KVM: X86: Provide a capability to disable HLT intercepts
If host CPUs are dedicated to a VM, we can avoid VM exits on HLT.
This patch adds the per-VM capability to disable them.
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Jan H. Schönherr <jschoenh@amazon.de>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index e2d3050..82055b9 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -135,6 +135,11 @@ int kvm_update_cpuid(struct kvm_vcpu *vcpu)
return -EINVAL;
}
+ best = kvm_find_cpuid_entry(vcpu, KVM_CPUID_FEATURES, 0);
+ if (kvm_hlt_in_guest(vcpu->kvm) && best &&
+ (best->eax & (1 << KVM_FEATURE_PV_UNHALT)))
+ best->eax &= ~(1 << KVM_FEATURE_PV_UNHALT);
+
/* Update physical-address width */
vcpu->arch.maxphyaddr = cpuid_query_maxphyaddr(vcpu);
kvm_mmu_reset_context(vcpu);
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index f6578ce..0f801d8 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1380,7 +1380,6 @@ static void init_vmcb(struct vcpu_svm *svm)
set_intercept(svm, INTERCEPT_RDPMC);
set_intercept(svm, INTERCEPT_CPUID);
set_intercept(svm, INTERCEPT_INVD);
- set_intercept(svm, INTERCEPT_HLT);
set_intercept(svm, INTERCEPT_INVLPG);
set_intercept(svm, INTERCEPT_INVLPGA);
set_intercept(svm, INTERCEPT_IOIO_PROT);
@@ -1403,6 +1402,9 @@ static void init_vmcb(struct vcpu_svm *svm)
set_intercept(svm, INTERCEPT_MWAIT);
}
+ if (!kvm_hlt_in_guest(svm->vcpu.kvm))
+ set_intercept(svm, INTERCEPT_HLT);
+
control->iopm_base_pa = __sme_set(iopm_base);
control->msrpm_base_pa = __sme_set(__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 7cef183..65747d1 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2556,6 +2556,19 @@ static int nested_vmx_check_exception(struct kvm_vcpu *vcpu, unsigned long *exit
return 0;
}
+static void vmx_clear_hlt(struct kvm_vcpu *vcpu)
+{
+ /*
+ * Ensure that we clear the HLT state in the VMCS. We don't need to
+ * explicitly skip the instruction because if the HLT state is set,
+ * then the instruction is already executing and RIP has already been
+ * advanced.
+ */
+ if (kvm_hlt_in_guest(vcpu->kvm) &&
+ vmcs_read32(GUEST_ACTIVITY_STATE) == GUEST_ACTIVITY_HLT)
+ vmcs_write32(GUEST_ACTIVITY_STATE, GUEST_ACTIVITY_ACTIVE);
+}
+
static void vmx_queue_exception(struct kvm_vcpu *vcpu)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
@@ -2586,6 +2599,8 @@ static void vmx_queue_exception(struct kvm_vcpu *vcpu)
intr_info |= INTR_TYPE_HARD_EXCEPTION;
vmcs_write32(VM_ENTRY_INTR_INFO_FIELD, intr_info);
+
+ vmx_clear_hlt(vcpu);
}
static bool vmx_rdtscp_supported(void)
@@ -5545,6 +5560,8 @@ static u32 vmx_exec_control(struct vcpu_vmx *vmx)
if (kvm_mwait_in_guest(vmx->vcpu.kvm))
exec_control &= ~(CPU_BASED_MWAIT_EXITING |
CPU_BASED_MONITOR_EXITING);
+ if (kvm_hlt_in_guest(vmx->vcpu.kvm))
+ exec_control &= ~CPU_BASED_HLT_EXITING;
return exec_control;
}
@@ -5906,6 +5923,8 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
update_exception_bitmap(vcpu);
vpid_sync_context(vmx->vpid);
+ if (init_event)
+ vmx_clear_hlt(vcpu);
}
/*
@@ -5976,6 +5995,8 @@ static void vmx_inject_irq(struct kvm_vcpu *vcpu)
} else
intr |= INTR_TYPE_EXT_INTR;
vmcs_write32(VM_ENTRY_INTR_INFO_FIELD, intr);
+
+ vmx_clear_hlt(vcpu);
}
static void vmx_inject_nmi(struct kvm_vcpu *vcpu)
@@ -6006,6 +6027,8 @@ static void vmx_inject_nmi(struct kvm_vcpu *vcpu)
vmcs_write32(VM_ENTRY_INTR_INFO_FIELD,
INTR_TYPE_NMI_INTR | INTR_INFO_VALID_MASK | NMI_VECTOR);
+
+ vmx_clear_hlt(vcpu);
}
static bool vmx_get_nmi_mask(struct kvm_vcpu *vcpu)
@@ -12347,6 +12370,7 @@ static int vmx_pre_enter_smm(struct kvm_vcpu *vcpu, char *smstate)
vmx->nested.smm.vmxon = vmx->nested.vmxon;
vmx->nested.vmxon = false;
+ vmx_clear_hlt(vcpu);
return 0;
}
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index db95d4d..9e6aaf6 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2878,6 +2878,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
r = KVM_CLOCK_TSC_STABLE;
break;
case KVM_CAP_X86_DISABLE_EXITS:
+ r |= KVM_X86_DISABLE_EXITS_HTL;
if(kvm_can_mwait_in_guest())
r |= KVM_X86_DISABLE_EXITS_MWAIT;
break;
@@ -4232,6 +4233,8 @@ static int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
if ((cap->args[0] & KVM_X86_DISABLE_EXITS_MWAIT) &&
kvm_can_mwait_in_guest())
kvm->arch.mwait_in_guest = true;
+ if (cap->args[0] & KVM_X86_DISABLE_EXITS_HTL)
+ kvm->arch.hlt_in_guest = true;
r = 0;
break;
default:
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index 026b239..6d14589 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -265,11 +265,18 @@ static inline u64 nsec_to_cycles(struct kvm_vcpu *vcpu, u64 nsec)
})
#define KVM_X86_DISABLE_EXITS_MWAIT (1 << 0)
-#define KVM_X86_DISABLE_VALID_EXITS (KVM_X86_DISABLE_EXITS_MWAIT)
+#define KVM_X86_DISABLE_EXITS_HTL (1 << 1)
+#define KVM_X86_DISABLE_VALID_EXITS (KVM_X86_DISABLE_EXITS_MWAIT | \
+ KVM_X86_DISABLE_EXITS_HTL)
static inline bool kvm_mwait_in_guest(struct kvm *kvm)
{
return kvm->arch.mwait_in_guest;
}
+static inline bool kvm_hlt_in_guest(struct kvm *kvm)
+{
+ return kvm->arch.hlt_in_guest;
+}
+
#endif