From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Egger Subject: Xen HVM cpuid problem Date: Tue, 13 May 2008 14:41:05 +0200 Message-ID: <200805131441.05576.Christoph.Egger@amd.com> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Return-path: Content-Disposition: inline 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: xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org Hi Keir, =46or HVM guests, all cpuid Fn's going through domain_cpuid() iterate over the loop and then return 0 for all four registers. Guests OS's and cpuid tools in HVM which query for cpuid Fn 0000.0000 %eax and 8000.0000 %eax, see the value 0 and think, Xen emulates oldish 386/486 CPUs. This leads to strange boot failures, "your CPU does not support long mode" or "minimum required CPU is a 486DX CPU" when launching 32bit or 64bit HVM= =20 guests. To reproduce this, cpuid is NOT explicitely configured in the guest config file. BTW: Is there a reason for not handling cpuid in one central place? Christoph =2D-=20 AMD Saxony, Dresden, Germany Operating System Research Center Legal Information: AMD Saxony Limited Liability Company & Co. KG Sitz (Gesch=E4ftsanschrift): Wilschdorfer Landstr. 101, 01109 Dresden, Deutschland Registergericht Dresden: HRA 4896 vertretungsberechtigter Komplement=E4r: AMD Saxony LLC (Sitz Wilmington, Delaware, USA) Gesch=E4ftsf=FChrer der AMD Saxony LLC: Dr. Hans-R. Deppe, Thomas McCoy