3 files changed, 121 insertions, 0 deletions

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 68ac06fef4fa..88f0326c184a 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1095,6 +1095,7 @@ struct kvm_arch {
 	u64 last_tsc_nsec;
 	u64 last_tsc_write;
 	u32 last_tsc_khz;
+	u64 last_tsc_offset;
 	u64 cur_tsc_nsec;
 	u64 cur_tsc_write;
 	u64 cur_tsc_offset;
diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h
index 2ef1f6513c68..5a776a08f78c 100644
--- a/arch/x86/include/uapi/asm/kvm.h
+++ b/arch/x86/include/uapi/asm/kvm.h
@@ -504,4 +504,8 @@ struct kvm_pmu_event_filter {
 #define KVM_PMU_EVENT_ALLOW 0
 #define KVM_PMU_EVENT_DENY 1
 
+/* for KVM_{GET,SET,HAS}_DEVICE_ATTR */
+#define KVM_VCPU_TSC_CTRL 0 /* control group for the timestamp counter (TSC) */
+#define   KVM_VCPU_TSC_OFFSET 0 /* attribute for the TSC offset */
+
 #endif /* _ASM_X86_KVM_H */
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index c74a44f2a38c..afdc5d186c50 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2454,6 +2454,7 @@ static void __kvm_synchronize_tsc(struct kvm_vcpu *vcpu, u64 offset, u64 tsc,
 	kvm->arch.last_tsc_nsec = ns;
 	kvm->arch.last_tsc_write = tsc;
 	kvm->arch.last_tsc_khz = vcpu->arch.virtual_tsc_khz;
+	kvm->arch.last_tsc_offset = offset;
 
 	vcpu->arch.last_guest_tsc = tsc;
 
@@ -4054,6 +4055,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 	case KVM_CAP_VM_COPY_ENC_CONTEXT_FROM:
 	case KVM_CAP_SREGS2:
 	case KVM_CAP_EXIT_ON_EMULATION_FAILURE:
+	case KVM_CAP_VCPU_ATTRIBUTES:
 		r = 1;
 		break;
 	case KVM_CAP_EXIT_HYPERCALL:
@@ -4918,6 +4920,115 @@ static int kvm_set_guest_paused(struct kvm_vcpu *vcpu)
 	return 0;
 }
 
+static int kvm_arch_tsc_has_attr(struct kvm_vcpu *vcpu,
+				 struct kvm_device_attr *attr)
+{
+	int r;
+
+	switch (attr->attr) {
+	case KVM_VCPU_TSC_OFFSET:
+		r = 0;
+		break;
+	default:
+		r = -ENXIO;
+	}
+
+	return r;
+}
+
+static int kvm_arch_tsc_get_attr(struct kvm_vcpu *vcpu,
+				 struct kvm_device_attr *attr)
+{
+	u64 __user *uaddr = (u64 __user *)(unsigned long)attr->addr;
+	int r;
+
+	if ((u64)(unsigned long)uaddr != attr->addr)
+		return -EFAULT;
+
+	switch (attr->attr) {
+	case KVM_VCPU_TSC_OFFSET:
+		r = -EFAULT;
+		if (put_user(vcpu->arch.l1_tsc_offset, uaddr))
+			break;
+		r = 0;
+		break;
+	default:
+		r = -ENXIO;
+	}
+
+	return r;
+}
+
+static int kvm_arch_tsc_set_attr(struct kvm_vcpu *vcpu,
+				 struct kvm_device_attr *attr)
+{
+	u64 __user *uaddr = (u64 __user *)(unsigned long)attr->addr;
+	struct kvm *kvm = vcpu->kvm;
+	int r;
+
+	if ((u64)(unsigned long)uaddr != attr->addr)
+		return -EFAULT;
+
+	switch (attr->attr) {
+	case KVM_VCPU_TSC_OFFSET: {
+		u64 offset, tsc, ns;
+		unsigned long flags;
+		bool matched;
+
+		r = -EFAULT;
+		if (get_user(offset, uaddr))
+			break;
+
+		raw_spin_lock_irqsave(&kvm->arch.tsc_write_lock, flags);
+
+		matched = (vcpu->arch.virtual_tsc_khz &&
+			   kvm->arch.last_tsc_khz == vcpu->arch.virtual_tsc_khz &&
+			   kvm->arch.last_tsc_offset == offset);
+
+		tsc = kvm_scale_tsc(vcpu, rdtsc(), vcpu->arch.l1_tsc_scaling_ratio) + offset;
+		ns = get_kvmclock_base_ns();
+
+		__kvm_synchronize_tsc(vcpu, offset, tsc, ns, matched);
+		raw_spin_unlock_irqrestore(&kvm->arch.tsc_write_lock, flags);
+
+		r = 0;
+		break;
+	}
+	default:
+		r = -ENXIO;
+	}
+
+	return r;
+}
+
+static int kvm_vcpu_ioctl_device_attr(struct kvm_vcpu *vcpu,
+				      unsigned int ioctl,
+				      void __user *argp)
+{
+	struct kvm_device_attr attr;
+	int r;
+
+	if (copy_from_user(&attr, argp, sizeof(attr)))
+		return -EFAULT;
+
+	if (attr.group != KVM_VCPU_TSC_CTRL)
+		return -ENXIO;
+
+	switch (ioctl) {
+	case KVM_HAS_DEVICE_ATTR:
+		r = kvm_arch_tsc_has_attr(vcpu, &attr);
+		break;
+	case KVM_GET_DEVICE_ATTR:
+		r = kvm_arch_tsc_get_attr(vcpu, &attr);
+		break;
+	case KVM_SET_DEVICE_ATTR:
+		r = kvm_arch_tsc_set_attr(vcpu, &attr);
+		break;
+	}
+
+	return r;
+}
+
 static int kvm_vcpu_ioctl_enable_cap(struct kvm_vcpu *vcpu,
 				     struct kvm_enable_cap *cap)
 {
@@ -5372,6 +5483,11 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
 		r = __set_sregs2(vcpu, u.sregs2);
 		break;
 	}
+	case KVM_HAS_DEVICE_ATTR:
+	case KVM_GET_DEVICE_ATTR:
+	case KVM_SET_DEVICE_ATTR:
+		r = kvm_vcpu_ioctl_device_attr(vcpu, ioctl, argp);
+		break;
 	default:
 		r = -EINVAL;
 	}