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    Subject[PATCH 6/6] KVM: X86: Implement userspace interface to set virtual_tsc_khz
    Date
    This patch implements two new vm-ioctls to get and set the
    virtual_tsc_khz if the machine supports tsc-scaling. Setting
    the tsc-frequency is only possible before userspace creates
    any vcpu.

    Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
    ---
    arch/x86/include/asm/kvm_host.h | 1 +
    arch/x86/kvm/svm.c | 3 +++
    arch/x86/kvm/x86.c | 38 ++++++++++++++++++++++++++++++++++++++
    include/linux/kvm.h | 4 ++++
    4 files changed, 46 insertions(+), 0 deletions(-)

    diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
    index 8c40425..dfdd0aa 100644
    --- a/arch/x86/include/asm/kvm_host.h
    +++ b/arch/x86/include/asm/kvm_host.h
    @@ -633,6 +633,7 @@ int kvm_pv_mmu_op(struct kvm_vcpu *vcpu, unsigned long bytes,
    u8 kvm_get_guest_memory_type(struct kvm_vcpu *vcpu, gfn_t gfn);

    extern bool tdp_enabled;
    +extern int kvm_has_tsc_control;

    enum emulation_result {
    EMULATE_DONE, /* no further processing */
    diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
    index f938585..0b8f4f7 100644
    --- a/arch/x86/kvm/svm.c
    +++ b/arch/x86/kvm/svm.c
    @@ -797,6 +797,9 @@ static __init int svm_hardware_setup(void)
    if (boot_cpu_has(X86_FEATURE_FXSR_OPT))
    kvm_enable_efer_bits(EFER_FFXSR);

    + if (boot_cpu_has(X86_FEATURE_TSCRATEMSR))
    + kvm_has_tsc_control = 1;
    +
    if (nested) {
    printk(KERN_INFO "kvm: Nested Virtualization enabled\n");
    kvm_enable_efer_bits(EFER_SVME | EFER_LMSLE);
    diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
    index 6caaf4b..1ac94cc 100644
    --- a/arch/x86/kvm/x86.c
    +++ b/arch/x86/kvm/x86.c
    @@ -99,6 +99,9 @@ EXPORT_SYMBOL_GPL(kvm_x86_ops);
    int ignore_msrs = 0;
    module_param_named(ignore_msrs, ignore_msrs, bool, S_IRUGO | S_IWUSR);

    +int kvm_has_tsc_control;
    +EXPORT_SYMBOL_GPL(kvm_has_tsc_control);
    +
    #define KVM_NR_SHARED_MSRS 16

    struct kvm_shared_msrs_global {
    @@ -2024,6 +2027,9 @@ int kvm_dev_ioctl_check_extension(long ext)
    case KVM_CAP_XCRS:
    r = cpu_has_xsave;
    break;
    + case KVM_CAP_TSC_CONTROL:
    + r = kvm_has_tsc_control;
    + break;
    default:
    r = 0;
    break;
    @@ -3575,6 +3581,38 @@ long kvm_arch_vm_ioctl(struct file *filp,
    r = 0;
    break;
    }
    + case KVM_SET_TSC_KHZ: {
    + u32 user_tsc_khz;
    +
    + if (!kvm_has_tsc_control)
    + break;
    +
    + /*
    + * We force the tsc frequency to be set before any
    + * vcpu is created
    + */
    + if (atomic_read(&kvm->online_vcpus) > 0)
    + goto out;
    +
    + user_tsc_khz = arg;
    +
    + kvm_arch_set_tsc_khz(kvm, user_tsc_khz);
    +
    + r = 0;
    + goto out;
    + }
    + case KVM_GET_TSC_KHZ: {
    +
    + if (!kvm_has_tsc_control)
    + break;
    +
    + r = -EFAULT;
    + if (copy_to_user(argp, &kvm->arch.virtual_tsc_khz, sizeof(__u32)))
    + goto out;
    +
    + r = 0;
    + goto out;
    + }

    default:
    ;
    diff --git a/include/linux/kvm.h b/include/linux/kvm.h
    index ea2dc1a..a96ff92 100644
    --- a/include/linux/kvm.h
    +++ b/include/linux/kvm.h
    @@ -541,6 +541,7 @@ struct kvm_ppc_pvinfo {
    #define KVM_CAP_PPC_GET_PVINFO 57
    #define KVM_CAP_PPC_IRQ_LEVEL 58
    #define KVM_CAP_ASYNC_PF 59
    +#define KVM_CAP_TSC_CONTROL 60

    #ifdef KVM_CAP_IRQ_ROUTING

    @@ -677,6 +678,9 @@ struct kvm_clock_data {
    #define KVM_SET_PIT2 _IOW(KVMIO, 0xa0, struct kvm_pit_state2)
    /* Available with KVM_CAP_PPC_GET_PVINFO */
    #define KVM_PPC_GET_PVINFO _IOW(KVMIO, 0xa1, struct kvm_ppc_pvinfo)
    +/* Available with KVM_CAP_TSC_CONTROL */
    +#define KVM_SET_TSC_KHZ _IOW(KVMIO, 0xa2, __u32)
    +#define KVM_GET_TSC_KHZ _IOR(KVMIO, 0xa3, __u32)

    /*
    * ioctls for vcpu fds
    --
    1.7.1



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