x86: Reserve a CPUID feature bit to advertise new

MMU_PT_UPDATE_PRESERVE_AD hypercall command.
Signed-off-by: Keir Fraser <keir.fraser@citrix.com>

xen/arch/x86/traps.c

@@ -62,6 +62,7 @@
 #include <asm/shared.h>
 #include <asm/x86_emulate.h>
 #include <asm/hvm/vpt.h>
+#include <public/arch-x86/cpuid.h>
 
 /*
  * opt_nmi: one of 'ignore', 'dom0', or 'fatal'.
@@ -610,10 +611,10 @@ int cpuid_hypervisor_leaves(
     switch ( idx )
     {
     case 0:
-        *eax = 0x40000002; /* Largest leaf        */
-        *ebx = 0x566e6558; /* Signature 1: "XenV" */
-        *ecx = 0x65584d4d; /* Signature 2: "MMXe" */
-        *edx = 0x4d4d566e; /* Signature 3: "nVMM" */
+        *eax = 0x40000002; /* Largest leaf */
+        *ebx = XEN_CPUID_SIGNATURE_EBX;
+        *ecx = XEN_CPUID_SIGNATURE_ECX;
+        *edx = XEN_CPUID_SIGNATURE_EDX;
         break;
 
     case 1:
@@ -628,6 +629,8 @@ int cpuid_hypervisor_leaves(
         *ebx = 0x40000000; /* MSR base address */
         *ecx = 0;          /* Features 1 */
         *edx = 0;          /* Features 2 */
+        if ( !is_hvm_vcpu(current) )
+            *ecx |= XEN_CPUID_FEAT1_MMU_PT_UPDATE_PRESERVE_AD;
         break;
 
     default:

xen/include/public/arch-x86/cpuid.h

@@ -0,0 +1,68 @@
+/******************************************************************************
+ * arch-x86/cpuid.h
+ * 
+ * CPUID interface to Xen.
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ * 
+ * Copyright (c) 2007 Citrix Systems, Inc.
+ * 
+ * Authors:
+ *    Keir Fraser <keir.fraser@citrix.com>
+ */
+
+#ifndef __XEN_PUBLIC_ARCH_X86_CPUID_H__
+#define __XEN_PUBLIC_ARCH_X86_CPUID_H__
+
+/* Xen identification leaves start at 0x40000000. */
+#define XEN_CPUID_FIRST_LEAF 0x40000000
+#define XEN_CPUID_LEAF(i)    (XEN_CPUID_FIRST_LEAF + (i))
+
+/*
+ * Leaf 1 (0x40000000)
+ * EAX: Largest Xen-information leaf. All leaves up to an including @EAX
+ *      are supported by the Xen host.
+ * EBX-EDX: "XenVMMXenVMM" signature, allowing positive identification
+ *      of a Xen host.
+ */
+#define XEN_CPUID_SIGNATURE_EBX 0x566e6558 /* "XenV" */
+#define XEN_CPUID_SIGNATURE_ECX 0x65584d4d /* "MMXe" */
+#define XEN_CPUID_SIGNATURE_EDX 0x4d4d566e /* "nVMM" */
+
+/*
+ * Leaf 2 (0x40000001)
+ * EAX[31:16]: Xen major version.
+ * EAX[15: 0]: Xen minor version.
+ * EBX-EDX: Reserved (currently all zeroes).
+ */
+
+/*
+ * Leaf 3 (0x40000002)
+ * EAX: Number of hypercall transfer pages. This register is always guaranteed
+ *      to specify one hypercall page.
+ * EBX: Base address of Xen-specific MSRs.
+ * ECX: Features 1. Unused bits are set to zero.
+ * EDX: Features 2. Unused bits are set to zero.
+ */
+
+/* Does the host support MMU_PT_UPDATE_PRESERVE_AD for this guest? */
+#define _XEN_CPUID_FEAT1_MMU_PT_UPDATE_PRESERVE_AD 0
+#define XEN_CPUID_FEAT1_MMU_PT_UPDATE_PRESERVE_AD  (1u<<0)
+
+#endif /* __XEN_PUBLIC_ARCH_X86_CPUID_H__ */