diff options
| author |   Andrey Smetanin <asmetanin@virtuozzo.com> | 2015-12-14 18:33:05 +0300 |
|---|---|---|
| committer |   Paolo Bonzini <pbonzini@redhat.com> | 2015-12-16 18:51:22 +0100 |
| commit | 481d2bcc8454a44811db2bb68ac216fc6c5a23db (patch) | |
| tree | 7cf8ea522f040c305a0d2d871ad0eedb45d088fd /arch/x86/kvm | |
| parent | kvm: Dump guest rIP when the guest tried something unsupported (diff) | |
| download | linux-dev-481d2bcc8454a44811db2bb68ac216fc6c5a23db.tar.xz linux-dev-481d2bcc8454a44811db2bb68ac216fc6c5a23db.zip | |
kvm/x86: Remove Hyper-V SynIC timer stopping
It's possible that guest send us Hyper-V EOM at the middle
of Hyper-V SynIC timer running, so we start processing of Hyper-V
SynIC timers in vcpu context and stop the Hyper-V SynIC timer
unconditionally:
host guest
------------------------------------------------------------------------------
start periodic stimer
start periodic timer
timer expires after 15ms
send expiration message into guest
restart periodic timer
timer expires again after 15 ms
msg slot is still not cleared so
setup ->msg_pending
(1) restart periodic timer
process timer msg and clear slot
->msg_pending was set:
send EOM into host
received EOM
kvm_make_request(KVM_REQ_HV_STIMER)
kvm_hv_process_stimers():
...
stimer_stop()
if (time_now >= stimer->exp_time)
stimer_expiration(stimer);
Because the timer was rearmed at (1), time_now < stimer->exp_time
and stimer_expiration is not called. The timer then never fires.
The patch fixes such situation by not stopping Hyper-V SynIC timer
at all, because it's safe to restart it without stop in vcpu context
and timer callback always returns HRTIMER_NORESTART.
Signed-off-by: Andrey Smetanin <asmetanin@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>
Diffstat (limited to 'arch/x86/kvm')
| -rw-r--r-- | arch/x86/kvm/hyperv.c | 1 |
1 files changed, 0 insertions, 1 deletions
diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c index 8ff88293b906..f34f666778b2 100644 --- a/arch/x86/kvm/hyperv.c +++ b/arch/x86/kvm/hyperv.c @@ -598,7 +598,6 @@ void kvm_hv_process_stimers(struct kvm_vcpu *vcpu) for (i = 0; i < ARRAY_SIZE(hv_vcpu->stimer); i++) if (test_and_clear_bit(i, hv_vcpu->stimer_pending_bitmap)) { stimer = &hv_vcpu->stimer[i]; - stimer_stop(stimer); if (stimer->config & HV_STIMER_ENABLE) { time_now = get_time_ref_counter(vcpu->kvm); if (time_now >= stimer->exp_time) |