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KVM: X86: Implement userspace interface to set virtual_tsc_khz

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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>
This commit is contained in:
Joerg Roedel
2011-03-25 09:44:51 +01:00
committed by Avi Kivity
parent 857e40999e
commit 92a1f12d25
5 changed files with 90 additions and 0 deletions
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35
arch/x86/kvm/x86.c
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@@ -87,6 +87,11 @@ EXPORT_SYMBOL_GPL(kvm_x86_ops);
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 @@ int kvm_dev_ioctl_check_extension(long ext)
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 @@ 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;
@@ -3045,6 +3054,32 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
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;
}