diff options
| -rw-r--r-- | Documentation/virtual/kvm/api.txt | 9 | ||||
| -rw-r--r-- | arch/x86/kvm/svm.c | 7 | ||||
| -rw-r--r-- | arch/x86/kvm/vmx.c | 6 | ||||
| -rw-r--r-- | arch/x86/kvm/x86.c | 3 | ||||
| -rw-r--r-- | arch/x86/kvm/x86.h | 36 | ||||
| -rw-r--r-- | include/uapi/linux/kvm.h | 1 |
6 files changed, 58 insertions, 4 deletions
diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt index e60be91d8036..dc674c2b8b31 100644 --- a/Documentation/virtual/kvm/api.txt +++ b/Documentation/virtual/kvm/api.txt @@ -4111,3 +4111,12 @@ reserved. 2: MIPS64 or microMIPS64 with access to all address segments. Both registers and addresses are 64-bits wide. It will be possible to run 64-bit or 32-bit guest code. + +8.8 KVM_CAP_X86_GUEST_MWAIT + +Architectures: x86 + +This capability indicates that guest using memory monotoring instructions +(MWAIT/MWAITX) to stop the virtual CPU will not cause a VM exit. As such time +spent while virtual CPU is halted in this way will then be accounted for as +guest running time on the host (as opposed to e.g. HLT). diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index 1b203abf76e1..c41f03e5090a 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -1198,10 +1198,13 @@ static void init_vmcb(struct vcpu_svm *svm) set_intercept(svm, INTERCEPT_CLGI); set_intercept(svm, INTERCEPT_SKINIT); set_intercept(svm, INTERCEPT_WBINVD); - set_intercept(svm, INTERCEPT_MONITOR); - set_intercept(svm, INTERCEPT_MWAIT); set_intercept(svm, INTERCEPT_XSETBV); + if (!kvm_mwait_in_guest()) { + set_intercept(svm, INTERCEPT_MONITOR); + set_intercept(svm, INTERCEPT_MWAIT); + } + control->iopm_base_pa = iopm_base; control->msrpm_base_pa = __pa(svm->msrpm); control->int_ctl = V_INTR_MASKING_MASK; diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index c1a12b94e1fd..a4ef63718101 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -3527,11 +3527,13 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf) CPU_BASED_USE_IO_BITMAPS | CPU_BASED_MOV_DR_EXITING | CPU_BASED_USE_TSC_OFFSETING | - CPU_BASED_MWAIT_EXITING | - CPU_BASED_MONITOR_EXITING | CPU_BASED_INVLPG_EXITING | CPU_BASED_RDPMC_EXITING; + if (!kvm_mwait_in_guest()) + min |= CPU_BASED_MWAIT_EXITING | + CPU_BASED_MONITOR_EXITING; + opt = CPU_BASED_TPR_SHADOW | CPU_BASED_USE_MSR_BITMAPS | CPU_BASED_ACTIVATE_SECONDARY_CONTROLS; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 49a69c0a0d50..2f9fe6bf7091 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -2687,6 +2687,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) case KVM_CAP_ADJUST_CLOCK: r = KVM_CLOCK_TSC_STABLE; break; + case KVM_CAP_X86_GUEST_MWAIT: + r = kvm_mwait_in_guest(); + break; case KVM_CAP_X86_SMM: /* SMBASE is usually relocated above 1M on modern chipsets, * and SMM handlers might indeed rely on 4G segment limits, diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h index e8ff3e4ce38a..612067074905 100644 --- a/arch/x86/kvm/x86.h +++ b/arch/x86/kvm/x86.h @@ -1,6 +1,8 @@ #ifndef ARCH_X86_KVM_X86_H #define ARCH_X86_KVM_X86_H +#include <asm/processor.h> +#include <asm/mwait.h> #include <linux/kvm_host.h> #include <asm/pvclock.h> #include "kvm_cache_regs.h" @@ -212,4 +214,38 @@ static inline u64 nsec_to_cycles(struct kvm_vcpu *vcpu, u64 nsec) __rem; \ }) +static inline bool kvm_mwait_in_guest(void) +{ + unsigned int eax, ebx, ecx, edx; + + if (!cpu_has(&boot_cpu_data, X86_FEATURE_MWAIT)) + return false; + + switch (boot_cpu_data.x86_vendor) { + case X86_VENDOR_AMD: + /* All AMD CPUs have a working MWAIT implementation */ + return true; + case X86_VENDOR_INTEL: + /* Handle Intel below */ + break; + default: + return false; + } + + /* + * Intel CPUs without CPUID5_ECX_INTERRUPT_BREAK are problematic as + * they would allow guest to stop the CPU completely by disabling + * interrupts then invoking MWAIT. + */ + if (boot_cpu_data.cpuid_level < CPUID_MWAIT_LEAF) + return false; + + cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &edx); + + if (!(ecx & CPUID5_ECX_INTERRUPT_BREAK)) + return false; + + return true; +} + #endif diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 3c168b6fd74b..e43906b95d9f 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -893,6 +893,7 @@ struct kvm_ppc_resize_hpt { #define KVM_CAP_S390_GS 140 #define KVM_CAP_S390_AIS 141 #define KVM_CAP_SPAPR_TCE_VFIO 142 +#define KVM_CAP_X86_GUEST_MWAIT 143 #ifdef KVM_CAP_IRQ_ROUTING |