KVM: X86: Implement userspace interface to set virtual_tsc_khz
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>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 579ce34..1d5a7f4 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -87,6 +87,11 @@
int ignore_msrs = 0;
module_param_named(ignore_msrs, ignore_msrs, bool, S_IRUGO | S_IWUSR);
+bool kvm_has_tsc_control;
+EXPORT_SYMBOL_GPL(kvm_has_tsc_control);
+u32 kvm_max_guest_tsc_khz;
+EXPORT_SYMBOL_GPL(kvm_max_guest_tsc_khz);
+
#define KVM_NR_SHARED_MSRS 16
struct kvm_shared_msrs_global {
@@ -1986,6 +1991,7 @@
case KVM_CAP_X86_ROBUST_SINGLESTEP:
case KVM_CAP_XSAVE:
case KVM_CAP_ASYNC_PF:
+ case KVM_CAP_GET_TSC_KHZ:
r = 1;
break;
case KVM_CAP_COALESCED_MMIO:
@@ -2012,6 +2018,9 @@
case KVM_CAP_XCRS:
r = cpu_has_xsave;
break;
+ case KVM_CAP_TSC_CONTROL:
+ r = kvm_has_tsc_control;
+ break;
default:
r = 0;
break;
@@ -3045,6 +3054,32 @@
r = kvm_vcpu_ioctl_x86_set_xcrs(vcpu, u.xcrs);
break;
}
+ case KVM_SET_TSC_KHZ: {
+ u32 user_tsc_khz;
+
+ r = -EINVAL;
+ if (!kvm_has_tsc_control)
+ break;
+
+ user_tsc_khz = (u32)arg;
+
+ if (user_tsc_khz >= kvm_max_guest_tsc_khz)
+ goto out;
+
+ kvm_x86_ops->set_tsc_khz(vcpu, user_tsc_khz);
+
+ r = 0;
+ goto out;
+ }
+ case KVM_GET_TSC_KHZ: {
+ r = -EIO;
+ if (check_tsc_unstable())
+ goto out;
+
+ r = vcpu_tsc_khz(vcpu);
+
+ goto out;
+ }
default:
r = -EINVAL;
}