diff options
| -rw-r--r-- | Documentation/virtual/kvm/api.txt | 11 | ||||
| -rw-r--r-- | arch/x86/kvm/x86.c | 10 | ||||
| -rw-r--r-- | include/uapi/linux/kvm.h | 7 |
3 files changed, 25 insertions, 3 deletions
diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt index 739db9ab16b2..6bbceb9a3a19 100644 --- a/Documentation/virtual/kvm/api.txt +++ b/Documentation/virtual/kvm/api.txt @@ -777,6 +777,17 @@ Gets the current timestamp of kvmclock as seen by the current guest. In conjunction with KVM_SET_CLOCK, it is used to ensure monotonicity on scenarios such as migration. +When KVM_CAP_ADJUST_CLOCK is passed to KVM_CHECK_EXTENSION, it returns the +set of bits that KVM can return in struct kvm_clock_data's flag member. + +The only flag defined now is KVM_CLOCK_TSC_STABLE. If set, the returned +value is the exact kvmclock value seen by all VCPUs at the instant +when KVM_GET_CLOCK was called. If clear, the returned value is simply +CLOCK_MONOTONIC plus a constant offset; the offset can be modified +with KVM_SET_CLOCK. KVM will try to make all VCPUs follow this clock, +but the exact value read by each VCPU could differ, because the host +TSC is not stable. + struct kvm_clock_data { __u64 clock; /* kvmclock current value */ __u32 flags; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 2f27af4f312a..3320804bb2ac 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -2610,7 +2610,6 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) case KVM_CAP_PIT_STATE2: case KVM_CAP_SET_IDENTITY_MAP_ADDR: case KVM_CAP_XEN_HVM: - case KVM_CAP_ADJUST_CLOCK: case KVM_CAP_VCPU_EVENTS: case KVM_CAP_HYPERV: case KVM_CAP_HYPERV_VAPIC: @@ -2637,6 +2636,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) #endif r = 1; break; + case KVM_CAP_ADJUST_CLOCK: + r = KVM_CLOCK_TSC_STABLE; + break; case KVM_CAP_X86_SMM: /* SMBASE is usually relocated above 1M on modern chipsets, * and SMM handlers might indeed rely on 4G segment limits, @@ -4117,9 +4119,11 @@ long kvm_arch_vm_ioctl(struct file *filp, struct kvm_clock_data user_ns; u64 now_ns; - now_ns = get_kvmclock_ns(kvm); + local_irq_disable(); + now_ns = __get_kvmclock_ns(kvm); user_ns.clock = now_ns; - user_ns.flags = 0; + user_ns.flags = kvm->arch.use_master_clock ? KVM_CLOCK_TSC_STABLE : 0; + local_irq_enable(); memset(&user_ns.pad, 0, sizeof(user_ns.pad)); r = -EFAULT; diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 300ef255d1e0..4ee67cb99143 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -972,12 +972,19 @@ struct kvm_irqfd { __u8 pad[16]; }; +/* For KVM_CAP_ADJUST_CLOCK */ + +/* Do not use 1, KVM_CHECK_EXTENSION returned it before we had flags. */ +#define KVM_CLOCK_TSC_STABLE 2 + struct kvm_clock_data { __u64 clock; __u32 flags; __u32 pad[9]; }; +/* For KVM_CAP_SW_TLB */ + #define KVM_MMU_FSL_BOOKE_NOHV 0 #define KVM_MMU_FSL_BOOKE_HV 1 |