[PATCH] kvm tools: Exit properly on SMP guests

[PATCH] kvm tools: Exit properly on SMP guests

[Sasha Levin]

When shutting down SMP guests only VCPU #0 will receive
a KVM_EXIT_SHUTDOWN. Waiting for all VCPU threads to exit
causes them to hang.

Instead, notify all VCPU threads once VCPU #0 thread is terminated
so they could also stop properly.

Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
---
 tools/kvm/include/kvm/kvm.h |    2 ++
 tools/kvm/kvm-cpu.c         |   13 ++++++++++++-
 tools/kvm/kvm-run.c         |   10 +++++++---
 3 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/tools/kvm/include/kvm/kvm.h b/tools/kvm/include/kvm/kvm.h
index d9943bf..aafba87 100644
--- a/tools/kvm/include/kvm/kvm.h
+++ b/tools/kvm/include/kvm/kvm.h
@@ -11,6 +11,8 @@
 #define KVM_32BIT_GAP_SIZE	(512 << 20)
 #define KVM_32BIT_GAP_START	((1ULL << 32) - KVM_32BIT_GAP_SIZE)
 
+#define SIGKVMEXIT (SIGUSR1 + 2)
+
 struct kvm {
 	int			sys_fd;		/* For system ioctls(), i.e. /dev/kvm */
 	int			vm_fd;		/* For VM ioctls() */
diff --git a/tools/kvm/kvm-cpu.c b/tools/kvm/kvm-cpu.c
index cdfeb85..331e025 100644
--- a/tools/kvm/kvm-cpu.c
+++ b/tools/kvm/kvm-cpu.c
@@ -379,6 +379,11 @@ void kvm_cpu__run(struct kvm_cpu *vcpu)
 		die_perror("KVM_RUN failed");
 }
 
+static void kvm_cpu_exit_handler(int signum)
+{
+	/* Don't do anything here */
+}
+
 int kvm_cpu__start(struct kvm_cpu *cpu)
 {
 	sigset_t sigset;
@@ -388,6 +393,8 @@ int kvm_cpu__start(struct kvm_cpu *cpu)
 
 	pthread_sigmask(SIG_BLOCK, &sigset, NULL);
 
+	signal(SIGKVMEXIT, kvm_cpu_exit_handler);
+
 	kvm_cpu__setup_cpuid(cpu);
 	kvm_cpu__reset_vcpu(cpu);
 
@@ -430,7 +437,11 @@ int kvm_cpu__start(struct kvm_cpu *cpu)
 			break;
 		}
 		case KVM_EXIT_INTR:
-			break;
+			/*
+			 * Currently we only handle exit signal, which means
+			 * we just exit if KVM_RUN exited due to a signal.
+			 */
+			goto exit_kvm;
 		case KVM_EXIT_SHUTDOWN:
 			goto exit_kvm;
 		default:
diff --git a/tools/kvm/kvm-run.c b/tools/kvm/kvm-run.c
index 63181bf..8379a52 100644
--- a/tools/kvm/kvm-run.c
+++ b/tools/kvm/kvm-run.c
@@ -404,6 +404,7 @@ int kvm_cmd_run(int argc, const char **argv, const char *prefix)
 	int max_cpus;
 	char *hi;
 	int i;
+	void *ret;
 
 	signal(SIGALRM, handle_sigalrm);
 	signal(SIGQUIT, handle_sigquit);
@@ -583,14 +584,17 @@ int kvm_cmd_run(int argc, const char **argv, const char *prefix)
 			die("unable to create KVM VCPU thread");
 	}
 
-	for (i = 0; i < nrcpus; i++) {
-		void *ret;
+	/* Only VCPU #0 is going to exit by itself when shutting down */
+	if (pthread_join(kvm_cpus[0]->thread, &ret) != 0)
+		exit_code = 1;
 
+	for (i = 1; i < nrcpus; i++) {
+		pthread_kill(kvm_cpus[i]->thread, SIGKVMEXIT);
 		if (pthread_join(kvm_cpus[i]->thread, &ret) != 0)
 			die("pthread_join");
 
 		if (ret != NULL)
-			exit_code	= 1;
+			exit_code = 1;
 	}
 
 	kvm__delete(kvm);
-- 
1.7.5.rc3

Re: [PATCH] kvm tools: Exit properly on SMP guests

[Ingo Molnar]

* Sasha Levin <levinsasha928@gmail.com> wrote:

> +++ b/tools/kvm/include/kvm/kvm.h
> @@ -11,6 +11,8 @@
>  #define KVM_32BIT_GAP_SIZE	(512 << 20)
>  #define KVM_32BIT_GAP_START	((1ULL << 32) - KVM_32BIT_GAP_SIZE)
>  
> +#define SIGKVMEXIT (SIGUSR1 + 2)

Please preserve the vertical alignment that already exists in that place.

Thanks,

	Ingo