fe345a3d5d
When configured to inject an NMI, watchdog_perform_action() may cause the BQL to be temporarily relinquished (inject_nmi() → ... → s390_nmi() → s390_cpu_restart() → run_on_cpu()). When the guest issues diag 288 again in response to the NMI, the diag 288 operation will race against wdt_diag288_reset(). Depending on scheduler behaviour, wdt_diag288_reset() may be run after the guest issued a diag 288 Init. As a result, we will cancel the timer the guest just set up. The effect observed by the guest is that a second expiry does not trigger the watchdog action and diag 288 Change operations fail. Fix this by resetting the timer _before_ invoking the action. Signed-off-by: Sascha Silbe <silbe@linux.vnet.ibm.com> Acked-by: David Hildenbrand <dahi@linux.vnet.ibm.com> Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
143 lines
3.6 KiB
C
143 lines
3.6 KiB
C
/*
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* watchdog device diag288 support
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*
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* Copyright IBM, Corp. 2015
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*
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* Authors:
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* Xu Wang <gesaint@linux.vnet.ibm.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2 or (at your
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* option) any later version. See the COPYING file in the top-level directory.
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*
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*/
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#include "qemu/osdep.h"
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#include "sysemu/watchdog.h"
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#include "hw/sysbus.h"
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#include "qemu/timer.h"
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#include "hw/watchdog/wdt_diag288.h"
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static WatchdogTimerModel model = {
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.wdt_name = TYPE_WDT_DIAG288,
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.wdt_description = "diag288 device for s390x platform",
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};
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static const VMStateDescription vmstate_diag288 = {
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.name = "vmstate_diag288",
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.version_id = 0,
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.minimum_version_id = 0,
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.fields = (VMStateField[]) {
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VMSTATE_TIMER_PTR(timer, DIAG288State),
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VMSTATE_BOOL(enabled, DIAG288State),
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VMSTATE_END_OF_LIST()
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}
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};
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static void wdt_diag288_reset(DeviceState *dev)
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{
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DIAG288State *diag288 = DIAG288(dev);
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diag288->enabled = false;
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timer_del(diag288->timer);
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}
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static void diag288_reset(void *opaque)
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{
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DeviceState *diag288 = opaque;
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wdt_diag288_reset(diag288);
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}
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static void diag288_timer_expired(void *dev)
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{
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qemu_log_mask(CPU_LOG_RESET, "Watchdog timer expired.\n");
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/* Reset the watchdog only if the guest gets notified about
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* expiry. watchdog_perform_action() may temporarily relinquish
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* the BQL; reset before triggering the action to avoid races with
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* diag288 instructions. */
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switch (get_watchdog_action()) {
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case WDT_DEBUG:
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case WDT_NONE:
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case WDT_PAUSE:
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break;
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default:
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wdt_diag288_reset(dev);
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}
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watchdog_perform_action();
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}
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static int wdt_diag288_handle_timer(DIAG288State *diag288,
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uint64_t func, uint64_t timeout)
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{
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switch (func) {
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case WDT_DIAG288_INIT:
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diag288->enabled = true;
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/* fall through */
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case WDT_DIAG288_CHANGE:
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if (!diag288->enabled) {
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return -1;
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}
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timer_mod(diag288->timer,
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qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) +
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timeout * get_ticks_per_sec());
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break;
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case WDT_DIAG288_CANCEL:
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if (!diag288->enabled) {
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return -1;
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}
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diag288->enabled = false;
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timer_del(diag288->timer);
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break;
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default:
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return -1;
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}
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return 0;
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}
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static void wdt_diag288_realize(DeviceState *dev, Error **errp)
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{
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DIAG288State *diag288 = DIAG288(dev);
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qemu_register_reset(diag288_reset, diag288);
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diag288->timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, diag288_timer_expired,
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dev);
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}
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static void wdt_diag288_unrealize(DeviceState *dev, Error **errp)
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{
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DIAG288State *diag288 = DIAG288(dev);
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timer_del(diag288->timer);
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timer_free(diag288->timer);
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}
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static void wdt_diag288_class_init(ObjectClass *klass, void *data)
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{
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DeviceClass *dc = DEVICE_CLASS(klass);
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DIAG288Class *diag288 = DIAG288_CLASS(klass);
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dc->realize = wdt_diag288_realize;
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dc->unrealize = wdt_diag288_unrealize;
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dc->reset = wdt_diag288_reset;
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set_bit(DEVICE_CATEGORY_MISC, dc->categories);
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dc->vmsd = &vmstate_diag288;
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diag288->handle_timer = wdt_diag288_handle_timer;
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}
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static const TypeInfo wdt_diag288_info = {
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.class_init = wdt_diag288_class_init,
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.parent = TYPE_DEVICE,
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.name = TYPE_WDT_DIAG288,
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.instance_size = sizeof(DIAG288State),
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.class_size = sizeof(DIAG288Class),
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};
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static void wdt_diag288_register_types(void)
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{
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watchdog_add_model(&model);
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type_register_static(&wdt_diag288_info);
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}
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type_init(wdt_diag288_register_types)
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