[PATCH v2 04/15] kvm: x86: Add per-VM APICv state debugfs

[Suthikulpanit, Suravee]

Currently, there is no way to tell whether APICv is active
on a particular VM. This often cause confusion since APICv
can be deactivated at runtime.

Introduce a debugfs entry to report APICv state of a VM.
This creates a read-only file:

   /sys/kernel/debug/kvm/70860-14/apicv-state

Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx>
---
 arch/x86/kvm/debugfs.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/arch/x86/kvm/debugfs.c b/arch/x86/kvm/debugfs.c
index d62852c..bd9fd25 100644
--- a/arch/x86/kvm/debugfs.c
+++ b/arch/x86/kvm/debugfs.c
@@ -48,8 +48,30 @@ static int vcpu_get_tsc_scaling_frac_bits(void *data, u64 *val)
 
 DEFINE_SIMPLE_ATTRIBUTE(vcpu_tsc_scaling_frac_fops, vcpu_get_tsc_scaling_frac_bits, NULL, "%llu\n");
 
+static int kvm_get_apicv_state(void *data, u64 *val)
+{
+	struct kvm *kvm = (struct kvm *)data;
+
+	mutex_lock(&kvm->arch.apicv_lock);
+	*val = kvm->arch.apicv_state;
+	mutex_unlock(&kvm->arch.apicv_lock);
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(apicv_state_fops, kvm_get_apicv_state, NULL, "%llu\n");
+
 int kvm_arch_create_vm_debugfs(struct kvm *kvm)
 {
+	struct dentry *ret;
+
+	if (kvm_x86_ops->get_enable_apicv(kvm)) {
+		ret = debugfs_create_file("apicv-state", 0444,
+					  kvm->debugfs_dentry,
+					  kvm, &apicv_state_fops);
+		if (!ret)
+			return -ENOMEM;
+	}
+
 	return 0;
 }
 
-- 
1.8.3.1