UMWAIT and TPAUSE instructions use 32bit IA32_UMWAIT_CONTROL at MSR index E1H to determines the maximum time in TSC-quanta that the processor can reside in either C0.1 or C0.2.
This patch emulates MSR IA32_UMWAIT_CONTROL in guest and differentiate IA32_UMWAIT_CONTROL between host and guest. The variable mwait_control_cached in arch/x86/kernel/cpu/umwait.c caches the MSR value, so this patch uses it to avoid frequently rdmsr of IA32_UMWAIT_CONTROL. Co-developed-by: Jingqi Liu <[email protected]> Signed-off-by: Jingqi Liu <[email protected]> Signed-off-by: Tao Xu <[email protected]> --- Changes in v8: - Add an accessor to expose umwait_control_cached (Sean) - Set msr_ia32_umwait_control in vcpu_vmx u32 and raise #GP when [63:32] is set when rdmsr. (Sean) --- arch/x86/kernel/cpu/umwait.c | 6 ++++++ arch/x86/kvm/vmx/vmx.c | 37 ++++++++++++++++++++++++++++++++++++ arch/x86/kvm/vmx/vmx.h | 9 +++++++++ arch/x86/kvm/x86.c | 1 + 4 files changed, 53 insertions(+) diff --git a/arch/x86/kernel/cpu/umwait.c b/arch/x86/kernel/cpu/umwait.c index 6a204e7336c1..e7344be24a74 100644 --- a/arch/x86/kernel/cpu/umwait.c +++ b/arch/x86/kernel/cpu/umwait.c @@ -17,6 +17,12 @@ */ static u32 umwait_control_cached = UMWAIT_CTRL_VAL(100000, UMWAIT_C02_ENABLE); +u32 get_umwait_control_msr(void) +{ + return umwait_control_cached; +} +EXPORT_SYMBOL_GPL(get_umwait_control_msr); + /* * Serialize access to umwait_control_cached and IA32_UMWAIT_CONTROL MSR in * the sysfs write functions. diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index d4ee22ff7ccc..0224b087aad3 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -1676,6 +1676,12 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) #endif case MSR_EFER: return kvm_get_msr_common(vcpu, msr_info); + case MSR_IA32_UMWAIT_CONTROL: + if (!msr_info->host_initiated && !vmx_has_waitpkg(vmx)) + return 1; + + msr_info->data = vmx->msr_ia32_umwait_control; + break; case MSR_IA32_SPEC_CTRL: if (!msr_info->host_initiated && !guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL)) @@ -1838,6 +1844,16 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) return 1; vmcs_write64(GUEST_BNDCFGS, data); break; + case MSR_IA32_UMWAIT_CONTROL: + if (!msr_info->host_initiated && !vmx_has_waitpkg(vmx)) + return 1; + + /* The reserved bit 1 and non-32 bit [63:32] should be zero */ + if (data & (BIT_ULL(1) | GENMASK_ULL(63, 32))) + return 1; + + vmx->msr_ia32_umwait_control = data; + break; case MSR_IA32_SPEC_CTRL: if (!msr_info->host_initiated && !guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL)) @@ -4137,6 +4153,8 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) vmx->rmode.vm86_active = 0; vmx->spec_ctrl = 0; + vmx->msr_ia32_umwait_control = 0; + vcpu->arch.microcode_version = 0x100000000ULL; vmx->vcpu.arch.regs[VCPU_REGS_RDX] = get_rdx_init_val(); kvm_set_cr8(vcpu, 0); @@ -6350,6 +6368,23 @@ static void atomic_switch_perf_msrs(struct vcpu_vmx *vmx) msrs[i].host, false); } +static void atomic_switch_umwait_control_msr(struct vcpu_vmx *vmx) +{ + u32 host_umwait_control; + + if (!vmx_has_waitpkg(vmx)) + return; + + host_umwait_control = get_umwait_control_msr(); + + if (vmx->msr_ia32_umwait_control != host_umwait_control) + add_atomic_switch_msr(vmx, MSR_IA32_UMWAIT_CONTROL, + vmx->msr_ia32_umwait_control, + host_umwait_control, false); + else + clear_atomic_switch_msr(vmx, MSR_IA32_UMWAIT_CONTROL); +} + static void vmx_arm_hv_timer(struct vcpu_vmx *vmx, u32 val) { vmcs_write32(VMX_PREEMPTION_TIMER_VALUE, val); @@ -6458,6 +6493,8 @@ static void vmx_vcpu_run(struct kvm_vcpu *vcpu) atomic_switch_perf_msrs(vmx); + atomic_switch_umwait_control_msr(vmx); + vmx_update_hv_timer(vcpu); /* diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h index 61128b48c503..8e4869322eff 100644 --- a/arch/x86/kvm/vmx/vmx.h +++ b/arch/x86/kvm/vmx/vmx.h @@ -14,6 +14,8 @@ extern const u32 vmx_msr_index[]; extern u64 host_efer; +extern u32 get_umwait_control_msr(void); + #define MSR_TYPE_R 1 #define MSR_TYPE_W 2 #define MSR_TYPE_RW 3 @@ -194,6 +196,7 @@ struct vcpu_vmx { #endif u64 spec_ctrl; + u32 msr_ia32_umwait_control; u32 vm_entry_controls_shadow; u32 vm_exit_controls_shadow; @@ -523,6 +526,12 @@ static inline void decache_tsc_multiplier(struct vcpu_vmx *vmx) vmcs_write64(TSC_MULTIPLIER, vmx->current_tsc_ratio); } +static inline bool vmx_has_waitpkg(struct vcpu_vmx *vmx) +{ + return vmx->secondary_exec_control & + SECONDARY_EXEC_ENABLE_USR_WAIT_PAUSE; +} + void dump_vmcs(void); #endif /* __KVM_X86_VMX_H */ diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 63bb1ee8258e..e914e4d03cce 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1136,6 +1136,7 @@ static u32 msrs_to_save[] = { MSR_IA32_RTIT_ADDR1_A, MSR_IA32_RTIT_ADDR1_B, MSR_IA32_RTIT_ADDR2_A, MSR_IA32_RTIT_ADDR2_B, MSR_IA32_RTIT_ADDR3_A, MSR_IA32_RTIT_ADDR3_B, + MSR_IA32_UMWAIT_CONTROL, }; static unsigned num_msrs_to_save; -- 2.20.1
