kvm/x86: Reorg stimer_expiration() to better control timer restart

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 <asmetanin@virtuozzo.com>
Reviewed-by: Roman Kagan <rkagan@virtuozzo.com>
CC: Gleb Natapov <gleb@kernel.org>
CC: Paolo Bonzini <pbonzini@redhat.com>
CC: Roman Kagan <rkagan@virtuozzo.com>
CC: Denis V. Lunev <den@openvz.org>
CC: qemu-devel@nongnu.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 14 insertions, 12 deletions

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index 0dd7d1731c22..5f85c12b223c 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -554,30 +554,27 @@ 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)
@@ -594,6 +591,11 @@ 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);
                         }
                 }
 }