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    Subject[PATCH 5/5] KVM: x86: #GP when attempts to write reserved bits of Variable Range MTRRs
    Date
    Section 11.11.2.3 of the SDM mentions "All other bits in the IA32_MTRR_PHYSBASEn 
    and IA32_MTRR_PHYSMASKn registers are reserved; the processor generates a
    general-protection exception(#GP) if software attempts to write to them". This
    patch do it in kvm.

    Signed-off-by: Wanpeng Li <wanpeng.li@linux.intel.com>
    ---
    arch/x86/kvm/x86.c | 15 +++++++++++++--
    1 file changed, 13 insertions(+), 2 deletions(-)

    diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
    index caaffeb..aa64c70 100644
    --- a/arch/x86/kvm/x86.c
    +++ b/arch/x86/kvm/x86.c
    @@ -1769,11 +1769,22 @@ static bool mtrr_valid(struct kvm_vcpu *vcpu, u32 msr, u64 data)
    /* variable MTRRs */
    if (msr >= 0x200 && msr < 0x200 + 2 * KVM_NR_VAR_MTRR) {
    int idx, is_mtrr_mask;
    + u64 mask = 0;

    idx = (msr - 0x200) / 2;
    is_mtrr_mask = msr - 0x200 - 2 * idx;
    - if (!is_mtrr_mask)
    - return valid_mtrr_type(data & 0xff);
    + for (i = 63; i > boot_cpu_data.x86_phys_bits; i--)
    + mask |= (1ULL << i);
    + if (!is_mtrr_mask) {
    + if (!valid_mtrr_type(data & 0xff))
    + return false;
    + mask |= 0xf00;
    + } else
    + mask |= 0x7ff;
    + if (data & mask) {
    + kvm_inject_gp(vcpu, 0);
    + return false;
    + }
    }
    return true;
    }
    --
    1.9.1


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