Hardware watchdog

Here is an updated hardware watchdog patch, which should fix
everything that was raised about the previous version ...

Signed-off-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

9 files changed, 865 insertions, 0 deletions

diff --git a/Makefile.target b/Makefile.target
index 82ada5a0e6..f73510524c 100644
--- a/Makefile.target
+++ b/Makefile.target
@@ -582,6 +582,10 @@ OBJS += pcnet.o
 OBJS += rtl8139.o
 OBJS += e1000.o
 
+# Generic watchdog support and some watchdog devices
+OBJS += watchdog.o
+OBJS += wdt_ib700.o wdt_i6300esb.o
+
 ifeq ($(TARGET_BASE_ARCH), i386)
 # Hardware support
 OBJS+= ide.o pckbd.o vga.o $(SOUND_HW) dma.o
diff --git a/hw/pc.c b/hw/pc.c
index 07b75f38cf..340b313cd4 100644
--- a/hw/pc.c
+++ b/hw/pc.c
@@ -37,6 +37,7 @@
 #include "virtio-balloon.h"
 #include "virtio-console.h"
 #include "hpet_emul.h"
+#include "watchdog.h"
 #include "smbios.h"
 
 /* output Bochs bios info messages */
@@ -1023,6 +1024,8 @@ static void pc_init1(ram_addr_t ram_size, int vga_ram_size,
         }
     }
 
+    watchdog_pc_init(pci_bus);
+
     for(i = 0; i < nb_nics; i++) {
         NICInfo *nd = &nd_table[i];
 
diff --git a/hw/watchdog.c b/hw/watchdog.c
new file mode 100644
index 0000000000..c64868d2c4
--- /dev/null
+++ b/hw/watchdog.c
@@ -0,0 +1,136 @@
+/*
+ * Virtual hardware watchdog.
+ *
+ * Copyright (C) 2009 Red Hat Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
+ * USA.
+ *
+ * By Richard W.M. Jones (rjones@redhat.com).
+ */
+
+#include "qemu-common.h"
+#include "sys-queue.h"
+#include "sysemu.h"
+#include "hw/watchdog.h"
+
+static LIST_HEAD(watchdog_list, WatchdogTimerModel) watchdog_list;
+
+void watchdog_add_model(WatchdogTimerModel *model)
+{
+    LIST_INSERT_HEAD(&watchdog_list, model, entry);
+}
+
+/* Returns:
+ *   0 = continue
+ *   1 = exit program with error
+ *   2 = exit program without error
+ */
+int select_watchdog(const char *p)
+{
+    WatchdogTimerModel *model;
+
+    if (watchdog) {
+        fprintf(stderr,
+                 "qemu: only one watchdog option may be given\n");
+        return 1;
+    }
+
+    /* -watchdog ? lists available devices and exits cleanly. */
+    if (strcmp(p, "?") == 0) {
+        LIST_FOREACH(model, &watchdog_list, entry) {
+            fprintf(stderr, "\t%s\t%s\n",
+                     model->wdt_name, model->wdt_description);
+        }
+        return 2;
+    }
+
+    LIST_FOREACH(model, &watchdog_list, entry) {
+        if (strcasecmp(model->wdt_name, p) == 0) {
+            watchdog = model;
+            return 0;
+        }
+    }
+
+    fprintf(stderr, "Unknown -watchdog device. Supported devices are:\n");
+    LIST_FOREACH(model, &watchdog_list, entry) {
+        fprintf(stderr, "\t%s\t%s\n",
+                 model->wdt_name, model->wdt_description);
+    }
+    return 1;
+}
+
+int select_watchdog_action(const char *p)
+{
+    if (strcasecmp(p, "reset") == 0)
+        watchdog_action = WDT_RESET;
+    else if (strcasecmp(p, "shutdown") == 0)
+        watchdog_action = WDT_SHUTDOWN;
+    else if (strcasecmp(p, "poweroff") == 0)
+        watchdog_action = WDT_POWEROFF;
+    else if (strcasecmp(p, "pause") == 0)
+        watchdog_action = WDT_PAUSE;
+    else if (strcasecmp(p, "debug") == 0)
+        watchdog_action = WDT_DEBUG;
+    else if (strcasecmp(p, "none") == 0)
+        watchdog_action = WDT_NONE;
+    else
+        return -1;
+
+    return 0;
+}
+
+/* This actually performs the "action" once a watchdog has expired,
+ * ie. reboot, shutdown, exit, etc.
+ */
+void watchdog_perform_action(void)
+{
+    switch(watchdog_action) {
+    case WDT_RESET:             /* same as 'system_reset' in monitor */
+        qemu_system_reset_request();
+        break;
+
+    case WDT_SHUTDOWN:          /* same as 'system_powerdown' in monitor */
+        qemu_system_powerdown_request();
+        break;
+
+    case WDT_POWEROFF:          /* same as 'quit' command in monitor */
+        exit(0);
+        break;
+
+    case WDT_PAUSE:             /* same as 'stop' command in monitor */
+        vm_stop(0);
+        break;
+
+    case WDT_DEBUG:
+        fprintf(stderr, "watchdog: timer fired\n");
+        break;
+
+    case WDT_NONE:
+        break;
+    }
+}
+
+void watchdog_pc_init(PCIBus *pci_bus)
+{
+    if (watchdog)
+        watchdog->wdt_pc_init(pci_bus);
+}
+
+void register_watchdogs(void)
+{
+    wdt_ib700_init();
+    wdt_i6300esb_init();
+}
diff --git a/hw/watchdog.h b/hw/watchdog.h
new file mode 100644
index 0000000000..c2b2b36878
--- /dev/null
+++ b/hw/watchdog.h
@@ -0,0 +1,65 @@
+/*
+ * Virtual hardware watchdog.
+ *
+ * Copyright (C) 2009 Red Hat Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
+ * USA.
+ *
+ * By Richard W.M. Jones (rjones@redhat.com).
+ */
+
+#ifndef QEMU_WATCHDOG_H
+#define QEMU_WATCHDOG_H
+
+extern void wdt_i6300esb_init(void);
+extern void wdt_ib700_init(void);
+
+/* Possible values for action parameter. */
+#define WDT_RESET        1	/* Hard reset. */
+#define WDT_SHUTDOWN     2	/* Shutdown. */
+#define WDT_POWEROFF     3	/* Quit. */
+#define WDT_PAUSE        4	/* Pause. */
+#define WDT_DEBUG        5	/* Prints a message and continues running. */
+#define WDT_NONE         6	/* Do nothing. */
+
+struct WatchdogTimerModel {
+    LIST_ENTRY(WatchdogTimerModel) entry;
+
+    /* Short name of the device - used to select it on the command line. */
+    const char *wdt_name;
+    /* Longer description (eg. manufacturer and full model number). */
+    const char *wdt_description;
+
+    /* This callback should create/register the device.  It is called
+     * indirectly from hw/pc.c when the virtual PC is being set up.
+     */
+    void (*wdt_pc_init)(PCIBus *pci_bus);
+};
+typedef struct WatchdogTimerModel WatchdogTimerModel;
+
+/* in vl.c */
+extern WatchdogTimerModel *watchdog;
+extern int watchdog_action;
+
+/* in hw/watchdog.c */
+extern int select_watchdog(const char *p);
+extern int select_watchdog_action(const char *action);
+extern void watchdog_add_model(WatchdogTimerModel *model);
+extern void watchdog_perform_action(void);
+extern void watchdog_pc_init(PCIBus *pci_bus);
+extern void register_watchdogs(void);
+
+#endif /* QEMU_WATCHDOG_H */
diff --git a/hw/wdt_i6300esb.c b/hw/wdt_i6300esb.c
new file mode 100644
index 0000000000..f7ddea2795
--- /dev/null
+++ b/hw/wdt_i6300esb.c
@@ -0,0 +1,470 @@
+/*
+ * Virtual hardware watchdog.
+ *
+ * Copyright (C) 2009 Red Hat Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
+ * USA.
+ *
+ * By Richard W.M. Jones (rjones@redhat.com).
+ */
+
+#include <inttypes.h>
+
+#include "qemu-common.h"
+#include "qemu-timer.h"
+#include "watchdog.h"
+#include "hw.h"
+#include "isa.h"
+#include "pc.h"
+#include "pci.h"
+
+/*#define I6300ESB_DEBUG 1*/
+
+#ifdef I6300ESB_DEBUG
+#define i6300esb_debug(fs,...) \
+    fprintf(stderr,"i6300esb: %s: "fs,__func__,##__VA_ARGS__)
+#else
+#define i6300esb_debug(fs,...)
+#endif
+
+#ifndef PCI_DEVICE_ID_INTEL_ESB_9
+#define PCI_DEVICE_ID_INTEL_ESB_9 0x25ab
+#endif
+
+/* PCI configuration registers */
+#define ESB_CONFIG_REG  0x60            /* Config register                   */
+#define ESB_LOCK_REG    0x68            /* WDT lock register                 */
+
+/* Memory mapped registers (offset from base address) */
+#define ESB_TIMER1_REG  0x00            /* Timer1 value after each reset     */
+#define ESB_TIMER2_REG  0x04            /* Timer2 value after each reset     */
+#define ESB_GINTSR_REG  0x08            /* General Interrupt Status Register */
+#define ESB_RELOAD_REG  0x0c            /* Reload register                   */
+
+/* Lock register bits */
+#define ESB_WDT_FUNC    (0x01 << 2)   /* Watchdog functionality            */
+#define ESB_WDT_ENABLE  (0x01 << 1)   /* Enable WDT                        */
+#define ESB_WDT_LOCK    (0x01 << 0)   /* Lock (nowayout)                   */
+
+/* Config register bits */
+#define ESB_WDT_REBOOT  (0x01 << 5)   /* Enable reboot on timeout          */
+#define ESB_WDT_FREQ    (0x01 << 2)   /* Decrement frequency               */
+#define ESB_WDT_INTTYPE (0x11 << 0)   /* Interrupt type on timer1 timeout  */
+
+/* Reload register bits */
+#define ESB_WDT_RELOAD  (0x01 << 8)    /* prevent timeout                   */
+
+/* Magic constants */
+#define ESB_UNLOCK1     0x80            /* Step 1 to unlock reset registers  */
+#define ESB_UNLOCK2     0x86            /* Step 2 to unlock reset registers  */
+
+/* Device state. */
+struct I6300State {
+    PCIDevice dev;              /* PCI device state, must be first field. */
+
+    int reboot_enabled;         /* "Reboot" on timer expiry.  The real action
+                                 * performed depends on the -watchdog-action
+                                 * param passed on QEMU command line.
+                                 */
+    int clock_scale;            /* Clock scale. */
+#define CLOCK_SCALE_1KHZ 0
+#define CLOCK_SCALE_1MHZ 1
+
+    int int_type;               /* Interrupt type generated. */
+#define INT_TYPE_IRQ 0          /* APIC 1, INT 10 */
+#define INT_TYPE_SMI 2
+#define INT_TYPE_DISABLED 3
+
+    int free_run;               /* If true, reload timer on expiry. */
+    int locked;                 /* If true, enabled field cannot be changed. */
+    int enabled;                /* If true, watchdog is enabled. */
+
+    QEMUTimer *timer;           /* The actual watchdog timer. */
+
+    uint32_t timer1_preload;    /* Values preloaded into timer1, timer2. */
+    uint32_t timer2_preload;
+    int stage;                  /* Stage (1 or 2). */
+
+    int unlock_state;           /* Guest writes 0x80, 0x86 to unlock the
+                                 * registers, and we transition through
+                                 * states 0 -> 1 -> 2 when this happens.
+                                 */
+
+    int previous_reboot_flag;   /* If the watchdog caused the previous
+                                 * reboot, this flag will be set.
+                                 */
+};
+
+typedef struct I6300State I6300State;
+
+/* This function is called when the watchdog has either been enabled
+ * (hence it starts counting down) or has been keep-alived.
+ */
+static void i6300esb_restart_timer(I6300State *d, int stage)
+{
+    int64_t timeout;
+
+    if (!d->enabled)
+        return;
+
+    d->stage = stage;
+
+    if (d->stage <= 1)
+        timeout = d->timer1_preload;
+    else
+        timeout = d->timer2_preload;
+
+    if (d->clock_scale == CLOCK_SCALE_1KHZ)
+        timeout <<= 15;
+    else
+        timeout <<= 5;
+
+    /* Get the timeout in units of ticks_per_sec. */
+    timeout = ticks_per_sec * timeout / 33000000;
+
+    i6300esb_debug("stage %d, timeout %" PRIi64 "\n", d->stage, timeout);
+
+    qemu_mod_timer(d->timer, qemu_get_clock(vm_clock) + timeout);
+}
+
+/* This is called when the guest disables the watchdog. */
+static void i6300esb_disable_timer(I6300State *d)
+{
+    i6300esb_debug("timer disabled\n");
+
+    qemu_del_timer(d->timer);
+}
+
+static void i6300esb_reset(I6300State *d)
+{
+    /* XXX We should probably reset other parts of the state here,
+     * but we should also reset our state on general machine reset
+     * too.  For now just disable the timer so it doesn't fire
+     * again after the reboot.
+     */
+    i6300esb_disable_timer(d);
+}
+
+/* This function is called when the watchdog expires.  Note that
+ * the hardware has two timers, and so expiry happens in two stages.
+ * If d->stage == 1 then we perform the first stage action (usually,
+ * sending an interrupt) and then restart the timer again for the
+ * second stage.  If the second stage expires then the watchdog
+ * really has run out.
+ */
+static void i6300esb_timer_expired(void *vp)
+{
+    I6300State *d = (I6300State *) vp;
+
+    i6300esb_debug("stage %d\n", d->stage);
+
+    if (d->stage == 1) {
+        /* What to do at the end of stage 1? */
+        switch (d->int_type) {
+        case INT_TYPE_IRQ:
+            fprintf(stderr, "i6300esb_timer_expired: I would send APIC 1 INT 10 here if I knew how (XXX)\n");
+            break;
+        case INT_TYPE_SMI:
+            fprintf(stderr, "i6300esb_timer_expired: I would send SMI here if I knew how (XXX)\n");
+            break;
+        }
+
+        /* Start the second stage. */
+        i6300esb_restart_timer(d, 2);
+    } else {
+        /* Second stage expired, reboot for real. */
+        if (d->reboot_enabled) {
+            d->previous_reboot_flag = 1;
+            watchdog_perform_action(); /* This reboots, exits, etc */
+            i6300esb_reset(d);
+        }
+
+        /* In "free running mode" we start stage 1 again. */
+        if (d->free_run)
+            i6300esb_restart_timer(d, 1);
+    }
+}
+
+static void i6300esb_config_write(PCIDevice *dev, uint32_t addr,
+                                  uint32_t data, int len)
+{
+    I6300State *d = (I6300State *) dev;
+    int old;
+
+    i6300esb_debug("addr = %x, data = %x, len = %d\n", addr, data, len);
+
+    if (addr == ESB_CONFIG_REG && len == 2) {
+        d->reboot_enabled = (data & ESB_WDT_REBOOT) == 0;
+        d->clock_scale =
+            (data & ESB_WDT_FREQ) != 0 ? CLOCK_SCALE_1MHZ : CLOCK_SCALE_1KHZ;
+        d->int_type = (data & ESB_WDT_INTTYPE);
+    } else if (addr == ESB_LOCK_REG && len == 1) {
+        if (!d->locked) {
+            d->locked = (data & ESB_WDT_LOCK) != 0;
+            d->free_run = (data & ESB_WDT_FUNC) != 0;
+            old = d->enabled;
+            d->enabled = (data & ESB_WDT_ENABLE) != 0;
+            if (!old && d->enabled) /* Enabled transitioned from 0 -> 1 */
+                i6300esb_restart_timer(d, 1);
+            else if (!d->enabled)
+                i6300esb_disable_timer(d);
+        }
+    } else {
+        pci_default_write_config(dev, addr, data, len);
+    }
+}
+
+static uint32_t i6300esb_config_read(PCIDevice *dev, uint32_t addr, int len)
+{
+    I6300State *d = (I6300State *) dev;
+    uint32_t data;
+
+    i6300esb_debug ("addr = %x, len = %d\n", addr, len);
+
+    if (addr == ESB_CONFIG_REG && len == 2) {
+        data =
+            (d->reboot_enabled ? 0 : ESB_WDT_REBOOT) |
+            (d->clock_scale == CLOCK_SCALE_1MHZ ? ESB_WDT_FREQ : 0) |
+            d->int_type;
+        return data;
+    } else if (addr == ESB_LOCK_REG && len == 1) {
+        data =
+            (d->free_run ? ESB_WDT_FUNC : 0) |
+            (d->locked ? ESB_WDT_LOCK : 0) |
+            (d->enabled ? ESB_WDT_ENABLE : 0);
+        return data;
+    } else {
+        return pci_default_read_config(dev, addr, len);
+    }
+}
+
+static uint32_t i6300esb_mem_readb(void *vp, target_phys_addr_t addr)
+{
+    i6300esb_debug ("addr = %x\n", (int) addr);
+
+    return 0;
+}
+
+static uint32_t i6300esb_mem_readw(void *vp, target_phys_addr_t addr)
+{
+    uint32_t data = 0;
+    I6300State *d = (I6300State *) vp;
+
+    i6300esb_debug("addr = %x\n", (int) addr);
+
+    if (addr == 0xc) {
+        /* The previous reboot flag is really bit 9, but there is
+         * a bug in the Linux driver where it thinks it's bit 12.
+         * Set both.
+         */
+        data = d->previous_reboot_flag ? 0x1200 : 0;
+    }
+
+    return data;
+}
+
+static uint32_t i6300esb_mem_readl(void *vp, target_phys_addr_t addr)
+{
+    i6300esb_debug("addr = %x\n", (int) addr);
+
+    return 0;
+}
+
+static void i6300esb_mem_writeb(void *vp, target_phys_addr_t addr, uint32_t val)
+{
+    I6300State *d = (I6300State *) vp;
+
+    i6300esb_debug("addr = %x, val = %x\n", (int) addr, val);
+
+    if (addr == 0xc && val == 0x80)
+        d->unlock_state = 1;
+    else if (addr == 0xc && val == 0x86 && d->unlock_state == 1)
+        d->unlock_state = 2;
+}
+
+static void i6300esb_mem_writew(void *vp, target_phys_addr_t addr, uint32_t val)
+{
+    I6300State *d = (I6300State *) vp;
+
+    i6300esb_debug("addr = %x, val = %x\n", (int) addr, val);
+
+    if (addr == 0xc && val == 0x80)
+        d->unlock_state = 1;
+    else if (addr == 0xc && val == 0x86 && d->unlock_state == 1)
+        d->unlock_state = 2;
+    else {
+        if (d->unlock_state == 2) {
+            if (addr == 0xc) {
+                if ((val & 0x100) != 0)
+                    /* This is the "ping" from the userspace watchdog in
+                     * the guest ...
+                     */
+                    i6300esb_restart_timer(d, 1);
+
+                /* Setting bit 9 resets the previous reboot flag.
+                 * There's a bug in the Linux driver where it sets
+                 * bit 12 instead.
+                 */
+                if ((val & 0x200) != 0 || (val & 0x1000) != 0) {
+                    d->previous_reboot_flag = 0;
+                }
+            }
+
+            d->unlock_state = 0;
+        }
+    }
+}
+
+static void i6300esb_mem_writel(void *vp, target_phys_addr_t addr, uint32_t val)
+{
+    I6300State *d = (I6300State *) vp;
+
+    i6300esb_debug ("addr = %x, val = %x\n", (int) addr, val);
+
+    if (addr == 0xc && val == 0x80)
+        d->unlock_state = 1;
+    else if (addr == 0xc && val == 0x86 && d->unlock_state == 1)
+        d->unlock_state = 2;
+    else {
+        if (d->unlock_state == 2) {
+            if (addr == 0)
+                d->timer1_preload = val & 0xfffff;
+            else if (addr == 4)
+                d->timer2_preload = val & 0xfffff;
+
+            d->unlock_state = 0;
+        }
+    }
+}
+
+static void i6300esb_map(PCIDevice *dev, int region_num,
+                         uint32_t addr, uint32_t size, int type)
+{
+    static CPUReadMemoryFunc *mem_read[3] = {
+        i6300esb_mem_readb,
+        i6300esb_mem_readw,
+        i6300esb_mem_readl,
+    };
+    static CPUWriteMemoryFunc *mem_write[3] = {
+        i6300esb_mem_writeb,
+        i6300esb_mem_writew,
+        i6300esb_mem_writel,
+    };
+    I6300State *d = (I6300State *) dev;
+    int io_mem;
+
+    i6300esb_debug("addr = %x, size = %x, type = %d\n", addr, size, type);
+
+    io_mem = cpu_register_io_memory (0, mem_read, mem_write, d);
+    cpu_register_physical_memory (addr, 0x10, io_mem);
+    /* qemu_register_coalesced_mmio (addr, 0x10); ? */
+}
+
+static void i6300esb_save(QEMUFile *f, void *vp)
+{
+    I6300State *d = (I6300State *) vp;
+
+    pci_device_save(&d->dev, f);
+    qemu_put_be32(f, d->reboot_enabled);
+    qemu_put_be32(f, d->clock_scale);
+    qemu_put_be32(f, d->int_type);
+    qemu_put_be32(f, d->free_run);
+    qemu_put_be32(f, d->locked);
+    qemu_put_be32(f, d->enabled);
+    qemu_put_timer(f, d->timer);
+    qemu_put_be32(f, d->timer1_preload);
+    qemu_put_be32(f, d->timer2_preload);
+    qemu_put_be32(f, d->stage);
+    qemu_put_be32(f, d->unlock_state);
+    qemu_put_be32(f, d->previous_reboot_flag);
+}
+
+static int i6300esb_load(QEMUFile *f, void *vp, int version)
+{
+    I6300State *d = (I6300State *) vp;
+
+    if (version != sizeof (I6300State))
+        return -EINVAL;
+
+    pci_device_load(&d->dev, f);
+    d->reboot_enabled = qemu_get_be32(f);
+    d->clock_scale = qemu_get_be32(f);
+    d->int_type = qemu_get_be32(f);
+    d->free_run = qemu_get_be32(f);
+    d->locked = qemu_get_be32(f);
+    d->enabled = qemu_get_be32(f);
+    qemu_get_timer(f, d->timer);
+    d->timer1_preload = qemu_get_be32(f);
+    d->timer2_preload = qemu_get_be32(f);
+    d->stage = qemu_get_be32(f);
+    d->unlock_state = qemu_get_be32(f);
+    d->previous_reboot_flag = qemu_get_be32(f);
+
+    return 0;
+}
+
+/* Create and initialize a virtual Intel 6300ESB during PC creation. */
+static void i6300esb_pc_init(PCIBus *pci_bus)
+{
+    I6300State *d;
+    uint8_t *pci_conf;
+
+    if (!pci_bus) {
+        fprintf(stderr, "wdt_i6300esb: no PCI bus in this machine\n");
+        return;
+    }
+
+    d = (I6300State *)
+        pci_register_device (pci_bus, "i6300esb_wdt", sizeof (I6300State),
+                             -1,
+                             i6300esb_config_read, i6300esb_config_write);
+
+    d->reboot_enabled = 1;
+    d->clock_scale = CLOCK_SCALE_1KHZ;
+    d->int_type = INT_TYPE_IRQ;
+    d->free_run = 0;
+    d->locked = 0;
+    d->enabled = 0;
+    d->timer = qemu_new_timer(vm_clock, i6300esb_timer_expired, d);
+    d->timer1_preload = 0xfffff;
+    d->timer2_preload = 0xfffff;
+    d->stage = 1;
+    d->unlock_state = 0;
+    d->previous_reboot_flag = 0;
+
+    pci_conf = d->dev.config;
+    pci_config_set_vendor_id(pci_conf, PCI_VENDOR_ID_INTEL);
+    pci_config_set_device_id(pci_conf, PCI_DEVICE_ID_INTEL_ESB_9);
+    pci_config_set_class(pci_conf, PCI_CLASS_SYSTEM_OTHER);
+    pci_conf[0x0e] = 0x00;
+
+    pci_register_io_region(&d->dev, 0, 0x10,
+                            PCI_ADDRESS_SPACE_MEM, i6300esb_map);
+
+    register_savevm("i6300esb_wdt", -1, sizeof(I6300State),
+                     i6300esb_save, i6300esb_load, d);
+}
+
+static WatchdogTimerModel model = {
+    .wdt_name = "i6300esb",
+    .wdt_description = "Intel 6300ESB",
+    .wdt_pc_init = i6300esb_pc_init,
+};
+
+void wdt_i6300esb_init(void)
+{
+    watchdog_add_model(&model);
+}
diff --git a/hw/wdt_ib700.c b/hw/wdt_ib700.c
new file mode 100644
index 0000000000..d32aaf13ff
--- /dev/null
+++ b/hw/wdt_ib700.c
@@ -0,0 +1,112 @@
+/*
+ * Virtual hardware watchdog.
+ *
+ * Copyright (C) 2009 Red Hat Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
+ * USA.
+ *
+ * By Richard W.M. Jones (rjones@redhat.com).
+ */
+
+#include "qemu-common.h"
+#include "qemu-timer.h"
+#include "watchdog.h"
+#include "hw.h"
+#include "isa.h"
+#include "pc.h"
+
+/*#define IB700_DEBUG 1*/
+
+#ifdef IB700_DEBUG
+#define ib700_debug(fs,...)					\
+    fprintf(stderr,"ib700: %s: "fs,__func__,##__VA_ARGS__)
+#else
+#define ib700_debug(fs,...)
+#endif
+
+/* This is the timer.  We use a global here because the watchdog
+ * code ensures there is only one watchdog (it is located at a fixed,
+ * unchangable IO port, so there could only ever be one anyway).
+ */
+static QEMUTimer *timer = NULL;
+
+/* A write to this register enables the timer. */
+static void ib700_write_enable_reg(void *vp, uint32_t addr, uint32_t data)
+{
+    static int time_map[] = {
+        30, 28, 26, 24, 22, 20, 18, 16,
+        14, 12, 10,  8,  6,  4,  2,  0
+    };
+    int64 timeout;
+
+    ib700_debug("addr = %x, data = %x\n", addr, data);
+
+    timeout = (int64_t) time_map[data & 0xF] * ticks_per_sec;
+    qemu_mod_timer(timer, qemu_get_clock (vm_clock) + timeout);
+}
+
+/* A write (of any value) to this register disables the timer. */
+static void ib700_write_disable_reg(void *vp, uint32_t addr, uint32_t data)
+{
+    ib700_debug("addr = %x, data = %x\n", addr, data);
+
+    qemu_del_timer(timer);
+}
+
+/* This is called when the watchdog expires. */
+static void ib700_timer_expired(void *vp)
+{
+    ib700_debug("watchdog expired\n");
+
+    watchdog_perform_action();
+    qemu_del_timer(timer);
+}
+
+static void ib700_save(QEMUFile *f, void *vp)
+{
+    qemu_put_timer(f, timer);
+}
+
+static int ib700_load(QEMUFile *f, void *vp, int version)
+{
+    if (version != 0)
+        return -EINVAL;
+
+    qemu_get_timer(f, timer);
+
+    return 0;
+}
+
+/* Create and initialize a virtual IB700 during PC creation. */
+static void ib700_pc_init(PCIBus *unused)
+{
+    register_savevm("ib700_wdt", -1, 0, ib700_save, ib700_load, NULL);
+
+    register_ioport_write(0x441, 2, 1, ib700_write_disable_reg, NULL);
+    register_ioport_write(0x443, 2, 1, ib700_write_enable_reg, NULL);
+}
+
+static WatchdogTimerModel model = {
+    .wdt_name = "ib700",
+    .wdt_description = "iBASE 700",
+    .wdt_pc_init = ib700_pc_init,
+};
+
+void wdt_ib700_init(void)
+{
+    watchdog_add_model(&model);
+    timer = qemu_new_timer(vm_clock, ib700_timer_expired, NULL);
+}
diff --git a/monitor.c b/monitor.c
index b33fea1117..d64f459a6e 100644
--- a/monitor.c
+++ b/monitor.c
@@ -27,6 +27,7 @@
 #include "hw/pcmcia.h"
 #include "hw/pc.h"
 #include "hw/pci.h"
+#include "hw/watchdog.h"
 #include "gdbstub.h"
 #include "net.h"
 #include "qemu-char.h"
@@ -597,6 +598,13 @@ static void do_gdbserver(Monitor *mon, const char *device)
 }
 #endif
 
+static void do_watchdog_action(Monitor *mon, const char *action)
+{
+    if (select_watchdog_action(action) == -1) {
+        monitor_printf(mon, "Unknown watchdog action '%s'\n", action);
+    }
+}
+
 static void monitor_printc(Monitor *mon, int c)
 {
     monitor_printf(mon, "'");
@@ -1762,6 +1770,8 @@ static const mon_cmd_t mon_cmds[] = {
       "target", "request VM to change it's memory allocation (in MB)" },
     { "set_link", "ss", do_set_link,
       "name up|down", "change the link status of a network adapter" },
+    { "watchdog_action", "s", do_watchdog_action,
+      "[reset|shutdown|poweroff|pause|debug|none]", "change watchdog action" },
     { "acl", "sss?i?", do_acl, "<command> <aclname> [<match> [<index>]]\n",
                                "acl show vnc.username\n"
                                "acl policy vnc.username deny\n"
diff --git a/qemu-options.hx b/qemu-options.hx
index aa786e3bc1..342b0e63d1 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -1448,6 +1448,55 @@ order cores with complex cache hierarchies.  The number of instructions
 executed often has little or no correlation with actual performance.
 ETEXI
 
+DEF("watchdog", HAS_ARG, QEMU_OPTION_watchdog, \
+    "-watchdog i6300esb|ib700\n" \
+    "                enable virtual hardware watchdog [default=none]\n")
+STEXI
+@item -watchdog @var{model}
+Create a virtual hardware watchdog device.  Once enabled (by a guest
+action), the watchdog must be periodically polled by an agent inside
+the guest or else the guest will be restarted.
+
+The @var{model} is the model of hardware watchdog to emulate.  Choices
+for model are: @code{ib700} (iBASE 700) which is a very simple ISA
+watchdog with a single timer, or @code{i6300esb} (Intel 6300ESB I/O
+controller hub) which is a much more featureful PCI-based dual-timer
+watchdog.  Choose a model for which your guest has drivers.
+
+Use @code{-watchdog ?} to list available hardware models.  Only one
+watchdog can be enabled for a guest.
+ETEXI
+
+DEF("watchdog-action", HAS_ARG, QEMU_OPTION_watchdog_action, \
+    "-watchdog-action reset|shutdown|poweroff|pause|debug|none\n" \
+    "                action when watchdog fires [default=reset]\n")
+STEXI
+@item -watchdog-action @var{action}
+
+The @var{action} controls what QEMU will do when the watchdog timer
+expires.
+The default is
+@code{reset} (forcefully reset the guest).
+Other possible actions are:
+@code{shutdown} (attempt to gracefully shutdown the guest),
+@code{poweroff} (forcefully poweroff the guest),
+@code{pause} (pause the guest),
+@code{debug} (print a debug message and continue), or
+@code{none} (do nothing).
+
+Note that the @code{shutdown} action requires that the guest responds
+to ACPI signals, which it may not be able to do in the sort of
+situations where the watchdog would have expired, and thus
+@code{-watchdog-action shutdown} is not recommended for production use.
+
+Examples:
+
+@table @code
+@item -watchdog i6300esb -watchdog-action pause
+@item -watchdog ib700
+@end table
+ETEXI
+
 DEF("echr", HAS_ARG, QEMU_OPTION_echr, \
     "-echr chr       set terminal escape character instead of ctrl-a\n")
 STEXI
diff --git a/vl.c b/vl.c
index 04add689e5..2d38ded49d 100644
--- a/vl.c
+++ b/vl.c
@@ -138,6 +138,7 @@ int main(int argc, char **argv)
 #include "hw/isa.h"
 #include "hw/baum.h"
 #include "hw/bt.h"
+#include "hw/watchdog.h"
 #include "hw/smbios.h"
 #include "hw/xen.h"
 #include "bt-host.h"
@@ -252,6 +253,8 @@ int graphic_rotate = 0;
 #ifndef _WIN32
 int daemonize = 0;
 #endif
+WatchdogTimerModel *watchdog = NULL;
+int watchdog_action = WDT_RESET;
 const char *option_rom[MAX_OPTION_ROMS];
 int nb_option_roms;
 int semihosting_enabled = 0;
@@ -4917,6 +4920,8 @@ int main(int argc, char **argv, char **envp)
     tb_size = 0;
     autostart= 1;
 
+    register_watchdogs();
+
     optind = 1;
     for(;;) {
         if (optind >= argc)
@@ -5308,6 +5313,17 @@ int main(int argc, char **argv, char **envp)
                 serial_devices[serial_device_index] = optarg;
                 serial_device_index++;
                 break;
+            case QEMU_OPTION_watchdog:
+                i = select_watchdog(optarg);
+                if (i > 0)
+                    exit (i == 1 ? 1 : 0);
+                break;
+            case QEMU_OPTION_watchdog_action:
+                if (select_watchdog_action(optarg) == -1) {
+                    fprintf(stderr, "Unknown -watchdog-action parameter\n");
+                    exit(1);
+                }
+                break;
             case QEMU_OPTION_virtiocon:
                 if (virtio_console_index >= MAX_VIRTIO_CONSOLES) {
                     fprintf(stderr, "qemu: too many virtio consoles\n");