kvm: debugfs: add EXIT_REASON_PREEMPTION_TIMER to vcpu_stat

virt inclusion
category: feature
bugzilla: 46853
CVE: NA

Export EXIT_REASON_PREEMPTION_TIMER kvm exits to vcpu_stat debugfs.
Add a new column to vcpu_stat, and provide preemption_timer status to
virtualization detection tools.
Signed-off-by: Nchenjiajun <chenjiajun8@huawei.com>
Reviewed-by: NXiangyou Xie <xiexiangyou@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

arch/x86/include/asm/kvm_host.h

@@ -1070,6 +1070,7 @@ struct kvm_vcpu_stat {
 	u64 utime;
 	u64 stime;
 	u64 gtime;
+	u64 preemption_timer_exits;
 };
 
 struct x86_instruction_info;

arch/x86/kvm/vmx/vmx.c

@@ -5605,6 +5605,7 @@ static fastpath_t handle_fastpath_preemption_timer(struct kvm_vcpu *vcpu)
 
 static int handle_preemption_timer(struct kvm_vcpu *vcpu)
 {
+	++vcpu->stat.preemption_timer_exits;
 	handle_fastpath_preemption_timer(vcpu);
 	return 1;
 }
@@ -6598,6 +6599,7 @@ static fastpath_t vmx_exit_handlers_fastpath(struct kvm_vcpu *vcpu)
 		++vcpu->stat.msr_wr_exits;
 		return handle_fastpath_set_msr_irqoff(vcpu);
 	case EXIT_REASON_PREEMPTION_TIMER:
+		++vcpu->stat.preemption_timer_exits;
 		return handle_fastpath_preemption_timer(vcpu);
 	default:
 		return EXIT_FASTPATH_NONE;

arch/x86/kvm/x86.c

@@ -285,6 +285,7 @@ struct dfx_kvm_stats_debugfs_item dfx_debugfs_entries[] = {
 	DFX_STAT("utime", utime),
 	DFX_STAT("stime", stime),
 	DFX_STAT("gtime", gtime),
+	DFX_STAT("preemption_timer_exits", preemption_timer_exits),
 	{ NULL }
 };