This was tested by booting a nested guest with TSC=1Ghz,
observing the clocks, and doing about 100 cycles of migration.
Note that qemu patch is needed to support migration because
of a new MSR that needs to be placed in the migration state.
The patch will be sent to the qemu mailing list soon.
Signed-off-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
---
arch/x86/kvm/svm/nested.c | 29 +++++++++++++++++++++++++++--
arch/x86/kvm/svm/svm.c | 30 ++++++++++++++++++++++++++++--
arch/x86/kvm/svm/svm.h | 5 +++++
arch/x86/kvm/vmx/vmx.c | 1 +
arch/x86/kvm/x86.c | 1 +
5 files changed, 62 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index 29b5d0f85960..4c26417f36b8 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -572,8 +572,17 @@ static void nested_vmcb02_prepare_control(struct vcpu_svm *svm)
if (nested_npt_enabled(svm))
nested_svm_init_mmu_context(vcpu);
- svm->vmcb->control.tsc_offset = vcpu->arch.tsc_offset =
- vcpu->arch.l1_tsc_offset + svm->nested.ctl.tsc_offset;
+ vcpu->arch.tsc_offset = kvm_calc_nested_tsc_offset(
+ vcpu->arch.l1_tsc_offset,
+ svm->nested.ctl.tsc_offset,
+ svm->tsc_ratio_msr);
+
+ svm->vmcb->control.tsc_offset = vcpu->arch.tsc_offset;
+
+ if (svm->tsc_ratio_msr != kvm_default_tsc_scaling_ratio) {
+ WARN_ON(!svm->tsc_scaling_enabled);
+ nested_svm_update_tsc_ratio_msr(vcpu);
+ }
svm->vmcb->control.int_ctl =
(svm->nested.ctl.int_ctl & int_ctl_vmcb12_bits) |
@@ -872,6 +881,12 @@ int nested_svm_vmexit(struct vcpu_svm *svm)
vmcb_mark_dirty(svm->vmcb, VMCB_INTERCEPTS);
}
+ if (svm->tsc_ratio_msr != kvm_default_tsc_scaling_ratio) {
+ WARN_ON(!svm->tsc_scaling_enabled);
+ vcpu->arch.tsc_scaling_ratio = vcpu->arch.l1_tsc_scaling_ratio;
+ svm_write_tsc_multiplier(vcpu, vcpu->arch.tsc_scaling_ratio);
+ }
+
svm->nested.ctl.nested_cr3 = 0;
/*
@@ -1259,6 +1274,16 @@ int nested_svm_exit_special(struct vcpu_svm *svm)
return NESTED_EXIT_CONTINUE;
}
+void nested_svm_update_tsc_ratio_msr(struct kvm_vcpu *vcpu)
+{
+ struct vcpu_svm *svm = to_svm(vcpu);
+
+ vcpu->arch.tsc_scaling_ratio =
+ kvm_calc_nested_tsc_multiplier(vcpu->arch.l1_tsc_scaling_ratio,
+ svm->tsc_ratio_msr);
+ svm_write_tsc_multiplier(vcpu, vcpu->arch.tsc_scaling_ratio);
+}
+
static int svm_get_nested_state(struct kvm_vcpu *vcpu,
struct kvm_nested_state __user *user_kvm_nested_state,
u32 user_data_size)
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 001a5af842ba..0b797351cfb9 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -1023,6 +1023,9 @@ static __init void svm_set_cpu_caps(void)
if (vls)
kvm_cpu_cap_set(X86_FEATURE_V_VMSAVE_VMLOAD);
+ if (tsc_scaling)
+ kvm_cpu_cap_set(X86_FEATURE_TSCRATEMSR);
+
/* Nested VM can receive #VMEXIT instead of triggering #GP */
kvm_cpu_cap_set(X86_FEATURE_SVME_ADDR_CHK);
}
@@ -1215,7 +1218,9 @@ static u64 svm_get_l2_tsc_offset(struct kvm_vcpu *vcpu)
static u64 svm_get_l2_tsc_multiplier(struct kvm_vcpu *vcpu)
{
- return kvm_default_tsc_scaling_ratio;
+ struct vcpu_svm *svm = to_svm(vcpu);
+
+ return svm->tsc_ratio_msr;
}
static void svm_write_tsc_offset(struct kvm_vcpu *vcpu, u64 offset)
@@ -1227,7 +1232,7 @@ static void svm_write_tsc_offset(struct kvm_vcpu *vcpu, u64 offset)
vmcb_mark_dirty(svm->vmcb, VMCB_INTERCEPTS);
}
-static void svm_write_tsc_multiplier(struct kvm_vcpu *vcpu, u64 multiplier)
+void svm_write_tsc_multiplier(struct kvm_vcpu *vcpu, u64 multiplier)
{
wrmsrl(MSR_AMD64_TSC_RATIO, multiplier);
}
@@ -1405,6 +1410,7 @@ static void init_vmcb(struct kvm_vcpu *vcpu)
enable_gif(svm);
+ svm->tsc_ratio_msr = kvm_default_tsc_scaling_ratio;
}
static void svm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
@@ -2765,6 +2771,11 @@ static int svm_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
struct vcpu_svm *svm = to_svm(vcpu);
switch (msr_info->index) {
+ case MSR_AMD64_TSC_RATIO:
+ if (!msr_info->host_initiated && !svm->tsc_scaling_enabled)
+ return 1;
+ msr_info->data = svm->tsc_ratio_msr;
+ break;
case MSR_STAR:
msr_info->data = svm->vmcb01.ptr->save.star;
break;
@@ -2901,6 +2912,19 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr)
u32 ecx = msr->index;
u64 data = msr->data;
switch (ecx) {
+ case MSR_AMD64_TSC_RATIO:
+ if (!msr->host_initiated && !svm->tsc_scaling_enabled)
+ return 1;
+
+ if (data & TSC_RATIO_RSVD)
+ return 1;
+
+ svm->tsc_ratio_msr = data;
+
+ if (svm->tsc_scaling_enabled && is_guest_mode(vcpu))
+ nested_svm_update_tsc_ratio_msr(vcpu);
+
+ break;
case MSR_IA32_CR_PAT:
if (!kvm_mtrr_valid(vcpu, MSR_IA32_CR_PAT, data))
return 1;
@@ -4107,6 +4131,8 @@ static void svm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
svm->v_vmload_vmsave_enabled = vls && guest_cpuid_has(vcpu, X86_FEATURE_V_VMSAVE_VMLOAD);
+ svm->tsc_scaling_enabled = tsc_scaling && guest_cpuid_has(vcpu, X86_FEATURE_TSCRATEMSR);
+
svm_recalc_instruction_intercepts(vcpu, svm);
/* For sev guests, the memory encryption bit is not reserved in CR3. */
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 029340a7fbcc..c8ea3b14da73 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -140,6 +140,8 @@ struct vcpu_svm {
u64 next_rip;
u64 spec_ctrl;
+
+ u64 tsc_ratio_msr;
/*
* Contains guest-controlled bits of VIRT_SPEC_CTRL, which will be
* translated into the appropriate L2_CFG bits on the host to
@@ -163,6 +165,7 @@ struct vcpu_svm {
bool nrips_enabled : 1;
bool lbrv_enabled : 1;
bool v_vmload_vmsave_enabled : 1;
+ bool tsc_scaling_enabled : 1;
u32 ldr_reg;
u32 dfr_reg;
@@ -491,6 +494,8 @@ int nested_svm_check_permissions(struct kvm_vcpu *vcpu);
int nested_svm_check_exception(struct vcpu_svm *svm, unsigned nr,
bool has_error_code, u32 error_code);
int nested_svm_exit_special(struct vcpu_svm *svm);
+void nested_svm_update_tsc_ratio_msr(struct kvm_vcpu *vcpu);
+void svm_write_tsc_multiplier(struct kvm_vcpu *vcpu, u64 multiplier);
void nested_load_control_from_vmcb12(struct vcpu_svm *svm,
struct vmcb_control_area *control);
void nested_sync_control_from_vmcb02(struct vcpu_svm *svm);
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index fada1055f325..e1d8f0df8172 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6404,6 +6404,7 @@ static bool vmx_has_emulated_msr(struct kvm *kvm, u32 index)
case MSR_IA32_VMX_BASIC ... MSR_IA32_VMX_VMFUNC:
return nested;
case MSR_AMD64_VIRT_SPEC_CTRL:
+ case MSR_AMD64_TSC_RATIO:
/* This is AMD only. */
return false;
default:
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 86539c1686fa..1b7881c7a516 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1374,6 +1374,7 @@ static const u32 emulated_msrs_all[] = {
MSR_PLATFORM_INFO,
MSR_MISC_FEATURES_ENABLES,
MSR_AMD64_VIRT_SPEC_CTRL,
+ MSR_AMD64_TSC_RATIO,
MSR_IA32_POWER_CTL,
MSR_IA32_UCODE_REV,
--
2.26.3
