From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Jan Beulich" Subject: Re: [PATCH] xen: fix initialization of wallclock time for PVHVM on migration Date: Tue, 11 Jun 2013 13:12:02 +0100 Message-ID: <51B7303202000078000DD128@nat28.tlf.novell.com> References: <1370947577-5965-1-git-send-email-roger.pau@citrix.com> <51B72D3602000078000DD0FD@nat28.tlf.novell.com> <51B711A1.5080105@eu.citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <51B711A1.5080105@eu.citrix.com> Content-Disposition: inline List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: George Dunlap Cc: xen-devel@lists.xen.org, KeirFraser , Roger Pau Monne List-Id: xen-devel@lists.xenproject.org >>> On 11.06.13 at 14:01, George Dunlap wrote: > On 06/11/2013 12:59 PM, Jan Beulich wrote: >>>>> On 11.06.13 at 12:46, Roger Pau Monne wrote: >>> The initial values of the wallclock time in the shared info page are >>> set for PVHVM guests when the hypercall page is initialized, since the >>> hypercall page is not reinitialized on resume, the hypervisor >>> wallclock time is not properly set on resume. >>> >>> Fix it by forcing an update of the wallclock values when the shared >>> info page is mapped. >> >> NACK - this is a guest side bug. After migration, a guest _has_ to >> re-init the hypercall page, as it may have got migrated between >> a VMX and an SVM machine, and the hypercall instructions are >> different between them. > > Does migrating from VMX to SVM actually work? If you sufficiently feature-restrict both hosts, it should work. At least it was made work years ago iirc (see the sysenter/syscall emulation code in the x86 emulator - the only case where this may be needed is when doing cross vendor migration). Jan