Xen regression and bug fixes for 3.15-rc1.

- Fix completely broken 32-bit PV guests caused by x86 refactoring
   32-bit thread_info.
 - Only enable ticketlock slow path on Xen (not bare metal).
 - Fix two bugs with PV guests not shutting down when requested.
 - Fix a minor memory leak in xen-pciback error path.
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Merge tag 'stable/for-linus-3.15-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip

Pull Xen fixes from David Vrabel:
 "Xen regression and bug fixes for 3.15-rc1:

   - fix completely broken 32-bit PV guests caused by x86 refactoring
     32-bit thread_info.
   - only enable ticketlock slow path on Xen (not bare metal)
   - fix two bugs with PV guests not shutting down when requested
   - fix a minor memory leak in xen-pciback error path"

* tag 'stable/for-linus-3.15-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  xen/manage: Poweroff forcefully if user-space is not yet up.
  xen/xenbus: Avoid synchronous wait on XenBus stalling shutdown/restart.
  xen/spinlock: Don't enable them unconditionally.
  xen-pciback: silence an unwanted debug printk
  xen: fix memory leak in __xen_pcibk_add_pci_dev()
  x86/xen: Fix 32-bit PV guests's usage of kernel_stack

arch/x86/xen/smp.c

@@ -441,10 +441,11 @@ static int xen_cpu_up(unsigned int cpu, struct task_struct *idle)
 	irq_ctx_init(cpu);
 #else
 	clear_tsk_thread_flag(idle, TIF_FORK);
+#endif
 	per_cpu(kernel_stack, cpu) =
 		(unsigned long)task_stack_page(idle) -
 		KERNEL_STACK_OFFSET + THREAD_SIZE;
-#endif
+
 	xen_setup_runstate_info(cpu);
 	xen_setup_timer(cpu);
 	xen_init_lock_cpu(cpu);

arch/x86/xen/spinlock.c

@@ -274,7 +274,7 @@ void __init xen_init_spinlocks(void)
 		printk(KERN_DEBUG "xen: PV spinlocks disabled\n");
 		return;
 	}
-
+	printk(KERN_DEBUG "xen: PV spinlocks enabled\n");
 	pv_lock_ops.lock_spinning = PV_CALLEE_SAVE(xen_lock_spinning);
 	pv_lock_ops.unlock_kick = xen_unlock_kick;
 }
@@ -290,6 +290,9 @@ static __init int xen_init_spinlocks_jump(void)
 	if (!xen_pvspin)
 		return 0;
 
+	if (!xen_domain())
+		return 0;
+
 	static_key_slow_inc(&paravirt_ticketlocks_enabled);
 	return 0;
 }

arch/x86/xen/xen-asm_32.S

@@ -75,6 +75,17 @@ ENDPROC(xen_sysexit)
  * stack state in whatever form its in, we keep things simple by only
  * using a single register which is pushed/popped on the stack.
  */
+
+.macro POP_FS
+1:
+	popw %fs
+.pushsection .fixup, "ax"
+2:	movw $0, (%esp)
+	jmp 1b
+.popsection
+	_ASM_EXTABLE(1b,2b)
+.endm
+
 ENTRY(xen_iret)
 	/* test eflags for special cases */
 	testl $(X86_EFLAGS_VM | XEN_EFLAGS_NMI), 8(%esp)
@@ -83,15 +94,13 @@ ENTRY(xen_iret)
 	push %eax
 	ESP_OFFSET=4	# bytes pushed onto stack
 
-	/*
-	 * Store vcpu_info pointer for easy access.  Do it this way to
-	 * avoid having to reload %fs
-	 */
+	/* Store vcpu_info pointer for easy access */
 #ifdef CONFIG_SMP
-	GET_THREAD_INFO(%eax)
-	movl %ss:TI_cpu(%eax), %eax
-	movl %ss:__per_cpu_offset(,%eax,4), %eax
-	mov %ss:xen_vcpu(%eax), %eax
+	pushw %fs
+	movl $(__KERNEL_PERCPU), %eax
+	movl %eax, %fs
+	movl %fs:xen_vcpu, %eax
+	POP_FS
 #else
 	movl %ss:xen_vcpu, %eax
 #endif

drivers/xen/manage.c

@@ -198,10 +198,32 @@ struct shutdown_handler {
 	void (*cb)(void);
 };
 
+static int poweroff_nb(struct notifier_block *cb, unsigned long code, void *unused)
+{
+	switch (code) {
+	case SYS_DOWN:
+	case SYS_HALT:
+	case SYS_POWER_OFF:
+		shutting_down = SHUTDOWN_POWEROFF;
+	default:
+		break;
+	}
+	return NOTIFY_DONE;
+}
 static void do_poweroff(void)
 {
-	shutting_down = SHUTDOWN_POWEROFF;
-	orderly_poweroff(false);
+	switch (system_state) {
+	case SYSTEM_BOOTING:
+		orderly_poweroff(true);
+		break;
+	case SYSTEM_RUNNING:
+		orderly_poweroff(false);
+		break;
+	default:
+		/* Don't do it when we are halting/rebooting. */
+		pr_info("Ignoring Xen toolstack shutdown.\n");
+		break;
+	}
 }
 
 static void do_reboot(void)
@@ -307,6 +329,10 @@ static struct xenbus_watch shutdown_watch = {
 	.callback = shutdown_handler
 };
 
+static struct notifier_block xen_reboot_nb = {
+	.notifier_call = poweroff_nb,
+};
+
 static int setup_shutdown_watcher(void)
 {
 	int err;
@@ -317,6 +343,7 @@ static int setup_shutdown_watcher(void)
 		return err;
 	}
 
+
 #ifdef CONFIG_MAGIC_SYSRQ
 	err = register_xenbus_watch(&sysrq_watch);
 	if (err) {
@@ -345,6 +372,7 @@ int xen_setup_shutdown_event(void)
 	if (!xen_domain())
 		return -ENODEV;
 	register_xenstore_notifier(&xenstore_notifier);
+	register_reboot_notifier(&xen_reboot_nb);
 
 	return 0;
 }

drivers/xen/xen-pciback/pciback_ops.c

@@ -217,7 +217,7 @@ int xen_pcibk_enable_msix(struct xen_pcibk_device *pdev,
 	if (result == 0) {
 		for (i = 0; i < op->value; i++) {
 			op->msix_entries[i].entry = entries[i].entry;
-			if (entries[i].vector)
+			if (entries[i].vector) {
 				op->msix_entries[i].vector =
 					xen_pirq_from_irq(entries[i].vector);
 				if (unlikely(verbose_request))
@@ -225,6 +225,7 @@ int xen_pcibk_enable_msix(struct xen_pcibk_device *pdev,
 						"MSI-X[%d]: %d\n",
 						pci_name(dev), i,
 						op->msix_entries[i].vector);
+			}
 		}
 	} else
 		pr_warn_ratelimited("%s: error enabling MSI-X for guest %u: err %d!\n",

drivers/xen/xen-pciback/vpci.c

@@ -137,6 +137,8 @@ unlock:
 	/* Publish this device. */
 	if (!err)
 		err = publish_cb(pdev, 0, 0, PCI_DEVFN(slot, func), devid);
+	else
+		kfree(dev_entry);
 
 out:
 	return err;

drivers/xen/xenbus/xenbus_xs.c

@@ -50,6 +50,7 @@
 #include <xen/xenbus.h>
 #include <xen/xen.h>
 #include "xenbus_comms.h"
+#include "xenbus_probe.h"
 
 struct xs_stored_msg {
 	struct list_head list;
@@ -139,6 +140,29 @@ static int get_error(const char *errorstring)
 	return xsd_errors[i].errnum;
 }
 
+static bool xenbus_ok(void)
+{
+	switch (xen_store_domain_type) {
+	case XS_LOCAL:
+		switch (system_state) {
+		case SYSTEM_POWER_OFF:
+		case SYSTEM_RESTART:
+		case SYSTEM_HALT:
+			return false;
+		default:
+			break;
+		}
+		return true;
+	case XS_PV:
+	case XS_HVM:
+		/* FIXME: Could check that the remote domain is alive,
+		 * but it is normally initial domain. */
+		return true;
+	default:
+		break;
+	}
+	return false;
+}
 static void *read_reply(enum xsd_sockmsg_type *type, unsigned int *len)
 {
 	struct xs_stored_msg *msg;
@@ -148,9 +172,20 @@ static void *read_reply(enum xsd_sockmsg_type *type, unsigned int *len)
 
 	while (list_empty(&xs_state.reply_list)) {
 		spin_unlock(&xs_state.reply_lock);
-		/* XXX FIXME: Avoid synchronous wait for response here. */
-		wait_event(xs_state.reply_waitq,
-			   !list_empty(&xs_state.reply_list));
+		if (xenbus_ok())
+			/* XXX FIXME: Avoid synchronous wait for response here. */
+			wait_event_timeout(xs_state.reply_waitq,
+					   !list_empty(&xs_state.reply_list),
+					   msecs_to_jiffies(500));
+		else {
+			/*
+			 * If we are in the process of being shut-down there is
+			 * no point of trying to contact XenBus - it is either
+			 * killed (xenstored application) or the other domain
+			 * has been killed or is unreachable.
+			 */
+			return ERR_PTR(-EIO);
+		}
 		spin_lock(&xs_state.reply_lock);
 	}
 
@@ -215,6 +250,9 @@ void *xenbus_dev_request_and_reply(struct xsd_sockmsg *msg)
 
 	mutex_unlock(&xs_state.request_mutex);
 
+	if (IS_ERR(ret))
+		return ret;
+
 	if ((msg->type == XS_TRANSACTION_END) ||
 	    ((req_msg.type == XS_TRANSACTION_START) &&
 	     (msg->type == XS_ERROR)))