[RFC PATCH 2/2] Hyper-V iTSC handler

Vadim Rozenfeld
2013-05-13T11:45:46Z

Signed-off: Vadim Rozenfeld <vrozenfe@redhat.com>

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).
NOTE: This code will survive migration due to lack of VM stop/resume
handlers.

---
arch/x86/include/uapi/asm/hyperv.h | 10 ++++++++++
arch/x86/kvm/x86.c | 18 +++++++++++++-----
include/uapi/linux/kvm.h | 1 +
3 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/arch/x86/include/uapi/asm/hyperv.h b/arch/x86/include/uapi/asm/hyperv.h
index 9711819..2d9e666 100644
--- a/arch/x86/include/uapi/asm/hyperv.h
+++ b/arch/x86/include/uapi/asm/hyperv.h
@@ -182,6 +182,9 @@
#define HV_X64_MSR_APIC_ASSIST_PAGE_ADDRESS_MASK \
(~((1ull << HV_X64_MSR_APIC_ASSIST_PAGE_ADDRESS_SHIFT) - 1))

+#define HV_X64_MSR_TSC_REFERENCE_ENABLE 0x00000001
+#define HV_X64_MSR_TSC_REFERENCE_ADDRESS_SHIFT 12
+
#define HV_PROCESSOR_POWER_STATE_C0 0
#define HV_PROCESSOR_POWER_STATE_C1 1
#define HV_PROCESSOR_POWER_STATE_C2 2
@@ -194,4 +197,11 @@
#define HV_STATUS_INVALID_ALIGNMENT 4
#define HV_STATUS_INSUFFICIENT_BUFFERS 19

+typedef struct _HV_REFERENCE_TSC_PAGE {
+ uint32_t TscSequence;
+ uint32_t Rserved1;
+ uint64_t TscScale;
+ int64_t TscOffset;
+} HV_REFERENCE_TSC_PAGE, * PHV_REFERENCE_TSC_PAGE;
+
#endif
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 1a4036d..5788e8f 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1809,14 +1809,21 @@ static int set_msr_hyperv_pw(struct kvm_vcpu *vcpu, u32 msr, u64 data)
break;
}
case HV_X64_MSR_REFERENCE_TSC: {
- u64 gfn;
unsigned long addr;
- u32 tsc_ref;
- gfn = data >> HV_X64_MSR_HYPERCALL_PAGE_ADDRESS_SHIFT;
- addr = gfn_to_hva(kvm, gfn);
+ HV_REFERENCE_TSC_PAGE tsc_ref;
+ tsc_ref.TscSequence =
+ boot_cpu_has(X86_FEATURE_CONSTANT_TSC) ? 1 : 0;
+ tsc_ref.TscScale =
+ ((10000LL << 32) /vcpu->arch.virtual_tsc_khz) << 32;
+ tsc_ref.TscOffset = 0;
+ if (!(data & HV_X64_MSR_TSC_REFERENCE_ENABLE)) {
+ kvm->arch.hv_tsc_page = data;
+ break;
+ }
+ addr = gfn_to_hva(vcpu->kvm, data >>
+ HV_X64_MSR_TSC_REFERENCE_ADDRESS_SHIFT);
if (kvm_is_error_hva(addr))
return 1;
- tsc_ref = 0;
if(__copy_to_user((void __user *)addr, &tsc_ref, sizeof(tsc_ref)))
return 1;
kvm->arch.hv_tsc_page = data;
@@ -2553,6 +2560,7 @@ int kvm_dev_ioctl_check_extension(long ext)
case KVM_CAP_HYPERV:
case KVM_CAP_HYPERV_VAPIC:
case KVM_CAP_HYPERV_SPIN:
+ case KVM_CAP_HYPERV_TSC:
case KVM_CAP_PCI_SEGMENT:
case KVM_CAP_DEBUGREGS:
case KVM_CAP_X86_ROBUST_SINGLESTEP:
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index a5c86fc..8eff540 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -666,6 +666,7 @@ struct kvm_ppc_smmu_info {
#define KVM_CAP_IRQ_MPIC 90
#define KVM_CAP_PPC_RTAS 91
#define KVM_CAP_IRQ_XICS 92
+#define KVM_CAP_HYPERV_TSC 93

#ifdef KVM_CAP_IRQ_ROUTING

--
1.8.1.2