From patchwork Tue May 11 16:17:47 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Glauber Costa X-Patchwork-Id: 98761 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by demeter.kernel.org (8.14.3/8.14.3) with ESMTP id o4BGOWs0002277 for ; Tue, 11 May 2010 16:24:33 GMT Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754105Ab0EKQVl (ORCPT ); Tue, 11 May 2010 12:21:41 -0400 Received: from mx1.redhat.com ([209.132.183.28]:55649 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753604Ab0EKQVb (ORCPT ); Tue, 11 May 2010 12:21:31 -0400 Received: from int-mx04.intmail.prod.int.phx2.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.17]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id o4BGLUfo017529 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Tue, 11 May 2010 12:21:30 -0400 Received: from localhost.localdomain (virtlab1.virt.bos.redhat.com [10.16.72.21]) by int-mx04.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id o4BGLHQV003599; Tue, 11 May 2010 12:21:29 -0400 From: Glauber Costa To: kvm@vger.kernel.org Cc: linux-kernel@vger.kernel.org, avi@redhat.com, zamsden@redhat.com Subject: [PATCH 9/9] Add cpuid.txt file Date: Tue, 11 May 2010 12:17:47 -0400 Message-Id: <1273594667-17175-10-git-send-email-glommer@redhat.com> In-Reply-To: <1273594667-17175-9-git-send-email-glommer@redhat.com> References: <1273594667-17175-1-git-send-email-glommer@redhat.com> <1273594667-17175-2-git-send-email-glommer@redhat.com> <1273594667-17175-3-git-send-email-glommer@redhat.com> <1273594667-17175-4-git-send-email-glommer@redhat.com> <1273594667-17175-5-git-send-email-glommer@redhat.com> <1273594667-17175-6-git-send-email-glommer@redhat.com> <1273594667-17175-7-git-send-email-glommer@redhat.com> <1273594667-17175-8-git-send-email-glommer@redhat.com> <1273594667-17175-9-git-send-email-glommer@redhat.com> X-Scanned-By: MIMEDefang 2.67 on 10.5.11.17 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Greylist: IP, sender and recipient auto-whitelisted, not delayed by milter-greylist-4.2.3 (demeter.kernel.org [140.211.167.41]); Tue, 11 May 2010 16:24:33 +0000 (UTC) diff --git a/Documentation/kvm/cpuid.txt b/Documentation/kvm/cpuid.txt new file mode 100644 index 0000000..ca1e89f --- /dev/null +++ b/Documentation/kvm/cpuid.txt @@ -0,0 +1,44 @@ +KVM CPUID bits +Glauber Costa , Red Hat Inc, 2010 +===================================================== + +A guest running on a kvm host, can check some of its features using +cpuid. This is not always guaranteed to work, since userspace can +mask-out some, or even all KVM-related cpuid features before launching +a guest. + +KVM cpuid functions are: + +function: KVM_CPUID_SIGNATURE (0x40000000) +returns : eax = 0, + ebx = 0x4b4d564b, + ecx = 0x564b4d56, + edx = 0x4d. +Note that this value in ebx, ecx and edx corresponds to the string "KVMKVMKVM". +This function queries the presence of KVM cpuid leafs. + + +function: define KVM_CPUID_FEATURES (0x40000001) +returns : ebx, ecx, edx = 0 + eax = and OR'ed group of (1 << flag), where each flags is: + + +flag || value || meaning +============================================================================= +KVM_FEATURE_CLOCKSOURCE || 0 || kvmclock available at msrs + || || 0x11 and 0x12. +------------------------------------------------------------------------------ +KVM_FEATURE_NOP_IO_DELAY || 1 || not necessary to perform delays + || || on PIO operations. +------------------------------------------------------------------------------ +KVM_FEATURE_MMU_OP || 2 || deprecated. +------------------------------------------------------------------------------ +KVM_FEATURE_CLOCKSOURCE2 || 3 || kvmclock available at msrs + || || 0x4b564d00 and 0x4b564d01 +------------------------------------------------------------------------------ +KVM_FEATURE_CLOCKSOURCE_STABLE_BIT || 24 || host will wanr if no guest-side + || || per-cpu warps are expected in + || || kvmclock. +------------------------------------------------------------------------------ + +