kvm tools: Signal only one thread when injecting console interrupts

Send signals only to the thread which handles console injection
instead of the entire process.

This prevents every single thread from having to ignore SIGALRM
and will help scaling when running large amount of VCPU threads.

Tested-by: Asias He <asias.hejun@gmail.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Suggested-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>

diff --git a/tools/kvm/kvm.c b/tools/kvm/kvm.c
index 8874cf9192b8b381353a463664745e7c3513cf56..c400c70dddb7b3638bb27acc44cf845d2fd02d70 100644 (file)
--- a/tools/kvm/kvm.c
+++ b/tools/kvm/kvm.c
@@ -28,6 +28,7 @@
 #include <fcntl.h>
 #include <time.h>
 #include <sys/eventfd.h>
+#include <asm/unistd.h>
 
 #define DEFINE_KVM_EXIT_REASON(reason) [reason] = #reason
 
@@ -529,8 +530,9 @@ void kvm__start_timer(struct kvm *kvm)
 
        memset(&sev, 0, sizeof(struct sigevent));
        sev.sigev_value.sival_int       = 0;
-       sev.sigev_notify                = SIGEV_SIGNAL;
+       sev.sigev_notify                = SIGEV_THREAD_ID;
        sev.sigev_signo                 = SIGALRM;
+       sev._sigev_un._tid              = syscall(__NR_gettid);
 
        if (timer_create(CLOCK_REALTIME, &sev, &kvm->timerid) < 0)
                die("timer_create()");