KVM: x86: Add emulation of MSR_SMI_COUNT

This MSR returns the number of #SMIs that occurred on CPU since
boot.

It was seen to be used frequently by ESXi guest.

Patch adds a new vcpu-arch specific var called smi_count to
save the number of #SMIs which occurred on CPU since boot.
It is exposed as a read-only MSR to guest (causing #GP
on wrmsr) in RDMSR/WRMSR emulation code.
MSR_SMI_COUNT is also added to emulated_msrs[] to make sure
user-space can save/restore it for migration purposes.

Signed-off-by: Liran Alon <liran.alon@oracle.com>
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Nikita Leshenko <nikita.leshchenko@oracle.com>
Reviewed-by: Bhavesh Davda <bhavesh.davda@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 515db75..340e360 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -504,6 +504,7 @@ struct kvm_vcpu_arch {
        int mp_state;
        u64 ia32_misc_enable_msr;
        u64 smbase;
+       u64 smi_count;
        bool tpr_access_reporting;
        u64 ia32_xss;
 

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index dd2e80a..7ea9a57 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1039,6 +1039,7 @@ static u32 emulated_msrs[] = {
        MSR_IA32_MCG_CTL,
        MSR_IA32_MCG_EXT_CTL,
        MSR_IA32_SMBASE,
+       MSR_SMI_COUNT,
        MSR_PLATFORM_INFO,
        MSR_MISC_FEATURES_ENABLES,
 };
@@ -2231,6 +2232,11 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
                        return 1;
                vcpu->arch.smbase = data;
                break;
+       case MSR_SMI_COUNT:
+               if (!msr_info->host_initiated)
+                       return 1;
+               vcpu->arch.smi_count = data;
+               break;
        case MSR_KVM_WALL_CLOCK_NEW:
        case MSR_KVM_WALL_CLOCK:
                vcpu->kvm->arch.wall_clock = data;
@@ -2505,6 +2511,9 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
                        return 1;
                msr_info->data = vcpu->arch.smbase;
                break;
+       case MSR_SMI_COUNT:
+               msr_info->data = vcpu->arch.smi_count;
+               break;
        case MSR_IA32_PERF_STATUS:
                /* TSC increment by tick */
                msr_info->data = 1000ULL;
@@ -6451,6 +6460,7 @@ static int inject_pending_event(struct kvm_vcpu *vcpu, bool req_int_win)
                kvm_x86_ops->queue_exception(vcpu);
        } else if (vcpu->arch.smi_pending && !is_smm(vcpu) && kvm_x86_ops->smi_allowed(vcpu)) {
                vcpu->arch.smi_pending = false;
+               ++vcpu->arch.smi_count;
                enter_smm(vcpu);
        } else if (vcpu->arch.nmi_pending && kvm_x86_ops->nmi_allowed(vcpu)) {
                --vcpu->arch.nmi_pending;
@@ -7808,6 +7818,7 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
        vcpu->arch.hflags = 0;
 
        vcpu->arch.smi_pending = 0;
+       vcpu->arch.smi_count = 0;
        atomic_set(&vcpu->arch.nmi_queued, 0);
        vcpu->arch.nmi_pending = 0;
        vcpu->arch.nmi_injected = false;