corp.