[RFC PATCH v3 01/11] KVM: Capture VM start

[Raghavendra Rao Ananta <rananta@google.com>]

Capture the start of the KVM VM, which is basically the
start of any vCPU run. This state of the VM is helpful
in the upcoming patches to prevent user-space from
configuring certain VM features after the VM has started
running.

Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
---
 include/linux/kvm_host.h | 3 +++
 virt/kvm/kvm_main.c      | 9 +++++++++
 2 files changed, 12 insertions(+)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index c310648cc8f1..d0bd8f7a026c 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -623,6 +623,7 @@ struct kvm {
 	struct notifier_block pm_notifier;
 #endif
 	char stats_id[KVM_STATS_NAME_SIZE];
+	bool vm_started;
 };
 
 #define kvm_err(fmt, ...) \
@@ -1666,6 +1667,8 @@ static inline bool kvm_check_request(int req, struct kvm_vcpu *vcpu)
 	}
 }
 
+#define kvm_vm_has_started(kvm) (kvm->vm_started)
+
 extern bool kvm_rebooting;
 
 extern unsigned int halt_poll_ns;
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 72c4e6b39389..962b91ac2064 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -3686,6 +3686,7 @@ static long kvm_vcpu_ioctl(struct file *filp,
 	int r;
 	struct kvm_fpu *fpu = NULL;
 	struct kvm_sregs *kvm_sregs = NULL;
+	struct kvm *kvm = vcpu->kvm;
 
 	if (vcpu->kvm->mm != current->mm || vcpu->kvm->vm_dead)
 		return -EIO;
@@ -3723,6 +3724,14 @@ static long kvm_vcpu_ioctl(struct file *filp,
 			if (oldpid)
 				synchronize_rcu();
 			put_pid(oldpid);
+
+			/*
+			 * Since we land here even on the first vCPU run,
+			 * we can mark that the VM has started running.
+			 */
+			mutex_lock(&kvm->lock);
+			kvm->vm_started = true;
+			mutex_unlock(&kvm->lock);
 		}
 		r = kvm_arch_vcpu_ioctl_run(vcpu);
 		trace_kvm_userspace_exit(vcpu->run->exit_reason, r);
-- 
2.34.1.448.ga2b2bfdf31-goog