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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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20
arch/x86/kvm/svm.c
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@@ -64,6 +64,8 @@ MODULE_LICENSE("GPL");
#define DEBUGCTL_RESERVED_BITS (~(0x3fULL))
#define TSC_RATIO_RSVD 0xffffff0000000000ULL
#define TSC_RATIO_MIN 0x0000000000000001ULL
#define TSC_RATIO_MAX 0x000000ffffffffffULL
static bool erratum_383_found __read_mostly;
@@ -189,6 +191,7 @@ static int nested_svm_intercept(struct vcpu_svm *svm);
static int nested_svm_vmexit(struct vcpu_svm *svm);
static int nested_svm_check_exception(struct vcpu_svm *svm, unsigned nr,
bool has_error_code, u32 error_code);
static u64 __scale_tsc(u64 ratio, u64 tsc);
enum {
VMCB_INTERCEPTS, /* Intercept vectors, TSC offset,
@@ -798,6 +801,23 @@ 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)) {
u64 max;
kvm_has_tsc_control = true;
/*
* Make sure the user can only configure tsc_khz values that
* fit into a signed integer.
* A min value is not calculated needed because it will always
* be 1 on all machines and a value of 0 is used to disable
* tsc-scaling for the vcpu.
*/
max = min(0x7fffffffULL, __scale_tsc(tsc_khz, TSC_RATIO_MAX));
kvm_max_guest_tsc_khz = max;
}
if (nested) {
printk(KERN_INFO "kvm: Nested Virtualization enabled\n");
kvm_enable_efer_bits(EFER_SVME | EFER_LMSLE);