18 files changed, 447 insertions, 195 deletions

diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
index 5f7ff8e2fc14..8795480c2350 100644
--- a/drivers/xen/Kconfig
+++ b/drivers/xen/Kconfig
@@ -137,16 +137,6 @@ config XEN_GRANT_DEV_ALLOC
           to other domains. This can be used to implement frontend drivers
           or as part of an inter-domain shared memory channel.
 
-config XEN_PLATFORM_PCI
-        tristate "xen platform pci device driver"
-        depends on XEN_PVHVM && PCI
-        default m
-        help
-          Driver for the Xen PCI Platform device: it is responsible for
-          initializing xenbus and grant_table when running in a Xen HVM
-          domain. As a consequence this driver is required to run any Xen PV
-          frontend on Xen HVM.
-
 config SWIOTLB_XEN
         def_bool y
         depends on PCI
diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile
index 72bbb27d7a68..974fffdf22b2 100644
--- a/drivers/xen/Makefile
+++ b/drivers/xen/Makefile
@@ -14,7 +14,7 @@ obj-$(CONFIG_XEN_GNTDEV)		+= xen-gntdev.o
 obj-$(CONFIG_XEN_GRANT_DEV_ALLOC)       += xen-gntalloc.o
 obj-$(CONFIG_XENFS)                     += xenfs/
 obj-$(CONFIG_XEN_SYS_HYPERVISOR)        += sys-hypervisor.o
-obj-$(CONFIG_XEN_PLATFORM_PCI)          += xen-platform-pci.o
+obj-$(CONFIG_XEN_PVHVM)                 += platform-pci.o
 obj-$(CONFIG_XEN_TMEM)                  += tmem.o
 obj-$(CONFIG_SWIOTLB_XEN)               += swiotlb-xen.o
 obj-$(CONFIG_XEN_DOM0)                  += pci.o
@@ -23,5 +23,3 @@ obj-$(CONFIG_XEN_PCIDEV_BACKEND)	+= xen-pciback/
 xen-evtchn-y                            := evtchn.o
 xen-gntdev-y                            := gntdev.o
 xen-gntalloc-y                          := gntalloc.o
-
-xen-platform-pci-y                      := platform-pci.o
diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index 212a5c871bf4..7a55b292bf39 100644
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -873,11 +873,32 @@ static int bind_interdomain_evtchn_to_irq(unsigned int remote_domain,
         return err ? : bind_evtchn_to_irq(bind_interdomain.local_port);
 }
 
+static int find_virq(unsigned int virq, unsigned int cpu)
+{
+        struct evtchn_status status;
+        int port, rc = -ENOENT;
+
+        memset(&status, 0, sizeof(status));
+        for (port = 0; port <= NR_EVENT_CHANNELS; port++) {
+                status.dom = DOMID_SELF;
+                status.port = port;
+                rc = HYPERVISOR_event_channel_op(EVTCHNOP_status, &status);
+                if (rc < 0)
+                        continue;
+                if (status.status != EVTCHNSTAT_virq)
+                        continue;
+                if (status.u.virq == virq && status.vcpu == cpu) {
+                        rc = port;
+                        break;
+                }
+        }
+        return rc;
+}
 
 int bind_virq_to_irq(unsigned int virq, unsigned int cpu)
 {
         struct evtchn_bind_virq bind_virq;
-        int evtchn, irq;
+        int evtchn, irq, ret;
 
         mutex_lock(&irq_mapping_update_lock);
 
@@ -893,10 +914,16 @@ int bind_virq_to_irq(unsigned int virq, unsigned int cpu)
 
                 bind_virq.virq = virq;
                 bind_virq.vcpu = cpu;
-                if (HYPERVISOR_event_channel_op(EVTCHNOP_bind_virq,
-                                                &bind_virq) != 0)
-                        BUG();
-                evtchn = bind_virq.port;
+                ret = HYPERVISOR_event_channel_op(EVTCHNOP_bind_virq,
+                                                &bind_virq);
+                if (ret == 0)
+                        evtchn = bind_virq.port;
+                else {
+                        if (ret == -EEXIST)
+                                ret = find_virq(virq, cpu);
+                        BUG_ON(ret < 0);
+                        evtchn = ret;
+                }
 
                 xen_irq_info_virq_init(cpu, irq, evtchn, virq);
 
diff --git a/drivers/xen/pci.c b/drivers/xen/pci.c
index cef4bafc07dc..66057075d6e2 100644
--- a/drivers/xen/pci.c
+++ b/drivers/xen/pci.c
@@ -18,6 +18,7 @@
  */
 
 #include <linux/pci.h>
+#include <linux/acpi.h>
 #include <xen/xen.h>
 #include <xen/interface/physdev.h>
 #include <xen/interface/xen.h>
@@ -26,26 +27,85 @@
 #include <asm/xen/hypercall.h>
 #include "../pci/pci.h"
 
+static bool __read_mostly pci_seg_supported = true;
+
 static int xen_add_device(struct device *dev)
 {
         int r;
         struct pci_dev *pci_dev = to_pci_dev(dev);
+#ifdef CONFIG_PCI_IOV
+        struct pci_dev *physfn = pci_dev->physfn;
+#endif
+
+        if (pci_seg_supported) {
+                struct physdev_pci_device_add add = {
+                        .seg = pci_domain_nr(pci_dev->bus),
+                        .bus = pci_dev->bus->number,
+                        .devfn = pci_dev->devfn
+                };
+#ifdef CONFIG_ACPI
+                acpi_handle handle;
+#endif
+
+#ifdef CONFIG_PCI_IOV
+                if (pci_dev->is_virtfn) {
+                        add.flags = XEN_PCI_DEV_VIRTFN;
+                        add.physfn.bus = physfn->bus->number;
+                        add.physfn.devfn = physfn->devfn;
+                } else
+#endif
+                if (pci_ari_enabled(pci_dev->bus) && PCI_SLOT(pci_dev->devfn))
+                        add.flags = XEN_PCI_DEV_EXTFN;
+
+#ifdef CONFIG_ACPI
+                handle = DEVICE_ACPI_HANDLE(&pci_dev->dev);
+                if (!handle)
+                        handle = DEVICE_ACPI_HANDLE(pci_dev->bus->bridge);
+#ifdef CONFIG_PCI_IOV
+                if (!handle && pci_dev->is_virtfn)
+                        handle = DEVICE_ACPI_HANDLE(physfn->bus->bridge);
+#endif
+                if (handle) {
+                        acpi_status status;
+
+                        do {
+                                unsigned long long pxm;
+
+                                status = acpi_evaluate_integer(handle, "_PXM",
+                                                               NULL, &pxm);
+                                if (ACPI_SUCCESS(status)) {
+                                        add.optarr[0] = pxm;
+                                        add.flags |= XEN_PCI_DEV_PXM;
+                                        break;
+                                }
+                                status = acpi_get_parent(handle, &handle);
+                        } while (ACPI_SUCCESS(status));
+                }
+#endif /* CONFIG_ACPI */
+
+                r = HYPERVISOR_physdev_op(PHYSDEVOP_pci_device_add, &add);
+                if (r != -ENOSYS)
+                        return r;
+                pci_seg_supported = false;
+        }
 
+        if (pci_domain_nr(pci_dev->bus))
+                r = -ENOSYS;
 #ifdef CONFIG_PCI_IOV
-        if (pci_dev->is_virtfn) {
+        else if (pci_dev->is_virtfn) {
                 struct physdev_manage_pci_ext manage_pci_ext = {
                         .bus            = pci_dev->bus->number,
                         .devfn          = pci_dev->devfn,
                         .is_virtfn      = 1,
-                        .physfn.bus     = pci_dev->physfn->bus->number,
-                        .physfn.devfn   = pci_dev->physfn->devfn,
+                        .physfn.bus     = physfn->bus->number,
+                        .physfn.devfn   = physfn->devfn,
                 };
 
                 r = HYPERVISOR_physdev_op(PHYSDEVOP_manage_pci_add_ext,
                         &manage_pci_ext);
-        } else
+        }
 #endif
-        if (pci_ari_enabled(pci_dev->bus) && PCI_SLOT(pci_dev->devfn)) {
+        else if (pci_ari_enabled(pci_dev->bus) && PCI_SLOT(pci_dev->devfn)) {
                 struct physdev_manage_pci_ext manage_pci_ext = {
                         .bus            = pci_dev->bus->number,
                         .devfn          = pci_dev->devfn,
@@ -71,13 +131,27 @@ static int xen_remove_device(struct device *dev)
 {
         int r;
         struct pci_dev *pci_dev = to_pci_dev(dev);
-        struct physdev_manage_pci manage_pci;
 
-        manage_pci.bus = pci_dev->bus->number;
-        manage_pci.devfn = pci_dev->devfn;
+        if (pci_seg_supported) {
+                struct physdev_pci_device device = {
+                        .seg = pci_domain_nr(pci_dev->bus),
+                        .bus = pci_dev->bus->number,
+                        .devfn = pci_dev->devfn
+                };
 
-        r = HYPERVISOR_physdev_op(PHYSDEVOP_manage_pci_remove,
-                &manage_pci);
+                r = HYPERVISOR_physdev_op(PHYSDEVOP_pci_device_remove,
+                                          &device);
+        } else if (pci_domain_nr(pci_dev->bus))
+                r = -ENOSYS;
+        else {
+                struct physdev_manage_pci manage_pci = {
+                        .bus = pci_dev->bus->number,
+                        .devfn = pci_dev->devfn
+                };
+
+                r = HYPERVISOR_physdev_op(PHYSDEVOP_manage_pci_remove,
+                                          &manage_pci);
+        }
 
         return r;
 }
@@ -96,13 +170,16 @@ static int xen_pci_notifier(struct notifier_block *nb,
                 r = xen_remove_device(dev);
                 break;
         default:
-                break;
+                return NOTIFY_DONE;
         }
-
-        return r;
+        if (r)
+                dev_err(dev, "Failed to %s - passthrough or MSI/MSI-X might fail!\n",
+                        action == BUS_NOTIFY_ADD_DEVICE ? "add" :
+                        (action == BUS_NOTIFY_DEL_DEVICE ? "delete" : "?"));
+        return NOTIFY_OK;
 }
 
-struct notifier_block device_nb = {
+static struct notifier_block device_nb = {
         .notifier_call = xen_pci_notifier,
 };
 
diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index 6e8c15a23201..c984768d98ca 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -38,6 +38,7 @@
 #include <xen/swiotlb-xen.h>
 #include <xen/page.h>
 #include <xen/xen-ops.h>
+#include <xen/hvc-console.h>
 /*
  * Used to do a quick range check in swiotlb_tbl_unmap_single and
  * swiotlb_tbl_sync_single_*, to see if the memory was in fact allocated by this
@@ -146,8 +147,10 @@ xen_swiotlb_fixup(void *buf, size_t size, unsigned long nslabs)
 void __init xen_swiotlb_init(int verbose)
 {
         unsigned long bytes;
-        int rc;
+        int rc = -ENOMEM;
         unsigned long nr_tbl;
+        char *m = NULL;
+        unsigned int repeat = 3;
 
         nr_tbl = swioltb_nr_tbl();
         if (nr_tbl)
@@ -156,16 +159,17 @@ void __init xen_swiotlb_init(int verbose)
                 xen_io_tlb_nslabs = (64 * 1024 * 1024 >> IO_TLB_SHIFT);
                 xen_io_tlb_nslabs = ALIGN(xen_io_tlb_nslabs, IO_TLB_SEGSIZE);
         }
-
+retry:
         bytes = xen_io_tlb_nslabs << IO_TLB_SHIFT;
 
         /*
          * Get IO TLB memory from any location.
          */
         xen_io_tlb_start = alloc_bootmem(bytes);
-        if (!xen_io_tlb_start)
-                panic("Cannot allocate SWIOTLB buffer");
-
+        if (!xen_io_tlb_start) {
+                m = "Cannot allocate Xen-SWIOTLB buffer!\n";
+                goto error;
+        }
         xen_io_tlb_end = xen_io_tlb_start + bytes;
         /*
          * And replace that memory with pages under 4GB.
@@ -173,17 +177,28 @@ void __init xen_swiotlb_init(int verbose)
         rc = xen_swiotlb_fixup(xen_io_tlb_start,
                                bytes,
                                xen_io_tlb_nslabs);
-        if (rc)
+        if (rc) {
+                free_bootmem(__pa(xen_io_tlb_start), bytes);
+                m = "Failed to get contiguous memory for DMA from Xen!\n"\
+                    "You either: don't have the permissions, do not have"\
+                    " enough free memory under 4GB, or the hypervisor memory"\
+                    "is too fragmented!";
                 goto error;
-
+        }
         start_dma_addr = xen_virt_to_bus(xen_io_tlb_start);
         swiotlb_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs, verbose);
 
         return;
 error:
-        panic("DMA(%d): Failed to exchange pages allocated for DMA with Xen! "\
-              "We either don't have the permission or you do not have enough"\
-              "free memory under 4GB!\n", rc);
+        if (repeat--) {
+                xen_io_tlb_nslabs = max(1024UL, /* Min is 2MB */
+                                        (xen_io_tlb_nslabs >> 1));
+                printk(KERN_INFO "Xen-SWIOTLB: Lowering to %luMB\n",
+                      (xen_io_tlb_nslabs << IO_TLB_SHIFT) >> 20);
+                goto retry;
+        }
+        xen_raw_printk("%s (rc:%d)", m, rc);
+        panic("%s (rc:%d)", m, rc);
 }
 
 void *
@@ -194,6 +209,8 @@ xen_swiotlb_alloc_coherent(struct device *hwdev, size_t size,
         int order = get_order(size);
         u64 dma_mask = DMA_BIT_MASK(32);
         unsigned long vstart;
+        phys_addr_t phys;
+        dma_addr_t dev_addr;
 
         /*
         * Ignore region specifiers - the kernel's ideas of
@@ -209,18 +226,26 @@ xen_swiotlb_alloc_coherent(struct device *hwdev, size_t size,
         vstart = __get_free_pages(flags, order);
         ret = (void *)vstart;
 
+        if (!ret)
+                return ret;
+
         if (hwdev && hwdev->coherent_dma_mask)
-                dma_mask = dma_alloc_coherent_mask(hwdev, flags);
+                dma_mask = hwdev->coherent_dma_mask;
 
-        if (ret) {
+        phys = virt_to_phys(ret);
+        dev_addr = xen_phys_to_bus(phys);
+        if (((dev_addr + size - 1 <= dma_mask)) &&
+            !range_straddles_page_boundary(phys, size))
+                *dma_handle = dev_addr;
+        else {
                 if (xen_create_contiguous_region(vstart, order,
                                                  fls64(dma_mask)) != 0) {
                         free_pages(vstart, order);
                         return NULL;
                 }
-                memset(ret, 0, size);
                 *dma_handle = virt_to_machine(ret).maddr;
         }
+        memset(ret, 0, size);
         return ret;
 }
 EXPORT_SYMBOL_GPL(xen_swiotlb_alloc_coherent);
@@ -230,11 +255,21 @@ xen_swiotlb_free_coherent(struct device *hwdev, size_t size, void *vaddr,
                           dma_addr_t dev_addr)
 {
         int order = get_order(size);
+        phys_addr_t phys;
+        u64 dma_mask = DMA_BIT_MASK(32);
 
         if (dma_release_from_coherent(hwdev, order, vaddr))
                 return;
 
-        xen_destroy_contiguous_region((unsigned long)vaddr, order);
+        if (hwdev && hwdev->coherent_dma_mask)
+                dma_mask = hwdev->coherent_dma_mask;
+
+        phys = virt_to_phys(vaddr);
+
+        if (((dev_addr + size - 1 > dma_mask)) ||
+            range_straddles_page_boundary(phys, size))
+                xen_destroy_contiguous_region((unsigned long)vaddr, order);
+
         free_pages((unsigned long)vaddr, order);
 }
 EXPORT_SYMBOL_GPL(xen_swiotlb_free_coherent);
@@ -278,9 +313,10 @@ dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page,
         /*
          * Ensure that the address returned is DMA'ble
          */
-        if (!dma_capable(dev, dev_addr, size))
-                panic("map_single: bounce buffer is not DMA'ble");
-
+        if (!dma_capable(dev, dev_addr, size)) {
+                swiotlb_tbl_unmap_single(dev, map, size, dir);
+                dev_addr = 0;
+        }
         return dev_addr;
 }
 EXPORT_SYMBOL_GPL(xen_swiotlb_map_page);
diff --git a/drivers/xen/xen-pciback/conf_space.c b/drivers/xen/xen-pciback/conf_space.c
index a8031445d94e..444345afbd5c 100644
--- a/drivers/xen/xen-pciback/conf_space.c
+++ b/drivers/xen/xen-pciback/conf_space.c
@@ -15,7 +15,6 @@
 #include "conf_space.h"
 #include "conf_space_quirks.h"
 
-#define DRV_NAME        "xen-pciback"
 static int permissive;
 module_param(permissive, bool, 0644);
 
diff --git a/drivers/xen/xen-pciback/conf_space_header.c b/drivers/xen/xen-pciback/conf_space_header.c
index da3cbdfcb5dc..3daf862d739d 100644
--- a/drivers/xen/xen-pciback/conf_space_header.c
+++ b/drivers/xen/xen-pciback/conf_space_header.c
@@ -15,7 +15,6 @@ struct pci_bar_info {
         int which;
 };
 
-#define DRV_NAME        "xen-pciback"
 #define is_enable_cmd(value) ((value)&(PCI_COMMAND_MEMORY|PCI_COMMAND_IO))
 #define is_master_cmd(value) ((value)&PCI_COMMAND_MASTER)
 
@@ -25,7 +24,7 @@ static int command_read(struct pci_dev *dev, int offset, u16 *value, void *data)
         int ret;
 
         ret = xen_pcibk_read_config_word(dev, offset, value, data);
-        if (!atomic_read(&dev->enable_cnt))
+        if (!pci_is_enabled(dev))
                 return ret;
 
         for (i = 0; i < PCI_ROM_RESOURCE; i++) {
@@ -187,7 +186,7 @@ static inline void read_dev_bar(struct pci_dev *dev,
 
         bar_info->val = res[pos].start |
                         (res[pos].flags & PCI_REGION_FLAG_MASK);
-        bar_info->len_val = res[pos].end - res[pos].start + 1;
+        bar_info->len_val = resource_size(&res[pos]);
 }
 
 static void *bar_init(struct pci_dev *dev, int offset)
diff --git a/drivers/xen/xen-pciback/conf_space_quirks.c b/drivers/xen/xen-pciback/conf_space_quirks.c
index 921a889e65eb..7476791cab40 100644
--- a/drivers/xen/xen-pciback/conf_space_quirks.c
+++ b/drivers/xen/xen-pciback/conf_space_quirks.c
@@ -12,7 +12,6 @@
 #include "conf_space_quirks.h"
 
 LIST_HEAD(xen_pcibk_quirks);
-#define DRV_NAME        "xen-pciback"
 static inline const struct pci_device_id *
 match_one_device(const struct pci_device_id *id, const struct pci_dev *dev)
 {
@@ -36,7 +35,7 @@ static struct xen_pcibk_config_quirk *xen_pcibk_find_quirk(struct pci_dev *dev)
                         goto out;
         tmp_quirk = NULL;
         printk(KERN_DEBUG DRV_NAME
-               ":quirk didn't match any device xen_pciback knows about\n");
+               ": quirk didn't match any device known\n");
 out:
         return tmp_quirk;
 }
diff --git a/drivers/xen/xen-pciback/passthrough.c b/drivers/xen/xen-pciback/passthrough.c
index 1d32a9a42c01..828dddc360df 100644
--- a/drivers/xen/xen-pciback/passthrough.c
+++ b/drivers/xen/xen-pciback/passthrough.c
@@ -7,13 +7,13 @@
 
 #include <linux/list.h>
 #include <linux/pci.h>
-#include <linux/spinlock.h>
+#include <linux/mutex.h>
 #include "pciback.h"
 
 struct passthrough_dev_data {
         /* Access to dev_list must be protected by lock */
         struct list_head dev_list;
-        spinlock_t lock;
+        struct mutex lock;
 };
 
 static struct pci_dev *__xen_pcibk_get_pci_dev(struct xen_pcibk_device *pdev,
@@ -24,9 +24,8 @@ static struct pci_dev *__xen_pcibk_get_pci_dev(struct xen_pcibk_device *pdev,
         struct passthrough_dev_data *dev_data = pdev->pci_dev_data;
         struct pci_dev_entry *dev_entry;
         struct pci_dev *dev = NULL;
-        unsigned long flags;
 
-        spin_lock_irqsave(&dev_data->lock, flags);
+        mutex_lock(&dev_data->lock);
 
         list_for_each_entry(dev_entry, &dev_data->dev_list, list) {
                 if (domain == (unsigned int)pci_domain_nr(dev_entry->dev->bus)
@@ -37,7 +36,7 @@ static struct pci_dev *__xen_pcibk_get_pci_dev(struct xen_pcibk_device *pdev,
                 }
         }
 
-        spin_unlock_irqrestore(&dev_data->lock, flags);
+        mutex_unlock(&dev_data->lock);
 
         return dev;
 }
@@ -48,7 +47,6 @@ static int __xen_pcibk_add_pci_dev(struct xen_pcibk_device *pdev,
 {
         struct passthrough_dev_data *dev_data = pdev->pci_dev_data;
         struct pci_dev_entry *dev_entry;
-        unsigned long flags;
         unsigned int domain, bus, devfn;
         int err;
 
@@ -57,9 +55,9 @@ static int __xen_pcibk_add_pci_dev(struct xen_pcibk_device *pdev,
                 return -ENOMEM;
         dev_entry->dev = dev;
 
-        spin_lock_irqsave(&dev_data->lock, flags);
+        mutex_lock(&dev_data->lock);
         list_add_tail(&dev_entry->list, &dev_data->dev_list);
-        spin_unlock_irqrestore(&dev_data->lock, flags);
+        mutex_unlock(&dev_data->lock);
 
         /* Publish this device. */
         domain = (unsigned int)pci_domain_nr(dev->bus);
@@ -76,9 +74,8 @@ static void __xen_pcibk_release_pci_dev(struct xen_pcibk_device *pdev,
         struct passthrough_dev_data *dev_data = pdev->pci_dev_data;
         struct pci_dev_entry *dev_entry, *t;
         struct pci_dev *found_dev = NULL;
-        unsigned long flags;
 
-        spin_lock_irqsave(&dev_data->lock, flags);
+        mutex_lock(&dev_data->lock);
 
         list_for_each_entry_safe(dev_entry, t, &dev_data->dev_list, list) {
                 if (dev_entry->dev == dev) {
@@ -88,7 +85,7 @@ static void __xen_pcibk_release_pci_dev(struct xen_pcibk_device *pdev,
                 }
         }
 
-        spin_unlock_irqrestore(&dev_data->lock, flags);
+        mutex_unlock(&dev_data->lock);
 
         if (found_dev)
                 pcistub_put_pci_dev(found_dev);
@@ -102,7 +99,7 @@ static int __xen_pcibk_init_devices(struct xen_pcibk_device *pdev)
         if (!dev_data)
                 return -ENOMEM;
 
-        spin_lock_init(&dev_data->lock);
+        mutex_init(&dev_data->lock);
 
         INIT_LIST_HEAD(&dev_data->dev_list);
 
@@ -116,14 +113,14 @@ static int __xen_pcibk_publish_pci_roots(struct xen_pcibk_device *pdev,
 {
         int err = 0;
         struct passthrough_dev_data *dev_data = pdev->pci_dev_data;
-        struct pci_dev_entry *dev_entry, *e, *tmp;
+        struct pci_dev_entry *dev_entry, *e;
         struct pci_dev *dev;
         int found;
         unsigned int domain, bus;
 
-        spin_lock(&dev_data->lock);
+        mutex_lock(&dev_data->lock);
 
-        list_for_each_entry_safe(dev_entry, tmp, &dev_data->dev_list, list) {
+        list_for_each_entry(dev_entry, &dev_data->dev_list, list) {
                 /* Only publish this device as a root if none of its
                  * parent bridges are exported
                  */
@@ -142,16 +139,13 @@ static int __xen_pcibk_publish_pci_roots(struct xen_pcibk_device *pdev,
                 bus = (unsigned int)dev_entry->dev->bus->number;
 
                 if (!found) {
-                        spin_unlock(&dev_data->lock);
                         err = publish_root_cb(pdev, domain, bus);
                         if (err)
                                 break;
-                        spin_lock(&dev_data->lock);
                 }
         }
 
-        if (!err)
-                spin_unlock(&dev_data->lock);
+        mutex_unlock(&dev_data->lock);
 
         return err;
 }
@@ -182,7 +176,7 @@ static int __xen_pcibk_get_pcifront_dev(struct pci_dev *pcidev,
         return 1;
 }
 
-struct xen_pcibk_backend xen_pcibk_passthrough_backend = {
+const struct xen_pcibk_backend xen_pcibk_passthrough_backend = {
         .name           = "passthrough",
         .init           = __xen_pcibk_init_devices,
         .free           = __xen_pcibk_release_devices,
diff --git a/drivers/xen/xen-pciback/pci_stub.c b/drivers/xen/xen-pciback/pci_stub.c
index aec214ac0a14..8f06e1ed028c 100644
--- a/drivers/xen/xen-pciback/pci_stub.c
+++ b/drivers/xen/xen-pciback/pci_stub.c
@@ -21,8 +21,6 @@
 #include "conf_space.h"
 #include "conf_space_quirks.h"
 
-#define DRV_NAME        "xen-pciback"
-
 static char *pci_devs_to_hide;
 wait_queue_head_t xen_pcibk_aer_wait_queue;
 /*Add sem for sync AER handling and xen_pcibk remove/reconfigue ops,
@@ -222,6 +220,8 @@ void pcistub_put_pci_dev(struct pci_dev *dev)
         }
 
         spin_unlock_irqrestore(&pcistub_devices_lock, flags);
+        if (WARN_ON(!found_psdev))
+                return;
 
         /*hold this lock for avoiding breaking link between
         * pcistub and xen_pcibk when AER is in processing
@@ -514,12 +514,9 @@ static void kill_domain_by_device(struct pcistub_device *psdev)
         int err;
         char nodename[PCI_NODENAME_MAX];
 
-        if (!psdev)
-                dev_err(&psdev->dev->dev,
-                        "device is NULL when do AER recovery/kill_domain\n");
+        BUG_ON(!psdev);
         snprintf(nodename, PCI_NODENAME_MAX, "/local/domain/0/backend/pci/%d/0",
                 psdev->pdev->xdev->otherend_id);
-        nodename[strlen(nodename)] = '\0';
 
 again:
         err = xenbus_transaction_start(&xbt);
@@ -605,7 +602,7 @@ static pci_ers_result_t common_process(struct pcistub_device *psdev,
         if (test_bit(_XEN_PCIF_active,
                 (unsigned long *)&psdev->pdev->sh_info->flags)) {
                 dev_dbg(&psdev->dev->dev,
-                        "schedule pci_conf service in xen_pcibk\n");
+                        "schedule pci_conf service in " DRV_NAME "\n");
                 xen_pcibk_test_and_schedule_op(psdev->pdev);
         }
 
@@ -995,8 +992,7 @@ out:
                 err = count;
         return err;
 }
-
-DRIVER_ATTR(new_slot, S_IWUSR, NULL, pcistub_slot_add);
+static DRIVER_ATTR(new_slot, S_IWUSR, NULL, pcistub_slot_add);
 
 static ssize_t pcistub_slot_remove(struct device_driver *drv, const char *buf,
                                    size_t count)
@@ -1015,8 +1011,7 @@ out:
                 err = count;
         return err;
 }
-
-DRIVER_ATTR(remove_slot, S_IWUSR, NULL, pcistub_slot_remove);
+static DRIVER_ATTR(remove_slot, S_IWUSR, NULL, pcistub_slot_remove);
 
 static ssize_t pcistub_slot_show(struct device_driver *drv, char *buf)
 {
@@ -1039,8 +1034,7 @@ static ssize_t pcistub_slot_show(struct device_driver *drv, char *buf)
 
         return count;
 }
-
-DRIVER_ATTR(slots, S_IRUSR, pcistub_slot_show, NULL);
+static DRIVER_ATTR(slots, S_IRUSR, pcistub_slot_show, NULL);
 
 static ssize_t pcistub_irq_handler_show(struct device_driver *drv, char *buf)
 {
@@ -1069,8 +1063,7 @@ static ssize_t pcistub_irq_handler_show(struct device_driver *drv, char *buf)
         spin_unlock_irqrestore(&pcistub_devices_lock, flags);
         return count;
 }
-
-DRIVER_ATTR(irq_handlers, S_IRUSR, pcistub_irq_handler_show, NULL);
+static DRIVER_ATTR(irq_handlers, S_IRUSR, pcistub_irq_handler_show, NULL);
 
 static ssize_t pcistub_irq_handler_switch(struct device_driver *drv,
                                           const char *buf,
@@ -1106,7 +1099,8 @@ out:
                 err = count;
         return err;
 }
-DRIVER_ATTR(irq_handler_state, S_IWUSR, NULL, pcistub_irq_handler_switch);
+static DRIVER_ATTR(irq_handler_state, S_IWUSR, NULL,
+                   pcistub_irq_handler_switch);
 
 static ssize_t pcistub_quirk_add(struct device_driver *drv, const char *buf,
                                  size_t count)
@@ -1170,8 +1164,8 @@ out:
 
         return count;
 }
-
-DRIVER_ATTR(quirks, S_IRUSR | S_IWUSR, pcistub_quirk_show, pcistub_quirk_add);
+static DRIVER_ATTR(quirks, S_IRUSR | S_IWUSR, pcistub_quirk_show,
+                   pcistub_quirk_add);
 
 static ssize_t permissive_add(struct device_driver *drv, const char *buf,
                               size_t count)
@@ -1236,8 +1230,8 @@ static ssize_t permissive_show(struct device_driver *drv, char *buf)
         spin_unlock_irqrestore(&pcistub_devices_lock, flags);
         return count;
 }
-
-DRIVER_ATTR(permissive, S_IRUSR | S_IWUSR, permissive_show, permissive_add);
+static DRIVER_ATTR(permissive, S_IRUSR | S_IWUSR, permissive_show,
+                   permissive_add);
 
 static void pcistub_exit(void)
 {
@@ -1374,3 +1368,4 @@ module_init(xen_pcibk_init);
 module_exit(xen_pcibk_cleanup);
 
 MODULE_LICENSE("Dual BSD/GPL");
+MODULE_ALIAS("xen-backend:pci");
diff --git a/drivers/xen/xen-pciback/pciback.h b/drivers/xen/xen-pciback/pciback.h
index a0e131a81503..e9b4011c5f9a 100644
--- a/drivers/xen/xen-pciback/pciback.h
+++ b/drivers/xen/xen-pciback/pciback.h
@@ -15,6 +15,8 @@
 #include <linux/atomic.h>
 #include <xen/interface/io/pciif.h>
 
+#define DRV_NAME        "xen-pciback"
+
 struct pci_dev_entry {
         struct list_head list;
         struct pci_dev *dev;
@@ -27,7 +29,7 @@ struct pci_dev_entry {
 
 struct xen_pcibk_device {
         void *pci_dev_data;
-        spinlock_t dev_lock;
+        struct mutex dev_lock;
         struct xenbus_device *xdev;
         struct xenbus_watch be_watch;
         u8 be_watching;
@@ -89,7 +91,7 @@ typedef int (*publish_pci_root_cb) (struct xen_pcibk_device *pdev,
  *  passthrough - BDFs are exactly like in the host.
  */
 struct xen_pcibk_backend {
-        char *name;
+        const char *name;
         int (*init)(struct xen_pcibk_device *pdev);
         void (*free)(struct xen_pcibk_device *pdev);
         int (*find)(struct pci_dev *pcidev, struct xen_pcibk_device *pdev,
@@ -104,9 +106,9 @@ struct xen_pcibk_backend {
                                unsigned int devfn);
 };
 
-extern struct xen_pcibk_backend xen_pcibk_vpci_backend;
-extern struct xen_pcibk_backend xen_pcibk_passthrough_backend;
-extern struct xen_pcibk_backend *xen_pcibk_backend;
+extern const struct xen_pcibk_backend xen_pcibk_vpci_backend;
+extern const struct xen_pcibk_backend xen_pcibk_passthrough_backend;
+extern const struct xen_pcibk_backend *xen_pcibk_backend;
 
 static inline int xen_pcibk_add_pci_dev(struct xen_pcibk_device *pdev,
                                         struct pci_dev *dev,
@@ -116,13 +118,14 @@ static inline int xen_pcibk_add_pci_dev(struct xen_pcibk_device *pdev,
         if (xen_pcibk_backend && xen_pcibk_backend->add)
                 return xen_pcibk_backend->add(pdev, dev, devid, publish_cb);
         return -1;
-};
+}
+
 static inline void xen_pcibk_release_pci_dev(struct xen_pcibk_device *pdev,
                                              struct pci_dev *dev)
 {
         if (xen_pcibk_backend && xen_pcibk_backend->free)
                 return xen_pcibk_backend->release(pdev, dev);
-};
+}
 
 static inline struct pci_dev *
 xen_pcibk_get_pci_dev(struct xen_pcibk_device *pdev, unsigned int domain,
@@ -131,7 +134,8 @@ xen_pcibk_get_pci_dev(struct xen_pcibk_device *pdev, unsigned int domain,
         if (xen_pcibk_backend && xen_pcibk_backend->get)
                 return xen_pcibk_backend->get(pdev, domain, bus, devfn);
         return NULL;
-};
+}
+
 /**
 * Add for domain0 PCIE-AER handling. Get guest domain/bus/devfn in xen_pcibk
 * before sending aer request to pcifront, so that guest could identify
@@ -148,25 +152,29 @@ static inline int xen_pcibk_get_pcifront_dev(struct pci_dev *pcidev,
                 return xen_pcibk_backend->find(pcidev, pdev, domain, bus,
                                                devfn);
         return -1;
-};
+}
+
 static inline int xen_pcibk_init_devices(struct xen_pcibk_device *pdev)
 {
         if (xen_pcibk_backend && xen_pcibk_backend->init)
                 return xen_pcibk_backend->init(pdev);
         return -1;
-};
+}
+
 static inline int xen_pcibk_publish_pci_roots(struct xen_pcibk_device *pdev,
                                               publish_pci_root_cb cb)
 {
         if (xen_pcibk_backend && xen_pcibk_backend->publish)
                 return xen_pcibk_backend->publish(pdev, cb);
         return -1;
-};
+}
+
 static inline void xen_pcibk_release_devices(struct xen_pcibk_device *pdev)
 {
         if (xen_pcibk_backend && xen_pcibk_backend->free)
                 return xen_pcibk_backend->free(pdev);
-};
+}
+
 /* Handles events from front-end */
 irqreturn_t xen_pcibk_handle_event(int irq, void *dev_id);
 void xen_pcibk_do_op(struct work_struct *data);
diff --git a/drivers/xen/xen-pciback/pciback_ops.c b/drivers/xen/xen-pciback/pciback_ops.c
index 8c95c3415b75..63616d7453e6 100644
--- a/drivers/xen/xen-pciback/pciback_ops.c
+++ b/drivers/xen/xen-pciback/pciback_ops.c
@@ -10,7 +10,6 @@
 #include <linux/sched.h>
 #include "pciback.h"
 
-#define DRV_NAME        "xen-pciback"
 int verbose_request;
 module_param(verbose_request, int, 0644);
 
diff --git a/drivers/xen/xen-pciback/vpci.c b/drivers/xen/xen-pciback/vpci.c
index 4a42cfb0959d..46d140baebd8 100644
--- a/drivers/xen/xen-pciback/vpci.c
+++ b/drivers/xen/xen-pciback/vpci.c
@@ -8,16 +8,15 @@
 #include <linux/list.h>
 #include <linux/slab.h>
 #include <linux/pci.h>
-#include <linux/spinlock.h>
+#include <linux/mutex.h>
 #include "pciback.h"
 
 #define PCI_SLOT_MAX 32
-#define DRV_NAME        "xen-pciback"
 
 struct vpci_dev_data {
         /* Access to dev_list must be protected by lock */
         struct list_head dev_list[PCI_SLOT_MAX];
-        spinlock_t lock;
+        struct mutex lock;
 };
 
 static inline struct list_head *list_first(struct list_head *head)
@@ -33,13 +32,12 @@ static struct pci_dev *__xen_pcibk_get_pci_dev(struct xen_pcibk_device *pdev,
         struct pci_dev_entry *entry;
         struct pci_dev *dev = NULL;
         struct vpci_dev_data *vpci_dev = pdev->pci_dev_data;
-        unsigned long flags;
 
         if (domain != 0 || bus != 0)
                 return NULL;
 
         if (PCI_SLOT(devfn) < PCI_SLOT_MAX) {
-                spin_lock_irqsave(&vpci_dev->lock, flags);
+                mutex_lock(&vpci_dev->lock);
 
                 list_for_each_entry(entry,
                                     &vpci_dev->dev_list[PCI_SLOT(devfn)],
@@ -50,7 +48,7 @@ static struct pci_dev *__xen_pcibk_get_pci_dev(struct xen_pcibk_device *pdev,
                         }
                 }
 
-                spin_unlock_irqrestore(&vpci_dev->lock, flags);
+                mutex_unlock(&vpci_dev->lock);
         }
         return dev;
 }
@@ -71,7 +69,6 @@ static int __xen_pcibk_add_pci_dev(struct xen_pcibk_device *pdev,
         int err = 0, slot, func = -1;
         struct pci_dev_entry *t, *dev_entry;
         struct vpci_dev_data *vpci_dev = pdev->pci_dev_data;
-        unsigned long flags;
 
         if ((dev->class >> 24) == PCI_BASE_CLASS_BRIDGE) {
                 err = -EFAULT;
@@ -90,7 +87,7 @@ static int __xen_pcibk_add_pci_dev(struct xen_pcibk_device *pdev,
 
         dev_entry->dev = dev;
 
-        spin_lock_irqsave(&vpci_dev->lock, flags);
+        mutex_lock(&vpci_dev->lock);
 
         /* Keep multi-function devices together on the virtual PCI bus */
         for (slot = 0; slot < PCI_SLOT_MAX; slot++) {
@@ -129,7 +126,7 @@ static int __xen_pcibk_add_pci_dev(struct xen_pcibk_device *pdev,
                          "No more space on root virtual PCI bus");
 
 unlock:
-        spin_unlock_irqrestore(&vpci_dev->lock, flags);
+        mutex_unlock(&vpci_dev->lock);
 
         /* Publish this device. */
         if (!err)
@@ -145,14 +142,13 @@ static void __xen_pcibk_release_pci_dev(struct xen_pcibk_device *pdev,
         int slot;
         struct vpci_dev_data *vpci_dev = pdev->pci_dev_data;
         struct pci_dev *found_dev = NULL;
-        unsigned long flags;
 
-        spin_lock_irqsave(&vpci_dev->lock, flags);
+        mutex_lock(&vpci_dev->lock);
 
         for (slot = 0; slot < PCI_SLOT_MAX; slot++) {
-                struct pci_dev_entry *e, *tmp;
-                list_for_each_entry_safe(e, tmp, &vpci_dev->dev_list[slot],
-                                         list) {
+                struct pci_dev_entry *e;
+
+                list_for_each_entry(e, &vpci_dev->dev_list[slot], list) {
                         if (e->dev == dev) {
                                 list_del(&e->list);
                                 found_dev = e->dev;
@@ -163,7 +159,7 @@ static void __xen_pcibk_release_pci_dev(struct xen_pcibk_device *pdev,
         }
 
 out:
-        spin_unlock_irqrestore(&vpci_dev->lock, flags);
+        mutex_unlock(&vpci_dev->lock);
 
         if (found_dev)
                 pcistub_put_pci_dev(found_dev);
@@ -178,7 +174,7 @@ static int __xen_pcibk_init_devices(struct xen_pcibk_device *pdev)
         if (!vpci_dev)
                 return -ENOMEM;
 
-        spin_lock_init(&vpci_dev->lock);
+        mutex_init(&vpci_dev->lock);
 
         for (slot = 0; slot < PCI_SLOT_MAX; slot++)
                 INIT_LIST_HEAD(&vpci_dev->dev_list[slot]);
@@ -222,10 +218,9 @@ static int __xen_pcibk_get_pcifront_dev(struct pci_dev *pcidev,
         struct pci_dev_entry *entry;
         struct pci_dev *dev = NULL;
         struct vpci_dev_data *vpci_dev = pdev->pci_dev_data;
-        unsigned long flags;
         int found = 0, slot;
 
-        spin_lock_irqsave(&vpci_dev->lock, flags);
+        mutex_lock(&vpci_dev->lock);
         for (slot = 0; slot < PCI_SLOT_MAX; slot++) {
                 list_for_each_entry(entry,
                             &vpci_dev->dev_list[slot],
@@ -243,11 +238,11 @@ static int __xen_pcibk_get_pcifront_dev(struct pci_dev *pcidev,
                         }
                 }
         }
-        spin_unlock_irqrestore(&vpci_dev->lock, flags);
+        mutex_unlock(&vpci_dev->lock);
         return found;
 }
 
-struct xen_pcibk_backend xen_pcibk_vpci_backend = {
+const struct xen_pcibk_backend xen_pcibk_vpci_backend = {
         .name           = "vpci",
         .init           = __xen_pcibk_init_devices,
         .free           = __xen_pcibk_release_devices,
diff --git a/drivers/xen/xen-pciback/xenbus.c b/drivers/xen/xen-pciback/xenbus.c
index 978d2c6f5dca..474d52ec3374 100644
--- a/drivers/xen/xen-pciback/xenbus.c
+++ b/drivers/xen/xen-pciback/xenbus.c
@@ -13,7 +13,6 @@
 #include <asm/xen/pci.h>
 #include "pciback.h"
 
-#define DRV_NAME        "xen-pciback"
 #define INVALID_EVTCHN_IRQ  (-1)
 struct workqueue_struct *xen_pcibk_wq;
 
@@ -44,7 +43,7 @@ static struct xen_pcibk_device *alloc_pdev(struct xenbus_device *xdev)
         pdev->xdev = xdev;
         dev_set_drvdata(&xdev->dev, pdev);
 
-        spin_lock_init(&pdev->dev_lock);
+        mutex_init(&pdev->dev_lock);
 
         pdev->sh_info = NULL;
         pdev->evtchn_irq = INVALID_EVTCHN_IRQ;
@@ -62,14 +61,12 @@ out:
 
 static void xen_pcibk_disconnect(struct xen_pcibk_device *pdev)
 {
-        spin_lock(&pdev->dev_lock);
-
+        mutex_lock(&pdev->dev_lock);
         /* Ensure the guest can't trigger our handler before removing devices */
         if (pdev->evtchn_irq != INVALID_EVTCHN_IRQ) {
                 unbind_from_irqhandler(pdev->evtchn_irq, pdev);
                 pdev->evtchn_irq = INVALID_EVTCHN_IRQ;
         }
-        spin_unlock(&pdev->dev_lock);
 
         /* If the driver domain started an op, make sure we complete it
          * before releasing the shared memory */
@@ -77,13 +74,11 @@ static void xen_pcibk_disconnect(struct xen_pcibk_device *pdev)
         /* Note, the workqueue does not use spinlocks at all.*/
         flush_workqueue(xen_pcibk_wq);
 
-        spin_lock(&pdev->dev_lock);
         if (pdev->sh_info != NULL) {
                 xenbus_unmap_ring_vfree(pdev->xdev, pdev->sh_info);
                 pdev->sh_info = NULL;
         }
-        spin_unlock(&pdev->dev_lock);
-
+        mutex_unlock(&pdev->dev_lock);
 }
 
 static void free_pdev(struct xen_pcibk_device *pdev)
@@ -120,9 +115,7 @@ static int xen_pcibk_do_attach(struct xen_pcibk_device *pdev, int gnt_ref,
                 goto out;
         }
 
-        spin_lock(&pdev->dev_lock);
         pdev->sh_info = vaddr;
-        spin_unlock(&pdev->dev_lock);
 
         err = bind_interdomain_evtchn_to_irqhandler(
                 pdev->xdev->otherend_id, remote_evtchn, xen_pcibk_handle_event,
@@ -132,10 +125,7 @@ static int xen_pcibk_do_attach(struct xen_pcibk_device *pdev, int gnt_ref,
                                  "Error binding event channel to IRQ");
                 goto out;
         }
-
-        spin_lock(&pdev->dev_lock);
         pdev->evtchn_irq = err;
-        spin_unlock(&pdev->dev_lock);
         err = 0;
 
         dev_dbg(&pdev->xdev->dev, "Attached!\n");
@@ -150,6 +140,7 @@ static int xen_pcibk_attach(struct xen_pcibk_device *pdev)
         char *magic = NULL;
 
 
+        mutex_lock(&pdev->dev_lock);
         /* Make sure we only do this setup once */
         if (xenbus_read_driver_state(pdev->xdev->nodename) !=
             XenbusStateInitialised)
@@ -176,7 +167,7 @@ static int xen_pcibk_attach(struct xen_pcibk_device *pdev)
         if (magic == NULL || strcmp(magic, XEN_PCI_MAGIC) != 0) {
                 xenbus_dev_fatal(pdev->xdev, -EFAULT,
                                  "version mismatch (%s/%s) with pcifront - "
-                                 "halting xen_pcibk",
+                                 "halting " DRV_NAME,
                                  magic, XEN_PCI_MAGIC);
                 goto out;
         }
@@ -194,6 +185,7 @@ static int xen_pcibk_attach(struct xen_pcibk_device *pdev)
 
         dev_dbg(&pdev->xdev->dev, "Connected? %d\n", err);
 out:
+        mutex_unlock(&pdev->dev_lock);
 
         kfree(magic);
 
@@ -369,6 +361,7 @@ static int xen_pcibk_reconfigure(struct xen_pcibk_device *pdev)
 
         dev_dbg(&pdev->xdev->dev, "Reconfiguring device ...\n");
 
+        mutex_lock(&pdev->dev_lock);
         /* Make sure we only reconfigure once */
         if (xenbus_read_driver_state(pdev->xdev->nodename) !=
             XenbusStateReconfiguring)
@@ -506,6 +499,7 @@ static int xen_pcibk_reconfigure(struct xen_pcibk_device *pdev)
         }
 
 out:
+        mutex_unlock(&pdev->dev_lock);
         return 0;
 }
 
@@ -562,6 +556,7 @@ static int xen_pcibk_setup_backend(struct xen_pcibk_device *pdev)
         char dev_str[64];
         char state_str[64];
 
+        mutex_lock(&pdev->dev_lock);
         /* It's possible we could get the call to setup twice, so make sure
          * we're not already connected.
          */
@@ -642,10 +637,10 @@ static int xen_pcibk_setup_backend(struct xen_pcibk_device *pdev)
                                  "Error switching to initialised state!");
 
 out:
+        mutex_unlock(&pdev->dev_lock);
         if (!err)
                 /* see if pcifront is already configured (if not, we'll wait) */
                 xen_pcibk_attach(pdev);
-
         return err;
 }
 
@@ -724,7 +719,7 @@ static struct xenbus_driver xenbus_xen_pcibk_driver = {
         .otherend_changed       = xen_pcibk_frontend_changed,
 };
 
-struct xen_pcibk_backend *xen_pcibk_backend;
+const struct xen_pcibk_backend *__read_mostly xen_pcibk_backend;
 
 int __init xen_pcibk_xenbus_register(void)
 {
diff --git a/drivers/xen/xenbus/xenbus_comms.c b/drivers/xen/xenbus/xenbus_comms.c
index 090c61ee8fd0..2eff7a6aaa20 100644
--- a/drivers/xen/xenbus/xenbus_comms.c
+++ b/drivers/xen/xenbus/xenbus_comms.c
@@ -212,7 +212,9 @@ int xb_init_comms(void)
                 printk(KERN_WARNING "XENBUS response ring is not quiescent "
                        "(%08x:%08x): fixing up\n",
                        intf->rsp_cons, intf->rsp_prod);
-                intf->rsp_cons = intf->rsp_prod;
+                /* breaks kdump */
+                if (!reset_devices)
+                        intf->rsp_cons = intf->rsp_prod;
         }
 
         if (xenbus_irq) {
diff --git a/drivers/xen/xenbus/xenbus_probe.c b/drivers/xen/xenbus/xenbus_probe.c
index bd2f90c9ac8b..cef9b0bf63d5 100644
--- a/drivers/xen/xenbus/xenbus_probe.c
+++ b/drivers/xen/xenbus/xenbus_probe.c
@@ -684,64 +684,74 @@ static int __init xenbus_probe_initcall(void)
 
 device_initcall(xenbus_probe_initcall);
 
-static int __init xenbus_init(void)
+/* Set up event channel for xenstored which is run as a local process
+ * (this is normally used only in dom0)
+ */
+static int __init xenstored_local_init(void)
 {
         int err = 0;
         unsigned long page = 0;
+        struct evtchn_alloc_unbound alloc_unbound;
 
-        DPRINTK("");
+        /* Allocate Xenstore page */
+        page = get_zeroed_page(GFP_KERNEL);
+        if (!page)
+                goto out_err;
 
-        err = -ENODEV;
-        if (!xen_domain())
-                return err;
+        xen_store_mfn = xen_start_info->store_mfn =
+                pfn_to_mfn(virt_to_phys((void *)page) >>
+                           PAGE_SHIFT);
 
-        /*
-         * Domain0 doesn't have a store_evtchn or store_mfn yet.
-         */
-        if (xen_initial_domain()) {
-                struct evtchn_alloc_unbound alloc_unbound;
+        /* Next allocate a local port which xenstored can bind to */
+        alloc_unbound.dom        = DOMID_SELF;
+        alloc_unbound.remote_dom = DOMID_SELF;
 
-                /* Allocate Xenstore page */
-                page = get_zeroed_page(GFP_KERNEL);
-                if (!page)
-                        goto out_error;
+        err = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound,
+                                          &alloc_unbound);
+        if (err == -ENOSYS)
+                goto out_err;
 
-                xen_store_mfn = xen_start_info->store_mfn =
-                        pfn_to_mfn(virt_to_phys((void *)page) >>
-                                   PAGE_SHIFT);
+        BUG_ON(err);
+        xen_store_evtchn = xen_start_info->store_evtchn =
+                alloc_unbound.port;
 
-                /* Next allocate a local port which xenstored can bind to */
-                alloc_unbound.dom        = DOMID_SELF;
-                alloc_unbound.remote_dom = 0;
+        return 0;
 
-                err = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound,
-                                                  &alloc_unbound);
-                if (err == -ENOSYS)
-                        goto out_error;
+ out_err:
+        if (page != 0)
+                free_page(page);
+        return err;
+}
 
-                BUG_ON(err);
-                xen_store_evtchn = xen_start_info->store_evtchn =
-                        alloc_unbound.port;
+static int __init xenbus_init(void)
+{
+        int err = 0;
 
-                xen_store_interface = mfn_to_virt(xen_store_mfn);
+        if (!xen_domain())
+                return -ENODEV;
+
+        if (xen_hvm_domain()) {
+                uint64_t v = 0;
+                err = hvm_get_parameter(HVM_PARAM_STORE_EVTCHN, &v);
+                if (err)
+                        goto out_error;
+                xen_store_evtchn = (int)v;
+                err = hvm_get_parameter(HVM_PARAM_STORE_PFN, &v);
+                if (err)
+                        goto out_error;
+                xen_store_mfn = (unsigned long)v;
+                xen_store_interface = ioremap(xen_store_mfn << PAGE_SHIFT, PAGE_SIZE);
         } else {
-                if (xen_hvm_domain()) {
-                        uint64_t v = 0;
-                        err = hvm_get_parameter(HVM_PARAM_STORE_EVTCHN, &v);
-                        if (err)
-                                goto out_error;
-                        xen_store_evtchn = (int)v;
-                        err = hvm_get_parameter(HVM_PARAM_STORE_PFN, &v);
+                xen_store_evtchn = xen_start_info->store_evtchn;
+                xen_store_mfn = xen_start_info->store_mfn;
+                if (xen_store_evtchn)
+                        xenstored_ready = 1;
+                else {
+                        err = xenstored_local_init();
                         if (err)
                                 goto out_error;
-                        xen_store_mfn = (unsigned long)v;
-                        xen_store_interface = ioremap(xen_store_mfn << PAGE_SHIFT, PAGE_SIZE);
-                } else {
-                        xen_store_evtchn = xen_start_info->store_evtchn;
-                        xen_store_mfn = xen_start_info->store_mfn;
-                        xen_store_interface = mfn_to_virt(xen_store_mfn);
-                        xenstored_ready = 1;
                 }
+                xen_store_interface = mfn_to_virt(xen_store_mfn);
         }
 
         /* Initialize the interface to xenstore. */
@@ -760,12 +770,7 @@ static int __init xenbus_init(void)
         proc_mkdir("xen", NULL);
 #endif
 
-        return 0;
-
-  out_error:
-        if (page != 0)
-                free_page(page);
-
+ out_error:
         return err;
 }
 
diff --git a/drivers/xen/xenbus/xenbus_probe_frontend.c b/drivers/xen/xenbus/xenbus_probe_frontend.c
index ed2ba474a560..540587e18a94 100644
--- a/drivers/xen/xenbus/xenbus_probe_frontend.c
+++ b/drivers/xen/xenbus/xenbus_probe_frontend.c
@@ -248,10 +248,131 @@ int __xenbus_register_frontend(struct xenbus_driver *drv,
 }
 EXPORT_SYMBOL_GPL(__xenbus_register_frontend);
 
+static DECLARE_WAIT_QUEUE_HEAD(backend_state_wq);
+static int backend_state;
+
+static void xenbus_reset_backend_state_changed(struct xenbus_watch *w,
+                                        const char **v, unsigned int l)
+{
+        xenbus_scanf(XBT_NIL, v[XS_WATCH_PATH], "", "%i", &backend_state);
+        printk(KERN_DEBUG "XENBUS: backend %s %s\n",
+                        v[XS_WATCH_PATH], xenbus_strstate(backend_state));
+        wake_up(&backend_state_wq);
+}
+
+static void xenbus_reset_wait_for_backend(char *be, int expected)
+{
+        long timeout;
+        timeout = wait_event_interruptible_timeout(backend_state_wq,
+                        backend_state == expected, 5 * HZ);
+        if (timeout <= 0)
+                printk(KERN_INFO "XENBUS: backend %s timed out.\n", be);
+}
+
+/*
+ * Reset frontend if it is in Connected or Closed state.
+ * Wait for backend to catch up.
+ * State Connected happens during kdump, Closed after kexec.
+ */
+static void xenbus_reset_frontend(char *fe, char *be, int be_state)
+{
+        struct xenbus_watch be_watch;
+
+        printk(KERN_DEBUG "XENBUS: backend %s %s\n",
+                        be, xenbus_strstate(be_state));
+
+        memset(&be_watch, 0, sizeof(be_watch));
+        be_watch.node = kasprintf(GFP_NOIO | __GFP_HIGH, "%s/state", be);
+        if (!be_watch.node)
+                return;
+
+        be_watch.callback = xenbus_reset_backend_state_changed;
+        backend_state = XenbusStateUnknown;
+
+        printk(KERN_INFO "XENBUS: triggering reconnect on %s\n", be);
+        register_xenbus_watch(&be_watch);
+
+        /* fall through to forward backend to state XenbusStateInitialising */
+        switch (be_state) {
+        case XenbusStateConnected:
+                xenbus_printf(XBT_NIL, fe, "state", "%d", XenbusStateClosing);
+                xenbus_reset_wait_for_backend(be, XenbusStateClosing);
+
+        case XenbusStateClosing:
+                xenbus_printf(XBT_NIL, fe, "state", "%d", XenbusStateClosed);
+                xenbus_reset_wait_for_backend(be, XenbusStateClosed);
+
+        case XenbusStateClosed:
+                xenbus_printf(XBT_NIL, fe, "state", "%d", XenbusStateInitialising);
+                xenbus_reset_wait_for_backend(be, XenbusStateInitWait);
+        }
+
+        unregister_xenbus_watch(&be_watch);
+        printk(KERN_INFO "XENBUS: reconnect done on %s\n", be);
+        kfree(be_watch.node);
+}
+
+static void xenbus_check_frontend(char *class, char *dev)
+{
+        int be_state, fe_state, err;
+        char *backend, *frontend;
+
+        frontend = kasprintf(GFP_NOIO | __GFP_HIGH, "device/%s/%s", class, dev);
+        if (!frontend)
+                return;
+
+        err = xenbus_scanf(XBT_NIL, frontend, "state", "%i", &fe_state);
+        if (err != 1)
+                goto out;
+
+        switch (fe_state) {
+        case XenbusStateConnected:
+        case XenbusStateClosed:
+                printk(KERN_DEBUG "XENBUS: frontend %s %s\n",
+                                frontend, xenbus_strstate(fe_state));
+                backend = xenbus_read(XBT_NIL, frontend, "backend", NULL);
+                if (!backend || IS_ERR(backend))
+                        goto out;
+                err = xenbus_scanf(XBT_NIL, backend, "state", "%i", &be_state);
+                if (err == 1)
+                        xenbus_reset_frontend(frontend, backend, be_state);
+                kfree(backend);
+                break;
+        default:
+                break;
+        }
+out:
+        kfree(frontend);
+}
+
+static void xenbus_reset_state(void)
+{
+        char **devclass, **dev;
+        int devclass_n, dev_n;
+        int i, j;
+
+        devclass = xenbus_directory(XBT_NIL, "device", "", &devclass_n);
+        if (IS_ERR(devclass))
+                return;
+
+        for (i = 0; i < devclass_n; i++) {
+                dev = xenbus_directory(XBT_NIL, "device", devclass[i], &dev_n);
+                if (IS_ERR(dev))
+                        continue;
+                for (j = 0; j < dev_n; j++)
+                        xenbus_check_frontend(devclass[i], dev[j]);
+                kfree(dev);
+        }
+        kfree(devclass);
+}
+
 static int frontend_probe_and_watch(struct notifier_block *notifier,
                                    unsigned long event,
                                    void *data)
 {
+        /* reset devices in Connected or Closed state */
+        if (xen_hvm_domain())
+                xenbus_reset_state();
         /* Enumerate devices in xenstore and watch for changes. */
         xenbus_probe_devices(&xenbus_frontend);
         register_xenbus_watch(&fe_watch);
diff --git a/drivers/xen/xenbus/xenbus_xs.c b/drivers/xen/xenbus/xenbus_xs.c
index 5534690075af..b3b8f2f3ad10 100644
--- a/drivers/xen/xenbus/xenbus_xs.c
+++ b/drivers/xen/xenbus/xenbus_xs.c
@@ -45,6 +45,7 @@
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <xen/xenbus.h>
+#include <xen/xen.h>
 #include "xenbus_comms.h"
 
 struct xs_stored_msg {
@@ -620,6 +621,15 @@ static struct xenbus_watch *find_watch(const char *token)
         return NULL;
 }
 
+static void xs_reset_watches(void)
+{
+        int err;
+
+        err = xs_error(xs_single(XBT_NIL, XS_RESET_WATCHES, "", NULL));
+        if (err && err != -EEXIST)
+                printk(KERN_WARNING "xs_reset_watches failed: %d\n", err);
+}
+
 /* Register callback to watch this node. */
 int register_xenbus_watch(struct xenbus_watch *watch)
 {
@@ -638,8 +648,7 @@ int register_xenbus_watch(struct xenbus_watch *watch)
 
         err = xs_watch(watch->node, token);
 
-        /* Ignore errors due to multiple registration. */
-        if ((err != 0) && (err != -EEXIST)) {
+        if (err) {
                 spin_lock(&watches_lock);
                 list_del(&watch->list);
                 spin_unlock(&watches_lock);
@@ -897,5 +906,9 @@ int xs_init(void)
         if (IS_ERR(task))
                 return PTR_ERR(task);
 
+        /* shutdown watches for kexec boot */
+        if (xen_hvm_domain())
+                xs_reset_watches();
+
         return 0;
 }