KVM: LAPIC: Expose per-vCPU timer_advance_ns to userspace

Expose per-vCPU timer_advance_ns to userspace, so it is able to
query the auto-adjusted value.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: Liran Alon <liran.alon@oracle.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/debugfs.c b/arch/x86/kvm/debugfs.c
index c19c7ede9bd6c8c8058a8a147f7e65c391a85bf0..a2f3432ce090eba4850cccf797a66bd0e533a1ed 100644 (file)
--- a/arch/x86/kvm/debugfs.c
+++ b/arch/x86/kvm/debugfs.c
@@ -9,12 +9,22 @@
  */
 #include <linux/kvm_host.h>
 #include <linux/debugfs.h>
+#include "lapic.h"
 
 bool kvm_arch_has_vcpu_debugfs(void)
 {
        return true;
 }
 
+static int vcpu_get_timer_advance_ns(void *data, u64 *val)
+{
+       struct kvm_vcpu *vcpu = (struct kvm_vcpu *) data;
+       *val = vcpu->arch.apic->lapic_timer.timer_advance_ns;
+       return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(vcpu_timer_advance_ns_fops, vcpu_get_timer_advance_ns, NULL, "%llu\n");
+
 static int vcpu_get_tsc_offset(void *data, u64 *val)
 {
        struct kvm_vcpu *vcpu = (struct kvm_vcpu *) data;
@@ -51,6 +61,14 @@ int kvm_arch_create_vcpu_debugfs(struct kvm_vcpu *vcpu)
        if (!ret)
                return -ENOMEM;
 
+       if (lapic_in_kernel(vcpu)) {
+               ret = debugfs_create_file("lapic_timer_advance_ns", 0444,
+                                                               vcpu->debugfs_dentry,
+                                                               vcpu, &vcpu_timer_advance_ns_fops);
+               if (!ret)
+                       return -ENOMEM;
+       }
+
        if (kvm_has_tsc_control) {
                ret = debugfs_create_file("tsc-scaling-ratio", 0444,
                                                        vcpu->debugfs_dentry,