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    Subject[PATCH v3 18/25] KVM: x86: Add reverse-CPUID lookup support for scattered SGX features
    Date
    From: Sean Christopherson <seanjc@google.com>

    Define a new KVM-only feature word for advertising and querying SGX
    sub-features in CPUID.0x12.0x0.EAX. Because SGX1 and SGX2 are scattered
    in the kernel's feature word, they need to be translated so that the
    bit numbers match those of hardware.

    Signed-off-by: Sean Christopherson <seanjc@google.com>
    Signed-off-by: Kai Huang <kai.huang@intel.com>
    ---
    arch/x86/kvm/cpuid.h | 13 ++++++++++++-
    1 file changed, 12 insertions(+), 1 deletion(-)

    diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h
    index 8925a929186c..a175ff75bbbe 100644
    --- a/arch/x86/kvm/cpuid.h
    +++ b/arch/x86/kvm/cpuid.h
    @@ -13,13 +13,18 @@
    * "bug" caps, but KVM doesn't use those.
    */
    enum kvm_only_cpuid_leafs {
    - NR_KVM_CPU_CAPS = NCAPINTS,
    + CPUID_12_EAX = NCAPINTS,
    + NR_KVM_CPU_CAPS,

    NKVMCAPINTS = NR_KVM_CPU_CAPS - NCAPINTS,
    };

    #define X86_KVM_FEATURE(w, f) ((w)*32 + (f))

    +/* Intel-defined SGX sub-features, CPUID level 0x12 (EAX). */
    +#define __X86_FEATURE_SGX1 X86_KVM_FEATURE(CPUID_12_EAX, 0)
    +#define __X86_FEATURE_SGX2 X86_KVM_FEATURE(CPUID_12_EAX, 1)
    +
    extern u32 kvm_cpu_caps[NR_KVM_CPU_CAPS] __read_mostly;
    void kvm_set_cpu_caps(void);

    @@ -93,6 +98,7 @@ static const struct cpuid_reg reverse_cpuid[] = {
    [CPUID_8000_0007_EBX] = {0x80000007, 0, CPUID_EBX},
    [CPUID_7_EDX] = { 7, 0, CPUID_EDX},
    [CPUID_7_1_EAX] = { 7, 1, CPUID_EAX},
    + [CPUID_12_EAX] = {0x00000012, 0, CPUID_EAX},
    };

    /*
    @@ -119,6 +125,11 @@ static __always_inline void reverse_cpuid_check(unsigned int x86_leaf)
    */
    static __always_inline u32 __feature_translate(int x86_feature)
    {
    + if (x86_feature == X86_FEATURE_SGX1)
    + return __X86_FEATURE_SGX1;
    + else if (x86_feature == X86_FEATURE_SGX2)
    + return __X86_FEATURE_SGX2;
    +
    return x86_feature;
    }

    --
    2.30.2
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