From mboxrd@z Thu Jan 1 00:00:00 1970 From: Keir Fraser Subject: Re: [PATCH] [SVM]: Make 32bit legacy guests boot again Date: Sat, 27 Jun 2009 10:35:20 +0100 Message-ID: References: <200906261719.55259.Christoph.Egger@amd.com> Mime-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <200906261719.55259.Christoph.Egger@amd.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: Christoph Egger , "xen-devel@lists.xensource.com" List-Id: xen-devel@lists.xenproject.org Changeset 19856 is a cleaned up and streamlined version of this patch. Please take a look. It also fixes a couple of largely theoretical issues: * Should depend on EFER.LMA not EFER.LME * Should handle the LMA 1->0 transition (i.e., return to legacy mode). -- Keir On 26/06/2009 16:19, "Christoph Egger" wrote: > > Hi! > > Attached patch fixes a bug introduced in c/s 19648. > > 32bit legacy guests have the sysenter/sysexit instructions available. > Therefore, we have to disable intercepts for the sysenter MSRs or the > guest stucks in an infinite loop of #GPs, otherwise. > > For guests in 64bit mode and 32bit compat mode, sysenter/sysexit instructions > aren't available. The sysenter MSRs have to be intercepted to make the > instruction emulation working. > > Attach patch first assumes the guest is in 32bit legacy mode and therefore > disables the sysenter MSRs in construct_vmcb(). > Access to the MSR_EFER is intercepted. When the guest enables longmode, > then enable interception of the sysenter MSRs. > > Signed-off-by: Christoph Egger >