[Qemu-devel] [PATCH v1 3/6] kvm/x86: Reorg stimer_expiration() to better control timer restart

[Andrey Smetanin]

Split stimer_expiration() into two parts - timer expiration message
sending and timer restart/cleanup based on timer state(config).

This also fixes a bug where a one-shot timer message whose delivery
failed once would get lost for good.

Signed-off-by: Andrey Smetanin <address@hidden>
Reviewed-by: Roman Kagan <address@hidden>
CC: Gleb Natapov <address@hidden>
CC: Paolo Bonzini <address@hidden>
CC: Roman Kagan <address@hidden>
CC: Denis V. Lunev <address@hidden>
CC: address@hidden
---
 arch/x86/kvm/hyperv.c | 26 ++++++++++++++------------
 1 file changed, 14 insertions(+), 12 deletions(-)

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index 8623aa6..ce17529 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -552,30 +552,27 @@ static int synic_deliver_msg(struct kvm_vcpu_hv_synic 
*synic, u32 sint,
        return r;
 }
 
-static void stimer_send_msg(struct kvm_vcpu_hv_stimer *stimer)
+static int stimer_send_msg(struct kvm_vcpu_hv_stimer *stimer)
 {
        struct kvm_vcpu *vcpu = stimer_to_vcpu(stimer);
        struct hv_message *msg = &stimer->msg;
        struct hv_timer_message_payload *payload =
                        (struct hv_timer_message_payload *)&msg->u.payload;
-       int r;
 
-       stimer->msg_pending = true;
        payload->expiration_time = stimer->exp_time;
        payload->delivery_time = get_time_ref_counter(vcpu->kvm);
-       r = synic_deliver_msg(vcpu_to_synic(vcpu),
-                             HV_STIMER_SINT(stimer->config), msg);
-       if (!r)
-               stimer->msg_pending = false;
+       return synic_deliver_msg(vcpu_to_synic(vcpu),
+                                HV_STIMER_SINT(stimer->config), msg);
 }
 
 static void stimer_expiration(struct kvm_vcpu_hv_stimer *stimer)
 {
-       stimer_send_msg(stimer);
-       if (!(stimer->config & HV_STIMER_PERIODIC))
-               stimer->config |= ~HV_STIMER_ENABLE;
-       else
-               stimer_start(stimer);
+       stimer->msg_pending = true;
+       if (!stimer_send_msg(stimer)) {
+               stimer->msg_pending = false;
+               if (!(stimer->config & HV_STIMER_PERIODIC))
+                       stimer->config |= ~HV_STIMER_ENABLE;
+       }
 }
 
 void kvm_hv_process_stimers(struct kvm_vcpu *vcpu)
@@ -592,6 +589,11 @@ void kvm_hv_process_stimers(struct kvm_vcpu *vcpu)
                                time_now = get_time_ref_counter(vcpu->kvm);
                                if (time_now >= stimer->exp_time)
                                        stimer_expiration(stimer);
+
+                               if (stimer->config & HV_STIMER_ENABLE)
+                                       stimer_start(stimer);
+                               else
+                                       stimer_cleanup(stimer);
                        }
                }
 }
-- 
2.4.3