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@redhat.com --- 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,