The new PAPR 2.12 defines a watchdog facility managed via the new
H_WATCHDOG hypercall.

This adds H_WATCHDOG support which a proposed driver for pseries uses:
https://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=303120

This was tested by running QEMU with a debug kernel and command line:
-append \
 "pseries-wdt.timeout=60 pseries-wdt.nowayout=1 pseries-wdt.action=2"

and running "echo V > /dev/watchdog0" inside the VM.

Signed-off-by: Alexey Kardashevskiy <a...@ozlabs.ru>
---
 include/hw/ppc/spapr.h  |  23 +++-
 hw/ppc/spapr.c          |   5 +
 hw/ppc/spapr_watchdog.c | 239 ++++++++++++++++++++++++++++++++++++++++
 hw/ppc/meson.build      |   1 +
 hw/ppc/trace-events     |   7 ++
 5 files changed, 274 insertions(+), 1 deletion(-)
 create mode 100644 hw/ppc/spapr_watchdog.c

diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
index 072dda2c7265..39aa8609df7b 100644
--- a/include/hw/ppc/spapr.h
+++ b/include/hw/ppc/spapr.h
@@ -164,6 +164,19 @@ struct SpaprMachineClass {
     SpaprIrq *irq;
 };
 
+#define WDT_MAX_WATCHDOGS       4      /* Maximum number of watchdog devices */
+
+#define WDT_HARD_POWER_OFF      0
+#define WDT_HARD_RESTART        1
+#define WDT_DUMP_RESTART        2
+
+typedef struct SpaprWatchdog {
+    unsigned num;
+    QEMUTimer timer;
+    uint8_t action;
+    uint64_t timeout;
+} SpaprWatchdog;
+
 /**
  * SpaprMachineState:
  */
@@ -264,6 +277,8 @@ struct SpaprMachineState {
     uint32_t FORM2_assoc_array[NUMA_NODES_MAX_NUM][FORM2_NUMA_ASSOC_SIZE];
 
     Error *fwnmi_migration_blocker;
+
+    SpaprWatchdog wds[WDT_MAX_WATCHDOGS];
 };
 
 #define H_SUCCESS         0
@@ -344,6 +359,7 @@ struct SpaprMachineState {
 #define H_P7              -60
 #define H_P8              -61
 #define H_P9              -62
+#define H_NOOP            -63
 #define H_UNSUPPORTED     -67
 #define H_OVERLAP         -68
 #define H_UNSUPPORTED_FLAG -256
@@ -564,8 +580,9 @@ struct SpaprMachineState {
 #define H_SCM_HEALTH            0x400
 #define H_RPT_INVALIDATE        0x448
 #define H_SCM_FLUSH             0x44C
+#define H_WATCHDOG              0x45C
 
-#define MAX_HCALL_OPCODE        H_SCM_FLUSH
+#define MAX_HCALL_OPCODE        H_WATCHDOG
 
 /* The hcalls above are standardized in PAPR and implemented by pHyp
  * as well.
@@ -1027,6 +1044,7 @@ extern const VMStateDescription 
vmstate_spapr_cap_large_decr;
 extern const VMStateDescription vmstate_spapr_cap_ccf_assist;
 extern const VMStateDescription vmstate_spapr_cap_fwnmi;
 extern const VMStateDescription vmstate_spapr_cap_rpt_invalidate;
+extern const VMStateDescription vmstate_spapr_wdt;
 
 static inline uint8_t spapr_get_cap(SpaprMachineState *spapr, int cap)
 {
@@ -1063,4 +1081,7 @@ target_ulong 
spapr_vof_client_architecture_support(MachineState *ms,
                                                    target_ulong ovec_addr);
 void spapr_vof_client_dt_finalize(SpaprMachineState *spapr, void *fdt);
 
+/* H_WATCHDOG */
+void spapr_watchdog_init(SpaprMachineState *spapr);
+
 #endif /* HW_SPAPR_H */
diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index fd4942e8813c..eaa75f5afd02 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -898,6 +898,8 @@ static void spapr_dt_rtas(SpaprMachineState *spapr, void 
*fdt)
         add_str(hypertas, "hcall-hpt-resize");
     }
 
+    add_str(hypertas, "hcall-watchdog");
+
     _FDT(fdt_setprop(fdt, rtas, "ibm,hypertas-functions",
                      hypertas->str, hypertas->len));
     g_string_free(hypertas, TRUE);
@@ -2067,6 +2069,7 @@ static const VMStateDescription vmstate_spapr = {
         &vmstate_spapr_cap_fwnmi,
         &vmstate_spapr_fwnmi,
         &vmstate_spapr_cap_rpt_invalidate,
+        &vmstate_spapr_wdt,
         NULL
     }
 };
@@ -3051,6 +3054,8 @@ static void spapr_machine_init(MachineState *machine)
         spapr->vof->fw_size = fw_size; /* for claim() on itself */
         spapr_register_hypercall(KVMPPC_H_VOF_CLIENT, spapr_h_vof_client);
     }
+
+    spapr_watchdog_init(spapr);
 }
 
 #define DEFAULT_KVM_TYPE "auto"
diff --git a/hw/ppc/spapr_watchdog.c b/hw/ppc/spapr_watchdog.c
new file mode 100644
index 000000000000..5206e40078b5
--- /dev/null
+++ b/hw/ppc/spapr_watchdog.c
@@ -0,0 +1,239 @@
+/*
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "qemu/osdep.h"
+#include "sysemu/runstate.h"
+#include "migration/vmstate.h"
+#include "trace.h"
+
+#include "hw/ppc/spapr.h"
+
+#define PPC_BITLSHIFT(be)       (BITS_PER_LONG - 1 - (be))
+
+#define SETFIELD(val, start, end)   \
+    (((unsigned long)(val) << PPC_BITLSHIFT(end)) & PPC_BITMASK(start, end))
+#define GETFIELD(val, start, end)   \
+    (((unsigned long)(val) & PPC_BITMASK(start, end)) >> PPC_BITLSHIFT(end))
+
+/*
+ * Bits 47: "leaveOtherWatchdogsRunningOnTimeout", specified on
+ * the "Start watchdog" operation,
+ * 0 - stop out-standing watchdogs on timeout,
+ * 1 - leave outstanding watchdogs running on timeout
+ */
+#define PSERIES_WDTF_LEAVE_OTHER    PPC_BIT(47)
+
+/*    Bits 48-55: "operation" */
+#define PSERIES_WDTF_OP(op)             SETFIELD((op), 48, 55)
+#define PSERIES_WDTF_OP_START           PSERIES_WDTF_OP(0x1)
+#define PSERIES_WDTF_OP_STOP            PSERIES_WDTF_OP(0x2)
+#define PSERIES_WDTF_OP_QUERY           PSERIES_WDTF_OP(0x3)
+#define PSERIES_WDTF_OP_QUERY_LPM       PSERIES_WDTF_OP(0x4)
+
+/*    Bits 56-63: "timeoutAction" */
+#define PSERIES_WDTF_ACTION(ac)             SETFIELD(ac, 56, 63)
+#define PSERIES_WDTF_ACTION_HARD_POWER_OFF  PSERIES_WDTF_ACTION(0x1)
+#define PSERIES_WDTF_ACTION_HARD_RESTART    PSERIES_WDTF_ACTION(0x2)
+#define PSERIES_WDTF_ACTION_DUMP_RESTART    PSERIES_WDTF_ACTION(0x3)
+
+#define PSERIES_WDTF_RESERVED           PPC_BITMASK(0, 46)
+
+/*
+ * For the "Query watchdog capabilities" operation, a uint64 structure
+ * defined as:
+ * Bits 0-15: The minimum supported timeout in milliseconds
+ * Bits 16-31: The number of watchdogs supported
+ * Bits 32-63: Reserved
+ */
+#define PSERIES_WDTQ_MIN_TIMEOUT(ms)    SETFIELD((ms), 0, 15)
+#define PSERIES_WDTQ_NUM(n)             SETFIELD((n), 16, 31)
+#define PSERIES_WDTQ_RESERVED           PPC_BITMASK(32, 63)
+
+/*
+ * For the "Query watchdog LPM requirement" operation:
+ * 1 = The given "watchdogNumber" must be stopped prior to suspending
+ * 2 = The given "watchdogNumber" does not have to be stopped prior to
+ * suspending
+ */
+#define PSERIES_WDTQL_STOPPED               1
+#define PSERIES_WDTQL_QUERY_NOT_STOPPED     2
+
+#define WDT_MIN_TIMEOUT 1 /* 1ms */
+
+static void watchdog_expired(void *pw)
+{
+    struct SpaprWatchdog *w = pw;
+    CPUState *cs;
+
+    trace_spapr_watchdog_expired(w->num, w->action);
+    switch (w->action) {
+    case WDT_HARD_POWER_OFF:
+        qemu_system_vmstop_request(RUN_STATE_SHUTDOWN);
+        break;
+    case WDT_HARD_RESTART:
+        qemu_system_reset_request(SHUTDOWN_CAUSE_GUEST_RESET);
+        break;
+    case WDT_DUMP_RESTART:
+        CPU_FOREACH(cs) {
+            async_run_on_cpu(cs, spapr_do_system_reset_on_cpu, 
RUN_ON_CPU_NULL);
+        }
+        break;
+    }
+}
+
+static target_ulong watchdog_stop(unsigned watchdogNumber,
+                                  struct SpaprWatchdog *w)
+{
+    target_ulong ret = H_NOOP;
+
+    if (timer_pending(&w->timer)) {
+        timer_del(&w->timer);
+        ret = H_SUCCESS;
+    }
+    trace_spapr_watchdog_stop(watchdogNumber, ret);
+
+    return ret;
+}
+
+static target_ulong h_watchdog(PowerPCCPU *cpu,
+                               SpaprMachineState *spapr,
+                               target_ulong opcode, target_ulong *args)
+{
+    target_ulong flags = args[0];
+    target_ulong watchdogNumber = args[1];
+    target_ulong timeoutInMs = args[2];
+    unsigned operation = flags & PSERIES_WDTF_OP(~0);
+    unsigned timeoutAction = flags & PSERIES_WDTF_ACTION(~0);
+    struct SpaprWatchdog *w;
+
+    if (flags & PSERIES_WDTF_RESERVED || watchdogNumber == 0) {
+        return H_PARAMETER;
+    }
+
+    switch (operation) {
+    case PSERIES_WDTF_OP_START:
+        if (watchdogNumber > ARRAY_SIZE(spapr->wds)) {
+            return H_P2;
+        }
+        if (timeoutInMs <= WDT_MIN_TIMEOUT) {
+            return H_P3;
+        }
+
+        w = &spapr->wds[watchdogNumber - 1];
+        switch (timeoutAction) {
+        case PSERIES_WDTF_ACTION_HARD_POWER_OFF:
+            w->action = WDT_HARD_POWER_OFF;
+            break;
+        case PSERIES_WDTF_ACTION_HARD_RESTART:
+            w->action = WDT_HARD_RESTART;
+            break;
+        case PSERIES_WDTF_ACTION_DUMP_RESTART:
+            w->action = WDT_DUMP_RESTART;
+            break;
+        default:
+            return H_PARAMETER;
+        }
+        timer_mod(&w->timer,
+                  qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) + timeoutInMs);
+        trace_spapr_watchdog_start(flags, watchdogNumber, timeoutInMs);
+        break;
+    case PSERIES_WDTF_OP_STOP:
+        if (watchdogNumber == (uint64_t) ~0) {
+            int i;
+
+            for (i = 1; i <= ARRAY_SIZE(spapr->wds); ++i) {
+                watchdog_stop(i, &spapr->wds[i - 1]);
+            }
+        } else if (watchdogNumber <= ARRAY_SIZE(spapr->wds)) {
+            watchdog_stop(watchdogNumber, &spapr->wds[watchdogNumber - 1]);
+        } else {
+            return H_P2;
+        }
+        break;
+    case PSERIES_WDTF_OP_QUERY:
+        args[0] = PSERIES_WDTQ_MIN_TIMEOUT(WDT_MIN_TIMEOUT) |
+            PSERIES_WDTQ_NUM(ARRAY_SIZE(spapr->wds));
+        trace_spapr_watchdog_query(args[0]);
+        break;
+    case PSERIES_WDTF_OP_QUERY_LPM:
+        if (watchdogNumber > ARRAY_SIZE(spapr->wds)) {
+            return H_P2;
+        }
+        args[0] = PSERIES_WDTQL_QUERY_NOT_STOPPED;
+        trace_spapr_watchdog_query_lpm(args[0]);
+        break;
+    default:
+        return H_PARAMETER;
+    }
+
+    return H_SUCCESS;
+}
+
+void spapr_watchdog_init(SpaprMachineState *spapr)
+{
+    int i;
+
+    for (i = 0; i < ARRAY_SIZE(spapr->wds); ++i) {
+        SpaprWatchdog *w = &spapr->wds[i];
+
+        w->num = i + 1;
+        timer_init_ms(&w->timer, QEMU_CLOCK_VIRTUAL, watchdog_expired, w);
+    }
+}
+
+static const VMStateDescription vmstate_wdt = {
+    .name = "spapr_watchdog",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT8(action, SpaprWatchdog),
+        VMSTATE_UINT64(timeout, SpaprWatchdog),
+        VMSTATE_TIMER(timer, SpaprWatchdog),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static bool watchdog_needed(void *opaque)
+{
+    SpaprMachineState *spapr = opaque;
+    int i;
+
+    for (i = 0; i < ARRAY_SIZE(spapr->wds); ++i) {
+        if (timer_pending(&spapr->wds[i].timer)) {
+            return true;
+        }
+    }
+
+    return false;
+}
+
+const VMStateDescription vmstate_spapr_wdt = {
+    .name = "spapr_watchdogs",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .needed = watchdog_needed,
+    .fields = (VMStateField[]) {
+        VMSTATE_STRUCT_ARRAY(wds, SpaprMachineState, WDT_MAX_WATCHDOGS, 0,
+                             vmstate_wdt, SpaprWatchdog),
+        VMSTATE_END_OF_LIST()
+    },
+};
+
+static void spapr_watchdog_register_types(void)
+{
+    spapr_register_hypercall(H_WATCHDOG, h_watchdog);
+}
+
+type_init(spapr_watchdog_register_types)
diff --git a/hw/ppc/meson.build b/hw/ppc/meson.build
index aa4c8e6a2eac..2d1f6c262ce9 100644
--- a/hw/ppc/meson.build
+++ b/hw/ppc/meson.build
@@ -27,6 +27,7 @@ ppc_ss.add(when: 'CONFIG_PSERIES', if_true: files(
   'spapr_nvdimm.c',
   'spapr_rtas_ddw.c',
   'spapr_numa.c',
+  'spapr_watchdog.c',
   'pef.c',
 ))
 ppc_ss.add(when: ['CONFIG_PSERIES', 'CONFIG_TCG'], if_true: files(
diff --git a/hw/ppc/trace-events b/hw/ppc/trace-events
index 5c0a215cad90..24f2eca26da0 100644
--- a/hw/ppc/trace-events
+++ b/hw/ppc/trace-events
@@ -71,6 +71,13 @@ spapr_rtas_ibm_configure_connector_invalid(uint32_t index) 
"DRC index: 0x%"PRIx3
 spapr_vio_h_reg_crq(uint64_t reg, uint64_t queue_addr, uint64_t queue_len) 
"CRQ for dev 0x%" PRIx64 " registered at 0x%" PRIx64 "/0x%" PRIx64
 spapr_vio_free_crq(uint32_t reg) "CRQ for dev 0x%" PRIx32 " freed"
 
+# spapr_watchdog.c
+spapr_watchdog_start(uint64_t flags, uint64_t num, uint64_t timeout) "Flags 
0x%" PRIx64 " num=%" PRId64 " %" PRIu64 "ms"
+spapr_watchdog_stop(uint64_t num, uint64_t ret) "num=%" PRIu64 " ret=%" PRId64
+spapr_watchdog_query(uint64_t caps) "caps=0x%" PRIx64
+spapr_watchdog_query_lpm(uint64_t caps) "caps=0x%" PRIx64
+spapr_watchdog_expired(uint64_t num, unsigned action) "num=%" PRIu64 " 
action=%u"
+
 # vof.c
 vof_error_str_truncated(const char *s, int len) "%s truncated to %d"
 vof_error_param(const char *method, int nargscheck, int nretcheck, int nargs, 
int nret) "%s takes/returns %d/%d, not %d/%d"
-- 
2.30.2


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