KVM: VMX: Add support for guest/host-only profiling

Support guest/host-only profiling by switch perf msrs on
a guest entry if needed.
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

arch/x86/kvm/vmx.c

@@ -39,6 +39,7 @@
 #include <asm/mce.h>
 #include <asm/i387.h>
 #include <asm/xcr.h>
+#include <asm/perf_event.h>
 
 #include "trace.h"
 
@@ -6050,6 +6051,24 @@ static void vmx_cancel_injection(struct kvm_vcpu *vcpu)
 	vmcs_write32(VM_ENTRY_INTR_INFO_FIELD, 0);
 }
 
+static void atomic_switch_perf_msrs(struct vcpu_vmx *vmx)
+{
+	int i, nr_msrs;
+	struct perf_guest_switch_msr *msrs;
+
+	msrs = perf_guest_get_msrs(&nr_msrs);
+
+	if (!msrs)
+		return;
+
+	for (i = 0; i < nr_msrs; i++)
+		if (msrs[i].host == msrs[i].guest)
+			clear_atomic_switch_msr(vmx, msrs[i].msr);
+		else
+			add_atomic_switch_msr(vmx, msrs[i].msr, msrs[i].guest,
+					msrs[i].host);
+}
+
 #ifdef CONFIG_X86_64
 #define R "r"
 #define Q "q"
@@ -6099,6 +6118,8 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu)
 	if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP)
 		vmx_set_interrupt_shadow(vcpu, 0);
 
+	atomic_switch_perf_msrs(vmx);
+
 	vmx->__launched = vmx->loaded_vmcs->launched;
 	asm(
 		/* Store host registers */