The following patch allows to activate a partition reference
time enlightenment that is based on the host platform's support
for an Invariant Time Stamp Counter (iTSC).
v2 -> v3
Handle TSC sequence, scale, and offest changing during migration.
v3 -> v4
1. Wrap access to iTSC page with kvm_read_guest/kvm_write_guest
suggested by Andrew Honig <ahonig@xxxxxxxxxx> and Marcelo
2. iTSC data calculation/access fixes suggested by Marcelo and Paolo
---
arch/x86/kvm/x86.c | 29 +++++++++++++++++++++++++++++
1 file changed, 29 insertions(+)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 496bdb1..6e6debf 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1873,6 +1873,7 @@ static int set_msr_hyperv_pw(struct kvm_vcpu *vcpu, u32 msr, u64 data)
case HV_X64_MSR_REFERENCE_TSC: {
u64 gfn;
unsigned long addr;
+ struct kvm_arch *ka = &kvm->arch;
HV_REFERENCE_TSC_PAGE tsc_ref;
memset(&tsc_ref, 0, sizeof(tsc_ref));
if (!(data & HV_X64_MSR_TSC_REFERENCE_ENABLE)) {
@@ -1883,6 +1884,13 @@ static int set_msr_hyperv_pw(struct kvm_vcpu *vcpu, u32 msr, u64 data)
addr = gfn_to_hva(kvm, gfn);
if (kvm_is_error_hva(addr))
return 1;
+ if (boot_cpu_has(X86_FEATURE_CONSTANT_TSC)
+ && ka->use_master_clock) {
+ tsc_ref.tsc_sequence = 1;
+ tsc_ref.tsc_scale = ((10000LL << 32) /
+ vcpu->arch.virtual_tsc_khz) << 32;
+ tsc_ref.tsc_offset = kvm->arch.kvmclock_offset;
+ }
if (__copy_to_user((void __user *)addr, &tsc_ref, sizeof(tsc_ref)))
return 1;
mark_page_dirty(kvm, gfn);
@@ -3871,6 +3879,27 @@ long kvm_arch_vm_ioctl(struct file *filp,
local_irq_enable();
kvm->arch.kvmclock_offset = delta;
kvm_gen_update_masterclock(kvm);
+ if (kvm->arch.hv_tsc_page & HV_X64_MSR_TSC_REFERENCE_ENABLE) {
+ HV_REFERENCE_TSC_PAGE tsc_ref;
+ struct kvm_arch *ka = &kvm->arch;
+ r = kvm_read_guest(kvm, kvm->arch.hv_tsc_page,
+ &tsc_ref, sizeof(tsc_ref));
+ if (r)
+ goto out;
+ if (tsc_ref.tsc_sequence
+ && boot_cpu_has(X86_FEATURE_CONSTANT_TSC)
+ && ka->use_master_clock) {
+ tsc_ref.tsc_sequence++;
+ tsc_ref.tsc_scale = ((10000LL << 32) /
+ __get_cpu_var(cpu_tsc_khz)) << 32;
+ tsc_ref.tsc_offset = kvm->arch.kvmclock_offset;
+ } else
+ tsc_ref.tsc_sequence = 0;
+ r = kvm_write_guest(kvm, kvm->arch.hv_tsc_page,
+ &tsc_ref, sizeof(tsc_ref));
+ if (r)
+ goto out;
+ }
break;
}
case KVM_GET_CLOCK: {
--
1.8.1.4
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