diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 478a2de543a5..67433714b791 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -1113,7 +1113,7 @@ static void __init xen_cleanhighmap(unsigned long vaddr,
 
 	/* NOTE: The loop is more greedy than the cleanup_highmap variant.
 	 * We include the PMD passed in on _both_ boundaries. */
-	for (; vaddr <= vaddr_end && (pmd < (level2_kernel_pgt + PAGE_SIZE));
+	for (; vaddr <= vaddr_end && (pmd < (level2_kernel_pgt + PTRS_PER_PMD));
 			pmd++, vaddr += PMD_SIZE) {
 		if (pmd_none(*pmd))
 			continue;
@@ -1551,41 +1551,6 @@ static void xen_pgd_free(struct mm_struct *mm, pgd_t *pgd)
 #endif
 }
 
-#ifdef CONFIG_X86_32
-static pte_t __init mask_rw_pte(pte_t *ptep, pte_t pte)
-{
-	/* If there's an existing pte, then don't allow _PAGE_RW to be set */
-	if (pte_val_ma(*ptep) & _PAGE_PRESENT)
-		pte = __pte_ma(((pte_val_ma(*ptep) & _PAGE_RW) | ~_PAGE_RW) &
-			       pte_val_ma(pte));
-
-	return pte;
-}
-#else /* CONFIG_X86_64 */
-static pte_t __init mask_rw_pte(pte_t *ptep, pte_t pte)
-{
-	unsigned long pfn;
-
-	if (xen_feature(XENFEAT_writable_page_tables) ||
-	    xen_feature(XENFEAT_auto_translated_physmap) ||
-	    xen_start_info->mfn_list >= __START_KERNEL_map)
-		return pte;
-
-	/*
-	 * Pages belonging to the initial p2m list mapped outside the default
-	 * address range must be mapped read-only. This region contains the
-	 * page tables for mapping the p2m list, too, and page tables MUST be
-	 * mapped read-only.
-	 */
-	pfn = pte_pfn(pte);
-	if (pfn >= xen_start_info->first_p2m_pfn &&
-	    pfn < xen_start_info->first_p2m_pfn + xen_start_info->nr_p2m_frames)
-		pte = __pte_ma(pte_val_ma(pte) & ~_PAGE_RW);
-
-	return pte;
-}
-#endif /* CONFIG_X86_64 */
-
 /*
  * Init-time set_pte while constructing initial pagetables, which
  * doesn't allow RO page table pages to be remapped RW.
@@ -1600,13 +1565,37 @@ static pte_t __init mask_rw_pte(pte_t *ptep, pte_t pte)
  * so always write the PTE directly and rely on Xen trapping and
  * emulating any updates as necessary.
  */
+__visible pte_t xen_make_pte_init(pteval_t pte)
+{
+#ifdef CONFIG_X86_64
+	unsigned long pfn;
+
+	/*
+	 * Pages belonging to the initial p2m list mapped outside the default
+	 * address range must be mapped read-only. This region contains the
+	 * page tables for mapping the p2m list, too, and page tables MUST be
+	 * mapped read-only.
+	 */
+	pfn = (pte & PTE_PFN_MASK) >> PAGE_SHIFT;
+	if (xen_start_info->mfn_list < __START_KERNEL_map &&
+	    pfn >= xen_start_info->first_p2m_pfn &&
+	    pfn < xen_start_info->first_p2m_pfn + xen_start_info->nr_p2m_frames)
+		pte &= ~_PAGE_RW;
+#endif
+	pte = pte_pfn_to_mfn(pte);
+	return native_make_pte(pte);
+}
+PV_CALLEE_SAVE_REGS_THUNK(xen_make_pte_init);
+
 static void __init xen_set_pte_init(pte_t *ptep, pte_t pte)
 {
-	if (pte_mfn(pte) != INVALID_P2M_ENTRY)
-		pte = mask_rw_pte(ptep, pte);
-	else
-		pte = __pte_ma(0);
-
+#ifdef CONFIG_X86_32
+	/* If there's an existing pte, then don't allow _PAGE_RW to be set */
+	if (pte_mfn(pte) != INVALID_P2M_ENTRY
+	    && pte_val_ma(*ptep) & _PAGE_PRESENT)
+		pte = __pte_ma(((pte_val_ma(*ptep) & _PAGE_RW) | ~_PAGE_RW) &
+			       pte_val_ma(pte));
+#endif
 	native_set_pte(ptep, pte);
 }
 
@@ -2407,6 +2396,7 @@ static void __init xen_post_allocator_init(void)
 	pv_mmu_ops.alloc_pud = xen_alloc_pud;
 	pv_mmu_ops.release_pud = xen_release_pud;
 #endif
+	pv_mmu_ops.make_pte = PV_CALLEE_SAVE(xen_make_pte);
 
 #ifdef CONFIG_X86_64
 	pv_mmu_ops.write_cr3 = &xen_write_cr3;
@@ -2455,7 +2445,7 @@ static const struct pv_mmu_ops xen_mmu_ops __initconst = {
 	.pte_val = PV_CALLEE_SAVE(xen_pte_val),
 	.pgd_val = PV_CALLEE_SAVE(xen_pgd_val),
 
-	.make_pte = PV_CALLEE_SAVE(xen_make_pte),
+	.make_pte = PV_CALLEE_SAVE(xen_make_pte_init),
 	.make_pgd = PV_CALLEE_SAVE(xen_make_pgd),
 
 #ifdef CONFIG_X86_PAE
diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index d46839f51e73..e4db19e88ab1 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -151,8 +151,6 @@ static DECLARE_WAIT_QUEUE_HEAD(balloon_wq);
 static void balloon_process(struct work_struct *work);
 static DECLARE_DELAYED_WORK(balloon_worker, balloon_process);
 
-static void release_memory_resource(struct resource *resource);
-
 /* When ballooning out (allocating memory to return to Xen) we don't really
    want the kernel to try too hard since that can trigger the oom killer. */
 #define GFP_BALLOON \
@@ -248,6 +246,19 @@ static enum bp_state update_schedule(enum bp_state state)
 }
 
 #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
+static void release_memory_resource(struct resource *resource)
+{
+	if (!resource)
+		return;
+
+	/*
+	 * No need to reset region to identity mapped since we now
+	 * know that no I/O can be in this region
+	 */
+	release_resource(resource);
+	kfree(resource);
+}
+
 static struct resource *additional_memory_resource(phys_addr_t size)
 {
 	struct resource *res;
@@ -286,19 +297,6 @@ static struct resource *additional_memory_resource(phys_addr_t size)
 	return res;
 }
 
-static void release_memory_resource(struct resource *resource)
-{
-	if (!resource)
-		return;
-
-	/*
-	 * No need to reset region to identity mapped since we now
-	 * know that no I/O can be in this region
-	 */
-	release_resource(resource);
-	kfree(resource);
-}
-
 static enum bp_state reserve_additional_memory(void)
 {
 	long credit;
diff --git a/drivers/xen/xen-pciback/conf_space.c b/drivers/xen/xen-pciback/conf_space.c
index 8e67336f8ddd..6a25533da237 100644
--- a/drivers/xen/xen-pciback/conf_space.c
+++ b/drivers/xen/xen-pciback/conf_space.c
@@ -183,8 +183,7 @@ int xen_pcibk_config_read(struct pci_dev *dev, int offset, int size,
 		field_start = OFFSET(cfg_entry);
 		field_end = OFFSET(cfg_entry) + field->size;
 
-		if ((req_start >= field_start && req_start < field_end)
-		    || (req_end > field_start && req_end <= field_end)) {
+		 if (req_end > field_start && field_end > req_start) {
 			err = conf_space_read(dev, cfg_entry, field_start,
 					      &tmp_val);
 			if (err)
@@ -230,8 +229,7 @@ int xen_pcibk_config_write(struct pci_dev *dev, int offset, int size, u32 value)
 		field_start = OFFSET(cfg_entry);
 		field_end = OFFSET(cfg_entry) + field->size;
 
-		if ((req_start >= field_start && req_start < field_end)
-		    || (req_end > field_start && req_end <= field_end)) {
+		 if (req_end > field_start && field_end > req_start) {
 			tmp_val = 0;
 
 			err = xen_pcibk_config_read(dev, field_start,
diff --git a/drivers/xen/xen-pciback/conf_space_header.c b/drivers/xen/xen-pciback/conf_space_header.c
index ad3d17d29c81..9ead1c2ff1dd 100644
--- a/drivers/xen/xen-pciback/conf_space_header.c
+++ b/drivers/xen/xen-pciback/conf_space_header.c
@@ -145,7 +145,7 @@ static int rom_write(struct pci_dev *dev, int offset, u32 value, void *data)
 	/* A write to obtain the length must happen as a 32-bit write.
 	 * This does not (yet) support writing individual bytes
 	 */
-	if (value == ~PCI_ROM_ADDRESS_ENABLE)
+	if ((value | ~PCI_ROM_ADDRESS_MASK) == ~0U)
 		bar->which = 1;
 	else {
 		u32 tmpval;
@@ -225,38 +225,42 @@ static inline void read_dev_bar(struct pci_dev *dev,
 			   (PCI_BASE_ADDRESS_SPACE_MEMORY |
 				PCI_BASE_ADDRESS_MEM_TYPE_64))) {
 			bar_info->val = res[pos - 1].start >> 32;
-			bar_info->len_val = res[pos - 1].end >> 32;
+			bar_info->len_val = -resource_size(&res[pos - 1]) >> 32;
 			return;
 		}
 	}
 
+	if (!res[pos].flags ||
+	    (res[pos].flags & (IORESOURCE_DISABLED | IORESOURCE_UNSET |
+			       IORESOURCE_BUSY)))
+		return;
+
 	bar_info->val = res[pos].start |
 			(res[pos].flags & PCI_REGION_FLAG_MASK);
-	bar_info->len_val = resource_size(&res[pos]);
+	bar_info->len_val = -resource_size(&res[pos]) |
+			    (res[pos].flags & PCI_REGION_FLAG_MASK);
 }
 
 static void *bar_init(struct pci_dev *dev, int offset)
 {
-	struct pci_bar_info *bar = kmalloc(sizeof(*bar), GFP_KERNEL);
+	struct pci_bar_info *bar = kzalloc(sizeof(*bar), GFP_KERNEL);
 
 	if (!bar)
 		return ERR_PTR(-ENOMEM);
 
 	read_dev_bar(dev, bar, offset, ~0);
-	bar->which = 0;
 
 	return bar;
 }
 
 static void *rom_init(struct pci_dev *dev, int offset)
 {
-	struct pci_bar_info *bar = kmalloc(sizeof(*bar), GFP_KERNEL);
+	struct pci_bar_info *bar = kzalloc(sizeof(*bar), GFP_KERNEL);
 
 	if (!bar)
 		return ERR_PTR(-ENOMEM);
 
 	read_dev_bar(dev, bar, offset, ~PCI_ROM_ADDRESS_ENABLE);
-	bar->which = 0;
 
 	return bar;
 }