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kvm/x86: Reorg stimer_expiration() to better control timer restart
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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>
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Andrey Smetanin authored and Paolo Bonzini committed Jan 8, 2016
1 parent f808495 commit 0cdeabb
Showing 1 changed file with 14 additions and 12 deletions.
26 changes: 14 additions & 12 deletions arch/x86/kvm/hyperv.c
Original file line number Diff line number Diff line change
Expand Up @@ -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)
Expand All @@ -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);
}
}
}
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