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    Subject[PATCH 4.19 152/190] KVM: x86: optimize check for valid PAT value
    Date
    [ Upstream commit 674ea351cdeb01d2740edce31db7f2d79ce6095d ]

    This check will soon be done on every nested vmentry and vmexit,
    "parallelize" it using bitwise operations.

    Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com>
    Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    arch/x86/kvm/mtrr.c | 10 +---------
    arch/x86/kvm/vmx.c | 2 +-
    arch/x86/kvm/x86.h | 10 ++++++++++
    3 files changed, 12 insertions(+), 10 deletions(-)

    diff --git a/arch/x86/kvm/mtrr.c b/arch/x86/kvm/mtrr.c
    index e9ea2d45ae66b..9f72cc427158e 100644
    --- a/arch/x86/kvm/mtrr.c
    +++ b/arch/x86/kvm/mtrr.c
    @@ -48,11 +48,6 @@ static bool msr_mtrr_valid(unsigned msr)
    return false;
    }

    -static bool valid_pat_type(unsigned t)
    -{
    - return t < 8 && (1 << t) & 0xf3; /* 0, 1, 4, 5, 6, 7 */
    -}
    -
    static bool valid_mtrr_type(unsigned t)
    {
    return t < 8 && (1 << t) & 0x73; /* 0, 1, 4, 5, 6 */
    @@ -67,10 +62,7 @@ bool kvm_mtrr_valid(struct kvm_vcpu *vcpu, u32 msr, u64 data)
    return false;

    if (msr == MSR_IA32_CR_PAT) {
    - for (i = 0; i < 8; i++)
    - if (!valid_pat_type((data >> (i * 8)) & 0xff))
    - return false;
    - return true;
    + return kvm_pat_valid(data);
    } else if (msr == MSR_MTRRdefType) {
    if (data & ~0xcff)
    return false;
    diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
    index ee9ff20da3902..feff7ed44a2bb 100644
    --- a/arch/x86/kvm/vmx.c
    +++ b/arch/x86/kvm/vmx.c
    @@ -4266,7 +4266,7 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
    break;
    case MSR_IA32_CR_PAT:
    if (vmcs_config.vmentry_ctrl & VM_ENTRY_LOAD_IA32_PAT) {
    - if (!kvm_mtrr_valid(vcpu, MSR_IA32_CR_PAT, data))
    + if (!kvm_pat_valid(data))
    return 1;
    vmcs_write64(GUEST_IA32_PAT, data);
    vcpu->arch.pat = data;
    diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
    index 8889e0c029a70..3a91ea760f073 100644
    --- a/arch/x86/kvm/x86.h
    +++ b/arch/x86/kvm/x86.h
    @@ -345,6 +345,16 @@ static inline void kvm_after_interrupt(struct kvm_vcpu *vcpu)
    __this_cpu_write(current_vcpu, NULL);
    }

    +
    +static inline bool kvm_pat_valid(u64 data)
    +{
    + if (data & 0xF8F8F8F8F8F8F8F8ull)
    + return false;
    + /* 0, 1, 4, 5, 6, 7 are valid values. */
    + return (data | ((data & 0x0202020202020202ull) << 1)) == data;
    +}
    +
    void kvm_load_guest_xcr0(struct kvm_vcpu *vcpu);
    void kvm_put_guest_xcr0(struct kvm_vcpu *vcpu);
    +
    #endif
    --
    2.20.1


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