[PATCH xenbus 06/12] Add functions to XEN_API to facilitate use of a domain watchdog

[Paul Durrant <paul@xxxxxxx>]

From: Paul Durrant <pdurrant@xxxxxxxxxx>

The SCHEDOP_watchdog hypercall allows a domain to program a watchdog time-
out (in seconds) after which it will be shut down.

This patch adds a helper function into sched.c to make the hypercall and also
adds new SystemSetWatchdog() and SystemStopWatchdog() functions that provide
a more friendly API to the functionality.

This patch does not introduce callers of the new API. Those will be
introduced in a subsequent patch.

Signed-off-by: Paul Durrant <pdurrant@xxxxxxxxxx>
---
 include/xen.h    | 19 +++++++++++++++
 src/xen/sched.c  | 36 ++++++++++++++++++++++++++--
 src/xen/system.c | 62 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 115 insertions(+), 2 deletions(-)

diff --git a/include/xen.h b/include/xen.h
index 3532de839176..4594db975332 100644
--- a/include/xen.h
+++ b/include/xen.h
@@ -308,6 +308,13 @@ SchedYield(
     VOID
     );
 
+XEN_API
+NTSTATUS
+SchedWatchdog(
+    IN OUT  PULONG  Id,
+    IN      ULONG   Seconds
+    );
+
 // XEN VERSION
 
 __checkReturn
@@ -465,4 +472,16 @@ SystemRealTimeIsUniversal(
     VOID
     );
 
+XEN_API
+NTSTATUS
+SystemSetWatchdog(
+    IN  ULONG       Seconds
+    );
+
+XEN_API
+VOID
+SystemStopWatchdog(
+    VOID
+    );
+
 #endif  // _XEN_H
diff --git a/src/xen/sched.c b/src/xen/sched.c
index 56cbcf7b3345..11ca52241650 100644
--- a/src/xen/sched.c
+++ b/src/xen/sched.c
@@ -51,7 +51,7 @@ __checkReturn
 XEN_API
 NTSTATUS
 SchedShutdownCode(
-    ULONG                   Reason
+    IN  ULONG               Reason
     )
 {
     struct sched_shutdown   op;
@@ -79,7 +79,7 @@ __checkReturn
 XEN_API
 NTSTATUS
 SchedShutdown(
-    ULONG                   Reason
+    IN  ULONG               Reason
     )
 {
     struct sched_shutdown   op;
@@ -119,3 +119,35 @@ SchedYield(
 {
     (VOID) SchedOp(SCHEDOP_yield, NULL);
 }
+
+XEN_API
+NTSTATUS
+SchedWatchdog(
+    IN OUT  PULONG          Id,
+    IN      ULONG           Seconds
+    )
+{
+    struct sched_watchdog   op;
+    LONG_PTR                rc;
+    NTSTATUS                status;
+
+    op.id = *Id;
+    op.timeout = Seconds;
+
+    rc = SchedOp(SCHEDOP_watchdog, &op);
+
+    if (rc < 0) {
+        ERRNO_TO_STATUS(-rc, status);
+        goto fail1;
+    }
+
+    if (*Id == 0)
+        *Id = (ULONG)rc;
+
+    return STATUS_SUCCESS;
+
+fail1:
+    Error("fail1 (%08x)\n", status);
+
+    return status;
+}
diff --git a/src/xen/system.c b/src/xen/system.c
index 45fe3b6c31bb..5a8ba16a6660 100644
--- a/src/xen/system.c
+++ b/src/xen/system.c
@@ -55,6 +55,11 @@ typedef struct _SYSTEM_PROCESSOR {
     UCHAR   ProcessorID;
 } SYSTEM_PROCESSOR, *PSYSTEM_PROCESSOR;
 
+typedef struct _SYSTEM_WATCHDOG {
+    ULONG   Id;
+    ULONG   Seconds;
+} SYSTEM_WATCHDOG, *PSYSTEM_WATCHDOG;
+
 typedef struct _SYSTEM_CONTEXT {
     LONG                References;
     PACPI_MADT          Madt;
@@ -64,6 +69,7 @@ typedef struct _SYSTEM_CONTEXT {
     PVOID               ProcessorChangeHandle;
     PHYSICAL_ADDRESS    MaximumPhysicalAddress;
     BOOLEAN             RealTimeIsUniversal;
+    SYSTEM_WATCHDOG     Watchdog;
 } SYSTEM_CONTEXT, *PSYSTEM_CONTEXT;
 
 static SYSTEM_CONTEXT   SystemContext;
@@ -1104,6 +1110,62 @@ SystemRealTimeIsUniversal(
     return Context->RealTimeIsUniversal;
 }
 
+XEN_API
+NTSTATUS
+SystemSetWatchdog(
+    IN  ULONG       Seconds
+    )
+{
+    PSYSTEM_CONTEXT Context = &SystemContext;
+    ULONG           Id = Context->Watchdog.Id;
+    NTSTATUS        status;
+
+    status = STATUS_INVALID_PARAMETER;
+    if (Seconds == 0)
+        goto fail1;
+
+    status = SchedWatchdog(&Id, Seconds);
+    if (!NT_SUCCESS(status))
+        goto fail2;
+
+    if (Context->Watchdog.Id == 0 || Context->Watchdog.Seconds != Seconds)
+        Info("%u: %us\n", Id, Seconds);
+
+    Context->Watchdog.Id = Id;
+    Context->Watchdog.Seconds = Seconds;
+
+    return STATUS_SUCCESS;
+
+fail2:
+    Error("fail2\n");
+
+fail1:
+    Error("fail1 (%08x)\n", status);
+
+    return status;
+}
+
+XEN_API
+VOID
+SystemStopWatchdog(
+    VOID
+    )
+{
+    PSYSTEM_CONTEXT Context = &SystemContext;
+    NTSTATUS        status;
+
+    if (Context->Watchdog.Id == 0)
+        return;
+
+    status = SchedWatchdog(&Context->Watchdog.Id, 0);
+    ASSERT(NT_SUCCESS(status));
+
+    Info("%u\n", Context->Watchdog.Id);
+
+    Context->Watchdog.Id = 0;
+    Context->Watchdog.Seconds = 0;
+}
+
 VOID
 SystemTeardown(
     VOID
-- 
2.17.1