From 04423b622a81a2f81428291c2f9a2c35ab00a03a Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Roger=20Pau=20Monn=C3=A9?= Date: Mon, 2 May 2016 16:13:11 +0000 Subject: [PATCH] xen/x86: don't lose event interrupts On slow platforms with unreliable TSC, such as QEMU emulated machines, it is possible for the FreeBSD kernel to request the next event in the past. In that case, in the current implementation of xentimer_vcpu_start_timer, we simply return -ETIME. To be precise Xen returns -ETIME and we pass it on. As a consequence we need to loop around to function to make sure that the timer is properly set. Instead it is better to always ask the hypervisor for a timer event, even if the timeout is past. To do that, remove the VCPU_SSHOTTMR_future flag. Submitted by: Stefano Stabellini Reviewed by: royger MFC after: 2 weeks --- sys/dev/xen/timer/timer.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/sys/dev/xen/timer/timer.c b/sys/dev/xen/timer/timer.c index 53aff0a4e4b..db9b19b6cd4 100644 --- a/sys/dev/xen/timer/timer.c +++ b/sys/dev/xen/timer/timer.c @@ -267,7 +267,8 @@ xentimer_vcpu_start_timer(int vcpu, uint64_t next_time) struct vcpu_set_singleshot_timer single; single.timeout_abs_ns = next_time; - single.flags = VCPU_SSHOTTMR_future; + /* Get an event anyway, even if the timeout is already expired */ + single.flags = 0; return (HYPERVISOR_vcpu_op(VCPUOP_set_singleshot_timer, vcpu, &single)); }