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    Subject[PATCH 3.2 05/87] KVM: x86: expose MSR_TSC_AUX to userspace
    3.2.77-rc1 review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Paolo Bonzini <pbonzini@redhat.com>

    commit 9dbe6cf941a6fe82933aef565e4095fb10f65023 upstream.

    If we do not do this, it is not properly saved and restored across
    migration. Windows notices due to its self-protection mechanisms,
    and is very upset about it (blue screen of death).

    Cc: Radim Krcmar <rkrcmar@redhat.com>
    Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
    [bwh: Backported to 3.2:
    - We didn't yet have the switch() in kvm_init_msr_list as MPX is not
    supported at all
    - Adjust context]
    Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
    ---
    --- a/arch/x86/kvm/x86.c
    +++ b/arch/x86/kvm/x86.c
    @@ -834,7 +834,8 @@ static u32 msrs_to_save[] = {
    #ifdef CONFIG_X86_64
    MSR_CSTAR, MSR_KERNEL_GS_BASE, MSR_SYSCALL_MASK, MSR_LSTAR,
    #endif
    - MSR_IA32_TSC, MSR_IA32_CR_PAT, MSR_VM_HSAVE_PA
    + MSR_IA32_TSC, MSR_IA32_CR_PAT, MSR_VM_HSAVE_PA,
    + MSR_TSC_AUX,
    };

    static unsigned num_msrs_to_save;
    @@ -3867,6 +3868,20 @@ static void kvm_init_msr_list(void)
    for (i = j = KVM_SAVE_MSRS_BEGIN; i < ARRAY_SIZE(msrs_to_save); i++) {
    if (rdmsr_safe(msrs_to_save[i], &dummy[0], &dummy[1]) < 0)
    continue;
    +
    + /*
    + * Even MSRs that are valid in the host may not be exposed
    + * to the guests in some cases.
    + */
    + switch (msrs_to_save[i]) {
    + case MSR_TSC_AUX:
    + if (!kvm_x86_ops->rdtscp_supported())
    + continue;
    + break;
    + default:
    + break;
    + }
    +
    if (j < i)
    msrs_to_save[j] = msrs_to_save[i];
    j++;
    \
     
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