From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Zhai, Edwin" Subject: Re: several Qs about domain live migration Date: Tue, 18 Nov 2008 16:22:46 +0800 Message-ID: <49227B56.4090602@intel.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Keir Fraser Cc: "Tian, Kevin" , Xen Developers List-Id: xen-devel@lists.xenproject.org Keir Fraser wrote: > On 18/11/08 01:17, "Zhai, Edwin" wrote: > > >> We are trying to fix a HVM live migration bug, and found "Use main memory for >> video memory" in r18383 cause guest hang after restore. >> >> Following changes make all valid pages migrated, including vlapic page >> (0xFEE00), and share page(0xFFFFF), so an extra memory population for these 2 >> pages would override previous mapping then cause guest hang (if using vlapic >> acceleration). >> >> What do you think of possible fixing? Skipping these specific pages in >> xc_domain_save except video memory, or change the HVM domain creation. >> > > Try changing gmfn_to_mfn(FOREIGNDOM, l1e_get_pfn(nl1e)) in mod_l1_entry() > to: > mfn = gfn_to_mfn(FOREIGNDOM, l1e_get_pfn(nl1e), &p2mt); > if ( !p2m_is_ram(p2mt) || (mfn == INVALID_MFN) ) > .... > > This will prevent foreign mappings of 'mmio' pages. Pretty sensible and will > fix this problem. > It's great! Does p2m_is_ram return 1 for video memory? I'll make a small patch and test it. Thanks, > -- Keir > > > -- best rgds, edwin