[PATCH] - add symmetry to para and fully virtualized domain shutdown/reboot

[Ben Thomas <bthomas@virtualiron.com>]

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Add code to make handling domain poweroff/reboot symmetrical
between paravirtualized and fully virtualized.

A paravirtualized domain uses sched_op to shut down and set the
reason code. This will send a VIRQ_DOM_EXC, which can be
handled in dom0 by control software.  In some ways, this resembles
SIGCHILD/waitpid, and is a reasonable model.

The fully virtualized case has qemu invoke xm directly. This is a
different path than paravirtualized. It also removes
decision and policy making choices from the rest of the control
software and places it within qemu. When any dom0 logic
eventually gets a VIRQ_DOM_EXC, the information about the
domain is gone having been destroyed by xm.

It would be useful if all shutdown/reboot operations were
symmetrical from domain 0's point of view. This approach
uses the new sched_op to handle other domains than
the current domain.  The new code, SCHEDOP_remote_shutdown,
is very much like SCHEDOP_shutdown, but is called with
the id of the domain which is to be shut down. This allows
fully virtualized shutdown and para-virtualized shutdown
to be identical from that point forward.

A libxenctrl wrapper, xc_shutdown_domain has been added
and qemu now calls it.

With this change, both domain types shutdown/reboot using
the same dom0 management logic. All control decisions are
removed from qemu, which now simply handles the request
and reason. At a very high level, the flow is "notify of
shutdown and reason", "send VIRQ_DOM_EXC", process, and
destroy domain.  Paravirtualized and fully-virtualized
domains would differ slightly in the first step of
notification.

Or, back to the opening sentence, make the operations as
symmetrical as possible.

As a freebie, #if 0 some very verbose logging code in qemu.
Totally unrelated, but as long as I was there...


Signed-off-by: Ben Thomas (ben@virtualiron.com)
-- 
------------------------------------------------------------------------
Ben Thomas                                         Virtual Iron Software
bthomas@virtualiron.com                            Tower 1, Floor 2
978-849-1214                                       900 Chelmsford Street
                                                    Lowell, MA 01851

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diff -r e1152d55ea31 linux-2.6-xen-sparse/drivers/xen/privcmd/privcmd.c
--- a/linux-2.6-xen-sparse/drivers/xen/privcmd/privcmd.c	Wed Apr  5 17:41:51 2006 +0100
+++ b/linux-2.6-xen-sparse/drivers/xen/privcmd/privcmd.c	Thu Apr  6 09:27:37 2006 -0400
@@ -277,6 +277,7 @@ static int __init privcmd_init(void)
 	set_bit(__HYPERVISOR_mmu_update,       hypercall_permission_map);
 	set_bit(__HYPERVISOR_mmuext_op,        hypercall_permission_map);
 	set_bit(__HYPERVISOR_xen_version,      hypercall_permission_map);
+	set_bit(__HYPERVISOR_sched_op,         hypercall_permission_map);
 
 	privcmd_intf = create_xen_proc_entry("privcmd", 0400);
 	if (privcmd_intf != NULL)
diff -r e1152d55ea31 tools/ioemu/target-i386-dm/helper2.c
--- a/tools/ioemu/target-i386-dm/helper2.c	Wed Apr  5 17:41:51 2006 +0100
+++ b/tools/ioemu/target-i386-dm/helper2.c	Thu Apr  6 09:27:37 2006 -0400
@@ -409,12 +409,20 @@ void
 void
 destroy_hvm_domain(void)
 {
-    extern FILE* logfile;
-    char destroy_cmd[32];
-
-    sprintf(destroy_cmd, "xm destroy %d", domid);
-    if (system(destroy_cmd) == -1)
-        fprintf(logfile, "%s failed.!\n", destroy_cmd);
+   int	xcHandle;
+   int	sts;
+ 
+   xcHandle = xc_interface_open();
+   if (xcHandle < 0)
+     fprintf(logfile, "Cannot acquire xenctrl handle\n");
+   else {
+     sts = xc_domain_shutdown(xcHandle, domid, SHUTDOWN_poweroff);
+     if (sts != 0)
+       fprintf(logfile, "? xc_domain_shutdown failed to issue poweroff, sts %d, errno %d\n", sts, errno);
+     else
+       fprintf(logfile, "Issued domain %d poweroff\n", domid);
+     xc_interface_close(xcHandle);
+   }
 }
 
 fd_set wakeup_rfds;
@@ -480,13 +488,24 @@ int main_loop(void)
 
 static void qemu_hvm_reset(void *unused)
 {
-    char cmd[64];
-
-    /* pause domain first, to avoid repeated reboot request*/
-    xc_domain_pause(xc_handle, domid);
-
-    sprintf(cmd, "xm shutdown -R %d", domid);
-    system(cmd);
+   int	xcHandle;
+   int	sts;
+
+   /* pause domain first, to avoid repeated reboot request*/
+   xc_domain_pause(xc_handle, domid);
+
+   xcHandle = xc_interface_open();
+   if (xcHandle < 0)
+     fprintf(logfile, "Cannot acquire xenctrl handle\n");
+   else {
+     sts = xc_domain_shutdown(xcHandle, domid, SHUTDOWN_reboot);
+     if (sts != 0)
+       fprintf(logfile, "? xc_domain_shutdown failed to issue reboot, sts %d\n", sts);
+     else
+       fprintf(logfile, "Issued domain %d reboot\n", domid);
+     xc_interface_close(xcHandle);
+   }
+ 
 }
 
 CPUState * cpu_init()
diff -r e1152d55ea31 tools/ioemu/vl.c
--- a/tools/ioemu/vl.c	Wed Apr  5 17:41:51 2006 +0100
+++ b/tools/ioemu/vl.c	Thu Apr  6 09:27:37 2006 -0400
@@ -2556,8 +2556,10 @@ static int set_mm_mapping(int xc_handle,
         return -1;
     }
 
+#if 0	/* Generates lots of log file output - turn on for debugging */
     for (i = 0; i < nr_pages; i++)
         fprintf(stderr, "set_map result i %x result %lx\n", i, extent_start[i]);
+#endif
 
     return 0;
 }
diff -r e1152d55ea31 tools/libxc/xc_domain.c
--- a/tools/libxc/xc_domain.c	Wed Apr  5 17:41:51 2006 +0100
+++ b/tools/libxc/xc_domain.c	Thu Apr  6 09:27:37 2006 -0400
@@ -57,6 +57,35 @@ int xc_domain_destroy(int xc_handle,
     op.u.destroydomain.domain = (domid_t)domid;
     return do_dom0_op(xc_handle, &op);
 }
+
+int xc_domain_shutdown(int xc_handle,
+                       uint32_t domid,
+		       int reason)
+{
+    int ret = -1;
+    sched_remote_shutdown_t arg;
+    DECLARE_HYPERCALL;
+
+    hypercall.op     = __HYPERVISOR_sched_op;
+    hypercall.arg[0] = (unsigned long)SCHEDOP_remote_shutdown;
+    hypercall.arg[1] = (unsigned long)&arg;
+    arg.domain_id = domid;
+    arg.reason = reason;
+
+    if ( mlock(&arg, sizeof(arg)) != 0 )
+    {
+        PERROR("Could not lock memory for Xen hypercall");
+        goto out1;
+    }
+
+    ret = do_xen_hypercall(xc_handle, &hypercall);
+
+    safe_munlock(&arg, sizeof(arg));
+
+ out1:
+    return ret;
+}
+
 
 int xc_vcpu_setaffinity(int xc_handle,
                         uint32_t domid, 
diff -r e1152d55ea31 tools/libxc/xenctrl.h
--- a/tools/libxc/xenctrl.h	Wed Apr  5 17:41:51 2006 +0100
+++ b/tools/libxc/xenctrl.h	Thu Apr  6 09:27:37 2006 -0400
@@ -205,6 +205,21 @@ int xc_domain_unpause(int xc_handle,
  */
 int xc_domain_destroy(int xc_handle, 
                       uint32_t domid);
+		      
+/**
+ * This function will shutdown a domain. This is intended for use in
+ * fully-virtualized domains where this operation is analogous to the
+ * sched_op operations in a paravirtualized domain. The caller is
+ * expected to give the reason for the shutdown.
+ *
+ * @parm xc_handle a handle to an open hypervisor interface
+ * @parm domid the domain id to destroy
+ * @parm reason is the reason (SHUTDOWN_xxx) for the shutdown
+ * @return 0 on success, -1 on failure
+ */
+int xc_domain_shutdown(int xc_handle, 
+                       uint32_t domid,
+       		       int reason);
 
 int xc_vcpu_setaffinity(int xc_handle,
                         uint32_t domid,
diff -r e1152d55ea31 xen/common/schedule.c
--- a/xen/common/schedule.c	Wed Apr  5 17:41:51 2006 +0100
+++ b/xen/common/schedule.c	Thu Apr  6 09:27:37 2006 -0400
@@ -413,6 +413,30 @@ long do_sched_op(int cmd, GUEST_HANDLE(v
         break;
     }
 
+    case SCHEDOP_remote_shutdown:
+    {
+        struct domain *d;
+        struct sched_remote_shutdown sched_remote_shutdown;
+
+        if ( !IS_PRIV(current->domain) )
+            return -EPERM;
+
+        ret = -EFAULT;
+        if ( copy_from_guest(&sched_remote_shutdown, arg, 1) )
+            break;
+
+        ret = -ESRCH;
+        d = find_domain_by_id(sched_remote_shutdown.domain_id);
+        if ( d != NULL )
+        {
+            domain_shutdown(d, (u8)sched_remote_shutdown.reason);
+            put_domain(d);
+            ret = 0;
+        }
+
+        break;
+    }
+
     default:
         ret = -ENOSYS;
     }
diff -r e1152d55ea31 xen/include/public/sched.h
--- a/xen/include/public/sched.h	Wed Apr  5 17:41:51 2006 +0100
+++ b/xen/include/public/sched.h	Thu Apr  6 09:27:37 2006 -0400
@@ -65,6 +65,19 @@ DEFINE_GUEST_HANDLE(sched_poll_t);
 DEFINE_GUEST_HANDLE(sched_poll_t);
 
 /*
+ * Declare a shutdown for another domain. The main use of this function is
+ * in interpreting shutdown requests and reasons for fully-virtualized
+ * domains.  A para-virtualized domain may use SCHEDOP_shutdown directly.
+ * @arg == pointer to sched_remote_shutdown structure.
+ */
+#define SCHEDOP_remote_shutdown        4
+typedef struct sched_remote_shutdown {
+    domid_t domain_id;     	/* Remote domain ID */
+    unsigned int reason;	/* SHUTDOWN_xxx reason */
+} sched_remote_shutdown_t;
+DEFINE_GUEST_HANDLE(sched_remote_shutdown_t);
+
+/*
  * Reason codes for SCHEDOP_shutdown. These may be interpreted by control
  * software to determine the appropriate action. For the most part, Xen does
  * not care about the shutdown code.

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