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    Subject[PATCH 3/6] KVM: X86: Let kvm-clock report the right tsc frequency
    Date
    This patch changes the kvm_guest_time_update function to use
    TSC frequency the guest actually has for updating its clock.

    Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
    ---
    arch/x86/include/asm/kvm_host.h | 2 ++
    arch/x86/kvm/svm.c | 8 ++++++++
    arch/x86/kvm/vmx.c | 6 ++++++
    arch/x86/kvm/x86.c | 12 ++++++++++--
    4 files changed, 26 insertions(+), 2 deletions(-)

    diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
    index ffd7f8d..9686950 100644
    --- a/arch/x86/include/asm/kvm_host.h
    +++ b/arch/x86/include/asm/kvm_host.h
    @@ -592,6 +592,8 @@ struct kvm_x86_ops {

    void (*write_tsc_offset)(struct kvm_vcpu *vcpu, u64 offset);

    + bool (*use_virtual_tsc_khz)(struct kvm_vcpu *vcpu);
    +
    void (*get_exit_info)(struct kvm_vcpu *vcpu, u64 *info1, u64 *info2);
    const struct trace_print_flags *exit_reasons_str;
    };
    diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
    index c96c0a6..f51f757 100644
    --- a/arch/x86/kvm/svm.c
    +++ b/arch/x86/kvm/svm.c
    @@ -905,6 +905,13 @@ static void svm_adjust_tsc_offset(struct kvm_vcpu *vcpu, s64 adjustment)
    mark_dirty(svm->vmcb, VMCB_INTERCEPTS);
    }

    +static bool svm_use_virtual_tsc_khz(struct kvm_vcpu *vcpu)
    +{
    + struct vcpu_svm *svm = to_svm(vcpu);
    +
    + return svm->tsc_scale.enabled;
    +}
    +
    static void init_vmcb(struct vcpu_svm *svm)
    {
    struct vmcb_control_area *control = &svm->vmcb->control;
    @@ -3976,6 +3983,7 @@ static struct kvm_x86_ops svm_x86_ops = {

    .write_tsc_offset = svm_write_tsc_offset,
    .adjust_tsc_offset = svm_adjust_tsc_offset,
    + .use_virtual_tsc_khz = svm_use_virtual_tsc_khz,

    .set_tdp_cr3 = set_tdp_cr3,
    };
    diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
    index ae4f02d..c227a6b 100644
    --- a/arch/x86/kvm/vmx.c
    +++ b/arch/x86/kvm/vmx.c
    @@ -1164,6 +1164,11 @@ static void vmx_adjust_tsc_offset(struct kvm_vcpu *vcpu, s64 adjustment)
    vmcs_write64(TSC_OFFSET, offset + adjustment);
    }

    +static bool vmx_use_virtual_tsc_khz(struct kvm_vcpu *vcpu)
    +{
    + return false;
    +}
    +
    /*
    * Reads an msr value (of 'msr_index') into 'pdata'.
    * Returns 0 on success, non-0 otherwise.
    @@ -4443,6 +4448,7 @@ static struct kvm_x86_ops vmx_x86_ops = {

    .write_tsc_offset = vmx_write_tsc_offset,
    .adjust_tsc_offset = vmx_adjust_tsc_offset,
    + .use_virtual_tsc_khz = vmx_use_virtual_tsc_khz,

    .set_tdp_cr3 = vmx_set_cr3,
    };
    diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
    index 8575d85..597abc8 100644
    --- a/arch/x86/kvm/x86.c
    +++ b/arch/x86/kvm/x86.c
    @@ -979,6 +979,14 @@ static inline int kvm_tsc_changes_freq(void)
    return ret;
    }

    +static u64 vcpu_tsc_khz(struct kvm_vcpu *vcpu)
    +{
    + if (kvm_x86_ops->use_virtual_tsc_khz(vcpu))
    + return vcpu->kvm->arch.virtual_tsc_khz;
    + else
    + return __this_cpu_read(cpu_tsc_khz);
    +}
    +
    static inline u64 nsec_to_cycles(u64 nsec)
    {
    u64 ret;
    @@ -1010,6 +1018,7 @@ static u64 compute_guest_tsc(struct kvm_vcpu *vcpu, s64 kernel_ns)
    return tsc;
    }

    +
    void kvm_write_tsc(struct kvm_vcpu *vcpu, u64 data)
    {
    struct kvm *kvm = vcpu->kvm;
    @@ -1072,8 +1081,7 @@ static int kvm_guest_time_update(struct kvm_vcpu *v)
    local_irq_save(flags);
    kvm_get_msr(v, MSR_IA32_TSC, &tsc_timestamp);
    kernel_ns = get_kernel_ns();
    - this_tsc_khz = __this_cpu_read(cpu_tsc_khz);
    -
    + this_tsc_khz = vcpu_tsc_khz(v);
    if (unlikely(this_tsc_khz == 0)) {
    local_irq_restore(flags);
    kvm_make_request(KVM_REQ_CLOCK_UPDATE, v);
    --
    1.7.1



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