xen: bug fixes for 4.2-rc6

- Revert a fix from 4.2-rc5 that was causing lots of WARNING spam.
 - Fix a memory leak affecting backends in HVM guests.
 - Fix PV domU hang with certain configurations.
 -----BEGIN PGP SIGNATURE-----
 Version: GnuPG v1
 
 iQEcBAABAgAGBQJVzHsAAAoJEFxbo/MsZsTR9Y0H/2j1PHt29RPcNdgGQ84AH0Wh
 tw1emL8rMcdhWQnsO7bNmywNNvRNQnU3ZJ8dzoq+5GPikNsbfQzYc7U2pIL4A+gB
 AAJsNDNzecuq4srk8vNxcmZ7ySvm9w6dccDUex2ge3sNWaq6gzSQvz6FSWiL0Sxg
 k3JcnemEg6JrYOTWdxKInAORMcRO6rgx9eIsdPUPOpgC5XLg6/mZOqBAWXIksDvs
 V9uCMqQicaUgBgKFIOSllqH6fcCNooRu3aDwNNj/2mMcJmEvMeBkHmNlQgEm2j5L
 ubdDyrC5y48TUPJm8i3+W2/AY+kgWzhThcqyVy6LRAAj5RItJFxMf0nMXzIEqlQ=
 =UgMy
 -----END PGP SIGNATURE-----

Merge tag 'for-linus-4.2-rc6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip

Pull xen bug fixes from David Vrabel:

 - revert a fix from 4.2-rc5 that was causing lots of WARNING spam.

 - fix a memory leak affecting backends in HVM guests.

 - fix PV domU hang with certain configurations.

* tag 'for-linus-4.2-rc6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  xen/xenbus: Don't leak memory when unmapping the ring on HVM backend
  Revert "xen/events/fifo: Handle linked events when closing a port"
  x86/xen: build "Xen PV" APIC driver for domU as well

arch/x86/xen/Makefile

@@ -13,13 +13,13 @@ CFLAGS_mmu.o			:= $(nostackp)
 obj-y		:= enlighten.o setup.o multicalls.o mmu.o irq.o \
 			time.o xen-asm.o xen-asm_$(BITS).o \
 			grant-table.o suspend.o platform-pci-unplug.o \
-			p2m.o
+			p2m.o apic.o
 
 obj-$(CONFIG_EVENT_TRACING) += trace.o
 
 obj-$(CONFIG_SMP)		+= smp.o
 obj-$(CONFIG_PARAVIRT_SPINLOCKS)+= spinlock.o
 obj-$(CONFIG_XEN_DEBUG_FS)	+= debugfs.o
-obj-$(CONFIG_XEN_DOM0)		+= apic.o vga.o
+obj-$(CONFIG_XEN_DOM0)		+= vga.o
 obj-$(CONFIG_SWIOTLB_XEN)	+= pci-swiotlb-xen.o
 obj-$(CONFIG_XEN_EFI)		+= efi.o

arch/x86/xen/xen-ops.h

@@ -101,17 +101,15 @@ struct dom0_vga_console_info;
 
 #ifdef CONFIG_XEN_DOM0
 void __init xen_init_vga(const struct dom0_vga_console_info *, size_t size);
-void __init xen_init_apic(void);
 #else
 static inline void __init xen_init_vga(const struct dom0_vga_console_info *info,
 				       size_t size)
 {
 }
-static inline void __init xen_init_apic(void)
-{
-}
 #endif
 
+void __init xen_init_apic(void);
+
 #ifdef CONFIG_XEN_EFI
 extern void xen_efi_init(void);
 #else

drivers/xen/events/events_base.c

@@ -452,12 +452,10 @@ static void xen_free_irq(unsigned irq)
 	irq_free_desc(irq);
 }
 
-static void xen_evtchn_close(unsigned int port, unsigned int cpu)
+static void xen_evtchn_close(unsigned int port)
 {
 	struct evtchn_close close;
 
-	xen_evtchn_op_close(port, cpu);
-
 	close.port = port;
 	if (HYPERVISOR_event_channel_op(EVTCHNOP_close, &close) != 0)
 		BUG();
@@ -546,7 +544,7 @@ out:
 
 err:
 	pr_err("irq%d: Failed to set port to irq mapping (%d)\n", irq, rc);
-	xen_evtchn_close(evtchn, NR_CPUS);
+	xen_evtchn_close(evtchn);
 	return 0;
 }
 
@@ -567,7 +565,7 @@ static void shutdown_pirq(struct irq_data *data)
 		return;
 
 	mask_evtchn(evtchn);
-	xen_evtchn_close(evtchn, cpu_from_evtchn(evtchn));
+	xen_evtchn_close(evtchn);
 	xen_irq_info_cleanup(info);
 }
 
@@ -611,7 +609,7 @@ static void __unbind_from_irq(unsigned int irq)
 	if (VALID_EVTCHN(evtchn)) {
 		unsigned int cpu = cpu_from_irq(irq);
 
-		xen_evtchn_close(evtchn, cpu);
+		xen_evtchn_close(evtchn);
 
 		switch (type_from_irq(irq)) {
 		case IRQT_VIRQ:

drivers/xen/events/events_fifo.c

@@ -255,12 +255,6 @@ static void evtchn_fifo_unmask(unsigned port)
 	}
 }
 
-static bool evtchn_fifo_is_linked(unsigned port)
-{
-	event_word_t *word = event_word_from_port(port);
-	return sync_test_bit(EVTCHN_FIFO_BIT(LINKED, word), BM(word));
-}
-
 static uint32_t clear_linked(volatile event_word_t *word)
 {
 	event_word_t new, old, w;
@@ -287,8 +281,7 @@ static void handle_irq_for_port(unsigned port)
 
 static void consume_one_event(unsigned cpu,
 			      struct evtchn_fifo_control_block *control_block,
-			      unsigned priority, unsigned long *ready,
+			      unsigned priority, unsigned long *ready)
-			      bool drop)
 {
 	struct evtchn_fifo_queue *q = &per_cpu(cpu_queue, cpu);
 	uint32_t head;
@@ -320,15 +313,13 @@ static void consume_one_event(unsigned cpu,
 	if (head == 0)
 		clear_bit(priority, ready);
 
-	if (evtchn_fifo_is_pending(port) && !evtchn_fifo_is_masked(port)) {
+	if (evtchn_fifo_is_pending(port) && !evtchn_fifo_is_masked(port))
-		if (likely(!drop))
+		handle_irq_for_port(port);
-			handle_irq_for_port(port);
-	}
 
 	q->head[priority] = head;
 }
 
-static void __evtchn_fifo_handle_events(unsigned cpu, bool drop)
+static void evtchn_fifo_handle_events(unsigned cpu)
 {
 	struct evtchn_fifo_control_block *control_block;
 	unsigned long ready;
@@ -340,16 +331,11 @@ static void __evtchn_fifo_handle_events(unsigned cpu, bool drop)
 
 	while (ready) {
 		q = find_first_bit(&ready, EVTCHN_FIFO_MAX_QUEUES);
-		consume_one_event(cpu, control_block, q, &ready, drop);
+		consume_one_event(cpu, control_block, q, &ready);
 		ready |= xchg(&control_block->ready, 0);
 	}
 }
 
-static void evtchn_fifo_handle_events(unsigned cpu)
-{
-	__evtchn_fifo_handle_events(cpu, false);
-}
-
 static void evtchn_fifo_resume(void)
 {
 	unsigned cpu;
@@ -385,26 +371,6 @@ static void evtchn_fifo_resume(void)
 	event_array_pages = 0;
 }
 
-static void evtchn_fifo_close(unsigned port, unsigned int cpu)
-{
-	if (cpu == NR_CPUS)
-		return;
-
-	get_online_cpus();
-	if (cpu_online(cpu)) {
-		if (WARN_ON(irqs_disabled()))
-			goto out;
-
-		while (evtchn_fifo_is_linked(port))
-			cpu_relax();
-	} else {
-		__evtchn_fifo_handle_events(cpu, true);
-	}
-
-out:
-	put_online_cpus();
-}
-
 static const struct evtchn_ops evtchn_ops_fifo = {
 	.max_channels      = evtchn_fifo_max_channels,
 	.nr_channels       = evtchn_fifo_nr_channels,
@@ -418,7 +384,6 @@ static const struct evtchn_ops evtchn_ops_fifo = {
 	.unmask            = evtchn_fifo_unmask,
 	.handle_events     = evtchn_fifo_handle_events,
 	.resume            = evtchn_fifo_resume,
-	.close             = evtchn_fifo_close,
 };
 
 static int evtchn_fifo_alloc_control_block(unsigned cpu)

drivers/xen/events/events_internal.h

@@ -68,7 +68,6 @@ struct evtchn_ops {
 	bool (*test_and_set_mask)(unsigned port);
 	void (*mask)(unsigned port);
 	void (*unmask)(unsigned port);
-	void (*close)(unsigned port, unsigned cpu);
 
 	void (*handle_events)(unsigned cpu);
 	void (*resume)(void);
@@ -146,12 +145,6 @@ static inline void xen_evtchn_resume(void)
 		evtchn_ops->resume();
 }
 
-static inline void xen_evtchn_op_close(unsigned port, unsigned cpu)
-{
-	if (evtchn_ops->close)
-		return evtchn_ops->close(port, cpu);
-}
-
 void xen_evtchn_2l_init(void);
 int xen_evtchn_fifo_init(void);
 

drivers/xen/xenbus/xenbus_client.c

@@ -814,8 +814,10 @@ static int xenbus_unmap_ring_vfree_hvm(struct xenbus_device *dev, void *vaddr)
 
 	rv = xenbus_unmap_ring(dev, node->handles, node->nr_handles,
 			       addrs);
-	if (!rv)
+	if (!rv) {
 		vunmap(vaddr);
+		free_xenballooned_pages(node->nr_handles, node->hvm.pages);
+	}
 	else
 		WARN(1, "Leaking %p, size %u page(s)\n", vaddr,
 		     node->nr_handles);