UMWAIT and TPAUSE instructions use 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/power/umwait.c caches the MSR value, so this patch uses it to avoid frequently rdmsr of IA32_UMWAIT_CONTROL. Co-developed-by: Jingqi Liu <jingqi.liu@xxxxxxxxx> Signed-off-by: Jingqi Liu <jingqi.liu@xxxxxxxxx> Signed-off-by: Tao Xu <tao3.xu@xxxxxxxxx> --- Changes in v6: add check msr_info->host_initiated in get/set msr(Xiaoyao) restore the atomic_switch_umwait_control_msr()(Xiaoyao) rebase the patch because the kernel dependcy patch updated to v5: https://lkml.org/lkml/2019/6/19/972 --- arch/x86/kernel/cpu/umwait.c | 3 ++- arch/x86/kvm/vmx/vmx.c | 33 +++++++++++++++++++++++++++++++++ arch/x86/kvm/vmx/vmx.h | 3 +++ arch/x86/kvm/x86.c | 1 + 4 files changed, 39 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/cpu/umwait.c b/arch/x86/kernel/cpu/umwait.c index 4b2aff7b2d4d..db5c193ef136 100644 --- a/arch/x86/kernel/cpu/umwait.c +++ b/arch/x86/kernel/cpu/umwait.c @@ -15,7 +15,8 @@ * MSR value. By default, umwait max time is 100000 in TSC-quanta and C0.2 * is enabled */ -static u32 umwait_control_cached = UMWAIT_CTRL_VAL(100000, UMWAIT_C02_ENABLED); +u32 umwait_control_cached = UMWAIT_CTRL_VAL(100000, UMWAIT_C02_ENABLED); +EXPORT_SYMBOL_GPL(umwait_control_cached); /* * Serialize access to umwait_control_cached and IA32_UMWAIT_CONTROL MSR diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index b35bfac30a34..0d81cb9b96cf 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -1679,6 +1679,13 @@ 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 && + !guest_cpuid_has(vcpu, X86_FEATURE_WAITPKG)) + 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)) @@ -1841,6 +1848,17 @@ 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 && + !guest_cpuid_has(vcpu, X86_FEATURE_WAITPKG)) + return 1; + + /* The reserved bit IA32_UMWAIT_CONTROL[1] should be zero */ + if (data & BIT_ULL(1)) + 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)) @@ -4126,6 +4144,8 @@ 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); @@ -6339,6 +6359,16 @@ 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) +{ + if (vmx->msr_ia32_umwait_control != umwait_control_cached) + add_atomic_switch_msr(vmx, MSR_IA32_UMWAIT_CONTROL, + vmx->msr_ia32_umwait_control, + umwait_control_cached, 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); @@ -6447,6 +6477,9 @@ static void vmx_vcpu_run(struct kvm_vcpu *vcpu) atomic_switch_perf_msrs(vmx); + if (guest_cpuid_has(vcpu, X86_FEATURE_WAITPKG)) + 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..8485bec7c38a 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 umwait_control_cached; + #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; + u64 msr_ia32_umwait_control; u32 vm_entry_controls_shadow; u32 vm_exit_controls_shadow; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 83aefd759846..4480de459bf4 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1138,6 +1138,7 @@ 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
