Merge tag 'for-linus-4.10-rc0-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip

Pull xen updates from Juergen Gross:
"Xen features and fixes for 4.10

These are some fixes, a move of some arm related headers to share them
between arm and arm64 and a series introducing a helper to make code
more readable.

The most notable change is David stepping down as maintainer of the
Xen hypervisor interface. This results in me sending you the pull
requests for Xen related code from now on"

* tag 'for-linus-4.10-rc0-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip: (29 commits)
xen/balloon: Only mark a page as managed when it is released
xenbus: fix deadlock on writes to /proc/xen/xenbus
xen/scsifront: don't request a slot on the ring until request is ready
xen/x86: Increase xen_e820_map to E820_X_MAX possible entries
x86: Make E820_X_MAX unconditionally larger than E820MAX
xen/pci: Bubble up error and fix description.
xen: xenbus: set error code on failure
xen: set error code on failures
arm/xen: Use alloc_percpu rather than __alloc_percpu
arm/arm64: xen: Move shared architecture headers to include/xen/arm
xen/events: use xen_vcpu_id mapping for EVTCHNOP_status
xen/gntdev: Use VM_MIXEDMAP instead of VM_IO to avoid NUMA balancing
xen-scsifront: Add a missing call to kfree
MAINTAINERS: update XEN HYPERVISOR INTERFACE
xenfs: Use proc_create_mount_point() to create /proc/xen
xen-platform: use builtin_pci_driver
xen-netback: fix error handling output
xen: make use of xenbus_read_unsigned() in xenbus
xen: make use of xenbus_read_unsigned() in xen-pciback
xen: make use of xenbus_read_unsigned() in xen-fbfront
...

MAINTAINERS

···
 
 XEN HYPERVISOR INTERFACE
 M:	Boris Ostrovsky <[e-mail]>
-M:	David Vrabel <[e-mail]>
 M:	Juergen Gross <[e-mail]>
 L:	[e-mail] (moderated for non-subscribers)
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip.git

arch/arm/include/asm/xen/hypercall.h

···
-/******************************************************************************
- * hypercall.h
- *
- * Linux-specific hypervisor handling.
- *
- * Stefano Stabellini <[e-mail]>, Citrix, 2012
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License version 2
- * as published by the Free Software Foundation; or, when distributed
- * separately from the Linux kernel or incorporated into other
- * software packages, subject to the following license:
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this source file (the "Software"), to deal in the Software without
- * restriction, including without limitation the rights to use, copy, modify,
- * merge, publish, distribute, sublicense, and/or sell copies of the Software,
- * and to permit persons to whom the Software is furnished to do so, subject to
- * the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in
- * all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
- * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
- * IN THE SOFTWARE.
- */
-
-#ifndef _ASM_ARM_XEN_HYPERCALL_H
-#define _ASM_ARM_XEN_HYPERCALL_H
-
-#include <linux/bug.h>
-
-#include <xen/interface/xen.h>
-#include <xen/interface/sched.h>
-#include <xen/interface/platform.h>
-
-long privcmd_call(unsigned call, unsigned long a1,
-		unsigned long a2, unsigned long a3,
-		unsigned long a4, unsigned long a5);
-int HYPERVISOR_xen_version(int cmd, void *arg);
-int HYPERVISOR_console_io(int cmd, int count, char *str);
-int HYPERVISOR_grant_table_op(unsigned int cmd, void *uop, unsigned int count);
-int HYPERVISOR_sched_op(int cmd, void *arg);
-int HYPERVISOR_event_channel_op(int cmd, void *arg);
-unsigned long HYPERVISOR_hvm_op(int op, void *arg);
-int HYPERVISOR_memory_op(unsigned int cmd, void *arg);
-int HYPERVISOR_physdev_op(int cmd, void *arg);
-int HYPERVISOR_vcpu_op(int cmd, int vcpuid, void *extra_args);
-int HYPERVISOR_tmem_op(void *arg);
-int HYPERVISOR_vm_assist(unsigned int cmd, unsigned int type);
-int HYPERVISOR_platform_op_raw(void *arg);
-static inline int HYPERVISOR_platform_op(struct xen_platform_op *op)
-{
-	op->interface_version = XENPF_INTERFACE_VERSION;
-	return HYPERVISOR_platform_op_raw(op);
-}
-int HYPERVISOR_multicall(struct multicall_entry *calls, uint32_t nr);
-
-static inline int
-HYPERVISOR_suspend(unsigned long start_info_mfn)
-{
-	struct sched_shutdown r = { .reason = SHUTDOWN_suspend };
-
-	/* start_info_mfn is unused on ARM */
-	return HYPERVISOR_sched_op(SCHEDOP_shutdown, &r);
-}
-
-static inline void
-MULTI_update_va_mapping(struct multicall_entry *mcl, unsigned long va,
-			unsigned int new_val, unsigned long flags)
-{
-	BUG();
-}
-
-static inline void
-MULTI_mmu_update(struct multicall_entry *mcl, struct mmu_update *req,
-		 int count, int *success_count, domid_t domid)
-{
-	BUG();
-}
-
-#endif /* _ASM_ARM_XEN_HYPERCALL_H */
+#include <xen/arm/hypercall.h>

arch/arm/include/asm/xen/hypervisor.h

···
-#ifndef _ASM_ARM_XEN_HYPERVISOR_H
-#define _ASM_ARM_XEN_HYPERVISOR_H
-
-#include <linux/init.h>
-
-extern struct shared_info *HYPERVISOR_shared_info;
-extern struct start_info *xen_start_info;
-
-/* Lazy mode for batching updates / context switch */
-enum paravirt_lazy_mode {
-	PARAVIRT_LAZY_NONE,
-	PARAVIRT_LAZY_MMU,
-	PARAVIRT_LAZY_CPU,
-};
-
-static inline enum paravirt_lazy_mode paravirt_get_lazy_mode(void)
-{
-	return PARAVIRT_LAZY_NONE;
-}
-
-extern struct dma_map_ops *xen_dma_ops;
-
-#ifdef CONFIG_XEN
-void __init xen_early_init(void);
-#else
-static inline void xen_early_init(void) { return; }
-#endif
-
-#ifdef CONFIG_HOTPLUG_CPU
-static inline void xen_arch_register_cpu(int num)
-{
-}
-
-static inline void xen_arch_unregister_cpu(int num)
-{
-}
-#endif
-
-#endif /* _ASM_ARM_XEN_HYPERVISOR_H */
+#include <xen/arm/hypervisor.h>

arch/arm/include/asm/xen/interface.h

···
-/******************************************************************************
- * Guest OS interface to ARM Xen.
- *
- * Stefano Stabellini <[e-mail]>, Citrix, 2012
- */
-
-#ifndef _ASM_ARM_XEN_INTERFACE_H
-#define _ASM_ARM_XEN_INTERFACE_H
-
-#include <linux/types.h>
-
-#define uint64_aligned_t uint64_t __attribute__((aligned(8)))
-
-#define __DEFINE_GUEST_HANDLE(name, type) \
-	typedef struct { union { type *p; uint64_aligned_t q; }; }  \
-        __guest_handle_ ## name
-
-#define DEFINE_GUEST_HANDLE_STRUCT(name) \
-	__DEFINE_GUEST_HANDLE(name, struct name)
-#define DEFINE_GUEST_HANDLE(name) __DEFINE_GUEST_HANDLE(name, name)
-#define GUEST_HANDLE(name)        __guest_handle_ ## name
-
-#define set_xen_guest_handle(hnd, val)			\
-	do {						\
-		if (sizeof(hnd) == 8)			\
-			*(uint64_t *)&(hnd) = 0;	\
-		(hnd).p = val;				\
-	} while (0)
-
-#define __HYPERVISOR_platform_op_raw __HYPERVISOR_platform_op
-
-#ifndef __ASSEMBLY__
-/* Explicitly size integers that represent pfns in the interface with
- * Xen so that we can have one ABI that works for 32 and 64 bit guests.
- * Note that this means that the xen_pfn_t type may be capable of
- * representing pfn's which the guest cannot represent in its own pfn
- * type. However since pfn space is controlled by the guest this is
- * fine since it simply wouldn't be able to create any sure pfns in
- * the first place.
- */
-typedef uint64_t xen_pfn_t;
-#define PRI_xen_pfn "llx"
-typedef uint64_t xen_ulong_t;
-#define PRI_xen_ulong "llx"
-typedef int64_t xen_long_t;
-#define PRI_xen_long "llx"
-/* Guest handles for primitive C types. */
-__DEFINE_GUEST_HANDLE(uchar, unsigned char);
-__DEFINE_GUEST_HANDLE(uint,  unsigned int);
-DEFINE_GUEST_HANDLE(char);
-DEFINE_GUEST_HANDLE(int);
-DEFINE_GUEST_HANDLE(void);
-DEFINE_GUEST_HANDLE(uint64_t);
-DEFINE_GUEST_HANDLE(uint32_t);
-DEFINE_GUEST_HANDLE(xen_pfn_t);
-DEFINE_GUEST_HANDLE(xen_ulong_t);
-
-/* Maximum number of virtual CPUs in multi-processor guests. */
-#define MAX_VIRT_CPUS 1
-
-struct arch_vcpu_info { };
-struct arch_shared_info { };
-
-/* TODO: Move pvclock definitions some place arch independent */
-struct pvclock_vcpu_time_info {
-	u32   version;
-	u32   pad0;
-	u64   tsc_timestamp;
-	u64   system_time;
-	u32   tsc_to_system_mul;
-	s8    tsc_shift;
-	u8    flags;
-	u8    pad[2];
-} __attribute__((__packed__)); /* 32 bytes */
-
-/* It is OK to have a 12 bytes struct with no padding because it is packed */
-struct pvclock_wall_clock {
-	u32   version;
-	u32   sec;
-	u32   nsec;
-	u32   sec_hi;
-} __attribute__((__packed__));
-#endif
-
-#endif /* _ASM_ARM_XEN_INTERFACE_H */
+#include <xen/arm/interface.h>

arch/arm/include/asm/xen/page-coherent.h

···
-#ifndef _ASM_ARM_XEN_PAGE_COHERENT_H
-#define _ASM_ARM_XEN_PAGE_COHERENT_H
-
-#include <asm/page.h>
-#include <linux/dma-mapping.h>
-
-void __xen_dma_map_page(struct device *hwdev, struct page *page,
-	     dma_addr_t dev_addr, unsigned long offset, size_t size,
-	     enum dma_data_direction dir, unsigned long attrs);
-void __xen_dma_unmap_page(struct device *hwdev, dma_addr_t handle,
-		size_t size, enum dma_data_direction dir,
-		unsigned long attrs);
-void __xen_dma_sync_single_for_cpu(struct device *hwdev,
-		dma_addr_t handle, size_t size, enum dma_data_direction dir);
-
-void __xen_dma_sync_single_for_device(struct device *hwdev,
-		dma_addr_t handle, size_t size, enum dma_data_direction dir);
-
-static inline void *xen_alloc_coherent_pages(struct device *hwdev, size_t size,
-		dma_addr_t *dma_handle, gfp_t flags, unsigned long attrs)
-{
-	return __generic_dma_ops(hwdev)->alloc(hwdev, size, dma_handle, flags, attrs);
-}
-
-static inline void xen_free_coherent_pages(struct device *hwdev, size_t size,
-		void *cpu_addr, dma_addr_t dma_handle, unsigned long attrs)
-{
-	__generic_dma_ops(hwdev)->free(hwdev, size, cpu_addr, dma_handle, attrs);
-}
-
-static inline void xen_dma_map_page(struct device *hwdev, struct page *page,
-	     dma_addr_t dev_addr, unsigned long offset, size_t size,
-	     enum dma_data_direction dir, unsigned long attrs)
-{
-	unsigned long page_pfn = page_to_xen_pfn(page);
-	unsigned long dev_pfn = XEN_PFN_DOWN(dev_addr);
-	unsigned long compound_pages =
-		(1<<compound_order(page)) * XEN_PFN_PER_PAGE;
-	bool local = (page_pfn <= dev_pfn) &&
-		(dev_pfn - page_pfn < compound_pages);
-
-	/*
-	 * Dom0 is mapped 1:1, while the Linux page can span across
-	 * multiple Xen pages, it's not possible for it to contain a
-	 * mix of local and foreign Xen pages. So if the first xen_pfn
-	 * == mfn the page is local otherwise it's a foreign page
-	 * grant-mapped in dom0. If the page is local we can safely
-	 * call the native dma_ops function, otherwise we call the xen
-	 * specific function.
-	 */
-	if (local)
-		__generic_dma_ops(hwdev)->map_page(hwdev, page, offset, size, dir, attrs);
-	else
-		__xen_dma_map_page(hwdev, page, dev_addr, offset, size, dir, attrs);
-}
-
-static inline void xen_dma_unmap_page(struct device *hwdev, dma_addr_t handle,
-		size_t size, enum dma_data_direction dir, unsigned long attrs)
-{
-	unsigned long pfn = PFN_DOWN(handle);
-	/*
-	 * Dom0 is mapped 1:1, while the Linux page can be spanned accross
-	 * multiple Xen page, it's not possible to have a mix of local and
-	 * foreign Xen page. Dom0 is mapped 1:1, so calling pfn_valid on a
-	 * foreign mfn will always return false. If the page is local we can
-	 * safely call the native dma_ops function, otherwise we call the xen
-	 * specific function.
-	 */
-	if (pfn_valid(pfn)) {
-		if (__generic_dma_ops(hwdev)->unmap_page)
-			__generic_dma_ops(hwdev)->unmap_page(hwdev, handle, size, dir, attrs);
-	} else
-		__xen_dma_unmap_page(hwdev, handle, size, dir, attrs);
-}
-
-static inline void xen_dma_sync_single_for_cpu(struct device *hwdev,
-		dma_addr_t handle, size_t size, enum dma_data_direction dir)
-{
-	unsigned long pfn = PFN_DOWN(handle);
-	if (pfn_valid(pfn)) {
-		if (__generic_dma_ops(hwdev)->sync_single_for_cpu)
-			__generic_dma_ops(hwdev)->sync_single_for_cpu(hwdev, handle, size, dir);
-	} else
-		__xen_dma_sync_single_for_cpu(hwdev, handle, size, dir);
-}
-
-static inline void xen_dma_sync_single_for_device(struct device *hwdev,
-		dma_addr_t handle, size_t size, enum dma_data_direction dir)
-{
-	unsigned long pfn = PFN_DOWN(handle);
-	if (pfn_valid(pfn)) {
-		if (__generic_dma_ops(hwdev)->sync_single_for_device)
-			__generic_dma_ops(hwdev)->sync_single_for_device(hwdev, handle, size, dir);
-	} else
-		__xen_dma_sync_single_for_device(hwdev, handle, size, dir);
-}
-
-#endif /* _ASM_ARM_XEN_PAGE_COHERENT_H */
+#include <xen/arm/page-coherent.h>

arch/arm/include/asm/xen/page.h

···
-#ifndef _ASM_ARM_XEN_PAGE_H
-#define _ASM_ARM_XEN_PAGE_H
-
-#include <asm/page.h>
-#include <asm/pgtable.h>
-
-#include <linux/pfn.h>
-#include <linux/types.h>
-#include <linux/dma-mapping.h>
-
-#include <xen/xen.h>
-#include <xen/interface/grant_table.h>
-
-#define phys_to_machine_mapping_valid(pfn) (1)
-
-/* Xen machine address */
-typedef struct xmaddr {
-	phys_addr_t maddr;
-} xmaddr_t;
-
-/* Xen pseudo-physical address */
-typedef struct xpaddr {
-	phys_addr_t paddr;
-} xpaddr_t;
-
-#define XMADDR(x)	((xmaddr_t) { .maddr = (x) })
-#define XPADDR(x)	((xpaddr_t) { .paddr = (x) })
-
-#define INVALID_P2M_ENTRY      (~0UL)
-
-/*
- * The pseudo-physical frame (pfn) used in all the helpers is always based
- * on Xen page granularity (i.e 4KB).
- *
- * A Linux page may be split across multiple non-contiguous Xen page so we
- * have to keep track with frame based on 4KB page granularity.
- *
- * PV drivers should never make a direct usage of those helpers (particularly
- * pfn_to_gfn and gfn_to_pfn).
- */
-
-unsigned long __pfn_to_mfn(unsigned long pfn);
-extern struct rb_root phys_to_mach;
-
-/* Pseudo-physical <-> Guest conversion */
-static inline unsigned long pfn_to_gfn(unsigned long pfn)
-{
-	return pfn;
-}
-
-static inline unsigned long gfn_to_pfn(unsigned long gfn)
-{
-	return gfn;
-}
-
-/* Pseudo-physical <-> BUS conversion */
-static inline unsigned long pfn_to_bfn(unsigned long pfn)
-{
-	unsigned long mfn;
-
-	if (phys_to_mach.rb_node != NULL) {
-		mfn = __pfn_to_mfn(pfn);
-		if (mfn != INVALID_P2M_ENTRY)
-			return mfn;
-	}
-
-	return pfn;
-}
-
-static inline unsigned long bfn_to_pfn(unsigned long bfn)
-{
-	return bfn;
-}
-
-#define bfn_to_local_pfn(bfn)	bfn_to_pfn(bfn)
-
-/* VIRT <-> GUEST conversion */
-#define virt_to_gfn(v)		(pfn_to_gfn(virt_to_phys(v) >> XEN_PAGE_SHIFT))
-#define gfn_to_virt(m)		(__va(gfn_to_pfn(m) << XEN_PAGE_SHIFT))
-
-/* Only used in PV code. But ARM guests are always HVM. */
-static inline xmaddr_t arbitrary_virt_to_machine(void *vaddr)
-{
-	BUG();
-}
-
-/* TODO: this shouldn't be here but it is because the frontend drivers
- * are using it (its rolled in headers) even though we won't hit the code path.
- * So for right now just punt with this.
- */
-static inline pte_t *lookup_address(unsigned long address, unsigned int *level)
-{
-	BUG();
-	return NULL;
-}
-
-extern int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops,
-				   struct gnttab_map_grant_ref *kmap_ops,
-				   struct page **pages, unsigned int count);
-
-extern int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops,
-				     struct gnttab_unmap_grant_ref *kunmap_ops,
-				     struct page **pages, unsigned int count);
-
-bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn);
-bool __set_phys_to_machine_multi(unsigned long pfn, unsigned long mfn,
-		unsigned long nr_pages);
-
-static inline bool set_phys_to_machine(unsigned long pfn, unsigned long mfn)
-{
-	return __set_phys_to_machine(pfn, mfn);
-}
-
-#define xen_remap(cookie, size) ioremap_cache((cookie), (size))
-#define xen_unmap(cookie) iounmap((cookie))
-
-bool xen_arch_need_swiotlb(struct device *dev,
-			   phys_addr_t phys,
-			   dma_addr_t dev_addr);
-unsigned long xen_get_swiotlb_free_pages(unsigned int order);
-
-#endif /* _ASM_ARM_XEN_PAGE_H */
+#include <xen/arm/page.h>

arch/arm/xen/enlighten.c

···
 	 * for secondary CPUs as they are brought up.
 	 * For uniformity we use VCPUOP_register_vcpu_info even on cpu0.
 	 */
-	xen_vcpu_info = __alloc_percpu(sizeof(struct vcpu_info),
-			                       sizeof(struct vcpu_info));
+	xen_vcpu_info = alloc_percpu(struct vcpu_info);
 	if (xen_vcpu_info == NULL)
 		return -ENOMEM;
 

arch/arm64/include/asm/xen/hypercall.h

···
-#include <../../arm/include/asm/xen/hypercall.h>
+#include <xen/arm/hypercall.h>

arch/arm64/include/asm/xen/hypervisor.h

···
-#include <../../arm/include/asm/xen/hypervisor.h>
+#include <xen/arm/hypervisor.h>

arch/arm64/include/asm/xen/interface.h

···
-#include <../../arm/include/asm/xen/interface.h>
+#include <xen/arm/interface.h>

arch/arm64/include/asm/xen/page-coherent.h

···
-#include <../../arm/include/asm/xen/page-coherent.h>
+#include <xen/arm/page-coherent.h>

arch/arm64/include/asm/xen/page.h

···
-#include <../../arm/include/asm/xen/page.h>
+#include <xen/arm/page.h>

arch/x86/include/asm/e820.h

···
 #ifndef _ASM_X86_E820_H
 #define _ASM_X86_E820_H
 
-#ifdef CONFIG_EFI
+/*
+ * E820_X_MAX is the maximum size of the extended E820 table.  The extended
+ * table may contain up to 3 extra E820 entries per possible NUMA node, so we
+ * make room for 3 * MAX_NUMNODES possible entries, beyond the standard 128.
+ * Also note that E820_X_MAX *must* be defined before we include uapi/asm/e820.h.
+ */
 #include <linux/numa.h>
 #define E820_X_MAX (E820MAX + 3 * MAX_NUMNODES)
-#else	/* ! CONFIG_EFI */
-#define E820_X_MAX E820MAX
-#endif
+
 #include <uapi/asm/e820.h>
+
 #ifndef __ASSEMBLY__
 /* see comment in arch/x86/kernel/e820.c */
 extern struct e820map *e820;

arch/x86/pci/xen.c

···
 	return 0;
 
 error:
-	dev_err(&dev->dev,
-		"Xen PCI frontend has not registered MSI/MSI-X support!\n");
+	dev_err(&dev->dev, "Failed to create MSI%s! ret=%d!\n",
+		type == PCI_CAP_ID_MSI ? "" : "-X", irq);
 	return irq;
 }
 

arch/x86/xen/setup.c

···
 unsigned long xen_released_pages;
 
 /* E820 map used during setting up memory. */
-static struct e820entry xen_e820_map[E820MAX] __initdata;
+static struct e820entry xen_e820_map[E820_X_MAX] __initdata;
 static u32 xen_e820_map_entries __initdata;
 
 /*
···
 	max_pfn = min(max_pfn, xen_start_info->nr_pages);
 	mem_end = PFN_PHYS(max_pfn);
 
-	memmap.nr_entries = E820MAX;
+	memmap.nr_entries = ARRAY_SIZE(xen_e820_map);
 	set_xen_guest_handle(memmap.buffer, xen_e820_map);
 
 	op = xen_initial_domain() ?
···
 	int i;
 	int rc;
 
-	memmap.nr_entries = E820MAX;
+	memmap.nr_entries = ARRAY_SIZE(xen_e820_map);
 	set_xen_guest_handle(memmap.buffer, xen_e820_map);
 
 	rc = HYPERVISOR_memory_op(XENMEM_memory_map, &memmap);

drivers/block/xen-blkback/xenbus.c

···
 	struct xenbus_device *dev = be->dev;
 	struct xen_blkif *blkif = be->blkif;
 	int err;
-	int state = 0, discard_enable;
+	int state = 0;
 	struct block_device *bdev = be->blkif->vbd.bdev;
 	struct request_queue *q = bdev_get_queue(bdev);
 
-	err = xenbus_scanf(XBT_NIL, dev->nodename, "discard-enable", "%d",
-			   &discard_enable);
-	if (err == 1 && !discard_enable)
+	if (!xenbus_read_unsigned(dev->nodename, "discard-enable", 1))
 		return;
 
 	if (blk_queue_discard(q)) {
···
 		xenbus_dev_fatal(dev, err, "unknown fe protocol %s", protocol);
 		return -ENOSYS;
 	}
-	err = xenbus_scanf(XBT_NIL, dev->otherend,
-			   "feature-persistent", "%u", &pers_grants);
-	if (err <= 0)
-		pers_grants = 0;
-
+	pers_grants = xenbus_read_unsigned(dev->otherend, "feature-persistent",
+					   0);
 	be->blkif->vbd.feature_gnt_persistent = pers_grants;
 	be->blkif->vbd.overflow_max_grants = 0;
 
 	/*
 	 * Read the number of hardware queues from frontend.
 	 */
-	err = xenbus_scanf(XBT_NIL, dev->otherend, "multi-queue-num-queues",
-			   "%u", &requested_num_queues);
-	if (err < 0) {
-		requested_num_queues = 1;
-	} else {
-		if (requested_num_queues > xenblk_max_queues
-		    || requested_num_queues == 0) {
-			/* Buggy or malicious guest. */
-			xenbus_dev_fatal(dev, err,
-					"guest requested %u queues, exceeding the maximum of %u.",
-					requested_num_queues, xenblk_max_queues);
-			return -ENOSYS;
-		}
+	requested_num_queues = xenbus_read_unsigned(dev->otherend,
+						    "multi-queue-num-queues",
+						    1);
+	if (requested_num_queues > xenblk_max_queues
+	    || requested_num_queues == 0) {
+		/* Buggy or malicious guest. */
+		xenbus_dev_fatal(dev, err,
+				"guest requested %u queues, exceeding the maximum of %u.",
+				requested_num_queues, xenblk_max_queues);
+		return -ENOSYS;
 	}
 	be->blkif->nr_rings = requested_num_queues;
 	if (xen_blkif_alloc_rings(be->blkif))

drivers/block/xen-blkfront.c

···
 	const char *message = NULL;
 	struct xenbus_transaction xbt;
 	int err;
-	unsigned int i, max_page_order = 0;
-	unsigned int ring_page_order = 0;
+	unsigned int i, max_page_order;
+	unsigned int ring_page_order;
 
-	err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
-			   "max-ring-page-order", "%u", &max_page_order);
-	if (err != 1)
-		info->nr_ring_pages = 1;
-	else {
-		ring_page_order = min(xen_blkif_max_ring_order, max_page_order);
-		info->nr_ring_pages = 1 << ring_page_order;
-	}
+	max_page_order = xenbus_read_unsigned(info->xbdev->otherend,
+					      "max-ring-page-order", 0);
+	ring_page_order = min(xen_blkif_max_ring_order, max_page_order);
+	info->nr_ring_pages = 1 << ring_page_order;
 
 	for (i = 0; i < info->nr_rings; i++) {
 		struct blkfront_ring_info *rinfo = &info->rinfo[i];
···
 
 static int negotiate_mq(struct blkfront_info *info)
 {
-	unsigned int backend_max_queues = 0;
-	int err;
+	unsigned int backend_max_queues;
 	unsigned int i;
 
 	BUG_ON(info->nr_rings);
 
 	/* Check if backend supports multiple queues. */
-	err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
-			   "multi-queue-max-queues", "%u", &backend_max_queues);
-	if (err < 0)
-		backend_max_queues = 1;
-
+	backend_max_queues = xenbus_read_unsigned(info->xbdev->otherend,
+						  "multi-queue-max-queues", 1);
 	info->nr_rings = min(backend_max_queues, xen_blkif_max_queues);
 	/* We need at least one ring. */
 	if (!info->nr_rings)
···
 	int err;
 	unsigned int discard_granularity;
 	unsigned int discard_alignment;
-	unsigned int discard_secure;
 
 	info->feature_discard = 1;
 	err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
···
 		info->discard_granularity = discard_granularity;
 		info->discard_alignment = discard_alignment;
 	}
-	err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
-			   "discard-secure", "%u", &discard_secure);
-	if (err > 0)
-		info->feature_secdiscard = !!discard_secure;
+	info->feature_secdiscard =
+		!!xenbus_read_unsigned(info->xbdev->otherend, "discard-secure",
+				       0);
 }
 
 static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo)
···
  */
 static void blkfront_gather_backend_features(struct blkfront_info *info)
 {
-	int err;
-	int barrier, flush, discard, persistent;
 	unsigned int indirect_segments;
 
 	info->feature_flush = 0;
 	info->feature_fua = 0;
-
-	err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
-			   "feature-barrier", "%d", &barrier);
 
 	/*
 	 * If there's no "feature-barrier" defined, then it means
···
 	 *
 	 * If there are barriers, then we use flush.
 	 */
-	if (err > 0 && barrier) {
+	if (xenbus_read_unsigned(info->xbdev->otherend, "feature-barrier", 0)) {
 		info->feature_flush = 1;
 		info->feature_fua = 1;
 	}
···
 	 * And if there is "feature-flush-cache" use that above
 	 * barriers.
 	 */
-	err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
-			   "feature-flush-cache", "%d", &flush);
-
-	if (err > 0 && flush) {
+	if (xenbus_read_unsigned(info->xbdev->otherend, "feature-flush-cache",
+				 0)) {
 		info->feature_flush = 1;
 		info->feature_fua = 0;
 	}
 
-	err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
-			   "feature-discard", "%d", &discard);
-
-	if (err > 0 && discard)
+	if (xenbus_read_unsigned(info->xbdev->otherend, "feature-discard", 0))
 		blkfront_setup_discard(info);
 
-	err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
-			   "feature-persistent", "%d", &persistent);
-	if (err <= 0)
-		info->feature_persistent = 0;
-	else
-		info->feature_persistent = persistent;
+	info->feature_persistent =
+		xenbus_read_unsigned(info->xbdev->otherend,
+				     "feature-persistent", 0);
 
-	err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
-			   "feature-max-indirect-segments", "%u",
-			   &indirect_segments);
-	if (err <= 0)
-		info->max_indirect_segments = 0;
-	else
-		info->max_indirect_segments = min(indirect_segments,
-						  xen_blkif_max_segments);
+	indirect_segments = xenbus_read_unsigned(info->xbdev->otherend,
+					"feature-max-indirect-segments", 0);
+	info->max_indirect_segments = min(indirect_segments,
+					  xen_blkif_max_segments);
 }
 
 /*
···
 	 * provide this. Assume physical sector size to be the same as
 	 * sector_size in that case.
 	 */
-	err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
-			   "physical-sector-size", "%u", &physical_sector_size);
-	if (err != 1)
-		physical_sector_size = sector_size;
-
+	physical_sector_size = xenbus_read_unsigned(info->xbdev->otherend,
+						    "physical-sector-size",
+						    sector_size);
 	blkfront_gather_backend_features(info);
 	for (i = 0; i < info->nr_rings; i++) {
 		err = blkfront_setup_indirect(&info->rinfo[i]);

drivers/char/tpm/xen-tpmfront.c

···
 static void backend_changed(struct xenbus_device *dev,
 		enum xenbus_state backend_state)
 {
-	int val;
-
 	switch (backend_state) {
 	case XenbusStateInitialised:
 	case XenbusStateConnected:
 		if (dev->state == XenbusStateConnected)
 			break;
 
-		if (xenbus_scanf(XBT_NIL, dev->otherend,
-				"feature-protocol-v2", "%d", &val) < 0)
-			val = 0;
-		if (!val) {
+		if (!xenbus_read_unsigned(dev->otherend, "feature-protocol-v2",
+					  0)) {
 			xenbus_dev_fatal(dev, -EINVAL,
 					"vTPM protocol 2 required");
 			return;

drivers/input/misc/xen-kbdfront.c

···
 static int xenkbd_probe(struct xenbus_device *dev,
 				  const struct xenbus_device_id *id)
 {
-	int ret, i, abs;
+	int ret, i;
+	unsigned int abs;
 	struct xenkbd_info *info;
 	struct input_dev *kbd, *ptr;
 
···
 	if (!info->page)
 		goto error_nomem;
 
-	if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-abs-pointer", "%d", &abs) < 0)
-		abs = 0;
+	abs = xenbus_read_unsigned(dev->otherend, "feature-abs-pointer", 0);
 	if (abs) {
 		ret = xenbus_write(XBT_NIL, dev->nodename,
 				   "request-abs-pointer", "1");
···
 
 	case XenbusStateInitWait:
 InitWait:
-		ret = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
-				   "feature-abs-pointer", "%d", &val);
-		if (ret < 0)
-			val = 0;
-		if (val) {
+		if (xenbus_read_unsigned(info->xbdev->otherend,
+					 "feature-abs-pointer", 0)) {
 			ret = xenbus_write(XBT_NIL, info->xbdev->nodename,
 					   "request-abs-pointer", "1");
 			if (ret)

drivers/net/xen-netback/xenbus.c

···
 	struct xenvif *vif = container_of(watch, struct xenvif,
 					  mcast_ctrl_watch);
 	struct xenbus_device *dev = xenvif_to_xenbus_device(vif);
-	int val;
 
-	if (xenbus_scanf(XBT_NIL, dev->otherend,
-			 "request-multicast-control", "%d", &val) < 0)
-		val = 0;
-	vif->multicast_control = !!val;
+	vif->multicast_control = !!xenbus_read_unsigned(dev->otherend,
+					"request-multicast-control", 0);
 }
 
 static int xen_register_mcast_ctrl_watch(struct xenbus_device *dev,
···
 	/* Check whether the frontend requested multiple queues
 	 * and read the number requested.
 	 */
-	err = xenbus_scanf(XBT_NIL, dev->otherend,
-			   "multi-queue-num-queues",
-			   "%u", &requested_num_queues);
-	if (err < 0) {
-		requested_num_queues = 1; /* Fall back to single queue */
-	} else if (requested_num_queues > xenvif_max_queues) {
+	requested_num_queues = xenbus_read_unsigned(dev->otherend,
+					"multi-queue-num-queues", 1);
+	if (requested_num_queues > xenvif_max_queues) {
 		/* buggy or malicious guest */
-		xenbus_dev_fatal(dev, err,
+		xenbus_dev_fatal(dev, -EINVAL,
 				 "guest requested %u queues, exceeding the maximum of %u.",
 				 requested_num_queues, xenvif_max_queues);
 		return;
···
 	struct xenvif *vif = be->vif;
 	struct xenbus_device *dev = be->dev;
 	unsigned int rx_copy;
-	int err, val;
+	int err;
 
 	err = xenbus_scanf(XBT_NIL, dev->otherend, "request-rx-copy", "%u",
 			   &rx_copy);
···
 	if (!rx_copy)
 		return -EOPNOTSUPP;
 
-	if (xenbus_scanf(XBT_NIL, dev->otherend,
-			 "feature-rx-notify", "%d", &val) < 0)
-		val = 0;
-	if (!val) {
+	if (!xenbus_read_unsigned(dev->otherend, "feature-rx-notify", 0)) {
 		/* - Reduce drain timeout to poll more frequently for
 		 *   Rx requests.
 		 * - Disable Rx stall detection.
···
 		be->vif->stall_timeout = 0;
 	}
 
-	if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-sg",
-			 "%d", &val) < 0)
-		val = 0;
-	vif->can_sg = !!val;
+	vif->can_sg = !!xenbus_read_unsigned(dev->otherend, "feature-sg", 0);
 
 	vif->gso_mask = 0;
 
-	if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-gso-tcpv4",
-			 "%d", &val) < 0)
-		val = 0;
-	if (val)
+	if (xenbus_read_unsigned(dev->otherend, "feature-gso-tcpv4", 0))
 		vif->gso_mask |= GSO_BIT(TCPV4);
 
-	if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-gso-tcpv6",
-			 "%d", &val) < 0)
-		val = 0;
-	if (val)
+	if (xenbus_read_unsigned(dev->otherend, "feature-gso-tcpv6", 0))
 		vif->gso_mask |= GSO_BIT(TCPV6);
 
-	if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-no-csum-offload",
-			 "%d", &val) < 0)
-		val = 0;
-	vif->ip_csum = !val;
+	vif->ip_csum = !xenbus_read_unsigned(dev->otherend,
+					     "feature-no-csum-offload", 0);
 
-	if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-ipv6-csum-offload",
-			 "%d", &val) < 0)
-		val = 0;
-	vif->ipv6_csum = !!val;
+	vif->ipv6_csum = !!xenbus_read_unsigned(dev->otherend,
+						"feature-ipv6-csum-offload", 0);
 
 	return 0;
 }

drivers/net/xen-netfront.c

···
 	netdev_features_t features)
 {
 	struct netfront_info *np = netdev_priv(dev);
-	int val;
 
-	if (features & NETIF_F_SG) {
-		if (xenbus_scanf(XBT_NIL, np->xbdev->otherend, "feature-sg",
-				 "%d", &val) < 0)
-			val = 0;
+	if (features & NETIF_F_SG &&
+	    !xenbus_read_unsigned(np->xbdev->otherend, "feature-sg", 0))
+		features &= ~NETIF_F_SG;
 
-		if (!val)
-			features &= ~NETIF_F_SG;
-	}
+	if (features & NETIF_F_IPV6_CSUM &&
+	    !xenbus_read_unsigned(np->xbdev->otherend,
+				  "feature-ipv6-csum-offload", 0))
+		features &= ~NETIF_F_IPV6_CSUM;
 
-	if (features & NETIF_F_IPV6_CSUM) {
-		if (xenbus_scanf(XBT_NIL, np->xbdev->otherend,
-				 "feature-ipv6-csum-offload", "%d", &val) < 0)
-			val = 0;
+	if (features & NETIF_F_TSO &&
+	    !xenbus_read_unsigned(np->xbdev->otherend, "feature-gso-tcpv4", 0))
+		features &= ~NETIF_F_TSO;
 
-		if (!val)
-			features &= ~NETIF_F_IPV6_CSUM;
-	}
-
-	if (features & NETIF_F_TSO) {
-		if (xenbus_scanf(XBT_NIL, np->xbdev->otherend,
-				 "feature-gso-tcpv4", "%d", &val) < 0)
-			val = 0;
-
-		if (!val)
-			features &= ~NETIF_F_TSO;
-	}
-
-	if (features & NETIF_F_TSO6) {
-		if (xenbus_scanf(XBT_NIL, np->xbdev->otherend,
-				 "feature-gso-tcpv6", "%d", &val) < 0)
-			val = 0;
-
-		if (!val)
-			features &= ~NETIF_F_TSO6;
-	}
+	if (features & NETIF_F_TSO6 &&
+	    !xenbus_read_unsigned(np->xbdev->otherend, "feature-gso-tcpv6", 0))
+		features &= ~NETIF_F_TSO6;
 
 	return features;
 }
···
 	info->netdev->irq = 0;
 
 	/* Check if backend supports multiple queues */
-	err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
-			   "multi-queue-max-queues", "%u", &max_queues);
-	if (err < 0)
-		max_queues = 1;
+	max_queues = xenbus_read_unsigned(info->xbdev->otherend,
+					  "multi-queue-max-queues", 1);
 	num_queues = min(max_queues, xennet_max_queues);
 
 	/* Check feature-split-event-channels */
-	err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
-			   "feature-split-event-channels", "%u",
-			   &feature_split_evtchn);
-	if (err < 0)
-		feature_split_evtchn = 0;
+	feature_split_evtchn = xenbus_read_unsigned(info->xbdev->otherend,
+					"feature-split-event-channels", 0);
 
 	/* Read mac addr. */
 	err = xen_net_read_mac(dev, info->netdev->dev_addr);
···
 	struct netfront_info *np = netdev_priv(dev);
 	unsigned int num_queues = 0;
 	int err;
-	unsigned int feature_rx_copy;
 	unsigned int j = 0;
 	struct netfront_queue *queue = NULL;
 
-	err = xenbus_scanf(XBT_NIL, np->xbdev->otherend,
-			   "feature-rx-copy", "%u", &feature_rx_copy);
-	if (err != 1)
-		feature_rx_copy = 0;
-
-	if (!feature_rx_copy) {
+	if (!xenbus_read_unsigned(np->xbdev->otherend, "feature-rx-copy", 0)) {
 		dev_info(&dev->dev,
 			 "backend does not support copying receive path\n");
 		return -ENODEV;

drivers/pci/xen-pcifront.c

···
 			err = -ENOMEM;
 			goto out;
 		}
-		err = xenbus_scanf(XBT_NIL, pdev->xdev->otherend, str, "%d",
-				   &state);
-		if (err != 1)
-			state = XenbusStateUnknown;
+		state = xenbus_read_unsigned(pdev->xdev->otherend, str,
+					     XenbusStateUnknown);
 
 		if (state != XenbusStateClosing)
 			continue;

drivers/scsi/xen-scsifront.c

···
 struct vscsifrnt_shadow {
 	/* command between backend and frontend */
 	unsigned char act;
+	uint8_t nr_segments;
 	uint16_t rqid;
+	uint16_t ref_rqid;
 
 	unsigned int nr_grants;		/* number of grants in gref[] */
 	struct scsiif_request_segment *sg;	/* scatter/gather elements */
+	struct scsiif_request_segment seg[VSCSIIF_SG_TABLESIZE];
 
 	/* Do reset or abort function. */
 	wait_queue_head_t wq_reset;	/* reset work queue           */
···
 		scsifront_wake_up(info);
 }
 
-static struct vscsiif_request *scsifront_pre_req(struct vscsifrnt_info *info)
+static int scsifront_do_request(struct vscsifrnt_info *info,
+				struct vscsifrnt_shadow *shadow)
 {
 	struct vscsiif_front_ring *ring = &(info->ring);
 	struct vscsiif_request *ring_req;
+	struct scsi_cmnd *sc = shadow->sc;
 	uint32_t id;
+	int i, notify;
+
+	if (RING_FULL(&info->ring))
+		return -EBUSY;
 
 	id = scsifront_get_rqid(info);	/* use id in response */
 	if (id >= VSCSIIF_MAX_REQS)
-		return NULL;
+		return -EBUSY;
+
+	info->shadow[id] = shadow;
+	shadow->rqid = id;
 
 	ring_req = RING_GET_REQUEST(&(info->ring), ring->req_prod_pvt);
-
 	ring->req_prod_pvt++;
 
-	ring_req->rqid = (uint16_t)id;
+	ring_req->rqid        = id;
+	ring_req->act         = shadow->act;
+	ring_req->ref_rqid    = shadow->ref_rqid;
+	ring_req->nr_segments = shadow->nr_segments;
 
-	return ring_req;
-}
+	ring_req->id      = sc->device->id;
+	ring_req->lun     = sc->device->lun;
+	ring_req->channel = sc->device->channel;
+	ring_req->cmd_len = sc->cmd_len;
 
-static void scsifront_do_request(struct vscsifrnt_info *info)
-{
-	struct vscsiif_front_ring *ring = &(info->ring);
-	int notify;
+	BUG_ON(sc->cmd_len > VSCSIIF_MAX_COMMAND_SIZE);
+
+	memcpy(ring_req->cmnd, sc->cmnd, sc->cmd_len);
+
+	ring_req->sc_data_direction   = (uint8_t)sc->sc_data_direction;
+	ring_req->timeout_per_command = sc->request->timeout / HZ;
+
+	for (i = 0; i < (shadow->nr_segments & ~VSCSIIF_SG_GRANT); i++)
+		ring_req->seg[i] = shadow->seg[i];
 
 	RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(ring, notify);
 	if (notify)
 		notify_remote_via_irq(info->irq);
+
+	return 0;
 }
 
-static void scsifront_gnttab_done(struct vscsifrnt_info *info, uint32_t id)
+static void scsifront_gnttab_done(struct vscsifrnt_info *info,
+				  struct vscsifrnt_shadow *shadow)
 {
-	struct vscsifrnt_shadow *s = info->shadow[id];
 	int i;
 
-	if (s->sc->sc_data_direction == DMA_NONE)
+	if (shadow->sc->sc_data_direction == DMA_NONE)
 		return;
 
-	for (i = 0; i < s->nr_grants; i++) {
-		if (unlikely(gnttab_query_foreign_access(s->gref[i]) != 0)) {
+	for (i = 0; i < shadow->nr_grants; i++) {
+		if (unlikely(gnttab_query_foreign_access(shadow->gref[i]))) {
 			shost_printk(KERN_ALERT, info->host, KBUILD_MODNAME
 				     "grant still in use by backend\n");
 			BUG();
 		}
-		gnttab_end_foreign_access(s->gref[i], 0, 0UL);
+		gnttab_end_foreign_access(shadow->gref[i], 0, 0UL);
 	}
 
-	kfree(s->sg);
+	kfree(shadow->sg);
 }
 
 static void scsifront_cdb_cmd_done(struct vscsifrnt_info *info,
 				   struct vscsiif_response *ring_rsp)
 {
+	struct vscsifrnt_shadow *shadow;
 	struct scsi_cmnd *sc;
 	uint32_t id;
 	uint8_t sense_len;
 
 	id = ring_rsp->rqid;
-	sc = info->shadow[id]->sc;
+	shadow = info->shadow[id];
+	sc = shadow->sc;
 
 	BUG_ON(sc == NULL);
 
-	scsifront_gnttab_done(info, id);
+	scsifront_gnttab_done(info, shadow);
 	scsifront_put_rqid(info, id);
 
 	sc->result = ring_rsp->rslt;
···
 
 static int map_data_for_request(struct vscsifrnt_info *info,
 				struct scsi_cmnd *sc,
-				struct vscsiif_request *ring_req,
 				struct vscsifrnt_shadow *shadow)
 {
 	grant_ref_t gref_head;
···
 	struct scatterlist *sg;
 	struct scsiif_request_segment *seg;
 
-	ring_req->nr_segments = 0;
 	if (sc->sc_data_direction == DMA_NONE || !data_len)
 		return 0;
 
···
 		if (!shadow->sg)
 			return -ENOMEM;
 	}
-	seg = shadow->sg ? : ring_req->seg;
+	seg = shadow->sg ? : shadow->seg;
 
 	err = gnttab_alloc_grant_references(seg_grants + data_grants,
 					    &gref_head);
···
 				info->dev->otherend_id,
 				xen_page_to_gfn(page), 1);
 			shadow->gref[ref_cnt] = ref;
-			ring_req->seg[ref_cnt].gref   = ref;
-			ring_req->seg[ref_cnt].offset = (uint16_t)off;
-			ring_req->seg[ref_cnt].length = (uint16_t)bytes;
+			shadow->seg[ref_cnt].gref   = ref;
+			shadow->seg[ref_cnt].offset = (uint16_t)off;
+			shadow->seg[ref_cnt].length = (uint16_t)bytes;
 
 			page++;
 			len -= bytes;
···
 	}
 
 	if (seg_grants)
-		ring_req->nr_segments = VSCSIIF_SG_GRANT | seg_grants;
+		shadow->nr_segments = VSCSIIF_SG_GRANT | seg_grants;
 	else
-		ring_req->nr_segments = (uint8_t)ref_cnt;
+		shadow->nr_segments = (uint8_t)ref_cnt;
 	shadow->nr_grants = ref_cnt;
 
 	return 0;
-}
-
-static struct vscsiif_request *scsifront_command2ring(
-		struct vscsifrnt_info *info, struct scsi_cmnd *sc,
-		struct vscsifrnt_shadow *shadow)
-{
-	struct vscsiif_request *ring_req;
-
-	memset(shadow, 0, sizeof(*shadow));
-
-	ring_req = scsifront_pre_req(info);
-	if (!ring_req)
-		return NULL;
-
-	info->shadow[ring_req->rqid] = shadow;
-	shadow->rqid = ring_req->rqid;
-
-	ring_req->id      = sc->device->id;
-	ring_req->lun     = sc->device->lun;
-	ring_req->channel = sc->device->channel;
-	ring_req->cmd_len = sc->cmd_len;
-
-	BUG_ON(sc->cmd_len > VSCSIIF_MAX_COMMAND_SIZE);
-
-	memcpy(ring_req->cmnd, sc->cmnd, sc->cmd_len);
-
-	ring_req->sc_data_direction   = (uint8_t)sc->sc_data_direction;
-	ring_req->timeout_per_command = sc->request->timeout / HZ;
-
-	return ring_req;
 }
 
 static int scsifront_enter(struct vscsifrnt_info *info)
···
 				  struct scsi_cmnd *sc)
 {
 	struct vscsifrnt_info *info = shost_priv(shost);
-	struct vscsiif_request *ring_req;
 	struct vscsifrnt_shadow *shadow = scsi_cmd_priv(sc);
 	unsigned long flags;
 	int err;
-	uint16_t rqid;
+
+	sc->result = 0;
+	memset(shadow, 0, sizeof(*shadow));
+
+	shadow->sc  = sc;
+	shadow->act = VSCSIIF_ACT_SCSI_CDB;
 
 	spin_lock_irqsave(shost->host_lock, flags);
 	if (scsifront_enter(info)) {
 		spin_unlock_irqrestore(shost->host_lock, flags);
 		return SCSI_MLQUEUE_HOST_BUSY;
 	}
-	if (RING_FULL(&info->ring))
-		goto busy;
 
-	ring_req = scsifront_command2ring(info, sc, shadow);
-	if (!ring_req)
-		goto busy;
-
-	sc->result = 0;
-
-	rqid = ring_req->rqid;
-	ring_req->act = VSCSIIF_ACT_SCSI_CDB;
-
-	shadow->sc  = sc;
-	shadow->act = VSCSIIF_ACT_SCSI_CDB;
-
-	err = map_data_for_request(info, sc, ring_req, shadow);
+	err = map_data_for_request(info, sc, shadow);
 	if (err < 0) {
 		pr_debug("%s: err %d\n", __func__, err);
-		scsifront_put_rqid(info, rqid);
 		scsifront_return(info);
 		spin_unlock_irqrestore(shost->host_lock, flags);
 		if (err == -ENOMEM)
···
 		return 0;
 	}
 
-	scsifront_do_request(info);
+	if (scsifront_do_request(info, shadow)) {
+		scsifront_gnttab_done(info, shadow);
+		goto busy;
+	}
+
 	scsifront_return(info);
 	spin_unlock_irqrestore(shost->host_lock, flags);
 
···
 	struct Scsi_Host *host = sc->device->host;
 	struct vscsifrnt_info *info = shost_priv(host);
 	struct vscsifrnt_shadow *shadow, *s = scsi_cmd_priv(sc);
-	struct vscsiif_request *ring_req;
 	int err = 0;
 
-	shadow = kmalloc(sizeof(*shadow), GFP_NOIO);
+	shadow = kzalloc(sizeof(*shadow), GFP_NOIO);
 	if (!shadow)
 		return FAILED;
+
+	shadow->act = act;
+	shadow->rslt_reset = RSLT_RESET_WAITING;
+	shadow->sc = sc;
+	shadow->ref_rqid = s->rqid;
+	init_waitqueue_head(&shadow->wq_reset);
 
 	spin_lock_irq(host->host_lock);
 
 	for (;;) {
-		if (!RING_FULL(&info->ring)) {
-			ring_req = scsifront_command2ring(info, sc, shadow);
-			if (ring_req)
-				break;
-		}
-		if (err || info->pause) {
-			spin_unlock_irq(host->host_lock);
-			kfree(shadow);
-			return FAILED;
-		}
+		if (scsifront_enter(info))
+			goto fail;
+
+		if (!scsifront_do_request(info, shadow))
+			break;
+
+		scsifront_return(info);
+		if (err)
+			goto fail;
 		info->wait_ring_available = 1;
 		spin_unlock_irq(host->host_lock);
 		err = wait_event_interruptible(info->wq_sync,
 					       !info->wait_ring_available);
 		spin_lock_irq(host->host_lock);
 	}
-
-	if (scsifront_enter(info)) {
-		spin_unlock_irq(host->host_lock);
-		return FAILED;
-	}
-
-	ring_req->act = act;
-	ring_req->ref_rqid = s->rqid;
-
-	shadow->act = act;
-	shadow->rslt_reset = RSLT_RESET_WAITING;
-	init_waitqueue_head(&shadow->wq_reset);
-
-	ring_req->nr_segments = 0;
-
-	scsifront_do_request(info);
 
 	spin_unlock_irq(host->host_lock);
 	err = wait_event_interruptible(shadow->wq_reset, shadow->wait_reset);
···
 	scsifront_return(info);
 	spin_unlock_irq(host->host_lock);
 	return err;
+
+fail:
+	spin_unlock_irq(host->host_lock);
+	kfree(shadow);
+	return FAILED;
 }
 
 static int scsifront_eh_abort_handler(struct scsi_cmnd *sc)
···
 					  struct vscsifrnt_info *info)
 {
 	unsigned int sg_grant, nr_segs;
-	int ret;
 	struct Scsi_Host *host = info->host;
 
-	ret = xenbus_scanf(XBT_NIL, dev->otherend, "feature-sg-grant", "%u",
-			   &sg_grant);
-	if (ret != 1)
-		sg_grant = 0;
+	sg_grant = xenbus_read_unsigned(dev->otherend, "feature-sg-grant", 0);
 	nr_segs = min_t(unsigned int, sg_grant, SG_ALL);
 	nr_segs = max_t(unsigned int, nr_segs, VSCSIIF_SG_TABLESIZE);
 	nr_segs = min_t(unsigned int, nr_segs,

drivers/video/fbdev/xen-fbfront.c

···
 				  enum xenbus_state backend_state)
 {
 	struct xenfb_info *info = dev_get_drvdata(&dev->dev);
-	int val;
 
 	switch (backend_state) {
 	case XenbusStateInitialising:
···
 		if (dev->state != XenbusStateConnected)
 			goto InitWait; /* no InitWait seen yet, fudge it */
 
-		if (xenbus_scanf(XBT_NIL, info->xbdev->otherend,
-				 "request-update", "%d", &val) < 0)
-			val = 0;
-		if (val)
+		if (xenbus_read_unsigned(info->xbdev->otherend,
+					 "request-update", 0))
 			info->update_wanted = 1;
 
-		if (xenbus_scanf(XBT_NIL, dev->otherend,
-				 "feature-resize", "%d", &val) < 0)
-			val = 0;
-		info->feature_resize = val;
+		info->feature_resize = xenbus_read_unsigned(dev->otherend,
+							"feature-resize", 0);
 		break;
 
 	case XenbusStateClosed:

drivers/xen/balloon.c

···
 static void balloon_append(struct page *page)
 {
 	__balloon_append(page);
-	adjust_managed_page_count(page, -1);
 }
 
 /* balloon_retrieve: rescue a page from the balloon, if it is not empty. */
···
 		balloon_stats.balloon_high--;
 	else
 		balloon_stats.balloon_low--;
-
-	adjust_managed_page_count(page, 1);
 
 	return page;
 }
···
 #endif
 
 		/* Relinquish the page back to the allocator. */
-		__free_reserved_page(page);
+		free_reserved_page(page);
 	}
 
 	balloon_stats.current_pages += rc;
···
 			state = BP_EAGAIN;
 			break;
 		}
+		adjust_managed_page_count(page, -1);
 		scrub_page(page);
 		list_add(&page->lru, &pages);
 	}

drivers/xen/events/events_base.c

···
 			continue;
 		if (status.status != EVTCHNSTAT_virq)
 			continue;
-		if (status.u.virq == virq && status.vcpu == cpu) {
+		if (status.u.virq == virq && status.vcpu == xen_vcpu_nr(cpu)) {
 			rc = port;
 			break;
 		}

drivers/xen/gntalloc.c

···
 	struct gntalloc_gref *gref, *next;
 
 	readonly = !(op->flags & GNTALLOC_FLAG_WRITABLE);
-	rc = -ENOMEM;
 	for (i = 0; i < op->count; i++) {
 		gref = kzalloc(sizeof(*gref), GFP_KERNEL);
-		if (!gref)
+		if (!gref) {
+			rc = -ENOMEM;
 			goto undo;
+		}
 		list_add_tail(&gref->next_gref, &queue_gref);
 		list_add_tail(&gref->next_file, &queue_file);
 		gref->users = 1;
 		gref->file_index = op->index + i * PAGE_SIZE;
 		gref->page = alloc_page(GFP_KERNEL|__GFP_ZERO);
-		if (!gref->page)
+		if (!gref->page) {
+			rc = -ENOMEM;
 			goto undo;
+		}
 
 		/* Grant foreign access to the page. */
 		rc = gnttab_grant_foreign_access(op->domid,

drivers/xen/gntdev.c

···
 
 	vma->vm_ops = &gntdev_vmops;
 
-	vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP | VM_IO;
+	vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP | VM_MIXEDMAP;
 
 	if (use_ptemod)
 		vma->vm_flags |= VM_DONTCOPY;

drivers/xen/platform-pci.c

···
 	.id_table =       platform_pci_tbl,
 };
 
-static int __init platform_pci_init(void)
-{
-	return pci_register_driver(&platform_driver);
-}
-device_initcall(platform_pci_init);
+builtin_pci_driver(platform_driver);

drivers/xen/xen-pciback/xenbus.c

···
 	int err = 0;
 	int num_devs;
 	int domain, bus, slot, func;
-	int substate;
+	unsigned int substate;
 	int i, len;
 	char state_str[64];
 	char dev_str[64];
···
 					 "configuration");
 			goto out;
 		}
-		err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename, state_str,
-				   "%d", &substate);
-		if (err != 1)
-			substate = XenbusStateUnknown;
+		substate = xenbus_read_unsigned(pdev->xdev->nodename, state_str,
+						XenbusStateUnknown);
 
 		switch (substate) {
 		case XenbusStateInitialising:

drivers/xen/xenbus/xenbus_dev_frontend.c

···
 
 	nonseekable_open(inode, filp);
 
+	filp->f_mode &= ~FMODE_ATOMIC_POS; /* cdev-style semantics */
+
 	u = kzalloc(sizeof(*u), GFP_KERNEL);
 	if (u == NULL)
 		return -ENOMEM;

drivers/xen/xenbus/xenbus_probe.c

···
  */
 static int __init xenstored_local_init(void)
 {
-	int err = 0;
+	int err = -ENOMEM;
 	unsigned long page = 0;
 	struct evtchn_alloc_unbound alloc_unbound;
 
···
 	 * Create xenfs mountpoint in /proc for compatibility with
 	 * utilities that expect to find "xenbus" under "/proc/xen".
 	 */
-	proc_mkdir("xen", NULL);
+	proc_create_mount_point("xen");
 #endif
 
 out_error:

drivers/xen/xenbus/xenbus_probe_backend.c

···
 
 int xenbus_dev_is_online(struct xenbus_device *dev)
 {
-	int rc, val;
-
-	rc = xenbus_scanf(XBT_NIL, dev->nodename, "online", "%d", &val);
-	if (rc != 1)
-		val = 0; /* no online node present */
-
-	return val;
+	return !!xenbus_read_unsigned(dev->nodename, "online", 0);
 }
 EXPORT_SYMBOL_GPL(xenbus_dev_is_online);
 

drivers/xen/xenbus/xenbus_xs.c

···
 }
 EXPORT_SYMBOL_GPL(xenbus_scanf);
 
+/* Read an (optional) unsigned value. */
+unsigned int xenbus_read_unsigned(const char *dir, const char *node,
+				  unsigned int default_val)
+{
+	unsigned int val;
+	int ret;
+
+	ret = xenbus_scanf(XBT_NIL, dir, node, "%u", &val);
+	if (ret <= 0)
+		val = default_val;
+
+	return val;
+}
+EXPORT_SYMBOL_GPL(xenbus_read_unsigned);
+
 /* Single printf and write: returns -errno or 0. */
 int xenbus_printf(struct xenbus_transaction t,
 		  const char *dir, const char *node, const char *fmt, ...)
···
 }
 static void xs_reset_watches(void)
 {
-	int err, supported = 0;
+	int err;
 
 	if (!xen_hvm_domain() || xen_initial_domain())
 		return;
···
 	if (xen_strict_xenbus_quirk())
 		return;
 
-	err = xenbus_scanf(XBT_NIL, "control",
-			"platform-feature-xs_reset_watches", "%d", &supported);
-	if (err != 1 || !supported)
+	if (!xenbus_read_unsigned("control",
+				  "platform-feature-xs_reset_watches", 0))
 		return;
 
 	err = xs_error(xs_single(XBT_NIL, XS_RESET_WATCHES, "", NULL));

fs/proc/generic.c

···
 	}
 	return ent;
 }
+EXPORT_SYMBOL(proc_create_mount_point);
 
 struct proc_dir_entry *proc_create_data(const char *name, umode_t mode,
 					struct proc_dir_entry *parent,

fs/proc/internal.h

···
 {
 	return S_ISDIR(pde->mode) && !pde->proc_iops;
 }
-struct proc_dir_entry *proc_create_mount_point(const char *name);
 
 /*
  * inode.c

include/linux/proc_fs.h

···
 					      struct proc_dir_entry *, void *);
 extern struct proc_dir_entry *proc_mkdir_mode(const char *, umode_t,
 					      struct proc_dir_entry *);
+struct proc_dir_entry *proc_create_mount_point(const char *name);
  
 extern struct proc_dir_entry *proc_create_data(const char *, umode_t,
 					       struct proc_dir_entry *,
···
 		struct proc_dir_entry *parent,const char *dest) { return NULL;}
 static inline struct proc_dir_entry *proc_mkdir(const char *name,
 	struct proc_dir_entry *parent) {return NULL;}
+static inline struct proc_dir_entry *proc_create_mount_point(const char *name) { return NULL; }
 static inline struct proc_dir_entry *proc_mkdir_data(const char *name,
 	umode_t mode, struct proc_dir_entry *parent, void *data) { return NULL; }
 static inline struct proc_dir_entry *proc_mkdir_mode(const char *name,

include/xen/arm/hypercall.h

···
+/******************************************************************************
+ * hypercall.h
+ *
+ * Linux-specific hypervisor handling.
+ *
+ * Stefano Stabellini <[e-mail]>, Citrix, 2012
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation; or, when distributed
+ * separately from the Linux kernel or incorporated into other
+ * software packages, subject to the following license:
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this source file (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy, modify,
+ * merge, publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#ifndef _ASM_ARM_XEN_HYPERCALL_H
+#define _ASM_ARM_XEN_HYPERCALL_H
+
+#include <linux/bug.h>
+
+#include <xen/interface/xen.h>
+#include <xen/interface/sched.h>
+#include <xen/interface/platform.h>
+
+long privcmd_call(unsigned call, unsigned long a1,
+		unsigned long a2, unsigned long a3,
+		unsigned long a4, unsigned long a5);
+int HYPERVISOR_xen_version(int cmd, void *arg);
+int HYPERVISOR_console_io(int cmd, int count, char *str);
+int HYPERVISOR_grant_table_op(unsigned int cmd, void *uop, unsigned int count);
+int HYPERVISOR_sched_op(int cmd, void *arg);
+int HYPERVISOR_event_channel_op(int cmd, void *arg);
+unsigned long HYPERVISOR_hvm_op(int op, void *arg);
+int HYPERVISOR_memory_op(unsigned int cmd, void *arg);
+int HYPERVISOR_physdev_op(int cmd, void *arg);
+int HYPERVISOR_vcpu_op(int cmd, int vcpuid, void *extra_args);
+int HYPERVISOR_tmem_op(void *arg);
+int HYPERVISOR_vm_assist(unsigned int cmd, unsigned int type);
+int HYPERVISOR_platform_op_raw(void *arg);
+static inline int HYPERVISOR_platform_op(struct xen_platform_op *op)
+{
+	op->interface_version = XENPF_INTERFACE_VERSION;
+	return HYPERVISOR_platform_op_raw(op);
+}
+int HYPERVISOR_multicall(struct multicall_entry *calls, uint32_t nr);
+
+static inline int
+HYPERVISOR_suspend(unsigned long start_info_mfn)
+{
+	struct sched_shutdown r = { .reason = SHUTDOWN_suspend };
+
+	/* start_info_mfn is unused on ARM */
+	return HYPERVISOR_sched_op(SCHEDOP_shutdown, &r);
+}
+
+static inline void
+MULTI_update_va_mapping(struct multicall_entry *mcl, unsigned long va,
+			unsigned int new_val, unsigned long flags)
+{
+	BUG();
+}
+
+static inline void
+MULTI_mmu_update(struct multicall_entry *mcl, struct mmu_update *req,
+		 int count, int *success_count, domid_t domid)
+{
+	BUG();
+}
+
+#endif /* _ASM_ARM_XEN_HYPERCALL_H */

include/xen/arm/hypervisor.h

···
+#ifndef _ASM_ARM_XEN_HYPERVISOR_H
+#define _ASM_ARM_XEN_HYPERVISOR_H
+
+#include <linux/init.h>
+
+extern struct shared_info *HYPERVISOR_shared_info;
+extern struct start_info *xen_start_info;
+
+/* Lazy mode for batching updates / context switch */
+enum paravirt_lazy_mode {
+	PARAVIRT_LAZY_NONE,
+	PARAVIRT_LAZY_MMU,
+	PARAVIRT_LAZY_CPU,
+};
+
+static inline enum paravirt_lazy_mode paravirt_get_lazy_mode(void)
+{
+	return PARAVIRT_LAZY_NONE;
+}
+
+extern struct dma_map_ops *xen_dma_ops;
+
+#ifdef CONFIG_XEN
+void __init xen_early_init(void);
+#else
+static inline void xen_early_init(void) { return; }
+#endif
+
+#ifdef CONFIG_HOTPLUG_CPU
+static inline void xen_arch_register_cpu(int num)
+{
+}
+
+static inline void xen_arch_unregister_cpu(int num)
+{
+}
+#endif
+
+#endif /* _ASM_ARM_XEN_HYPERVISOR_H */

include/xen/arm/interface.h

···
+/******************************************************************************
+ * Guest OS interface to ARM Xen.
+ *
+ * Stefano Stabellini <[e-mail]>, Citrix, 2012
+ */
+
+#ifndef _ASM_ARM_XEN_INTERFACE_H
+#define _ASM_ARM_XEN_INTERFACE_H
+
+#include <linux/types.h>
+
+#define uint64_aligned_t uint64_t __attribute__((aligned(8)))
+
+#define __DEFINE_GUEST_HANDLE(name, type) \
+	typedef struct { union { type *p; uint64_aligned_t q; }; }  \
+        __guest_handle_ ## name
+
+#define DEFINE_GUEST_HANDLE_STRUCT(name) \
+	__DEFINE_GUEST_HANDLE(name, struct name)
+#define DEFINE_GUEST_HANDLE(name) __DEFINE_GUEST_HANDLE(name, name)
+#define GUEST_HANDLE(name)        __guest_handle_ ## name
+
+#define set_xen_guest_handle(hnd, val)			\
+	do {						\
+		if (sizeof(hnd) == 8)			\
+			*(uint64_t *)&(hnd) = 0;	\
+		(hnd).p = val;				\
+	} while (0)
+
+#define __HYPERVISOR_platform_op_raw __HYPERVISOR_platform_op
+
+#ifndef __ASSEMBLY__
+/* Explicitly size integers that represent pfns in the interface with
+ * Xen so that we can have one ABI that works for 32 and 64 bit guests.
+ * Note that this means that the xen_pfn_t type may be capable of
+ * representing pfn's which the guest cannot represent in its own pfn
+ * type. However since pfn space is controlled by the guest this is
+ * fine since it simply wouldn't be able to create any sure pfns in
+ * the first place.
+ */
+typedef uint64_t xen_pfn_t;
+#define PRI_xen_pfn "llx"
+typedef uint64_t xen_ulong_t;
+#define PRI_xen_ulong "llx"
+typedef int64_t xen_long_t;
+#define PRI_xen_long "llx"
+/* Guest handles for primitive C types. */
+__DEFINE_GUEST_HANDLE(uchar, unsigned char);
+__DEFINE_GUEST_HANDLE(uint,  unsigned int);
+DEFINE_GUEST_HANDLE(char);
+DEFINE_GUEST_HANDLE(int);
+DEFINE_GUEST_HANDLE(void);
+DEFINE_GUEST_HANDLE(uint64_t);
+DEFINE_GUEST_HANDLE(uint32_t);
+DEFINE_GUEST_HANDLE(xen_pfn_t);
+DEFINE_GUEST_HANDLE(xen_ulong_t);
+
+/* Maximum number of virtual CPUs in multi-processor guests. */
+#define MAX_VIRT_CPUS 1
+
+struct arch_vcpu_info { };
+struct arch_shared_info { };
+
+/* TODO: Move pvclock definitions some place arch independent */
+struct pvclock_vcpu_time_info {
+	u32   version;
+	u32   pad0;
+	u64   tsc_timestamp;
+	u64   system_time;
+	u32   tsc_to_system_mul;
+	s8    tsc_shift;
+	u8    flags;
+	u8    pad[2];
+} __attribute__((__packed__)); /* 32 bytes */
+
+/* It is OK to have a 12 bytes struct with no padding because it is packed */
+struct pvclock_wall_clock {
+	u32   version;
+	u32   sec;
+	u32   nsec;
+	u32   sec_hi;
+} __attribute__((__packed__));
+#endif
+
+#endif /* _ASM_ARM_XEN_INTERFACE_H */

include/xen/arm/page-coherent.h

···
+#ifndef _ASM_ARM_XEN_PAGE_COHERENT_H
+#define _ASM_ARM_XEN_PAGE_COHERENT_H
+
+#include <asm/page.h>
+#include <linux/dma-mapping.h>
+
+void __xen_dma_map_page(struct device *hwdev, struct page *page,
+	     dma_addr_t dev_addr, unsigned long offset, size_t size,
+	     enum dma_data_direction dir, unsigned long attrs);
+void __xen_dma_unmap_page(struct device *hwdev, dma_addr_t handle,
+		size_t size, enum dma_data_direction dir,
+		unsigned long attrs);
+void __xen_dma_sync_single_for_cpu(struct device *hwdev,
+		dma_addr_t handle, size_t size, enum dma_data_direction dir);
+
+void __xen_dma_sync_single_for_device(struct device *hwdev,
+		dma_addr_t handle, size_t size, enum dma_data_direction dir);
+
+static inline void *xen_alloc_coherent_pages(struct device *hwdev, size_t size,
+		dma_addr_t *dma_handle, gfp_t flags, unsigned long attrs)
+{
+	return __generic_dma_ops(hwdev)->alloc(hwdev, size, dma_handle, flags, attrs);
+}
+
+static inline void xen_free_coherent_pages(struct device *hwdev, size_t size,
+		void *cpu_addr, dma_addr_t dma_handle, unsigned long attrs)
+{
+	__generic_dma_ops(hwdev)->free(hwdev, size, cpu_addr, dma_handle, attrs);
+}
+
+static inline void xen_dma_map_page(struct device *hwdev, struct page *page,
+	     dma_addr_t dev_addr, unsigned long offset, size_t size,
+	     enum dma_data_direction dir, unsigned long attrs)
+{
+	unsigned long page_pfn = page_to_xen_pfn(page);
+	unsigned long dev_pfn = XEN_PFN_DOWN(dev_addr);
+	unsigned long compound_pages =
+		(1<<compound_order(page)) * XEN_PFN_PER_PAGE;
+	bool local = (page_pfn <= dev_pfn) &&
+		(dev_pfn - page_pfn < compound_pages);
+
+	/*
+	 * Dom0 is mapped 1:1, while the Linux page can span across
+	 * multiple Xen pages, it's not possible for it to contain a
+	 * mix of local and foreign Xen pages. So if the first xen_pfn
+	 * == mfn the page is local otherwise it's a foreign page
+	 * grant-mapped in dom0. If the page is local we can safely
+	 * call the native dma_ops function, otherwise we call the xen
+	 * specific function.
+	 */
+	if (local)
+		__generic_dma_ops(hwdev)->map_page(hwdev, page, offset, size, dir, attrs);
+	else
+		__xen_dma_map_page(hwdev, page, dev_addr, offset, size, dir, attrs);
+}
+
+static inline void xen_dma_unmap_page(struct device *hwdev, dma_addr_t handle,
+		size_t size, enum dma_data_direction dir, unsigned long attrs)
+{
+	unsigned long pfn = PFN_DOWN(handle);
+	/*
+	 * Dom0 is mapped 1:1, while the Linux page can be spanned accross
+	 * multiple Xen page, it's not possible to have a mix of local and
+	 * foreign Xen page. Dom0 is mapped 1:1, so calling pfn_valid on a
+	 * foreign mfn will always return false. If the page is local we can
+	 * safely call the native dma_ops function, otherwise we call the xen
+	 * specific function.
+	 */
+	if (pfn_valid(pfn)) {
+		if (__generic_dma_ops(hwdev)->unmap_page)
+			__generic_dma_ops(hwdev)->unmap_page(hwdev, handle, size, dir, attrs);
+	} else
+		__xen_dma_unmap_page(hwdev, handle, size, dir, attrs);
+}
+
+static inline void xen_dma_sync_single_for_cpu(struct device *hwdev,
+		dma_addr_t handle, size_t size, enum dma_data_direction dir)
+{
+	unsigned long pfn = PFN_DOWN(handle);
+	if (pfn_valid(pfn)) {
+		if (__generic_dma_ops(hwdev)->sync_single_for_cpu)
+			__generic_dma_ops(hwdev)->sync_single_for_cpu(hwdev, handle, size, dir);
+	} else
+		__xen_dma_sync_single_for_cpu(hwdev, handle, size, dir);
+}
+
+static inline void xen_dma_sync_single_for_device(struct device *hwdev,
+		dma_addr_t handle, size_t size, enum dma_data_direction dir)
+{
+	unsigned long pfn = PFN_DOWN(handle);
+	if (pfn_valid(pfn)) {
+		if (__generic_dma_ops(hwdev)->sync_single_for_device)
+			__generic_dma_ops(hwdev)->sync_single_for_device(hwdev, handle, size, dir);
+	} else
+		__xen_dma_sync_single_for_device(hwdev, handle, size, dir);
+}
+
+#endif /* _ASM_ARM_XEN_PAGE_COHERENT_H */

include/xen/arm/page.h

···
+#ifndef _ASM_ARM_XEN_PAGE_H
+#define _ASM_ARM_XEN_PAGE_H
+
+#include <asm/page.h>
+#include <asm/pgtable.h>
+
+#include <linux/pfn.h>
+#include <linux/types.h>
+#include <linux/dma-mapping.h>
+
+#include <xen/xen.h>
+#include <xen/interface/grant_table.h>
+
+#define phys_to_machine_mapping_valid(pfn) (1)
+
+/* Xen machine address */
+typedef struct xmaddr {
+	phys_addr_t maddr;
+} xmaddr_t;
+
+/* Xen pseudo-physical address */
+typedef struct xpaddr {
+	phys_addr_t paddr;
+} xpaddr_t;
+
+#define XMADDR(x)	((xmaddr_t) { .maddr = (x) })
+#define XPADDR(x)	((xpaddr_t) { .paddr = (x) })
+
+#define INVALID_P2M_ENTRY      (~0UL)
+
+/*
+ * The pseudo-physical frame (pfn) used in all the helpers is always based
+ * on Xen page granularity (i.e 4KB).
+ *
+ * A Linux page may be split across multiple non-contiguous Xen page so we
+ * have to keep track with frame based on 4KB page granularity.
+ *
+ * PV drivers should never make a direct usage of those helpers (particularly
+ * pfn_to_gfn and gfn_to_pfn).
+ */
+
+unsigned long __pfn_to_mfn(unsigned long pfn);
+extern struct rb_root phys_to_mach;
+
+/* Pseudo-physical <-> Guest conversion */
+static inline unsigned long pfn_to_gfn(unsigned long pfn)
+{
+	return pfn;
+}
+
+static inline unsigned long gfn_to_pfn(unsigned long gfn)
+{
+	return gfn;
+}
+
+/* Pseudo-physical <-> BUS conversion */
+static inline unsigned long pfn_to_bfn(unsigned long pfn)
+{
+	unsigned long mfn;
+
+	if (phys_to_mach.rb_node != NULL) {
+		mfn = __pfn_to_mfn(pfn);
+		if (mfn != INVALID_P2M_ENTRY)
+			return mfn;
+	}
+
+	return pfn;
+}
+
+static inline unsigned long bfn_to_pfn(unsigned long bfn)
+{
+	return bfn;
+}
+
+#define bfn_to_local_pfn(bfn)	bfn_to_pfn(bfn)
+
+/* VIRT <-> GUEST conversion */
+#define virt_to_gfn(v)		(pfn_to_gfn(virt_to_phys(v) >> XEN_PAGE_SHIFT))
+#define gfn_to_virt(m)		(__va(gfn_to_pfn(m) << XEN_PAGE_SHIFT))
+
+/* Only used in PV code. But ARM guests are always HVM. */
+static inline xmaddr_t arbitrary_virt_to_machine(void *vaddr)
+{
+	BUG();
+}
+
+/* TODO: this shouldn't be here but it is because the frontend drivers
+ * are using it (its rolled in headers) even though we won't hit the code path.
+ * So for right now just punt with this.
+ */
+static inline pte_t *lookup_address(unsigned long address, unsigned int *level)
+{
+	BUG();
+	return NULL;
+}
+
+extern int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops,
+				   struct gnttab_map_grant_ref *kmap_ops,
+				   struct page **pages, unsigned int count);
+
+extern int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops,
+				     struct gnttab_unmap_grant_ref *kunmap_ops,
+				     struct page **pages, unsigned int count);
+
+bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn);
+bool __set_phys_to_machine_multi(unsigned long pfn, unsigned long mfn,
+		unsigned long nr_pages);
+
+static inline bool set_phys_to_machine(unsigned long pfn, unsigned long mfn)
+{
+	return __set_phys_to_machine(pfn, mfn);
+}
+
+#define xen_remap(cookie, size) ioremap_cache((cookie), (size))
+#define xen_unmap(cookie) iounmap((cookie))
+
+bool xen_arch_need_swiotlb(struct device *dev,
+			   phys_addr_t phys,
+			   dma_addr_t dev_addr);
+unsigned long xen_get_swiotlb_free_pages(unsigned int order);
+
+#endif /* _ASM_ARM_XEN_PAGE_H */

include/xen/xenbus.h

···
 int xenbus_scanf(struct xenbus_transaction t,
 		 const char *dir, const char *node, const char *fmt, ...);
 
+/* Read an (optional) unsigned value. */
+unsigned int xenbus_read_unsigned(const char *dir, const char *node,
+				  unsigned int default_val);
+
 /* Single printf and write: returns -errno or 0. */
 __printf(4, 5)
 int xenbus_printf(struct xenbus_transaction t,