16 files changed, 1024 insertions, 24 deletions

diff --git a/arch/x86/include/asm/xen/page.h b/arch/x86/include/asm/xen/page.h
index 018a0a400799..bf5f7d32bd08 100644
--- a/arch/x86/include/asm/xen/page.h
+++ b/arch/x86/include/asm/xen/page.h
@@ -112,13 +112,9 @@ static inline xpaddr_t machine_to_phys(xmaddr_t machine)
  */
 static inline unsigned long mfn_to_local_pfn(unsigned long mfn)
 {
-        extern unsigned long max_mapnr;
         unsigned long pfn = mfn_to_pfn(mfn);
-        if ((pfn < max_mapnr)
-            && !xen_feature(XENFEAT_auto_translated_physmap)
-            && (get_phys_to_machine(pfn) != mfn))
-                return max_mapnr; /* force !pfn_valid() */
-        /* XXX fixme; not true with sparsemem */
+        if (get_phys_to_machine(pfn) != mfn)
+                return -1; /* force !pfn_valid() */
         return pfn;
 }
 
diff --git a/arch/x86/include/asm/xen/swiotlb-xen.h b/arch/x86/include/asm/xen/swiotlb-xen.h
new file mode 100644
index 000000000000..1be1ab7d6a41
--- /dev/null
+++ b/arch/x86/include/asm/xen/swiotlb-xen.h
@@ -0,0 +1,14 @@
+#ifndef _ASM_X86_SWIOTLB_XEN_H
+#define _ASM_X86_SWIOTLB_XEN_H
+
+#ifdef CONFIG_SWIOTLB_XEN
+extern int xen_swiotlb;
+extern int __init pci_xen_swiotlb_detect(void);
+extern void __init pci_xen_swiotlb_init(void);
+#else
+#define xen_swiotlb (0)
+static inline int __init pci_xen_swiotlb_detect(void) { return 0; }
+static inline void __init pci_xen_swiotlb_init(void) { }
+#endif
+
+#endif /* _ASM_X86_SWIOTLB_XEN_H */
diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
index 4b7e3d8b01dd..9f07cfcbd3a5 100644
--- a/arch/x86/kernel/pci-dma.c
+++ b/arch/x86/kernel/pci-dma.c
@@ -13,6 +13,7 @@
 #include <asm/calgary.h>
 #include <asm/amd_iommu.h>
 #include <asm/x86_init.h>
+#include <asm/xen/swiotlb-xen.h>
 
 static int forbid_dac __read_mostly;
 
@@ -132,7 +133,7 @@ void __init pci_iommu_alloc(void)
         /* free the range so iommu could get some range less than 4G */
         dma32_free_bootmem();
 
-        if (pci_swiotlb_detect())
+        if (pci_xen_swiotlb_detect() || pci_swiotlb_detect())
                 goto out;
 
         gart_iommu_hole_init();
@@ -144,6 +145,8 @@ void __init pci_iommu_alloc(void)
         /* needs to be called after gart_iommu_hole_init */
         amd_iommu_detect();
 out:
+        pci_xen_swiotlb_init();
+
         pci_swiotlb_init();
 }
 
@@ -296,7 +299,7 @@ static int __init pci_iommu_init(void)
 #endif
         x86_init.iommu.iommu_init();
 
-        if (swiotlb) {
+        if (swiotlb || xen_swiotlb) {
                 printk(KERN_INFO "PCI-DMA: "
                        "Using software bounce buffering for IO (SWIOTLB)\n");
                 swiotlb_print_info();
diff --git a/arch/x86/xen/Makefile b/arch/x86/xen/Makefile
index 930954685980..779385158915 100644
--- a/arch/x86/xen/Makefile
+++ b/arch/x86/xen/Makefile
@@ -18,3 +18,4 @@ obj-$(CONFIG_SMP)		+= smp.o
 obj-$(CONFIG_PARAVIRT_SPINLOCKS)+= spinlock.o
 obj-$(CONFIG_XEN_DEBUG_FS)      += debugfs.o
 
+obj-$(CONFIG_SWIOTLB_XEN)       += pci-swiotlb-xen.o
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index d4ff5e83621d..7d46c8441418 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1172,6 +1172,10 @@ asmlinkage void __init xen_start_kernel(void)
 
         pgd = (pgd_t *)xen_start_info->pt_base;
 
+        if (!xen_initial_domain())
+                __supported_pte_mask &= ~(_PAGE_PWT | _PAGE_PCD);
+
+        __supported_pte_mask |= _PAGE_IOMAP;
         /* Don't do the full vcpu_info placement stuff until we have a
            possible map and a non-dummy shared_info. */
         per_cpu(xen_vcpu, 0) = &HYPERVISOR_shared_info->vcpu_info[0];
diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 413b19b3d0fe..42086ac406af 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -42,6 +42,7 @@
 #include <linux/highmem.h>
 #include <linux/debugfs.h>
 #include <linux/bug.h>
+#include <linux/vmalloc.h>
 #include <linux/module.h>
 #include <linux/gfp.h>
 
@@ -51,15 +52,19 @@
 #include <asm/mmu_context.h>
 #include <asm/setup.h>
 #include <asm/paravirt.h>
+#include <asm/e820.h>
 #include <asm/linkage.h>
+#include <asm/page.h>
 
 #include <asm/xen/hypercall.h>
 #include <asm/xen/hypervisor.h>
 
+#include <xen/xen.h>
 #include <xen/page.h>
 #include <xen/interface/xen.h>
 #include <xen/interface/hvm/hvm_op.h>
 #include <xen/interface/version.h>
+#include <xen/interface/memory.h>
 #include <xen/hvc-console.h>
 
 #include "multicalls.h"
@@ -68,6 +73,13 @@
 
 #define MMU_UPDATE_HISTO        30
 
+/*
+ * Protects atomic reservation decrease/increase against concurrent increases.
+ * Also protects non-atomic updates of current_pages and driver_pages, and
+ * balloon lists.
+ */
+DEFINE_SPINLOCK(xen_reservation_lock);
+
 #ifdef CONFIG_XEN_DEBUG_FS
 
 static struct {
@@ -378,6 +390,28 @@ static bool xen_page_pinned(void *ptr)
         return PagePinned(page);
 }
 
+static bool xen_iomap_pte(pte_t pte)
+{
+        return pte_flags(pte) & _PAGE_IOMAP;
+}
+
+static void xen_set_iomap_pte(pte_t *ptep, pte_t pteval)
+{
+        struct multicall_space mcs;
+        struct mmu_update *u;
+
+        mcs = xen_mc_entry(sizeof(*u));
+        u = mcs.args;
+
+        /* ptep might be kmapped when using 32-bit HIGHPTE */
+        u->ptr = arbitrary_virt_to_machine(ptep).maddr;
+        u->val = pte_val_ma(pteval);
+
+        MULTI_mmu_update(mcs.mc, mcs.args, 1, NULL, DOMID_IO);
+
+        xen_mc_issue(PARAVIRT_LAZY_MMU);
+}
+
 static void xen_extend_mmu_update(const struct mmu_update *update)
 {
         struct multicall_space mcs;
@@ -454,6 +488,11 @@ void set_pte_mfn(unsigned long vaddr, unsigned long mfn, pgprot_t flags)
 void xen_set_pte_at(struct mm_struct *mm, unsigned long addr,
                     pte_t *ptep, pte_t pteval)
 {
+        if (xen_iomap_pte(pteval)) {
+                xen_set_iomap_pte(ptep, pteval);
+                goto out;
+        }
+
         ADD_STATS(set_pte_at, 1);
 //      ADD_STATS(set_pte_at_pinned, xen_page_pinned(ptep));
         ADD_STATS(set_pte_at_current, mm == current->mm);
@@ -524,8 +563,25 @@ static pteval_t pte_pfn_to_mfn(pteval_t val)
         return val;
 }
 
+static pteval_t iomap_pte(pteval_t val)
+{
+        if (val & _PAGE_PRESENT) {
+                unsigned long pfn = (val & PTE_PFN_MASK) >> PAGE_SHIFT;
+                pteval_t flags = val & PTE_FLAGS_MASK;
+
+                /* We assume the pte frame number is a MFN, so
+                   just use it as-is. */
+                val = ((pteval_t)pfn << PAGE_SHIFT) | flags;
+        }
+
+        return val;
+}
+
 pteval_t xen_pte_val(pte_t pte)
 {
+        if (xen_initial_domain() && (pte.pte & _PAGE_IOMAP))
+                return pte.pte;
+
         return pte_mfn_to_pfn(pte.pte);
 }
 PV_CALLEE_SAVE_REGS_THUNK(xen_pte_val);
@@ -538,7 +594,22 @@ PV_CALLEE_SAVE_REGS_THUNK(xen_pgd_val);
 
 pte_t xen_make_pte(pteval_t pte)
 {
-        pte = pte_pfn_to_mfn(pte);
+        phys_addr_t addr = (pte & PTE_PFN_MASK);
+
+        /*
+         * Unprivileged domains are allowed to do IOMAPpings for
+         * PCI passthrough, but not map ISA space.  The ISA
+         * mappings are just dummy local mappings to keep other
+         * parts of the kernel happy.
+         */
+        if (unlikely(pte & _PAGE_IOMAP) &&
+            (xen_initial_domain() || addr >= ISA_END_ADDRESS)) {
+                pte = iomap_pte(pte);
+        } else {
+                pte &= ~_PAGE_IOMAP;
+                pte = pte_pfn_to_mfn(pte);
+        }
+
         return native_make_pte(pte);
 }
 PV_CALLEE_SAVE_REGS_THUNK(xen_make_pte);
@@ -594,6 +665,11 @@ void xen_set_pud(pud_t *ptr, pud_t val)
 
 void xen_set_pte(pte_t *ptep, pte_t pte)
 {
+        if (xen_iomap_pte(pte)) {
+                xen_set_iomap_pte(ptep, pte);
+                return;
+        }
+
         ADD_STATS(pte_update, 1);
 //      ADD_STATS(pte_update_pinned, xen_page_pinned(ptep));
         ADD_STATS(pte_update_batched, paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU);
@@ -610,6 +686,11 @@ void xen_set_pte(pte_t *ptep, pte_t pte)
 #ifdef CONFIG_X86_PAE
 void xen_set_pte_atomic(pte_t *ptep, pte_t pte)
 {
+        if (xen_iomap_pte(pte)) {
+                xen_set_iomap_pte(ptep, pte);
+                return;
+        }
+
         set_64bit((u64 *)ptep, native_pte_val(pte));
 }
 
@@ -936,8 +1017,6 @@ static int xen_pin_page(struct mm_struct *mm, struct page *page,
    read-only, and can be pinned. */
 static void __xen_pgd_pin(struct mm_struct *mm, pgd_t *pgd)
 {
-        vm_unmap_aliases();
-
         xen_mc_batch();
 
         if (__xen_pgd_walk(mm, pgd, xen_pin_page, USER_LIMIT)) {
@@ -1501,7 +1580,6 @@ static void xen_alloc_ptpage(struct mm_struct *mm, unsigned long pfn, unsigned l
         if (PagePinned(virt_to_page(mm->pgd))) {
                 SetPagePinned(page);
 
-                vm_unmap_aliases();
                 if (!PageHighMem(page)) {
                         make_lowmem_page_readonly(__va(PFN_PHYS((unsigned long)pfn)));
                         if (level == PT_PTE && USE_SPLIT_PTLOCKS)
@@ -1812,9 +1890,16 @@ static void xen_set_fixmap(unsigned idx, phys_addr_t phys, pgprot_t prot)
                 pte = pfn_pte(phys, prot);
                 break;
 
-        default:
+        case FIX_PARAVIRT_BOOTMAP:
+                /* This is an MFN, but it isn't an IO mapping from the
+                   IO domain */
                 pte = mfn_pte(phys, prot);
                 break;
+
+        default:
+                /* By default, set_fixmap is used for hardware mappings */
+                pte = mfn_pte(phys, __pgprot(pgprot_val(prot) | _PAGE_IOMAP));
+                break;
         }
 
         __native_set_fixmap(idx, pte);
@@ -1940,7 +2025,205 @@ void __init xen_init_mmu_ops(void)
         x86_init.paging.pagetable_setup_start = xen_pagetable_setup_start;
         x86_init.paging.pagetable_setup_done = xen_pagetable_setup_done;
         pv_mmu_ops = xen_mmu_ops;
+
+        vmap_lazy_unmap = false;
+}
+
+/* Protected by xen_reservation_lock. */
+#define MAX_CONTIG_ORDER 9 /* 2MB */
+static unsigned long discontig_frames[1<<MAX_CONTIG_ORDER];
+
+#define VOID_PTE (mfn_pte(0, __pgprot(0)))
+static void xen_zap_pfn_range(unsigned long vaddr, unsigned int order,
+                                unsigned long *in_frames,
+                                unsigned long *out_frames)
+{
+        int i;
+        struct multicall_space mcs;
+
+        xen_mc_batch();
+        for (i = 0; i < (1UL<<order); i++, vaddr += PAGE_SIZE) {
+                mcs = __xen_mc_entry(0);
+
+                if (in_frames)
+                        in_frames[i] = virt_to_mfn(vaddr);
+
+                MULTI_update_va_mapping(mcs.mc, vaddr, VOID_PTE, 0);
+                set_phys_to_machine(virt_to_pfn(vaddr), INVALID_P2M_ENTRY);
+
+                if (out_frames)
+                        out_frames[i] = virt_to_pfn(vaddr);
+        }
+        xen_mc_issue(0);
+}
+
+/*
+ * Update the pfn-to-mfn mappings for a virtual address range, either to
+ * point to an array of mfns, or contiguously from a single starting
+ * mfn.
+ */
+static void xen_remap_exchanged_ptes(unsigned long vaddr, int order,
+                                     unsigned long *mfns,
+                                     unsigned long first_mfn)
+{
+        unsigned i, limit;
+        unsigned long mfn;
+
+        xen_mc_batch();
+
+        limit = 1u << order;
+        for (i = 0; i < limit; i++, vaddr += PAGE_SIZE) {
+                struct multicall_space mcs;
+                unsigned flags;
+
+                mcs = __xen_mc_entry(0);
+                if (mfns)
+                        mfn = mfns[i];
+                else
+                        mfn = first_mfn + i;
+
+                if (i < (limit - 1))
+                        flags = 0;
+                else {
+                        if (order == 0)
+                                flags = UVMF_INVLPG | UVMF_ALL;
+                        else
+                                flags = UVMF_TLB_FLUSH | UVMF_ALL;
+                }
+
+                MULTI_update_va_mapping(mcs.mc, vaddr,
+                                mfn_pte(mfn, PAGE_KERNEL), flags);
+
+                set_phys_to_machine(virt_to_pfn(vaddr), mfn);
+        }
+
+        xen_mc_issue(0);
+}
+
+/*
+ * Perform the hypercall to exchange a region of our pfns to point to
+ * memory with the required contiguous alignment.  Takes the pfns as
+ * input, and populates mfns as output.
+ *
+ * Returns a success code indicating whether the hypervisor was able to
+ * satisfy the request or not.
+ */
+static int xen_exchange_memory(unsigned long extents_in, unsigned int order_in,
+                               unsigned long *pfns_in,
+                               unsigned long extents_out,
+                               unsigned int order_out,
+                               unsigned long *mfns_out,
+                               unsigned int address_bits)
+{
+        long rc;
+        int success;
+
+        struct xen_memory_exchange exchange = {
+                .in = {
+                        .nr_extents   = extents_in,
+                        .extent_order = order_in,
+                        .extent_start = pfns_in,
+                        .domid        = DOMID_SELF
+                },
+                .out = {
+                        .nr_extents   = extents_out,
+                        .extent_order = order_out,
+                        .extent_start = mfns_out,
+                        .address_bits = address_bits,
+                        .domid        = DOMID_SELF
+                }
+        };
+
+        BUG_ON(extents_in << order_in != extents_out << order_out);
+
+        rc = HYPERVISOR_memory_op(XENMEM_exchange, &exchange);
+        success = (exchange.nr_exchanged == extents_in);
+
+        BUG_ON(!success && ((exchange.nr_exchanged != 0) || (rc == 0)));
+        BUG_ON(success && (rc != 0));
+
+        return success;
+}
+
+int xen_create_contiguous_region(unsigned long vstart, unsigned int order,
+                                 unsigned int address_bits)
+{
+        unsigned long *in_frames = discontig_frames, out_frame;
+        unsigned long  flags;
+        int            success;
+
+        /*
+         * Currently an auto-translated guest will not perform I/O, nor will
+         * it require PAE page directories below 4GB. Therefore any calls to
+         * this function are redundant and can be ignored.
+         */
+
+        if (xen_feature(XENFEAT_auto_translated_physmap))
+                return 0;
+
+        if (unlikely(order > MAX_CONTIG_ORDER))
+                return -ENOMEM;
+
+        memset((void *) vstart, 0, PAGE_SIZE << order);
+
+        spin_lock_irqsave(&xen_reservation_lock, flags);
+
+        /* 1. Zap current PTEs, remembering MFNs. */
+        xen_zap_pfn_range(vstart, order, in_frames, NULL);
+
+        /* 2. Get a new contiguous memory extent. */
+        out_frame = virt_to_pfn(vstart);
+        success = xen_exchange_memory(1UL << order, 0, in_frames,
+                                      1, order, &out_frame,
+                                      address_bits);
+
+        /* 3. Map the new extent in place of old pages. */
+        if (success)
+                xen_remap_exchanged_ptes(vstart, order, NULL, out_frame);
+        else
+                xen_remap_exchanged_ptes(vstart, order, in_frames, 0);
+
+        spin_unlock_irqrestore(&xen_reservation_lock, flags);
+
+        return success ? 0 : -ENOMEM;
+}
+EXPORT_SYMBOL_GPL(xen_create_contiguous_region);
+
+void xen_destroy_contiguous_region(unsigned long vstart, unsigned int order)
+{
+        unsigned long *out_frames = discontig_frames, in_frame;
+        unsigned long  flags;
+        int success;
+
+        if (xen_feature(XENFEAT_auto_translated_physmap))
+                return;
+
+        if (unlikely(order > MAX_CONTIG_ORDER))
+                return;
+
+        memset((void *) vstart, 0, PAGE_SIZE << order);
+
+        spin_lock_irqsave(&xen_reservation_lock, flags);
+
+        /* 1. Find start MFN of contiguous extent. */
+        in_frame = virt_to_mfn(vstart);
+
+        /* 2. Zap current PTEs. */
+        xen_zap_pfn_range(vstart, order, NULL, out_frames);
+
+        /* 3. Do the exchange for non-contiguous MFNs. */
+        success = xen_exchange_memory(1, order, &in_frame, 1UL << order,
+                                        0, out_frames, 0);
+
+        /* 4. Map new pages in place of old pages. */
+        if (success)
+                xen_remap_exchanged_ptes(vstart, order, out_frames, 0);
+        else
+                xen_remap_exchanged_ptes(vstart, order, NULL, in_frame);
+
+        spin_unlock_irqrestore(&xen_reservation_lock, flags);
 }
+EXPORT_SYMBOL_GPL(xen_destroy_contiguous_region);
 
 #ifdef CONFIG_XEN_PVHVM
 static void xen_hvm_exit_mmap(struct mm_struct *mm)
diff --git a/arch/x86/xen/pci-swiotlb-xen.c b/arch/x86/xen/pci-swiotlb-xen.c
new file mode 100644
index 000000000000..a013ec9d0c54
--- /dev/null
+++ b/arch/x86/xen/pci-swiotlb-xen.c
@@ -0,0 +1,58 @@
+/* Glue code to lib/swiotlb-xen.c */
+
+#include <linux/dma-mapping.h>
+#include <xen/swiotlb-xen.h>
+
+#include <asm/xen/hypervisor.h>
+#include <xen/xen.h>
+
+int xen_swiotlb __read_mostly;
+
+static struct dma_map_ops xen_swiotlb_dma_ops = {
+        .mapping_error = xen_swiotlb_dma_mapping_error,
+        .alloc_coherent = xen_swiotlb_alloc_coherent,
+        .free_coherent = xen_swiotlb_free_coherent,
+        .sync_single_for_cpu = xen_swiotlb_sync_single_for_cpu,
+        .sync_single_for_device = xen_swiotlb_sync_single_for_device,
+        .sync_sg_for_cpu = xen_swiotlb_sync_sg_for_cpu,
+        .sync_sg_for_device = xen_swiotlb_sync_sg_for_device,
+        .map_sg = xen_swiotlb_map_sg_attrs,
+        .unmap_sg = xen_swiotlb_unmap_sg_attrs,
+        .map_page = xen_swiotlb_map_page,
+        .unmap_page = xen_swiotlb_unmap_page,
+        .dma_supported = xen_swiotlb_dma_supported,
+};
+
+/*
+ * pci_xen_swiotlb_detect - set xen_swiotlb to 1 if necessary
+ *
+ * This returns non-zero if we are forced to use xen_swiotlb (by the boot
+ * option).
+ */
+int __init pci_xen_swiotlb_detect(void)
+{
+
+        /* If running as PV guest, either iommu=soft, or swiotlb=force will
+         * activate this IOMMU. If running as PV privileged, activate it
+         * irregardlesss.
+         */
+        if ((xen_initial_domain() || swiotlb || swiotlb_force) &&
+            (xen_pv_domain()))
+                xen_swiotlb = 1;
+
+        /* If we are running under Xen, we MUST disable the native SWIOTLB.
+         * Don't worry about swiotlb_force flag activating the native, as
+         * the 'swiotlb' flag is the only one turning it on. */
+        if (xen_pv_domain())
+                swiotlb = 0;
+
+        return xen_swiotlb;
+}
+
+void __init pci_xen_swiotlb_init(void)
+{
+        if (xen_swiotlb) {
+                xen_swiotlb_init(1);
+                dma_ops = &xen_swiotlb_dma_ops;
+        }
+}
diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
index 0a8826936639..60d71e9abe9f 100644
--- a/drivers/xen/Kconfig
+++ b/drivers/xen/Kconfig
@@ -71,4 +71,9 @@ config XEN_PLATFORM_PCI
           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 SWIOTLB
+
 endmenu
diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile
index e392fb776af3..fcaf838f54be 100644
--- a/drivers/xen/Makefile
+++ b/drivers/xen/Makefile
@@ -11,3 +11,4 @@ obj-$(CONFIG_XEN_DEV_EVTCHN)	+= evtchn.o
 obj-$(CONFIG_XENFS)             += xenfs/
 obj-$(CONFIG_XEN_SYS_HYPERVISOR)        += sys-hypervisor.o
 obj-$(CONFIG_XEN_PLATFORM_PCI)  += platform-pci.o
+obj-$(CONFIG_SWIOTLB_XEN)       += swiotlb-xen.o
diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index 1a0d8c2a0354..500290b150bb 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -85,13 +85,6 @@ static struct sys_device balloon_sysdev;
 
 static int register_balloon(struct sys_device *sysdev);
 
-/*
- * Protects atomic reservation decrease/increase against concurrent increases.
- * Also protects non-atomic updates of current_pages and driver_pages, and
- * balloon lists.
- */
-static DEFINE_SPINLOCK(balloon_lock);
-
 static struct balloon_stats balloon_stats;
 
 /* We increase/decrease in batches which fit in a page */
@@ -210,7 +203,7 @@ static int increase_reservation(unsigned long nr_pages)
         if (nr_pages > ARRAY_SIZE(frame_list))
                 nr_pages = ARRAY_SIZE(frame_list);
 
-        spin_lock_irqsave(&balloon_lock, flags);
+        spin_lock_irqsave(&xen_reservation_lock, flags);
 
         page = balloon_first_page();
         for (i = 0; i < nr_pages; i++) {
@@ -254,7 +247,7 @@ static int increase_reservation(unsigned long nr_pages)
         balloon_stats.current_pages += rc;
 
  out:
-        spin_unlock_irqrestore(&balloon_lock, flags);
+        spin_unlock_irqrestore(&xen_reservation_lock, flags);
 
         return rc < 0 ? rc : rc != nr_pages;
 }
@@ -299,7 +292,7 @@ static int decrease_reservation(unsigned long nr_pages)
         kmap_flush_unused();
         flush_tlb_all();
 
-        spin_lock_irqsave(&balloon_lock, flags);
+        spin_lock_irqsave(&xen_reservation_lock, flags);
 
         /* No more mappings: invalidate P2M and add to balloon. */
         for (i = 0; i < nr_pages; i++) {
@@ -315,7 +308,7 @@ static int decrease_reservation(unsigned long nr_pages)
 
         balloon_stats.current_pages -= nr_pages;
 
-        spin_unlock_irqrestore(&balloon_lock, flags);
+        spin_unlock_irqrestore(&xen_reservation_lock, flags);
 
         return need_sleep;
 }
diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
new file mode 100644
index 000000000000..54469c3eeacd
--- /dev/null
+++ b/drivers/xen/swiotlb-xen.c
@@ -0,0 +1,515 @@
+/*
+ *  Copyright 2010
+ *  by Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
+ *
+ * This code provides a IOMMU for Xen PV guests with PCI passthrough.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License v2.0 as published by
+ * the Free Software Foundation
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * PV guests under Xen are running in an non-contiguous memory architecture.
+ *
+ * When PCI pass-through is utilized, this necessitates an IOMMU for
+ * translating bus (DMA) to virtual and vice-versa and also providing a
+ * mechanism to have contiguous pages for device drivers operations (say DMA
+ * operations).
+ *
+ * Specifically, under Xen the Linux idea of pages is an illusion. It
+ * assumes that pages start at zero and go up to the available memory. To
+ * help with that, the Linux Xen MMU provides a lookup mechanism to
+ * translate the page frame numbers (PFN) to machine frame numbers (MFN)
+ * and vice-versa. The MFN are the "real" frame numbers. Furthermore
+ * memory is not contiguous. Xen hypervisor stitches memory for guests
+ * from different pools, which means there is no guarantee that PFN==MFN
+ * and PFN+1==MFN+1. Lastly with Xen 4.0, pages (in debug mode) are
+ * allocated in descending order (high to low), meaning the guest might
+ * never get any MFN's under the 4GB mark.
+ *
+ */
+
+#include <linux/bootmem.h>
+#include <linux/dma-mapping.h>
+#include <xen/swiotlb-xen.h>
+#include <xen/page.h>
+#include <xen/xen-ops.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
+ * API.
+ */
+
+static char *xen_io_tlb_start, *xen_io_tlb_end;
+static unsigned long xen_io_tlb_nslabs;
+/*
+ * Quick lookup value of the bus address of the IOTLB.
+ */
+
+u64 start_dma_addr;
+
+static dma_addr_t xen_phys_to_bus(phys_addr_t paddr)
+{
+        return phys_to_machine(XPADDR(paddr)).maddr;;
+}
+
+static phys_addr_t xen_bus_to_phys(dma_addr_t baddr)
+{
+        return machine_to_phys(XMADDR(baddr)).paddr;
+}
+
+static dma_addr_t xen_virt_to_bus(void *address)
+{
+        return xen_phys_to_bus(virt_to_phys(address));
+}
+
+static int check_pages_physically_contiguous(unsigned long pfn,
+                                             unsigned int offset,
+                                             size_t length)
+{
+        unsigned long next_mfn;
+        int i;
+        int nr_pages;
+
+        next_mfn = pfn_to_mfn(pfn);
+        nr_pages = (offset + length + PAGE_SIZE-1) >> PAGE_SHIFT;
+
+        for (i = 1; i < nr_pages; i++) {
+                if (pfn_to_mfn(++pfn) != ++next_mfn)
+                        return 0;
+        }
+        return 1;
+}
+
+static int range_straddles_page_boundary(phys_addr_t p, size_t size)
+{
+        unsigned long pfn = PFN_DOWN(p);
+        unsigned int offset = p & ~PAGE_MASK;
+
+        if (offset + size <= PAGE_SIZE)
+                return 0;
+        if (check_pages_physically_contiguous(pfn, offset, size))
+                return 0;
+        return 1;
+}
+
+static int is_xen_swiotlb_buffer(dma_addr_t dma_addr)
+{
+        unsigned long mfn = PFN_DOWN(dma_addr);
+        unsigned long pfn = mfn_to_local_pfn(mfn);
+        phys_addr_t paddr;
+
+        /* If the address is outside our domain, it CAN
+         * have the same virtual address as another address
+         * in our domain. Therefore _only_ check address within our domain.
+         */
+        if (pfn_valid(pfn)) {
+                paddr = PFN_PHYS(pfn);
+                return paddr >= virt_to_phys(xen_io_tlb_start) &&
+                       paddr < virt_to_phys(xen_io_tlb_end);
+        }
+        return 0;
+}
+
+static int max_dma_bits = 32;
+
+static int
+xen_swiotlb_fixup(void *buf, size_t size, unsigned long nslabs)
+{
+        int i, rc;
+        int dma_bits;
+
+        dma_bits = get_order(IO_TLB_SEGSIZE << IO_TLB_SHIFT) + PAGE_SHIFT;
+
+        i = 0;
+        do {
+                int slabs = min(nslabs - i, (unsigned long)IO_TLB_SEGSIZE);
+
+                do {
+                        rc = xen_create_contiguous_region(
+                                (unsigned long)buf + (i << IO_TLB_SHIFT),
+                                get_order(slabs << IO_TLB_SHIFT),
+                                dma_bits);
+                } while (rc && dma_bits++ < max_dma_bits);
+                if (rc)
+                        return rc;
+
+                i += slabs;
+        } while (i < nslabs);
+        return 0;
+}
+
+void __init xen_swiotlb_init(int verbose)
+{
+        unsigned long bytes;
+        int rc;
+
+        xen_io_tlb_nslabs = (64 * 1024 * 1024 >> IO_TLB_SHIFT);
+        xen_io_tlb_nslabs = ALIGN(xen_io_tlb_nslabs, IO_TLB_SEGSIZE);
+
+        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");
+
+        xen_io_tlb_end = xen_io_tlb_start + bytes;
+        /*
+         * And replace that memory with pages under 4GB.
+         */
+        rc = xen_swiotlb_fixup(xen_io_tlb_start,
+                               bytes,
+                               xen_io_tlb_nslabs);
+        if (rc)
+                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);
+}
+
+void *
+xen_swiotlb_alloc_coherent(struct device *hwdev, size_t size,
+                           dma_addr_t *dma_handle, gfp_t flags)
+{
+        void *ret;
+        int order = get_order(size);
+        u64 dma_mask = DMA_BIT_MASK(32);
+        unsigned long vstart;
+
+        /*
+        * Ignore region specifiers - the kernel's ideas of
+        * pseudo-phys memory layout has nothing to do with the
+        * machine physical layout.  We can't allocate highmem
+        * because we can't return a pointer to it.
+        */
+        flags &= ~(__GFP_DMA | __GFP_HIGHMEM);
+
+        if (dma_alloc_from_coherent(hwdev, size, dma_handle, &ret))
+                return ret;
+
+        vstart = __get_free_pages(flags, order);
+        ret = (void *)vstart;
+
+        if (hwdev && hwdev->coherent_dma_mask)
+                dma_mask = dma_alloc_coherent_mask(hwdev, flags);
+
+        if (ret) {
+                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;
+        }
+        return ret;
+}
+EXPORT_SYMBOL_GPL(xen_swiotlb_alloc_coherent);
+
+void
+xen_swiotlb_free_coherent(struct device *hwdev, size_t size, void *vaddr,
+                          dma_addr_t dev_addr)
+{
+        int order = get_order(size);
+
+        if (dma_release_from_coherent(hwdev, order, vaddr))
+                return;
+
+        xen_destroy_contiguous_region((unsigned long)vaddr, order);
+        free_pages((unsigned long)vaddr, order);
+}
+EXPORT_SYMBOL_GPL(xen_swiotlb_free_coherent);
+
+
+/*
+ * Map a single buffer of the indicated size for DMA in streaming mode.  The
+ * physical address to use is returned.
+ *
+ * Once the device is given the dma address, the device owns this memory until
+ * either xen_swiotlb_unmap_page or xen_swiotlb_dma_sync_single is performed.
+ */
+dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page,
+                                unsigned long offset, size_t size,
+                                enum dma_data_direction dir,
+                                struct dma_attrs *attrs)
+{
+        phys_addr_t phys = page_to_phys(page) + offset;
+        dma_addr_t dev_addr = xen_phys_to_bus(phys);
+        void *map;
+
+        BUG_ON(dir == DMA_NONE);
+        /*
+         * If the address happens to be in the device's DMA window,
+         * we can safely return the device addr and not worry about bounce
+         * buffering it.
+         */
+        if (dma_capable(dev, dev_addr, size) &&
+            !range_straddles_page_boundary(phys, size) && !swiotlb_force)
+                return dev_addr;
+
+        /*
+         * Oh well, have to allocate and map a bounce buffer.
+         */
+        map = swiotlb_tbl_map_single(dev, start_dma_addr, phys, size, dir);
+        if (!map)
+                return DMA_ERROR_CODE;
+
+        dev_addr = xen_virt_to_bus(map);
+
+        /*
+         * Ensure that the address returned is DMA'ble
+         */
+        if (!dma_capable(dev, dev_addr, size))
+                panic("map_single: bounce buffer is not DMA'ble");
+
+        return dev_addr;
+}
+EXPORT_SYMBOL_GPL(xen_swiotlb_map_page);
+
+/*
+ * Unmap a single streaming mode DMA translation.  The dma_addr and size must
+ * match what was provided for in a previous xen_swiotlb_map_page call.  All
+ * other usages are undefined.
+ *
+ * After this call, reads by the cpu to the buffer are guaranteed to see
+ * whatever the device wrote there.
+ */
+static void xen_unmap_single(struct device *hwdev, dma_addr_t dev_addr,
+                             size_t size, enum dma_data_direction dir)
+{
+        phys_addr_t paddr = xen_bus_to_phys(dev_addr);
+
+        BUG_ON(dir == DMA_NONE);
+
+        /* NOTE: We use dev_addr here, not paddr! */
+        if (is_xen_swiotlb_buffer(dev_addr)) {
+                swiotlb_tbl_unmap_single(hwdev, phys_to_virt(paddr), size, dir);
+                return;
+        }
+
+        if (dir != DMA_FROM_DEVICE)
+                return;
+
+        /*
+         * phys_to_virt doesn't work with hihgmem page but we could
+         * call dma_mark_clean() with hihgmem page here. However, we
+         * are fine since dma_mark_clean() is null on POWERPC. We can
+         * make dma_mark_clean() take a physical address if necessary.
+         */
+        dma_mark_clean(phys_to_virt(paddr), size);
+}
+
+void xen_swiotlb_unmap_page(struct device *hwdev, dma_addr_t dev_addr,
+                            size_t size, enum dma_data_direction dir,
+                            struct dma_attrs *attrs)
+{
+        xen_unmap_single(hwdev, dev_addr, size, dir);
+}
+EXPORT_SYMBOL_GPL(xen_swiotlb_unmap_page);
+
+/*
+ * Make physical memory consistent for a single streaming mode DMA translation
+ * after a transfer.
+ *
+ * If you perform a xen_swiotlb_map_page() but wish to interrogate the buffer
+ * using the cpu, yet do not wish to teardown the dma mapping, you must
+ * call this function before doing so.  At the next point you give the dma
+ * address back to the card, you must first perform a
+ * xen_swiotlb_dma_sync_for_device, and then the device again owns the buffer
+ */
+static void
+xen_swiotlb_sync_single(struct device *hwdev, dma_addr_t dev_addr,
+                        size_t size, enum dma_data_direction dir,
+                        enum dma_sync_target target)
+{
+        phys_addr_t paddr = xen_bus_to_phys(dev_addr);
+
+        BUG_ON(dir == DMA_NONE);
+
+        /* NOTE: We use dev_addr here, not paddr! */
+        if (is_xen_swiotlb_buffer(dev_addr)) {
+                swiotlb_tbl_sync_single(hwdev, phys_to_virt(paddr), size, dir,
+                                       target);
+                return;
+        }
+
+        if (dir != DMA_FROM_DEVICE)
+                return;
+
+        dma_mark_clean(phys_to_virt(paddr), size);
+}
+
+void
+xen_swiotlb_sync_single_for_cpu(struct device *hwdev, dma_addr_t dev_addr,
+                                size_t size, enum dma_data_direction dir)
+{
+        xen_swiotlb_sync_single(hwdev, dev_addr, size, dir, SYNC_FOR_CPU);
+}
+EXPORT_SYMBOL_GPL(xen_swiotlb_sync_single_for_cpu);
+
+void
+xen_swiotlb_sync_single_for_device(struct device *hwdev, dma_addr_t dev_addr,
+                                   size_t size, enum dma_data_direction dir)
+{
+        xen_swiotlb_sync_single(hwdev, dev_addr, size, dir, SYNC_FOR_DEVICE);
+}
+EXPORT_SYMBOL_GPL(xen_swiotlb_sync_single_for_device);
+
+/*
+ * Map a set of buffers described by scatterlist in streaming mode for DMA.
+ * This is the scatter-gather version of the above xen_swiotlb_map_page
+ * interface.  Here the scatter gather list elements are each tagged with the
+ * appropriate dma address and length.  They are obtained via
+ * sg_dma_{address,length}(SG).
+ *
+ * NOTE: An implementation may be able to use a smaller number of
+ *       DMA address/length pairs than there are SG table elements.
+ *       (for example via virtual mapping capabilities)
+ *       The routine returns the number of addr/length pairs actually
+ *       used, at most nents.
+ *
+ * Device ownership issues as mentioned above for xen_swiotlb_map_page are the
+ * same here.
+ */
+int
+xen_swiotlb_map_sg_attrs(struct device *hwdev, struct scatterlist *sgl,
+                         int nelems, enum dma_data_direction dir,
+                         struct dma_attrs *attrs)
+{
+        struct scatterlist *sg;
+        int i;
+
+        BUG_ON(dir == DMA_NONE);
+
+        for_each_sg(sgl, sg, nelems, i) {
+                phys_addr_t paddr = sg_phys(sg);
+                dma_addr_t dev_addr = xen_phys_to_bus(paddr);
+
+                if (swiotlb_force ||
+                    !dma_capable(hwdev, dev_addr, sg->length) ||
+                    range_straddles_page_boundary(paddr, sg->length)) {
+                        void *map = swiotlb_tbl_map_single(hwdev,
+                                                           start_dma_addr,
+                                                           sg_phys(sg),
+                                                           sg->length, dir);
+                        if (!map) {
+                                /* Don't panic here, we expect map_sg users
+                                   to do proper error handling. */
+                                xen_swiotlb_unmap_sg_attrs(hwdev, sgl, i, dir,
+                                                           attrs);
+                                sgl[0].dma_length = 0;
+                                return DMA_ERROR_CODE;
+                        }
+                        sg->dma_address = xen_virt_to_bus(map);
+                } else
+                        sg->dma_address = dev_addr;
+                sg->dma_length = sg->length;
+        }
+        return nelems;
+}
+EXPORT_SYMBOL_GPL(xen_swiotlb_map_sg_attrs);
+
+int
+xen_swiotlb_map_sg(struct device *hwdev, struct scatterlist *sgl, int nelems,
+                   enum dma_data_direction dir)
+{
+        return xen_swiotlb_map_sg_attrs(hwdev, sgl, nelems, dir, NULL);
+}
+EXPORT_SYMBOL_GPL(xen_swiotlb_map_sg);
+
+/*
+ * Unmap a set of streaming mode DMA translations.  Again, cpu read rules
+ * concerning calls here are the same as for swiotlb_unmap_page() above.
+ */
+void
+xen_swiotlb_unmap_sg_attrs(struct device *hwdev, struct scatterlist *sgl,
+                           int nelems, enum dma_data_direction dir,
+                           struct dma_attrs *attrs)
+{
+        struct scatterlist *sg;
+        int i;
+
+        BUG_ON(dir == DMA_NONE);
+
+        for_each_sg(sgl, sg, nelems, i)
+                xen_unmap_single(hwdev, sg->dma_address, sg->dma_length, dir);
+
+}
+EXPORT_SYMBOL_GPL(xen_swiotlb_unmap_sg_attrs);
+
+void
+xen_swiotlb_unmap_sg(struct device *hwdev, struct scatterlist *sgl, int nelems,
+                     enum dma_data_direction dir)
+{
+        return xen_swiotlb_unmap_sg_attrs(hwdev, sgl, nelems, dir, NULL);
+}
+EXPORT_SYMBOL_GPL(xen_swiotlb_unmap_sg);
+
+/*
+ * Make physical memory consistent for a set of streaming mode DMA translations
+ * after a transfer.
+ *
+ * The same as swiotlb_sync_single_* but for a scatter-gather list, same rules
+ * and usage.
+ */
+static void
+xen_swiotlb_sync_sg(struct device *hwdev, struct scatterlist *sgl,
+                    int nelems, enum dma_data_direction dir,
+                    enum dma_sync_target target)
+{
+        struct scatterlist *sg;
+        int i;
+
+        for_each_sg(sgl, sg, nelems, i)
+                xen_swiotlb_sync_single(hwdev, sg->dma_address,
+                                        sg->dma_length, dir, target);
+}
+
+void
+xen_swiotlb_sync_sg_for_cpu(struct device *hwdev, struct scatterlist *sg,
+                            int nelems, enum dma_data_direction dir)
+{
+        xen_swiotlb_sync_sg(hwdev, sg, nelems, dir, SYNC_FOR_CPU);
+}
+EXPORT_SYMBOL_GPL(xen_swiotlb_sync_sg_for_cpu);
+
+void
+xen_swiotlb_sync_sg_for_device(struct device *hwdev, struct scatterlist *sg,
+                               int nelems, enum dma_data_direction dir)
+{
+        xen_swiotlb_sync_sg(hwdev, sg, nelems, dir, SYNC_FOR_DEVICE);
+}
+EXPORT_SYMBOL_GPL(xen_swiotlb_sync_sg_for_device);
+
+int
+xen_swiotlb_dma_mapping_error(struct device *hwdev, dma_addr_t dma_addr)
+{
+        return !dma_addr;
+}
+EXPORT_SYMBOL_GPL(xen_swiotlb_dma_mapping_error);
+
+/*
+ * Return whether the given device DMA address mask can be supported
+ * properly.  For example, if your device can only drive the low 24-bits
+ * during bus mastering, then you would pass 0x00ffffff as the mask to
+ * this function.
+ */
+int
+xen_swiotlb_dma_supported(struct device *hwdev, u64 mask)
+{
+        return xen_virt_to_bus(xen_io_tlb_end - 1) <= mask;
+}
+EXPORT_SYMBOL_GPL(xen_swiotlb_dma_supported);
diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index de05e96e0a70..01c2145118dc 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -7,6 +7,8 @@
 
 struct vm_area_struct;          /* vma defining user mapping in mm_types.h */
 
+extern bool vmap_lazy_unmap;
+
 /* bits in flags of vmalloc's vm_struct below */
 #define VM_IOREMAP      0x00000001      /* ioremap() and friends */
 #define VM_ALLOC        0x00000002      /* vmalloc() */
diff --git a/include/xen/interface/memory.h b/include/xen/interface/memory.h
index af36ead16817..d3938d3e71f8 100644
--- a/include/xen/interface/memory.h
+++ b/include/xen/interface/memory.h
@@ -9,6 +9,8 @@
 #ifndef __XEN_PUBLIC_MEMORY_H__
 #define __XEN_PUBLIC_MEMORY_H__
 
+#include <linux/spinlock.h>
+
 /*
  * Increase or decrease the specified domain's memory reservation. Returns a
  * -ve errcode on failure, or the # extents successfully allocated or freed.
@@ -53,6 +55,48 @@ struct xen_memory_reservation {
 DEFINE_GUEST_HANDLE_STRUCT(xen_memory_reservation);
 
 /*
+ * An atomic exchange of memory pages. If return code is zero then
+ * @out.extent_list provides GMFNs of the newly-allocated memory.
+ * Returns zero on complete success, otherwise a negative error code.
+ * On complete success then always @nr_exchanged == @in.nr_extents.
+ * On partial success @nr_exchanged indicates how much work was done.
+ */
+#define XENMEM_exchange             11
+struct xen_memory_exchange {
+    /*
+     * [IN] Details of memory extents to be exchanged (GMFN bases).
+     * Note that @in.address_bits is ignored and unused.
+     */
+    struct xen_memory_reservation in;
+
+    /*
+     * [IN/OUT] Details of new memory extents.
+     * We require that:
+     *  1. @in.domid == @out.domid
+     *  2. @in.nr_extents  << @in.extent_order ==
+     *     @out.nr_extents << @out.extent_order
+     *  3. @in.extent_start and @out.extent_start lists must not overlap
+     *  4. @out.extent_start lists GPFN bases to be populated
+     *  5. @out.extent_start is overwritten with allocated GMFN bases
+     */
+    struct xen_memory_reservation out;
+
+    /*
+     * [OUT] Number of input extents that were successfully exchanged:
+     *  1. The first @nr_exchanged input extents were successfully
+     *     deallocated.
+     *  2. The corresponding first entries in the output extent list correctly
+     *     indicate the GMFNs that were successfully exchanged.
+     *  3. All other input and output extents are untouched.
+     *  4. If not all input exents are exchanged then the return code of this
+     *     command will be non-zero.
+     *  5. THIS FIELD MUST BE INITIALISED TO ZERO BY THE CALLER!
+     */
+    unsigned long nr_exchanged;
+};
+
+DEFINE_GUEST_HANDLE_STRUCT(xen_memory_exchange);
+/*
  * Returns the maximum machine frame number of mapped RAM in this system.
  * This command always succeeds (it never returns an error code).
  * arg == NULL.
@@ -142,4 +186,10 @@ struct xen_translate_gpfn_list {
 };
 DEFINE_GUEST_HANDLE_STRUCT(xen_translate_gpfn_list);
 
+
+/*
+ * Prevent the balloon driver from changing the memory reservation
+ * during a driver critical region.
+ */
+extern spinlock_t xen_reservation_lock;
 #endif /* __XEN_PUBLIC_MEMORY_H__ */
diff --git a/include/xen/swiotlb-xen.h b/include/xen/swiotlb-xen.h
new file mode 100644
index 000000000000..2ea2fdc79c16
--- /dev/null
+++ b/include/xen/swiotlb-xen.h
@@ -0,0 +1,65 @@
+#ifndef __LINUX_SWIOTLB_XEN_H
+#define __LINUX_SWIOTLB_XEN_H
+
+#include <linux/swiotlb.h>
+
+extern void xen_swiotlb_init(int verbose);
+
+extern void
+*xen_swiotlb_alloc_coherent(struct device *hwdev, size_t size,
+                            dma_addr_t *dma_handle, gfp_t flags);
+
+extern void
+xen_swiotlb_free_coherent(struct device *hwdev, size_t size,
+                          void *vaddr, dma_addr_t dma_handle);
+
+extern dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page,
+                                       unsigned long offset, size_t size,
+                                       enum dma_data_direction dir,
+                                       struct dma_attrs *attrs);
+
+extern void xen_swiotlb_unmap_page(struct device *hwdev, dma_addr_t dev_addr,
+                                   size_t size, enum dma_data_direction dir,
+                                   struct dma_attrs *attrs);
+/*
+extern int
+xen_swiotlb_map_sg(struct device *hwdev, struct scatterlist *sg, int nents,
+                   enum dma_data_direction dir);
+
+extern void
+xen_swiotlb_unmap_sg(struct device *hwdev, struct scatterlist *sg, int nents,
+                     enum dma_data_direction dir);
+*/
+extern int
+xen_swiotlb_map_sg_attrs(struct device *hwdev, struct scatterlist *sgl,
+                         int nelems, enum dma_data_direction dir,
+                         struct dma_attrs *attrs);
+
+extern void
+xen_swiotlb_unmap_sg_attrs(struct device *hwdev, struct scatterlist *sgl,
+                           int nelems, enum dma_data_direction dir,
+                           struct dma_attrs *attrs);
+
+extern void
+xen_swiotlb_sync_single_for_cpu(struct device *hwdev, dma_addr_t dev_addr,
+                                size_t size, enum dma_data_direction dir);
+
+extern void
+xen_swiotlb_sync_sg_for_cpu(struct device *hwdev, struct scatterlist *sg,
+                            int nelems, enum dma_data_direction dir);
+
+extern void
+xen_swiotlb_sync_single_for_device(struct device *hwdev, dma_addr_t dev_addr,
+                                   size_t size, enum dma_data_direction dir);
+
+extern void
+xen_swiotlb_sync_sg_for_device(struct device *hwdev, struct scatterlist *sg,
+                               int nelems, enum dma_data_direction dir);
+
+extern int
+xen_swiotlb_dma_mapping_error(struct device *hwdev, dma_addr_t dma_addr);
+
+extern int
+xen_swiotlb_dma_supported(struct device *hwdev, u64 mask);
+
+#endif /* __LINUX_SWIOTLB_XEN_H */
diff --git a/include/xen/xen-ops.h b/include/xen/xen-ops.h
index 46bc81ef74c6..351f4051f6d8 100644
--- a/include/xen/xen-ops.h
+++ b/include/xen/xen-ops.h
@@ -17,4 +17,10 @@ void xen_arch_resume(void);
 
 int xen_setup_shutdown_event(void);
 
+extern unsigned long *xen_contiguous_bitmap;
+int xen_create_contiguous_region(unsigned long vstart, unsigned int order,
+                                unsigned int address_bits);
+
+void xen_destroy_contiguous_region(unsigned long vstart, unsigned int order);
+
 #endif /* INCLUDE_XEN_OPS_H */
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 918c51335d64..6b8889da69a6 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -31,6 +31,7 @@
 #include <asm/tlbflush.h>
 #include <asm/shmparam.h>
 
+bool vmap_lazy_unmap __read_mostly = true;
 
 /*** Page table manipulation functions ***/
 
@@ -502,6 +503,9 @@ static unsigned long lazy_max_pages(void)
 {
         unsigned int log;
 
+        if (!vmap_lazy_unmap)
+                return 0;
+
         log = fls(num_online_cpus());
 
         return log * (32UL * 1024 * 1024 / PAGE_SIZE);