    /******************************************************************************
     * 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@xen.org>
     */

    #ifndef __XEN_PUBLIC_ARCH_X86_CPUID_H__
    #define __XEN_PUBLIC_ARCH_X86_CPUID_H__

    /*
     * For compatibility with other hypervisor interfaces, the Xen cpuid leaves
     * can be found at the first otherwise unused 0x100 aligned boundary starting
     * from 0x40000000.
     *
     * e.g If viridian extensions are enabled for an HVM domain, the Xen cpuid
     * leaves will start at 0x40000100
     */

    #define XEN_CPUID_FIRST_LEAF 0x40000000
    #define XEN_CPUID_LEAF(i)    (XEN_CPUID_FIRST_LEAF + (i))

    /*
     * Leaf 1 (0x40000x00)
     * 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 (0x40000x01)
     * EAX[31:16]: Xen major version.
     * EAX[15: 0]: Xen minor version.
     * EBX-EDX: Reserved (currently all zeroes).
     */

    /*
     * Leaf 3 (0x40000x02)
     * 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)

    /*
     * Leaf 5 (0x40000x04)
     * HVM-specific features
     * EAX: Features
     * EBX: vcpu id (iff EAX has XEN_HVM_CPUID_VCPU_ID_PRESENT flag)
     */
    #define XEN_HVM_CPUID_APIC_ACCESS_VIRT (1u << 0) /* Virtualized APIC registers */
    #define XEN_HVM_CPUID_X2APIC_VIRT      (1u << 1) /* Virtualized x2APIC accesses */
    /* Memory mapped from other domains has valid IOMMU entries */
    #define XEN_HVM_CPUID_IOMMU_MAPPINGS   (1u << 2)
    #define XEN_HVM_CPUID_VCPU_ID_PRESENT  (1u << 3) /* vcpu id is present in EBX */

    #define XEN_CPUID_MAX_NUM_LEAVES 4

    #endif /* __XEN_PUBLIC_ARCH_X86_CPUID_H__ */