Merge tag 'stable/for-linus-3.17-b-rc4-arm-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip

Pull Xen ARM bugfix from Stefano Stabellini:
 "The patches fix the "xen_add_mach_to_phys_entry: cannot add" bug that
  has been affecting xen on arm and arm64 guests since 3.16.  They
  require a few hypervisor side changes that just went in xen-unstable.

  A couple of days ago David sent out a pull request with a few other
  Xen fixes (it is already in master).  Sorry we didn't synchronized
  better among us"

* tag 'stable/for-linus-3.17-b-rc4-arm-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  xen/arm: remove mach_to_phys rbtree
  xen/arm: reimplement xen_dma_unmap_page & friends
  xen/arm: introduce XENFEAT_grant_map_identity

6 files changed, 217 insertions, 93 deletions

diff --git a/arch/arm/include/asm/xen/page-coherent.h b/arch/arm/include/asm/xen/page-coherent.h
index 1109017499e5..e8275ea88e88 100644
--- a/arch/arm/include/asm/xen/page-coherent.h
+++ b/arch/arm/include/asm/xen/page-coherent.h
@@ -26,25 +26,14 @@ static inline void xen_dma_map_page(struct device *hwdev, struct page *page,
         __generic_dma_ops(hwdev)->map_page(hwdev, page, offset, size, dir, attrs);
 }
 
-static inline void xen_dma_unmap_page(struct device *hwdev, dma_addr_t handle,
+void xen_dma_unmap_page(struct device *hwdev, dma_addr_t handle,
                 size_t size, enum dma_data_direction dir,
-                struct dma_attrs *attrs)
-{
-        if (__generic_dma_ops(hwdev)->unmap_page)
-                __generic_dma_ops(hwdev)->unmap_page(hwdev, handle, size, dir, attrs);
-}
+                struct dma_attrs *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)
-{
-        if (__generic_dma_ops(hwdev)->sync_single_for_cpu)
-                __generic_dma_ops(hwdev)->sync_single_for_cpu(hwdev, handle, size, dir);
-}
+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_dma_sync_single_for_device(struct device *hwdev,
-                dma_addr_t handle, size_t size, enum dma_data_direction dir)
-{
-        if (__generic_dma_ops(hwdev)->sync_single_for_device)
-                __generic_dma_ops(hwdev)->sync_single_for_device(hwdev, handle, size, dir);
-}
 #endif /* _ASM_ARM_XEN_PAGE_COHERENT_H */
diff --git a/arch/arm/include/asm/xen/page.h b/arch/arm/include/asm/xen/page.h
index ded062f9b358..135c24a5ba26 100644
--- a/arch/arm/include/asm/xen/page.h
+++ b/arch/arm/include/asm/xen/page.h
@@ -33,7 +33,6 @@ typedef struct xpaddr {
 #define INVALID_P2M_ENTRY      (~0UL)
 
 unsigned long __pfn_to_mfn(unsigned long pfn);
-unsigned long __mfn_to_pfn(unsigned long mfn);
 extern struct rb_root phys_to_mach;
 
 static inline unsigned long pfn_to_mfn(unsigned long pfn)
@@ -51,14 +50,6 @@ static inline unsigned long pfn_to_mfn(unsigned long pfn)
 
 static inline unsigned long mfn_to_pfn(unsigned long mfn)
 {
-        unsigned long pfn;
-
-        if (phys_to_mach.rb_node != NULL) {
-                pfn = __mfn_to_pfn(mfn);
-                if (pfn != INVALID_P2M_ENTRY)
-                        return pfn;
-        }
-
         return mfn;
 }
 
diff --git a/arch/arm/xen/Makefile b/arch/arm/xen/Makefile
index 12969523414c..1f85bfe6b470 100644
--- a/arch/arm/xen/Makefile
+++ b/arch/arm/xen/Makefile
@@ -1 +1 @@
-obj-y           := enlighten.o hypercall.o grant-table.o p2m.o mm.o
+obj-y           := enlighten.o hypercall.o grant-table.o p2m.o mm.o mm32.o
diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c
index 98544c5f86e9..0e15f011f9c8 100644
--- a/arch/arm/xen/enlighten.c
+++ b/arch/arm/xen/enlighten.c
@@ -260,6 +260,12 @@ static int __init xen_guest_init(void)
         xen_domain_type = XEN_HVM_DOMAIN;
 
         xen_setup_features();
+
+        if (!xen_feature(XENFEAT_grant_map_identity)) {
+                pr_warn("Please upgrade your Xen.\n"
+                                "If your platform has any non-coherent DMA devices, they won't work properly.\n");
+        }
+
         if (xen_feature(XENFEAT_dom0))
                 xen_start_info->flags |= SIF_INITDOMAIN|SIF_PRIVILEGED;
         else
diff --git a/arch/arm/xen/mm32.c b/arch/arm/xen/mm32.c
new file mode 100644
index 000000000000..3b99860fd7ae
--- /dev/null
+++ b/arch/arm/xen/mm32.c
@@ -0,0 +1,202 @@
+#include <linux/cpu.h>
+#include <linux/dma-mapping.h>
+#include <linux/gfp.h>
+#include <linux/highmem.h>
+
+#include <xen/features.h>
+
+static DEFINE_PER_CPU(unsigned long, xen_mm32_scratch_virt);
+static DEFINE_PER_CPU(pte_t *, xen_mm32_scratch_ptep);
+
+static int alloc_xen_mm32_scratch_page(int cpu)
+{
+        struct page *page;
+        unsigned long virt;
+        pmd_t *pmdp;
+        pte_t *ptep;
+
+        if (per_cpu(xen_mm32_scratch_ptep, cpu) != NULL)
+                return 0;
+
+        page = alloc_page(GFP_KERNEL);
+        if (page == NULL) {
+                pr_warn("Failed to allocate xen_mm32_scratch_page for cpu %d\n", cpu);
+                return -ENOMEM;
+        }
+
+        virt = (unsigned long)__va(page_to_phys(page));
+        pmdp = pmd_offset(pud_offset(pgd_offset_k(virt), virt), virt);
+        ptep = pte_offset_kernel(pmdp, virt);
+
+        per_cpu(xen_mm32_scratch_virt, cpu) = virt;
+        per_cpu(xen_mm32_scratch_ptep, cpu) = ptep;
+
+        return 0;
+}
+
+static int xen_mm32_cpu_notify(struct notifier_block *self,
+                                    unsigned long action, void *hcpu)
+{
+        int cpu = (long)hcpu;
+        switch (action) {
+        case CPU_UP_PREPARE:
+                if (alloc_xen_mm32_scratch_page(cpu))
+                        return NOTIFY_BAD;
+                break;
+        default:
+                break;
+        }
+        return NOTIFY_OK;
+}
+
+static struct notifier_block xen_mm32_cpu_notifier = {
+        .notifier_call  = xen_mm32_cpu_notify,
+};
+
+static void* xen_mm32_remap_page(dma_addr_t handle)
+{
+        unsigned long virt = get_cpu_var(xen_mm32_scratch_virt);
+        pte_t *ptep = __get_cpu_var(xen_mm32_scratch_ptep);
+
+        *ptep = pfn_pte(handle >> PAGE_SHIFT, PAGE_KERNEL);
+        local_flush_tlb_kernel_page(virt);
+
+        return (void*)virt;
+}
+
+static void xen_mm32_unmap(void *vaddr)
+{
+        put_cpu_var(xen_mm32_scratch_virt);
+}
+
+
+/* functions called by SWIOTLB */
+
+static void dma_cache_maint(dma_addr_t handle, unsigned long offset,
+        size_t size, enum dma_data_direction dir,
+        void (*op)(const void *, size_t, int))
+{
+        unsigned long pfn;
+        size_t left = size;
+
+        pfn = (handle >> PAGE_SHIFT) + offset / PAGE_SIZE;
+        offset %= PAGE_SIZE;
+
+        do {
+                size_t len = left;
+                void *vaddr;
+        
+                if (!pfn_valid(pfn))
+                {
+                        /* Cannot map the page, we don't know its physical address.
+                         * Return and hope for the best */
+                        if (!xen_feature(XENFEAT_grant_map_identity))
+                                return;
+                        vaddr = xen_mm32_remap_page(handle) + offset;
+                        op(vaddr, len, dir);
+                        xen_mm32_unmap(vaddr - offset);
+                } else {
+                        struct page *page = pfn_to_page(pfn);
+
+                        if (PageHighMem(page)) {
+                                if (len + offset > PAGE_SIZE)
+                                        len = PAGE_SIZE - offset;
+
+                                if (cache_is_vipt_nonaliasing()) {
+                                        vaddr = kmap_atomic(page);
+                                        op(vaddr + offset, len, dir);
+                                        kunmap_atomic(vaddr);
+                                } else {
+                                        vaddr = kmap_high_get(page);
+                                        if (vaddr) {
+                                                op(vaddr + offset, len, dir);
+                                                kunmap_high(page);
+                                        }
+                                }
+                        } else {
+                                vaddr = page_address(page) + offset;
+                                op(vaddr, len, dir);
+                        }
+                }
+
+                offset = 0;
+                pfn++;
+                left -= len;
+        } while (left);
+}
+
+static void __xen_dma_page_dev_to_cpu(struct device *hwdev, dma_addr_t handle,
+                size_t size, enum dma_data_direction dir)
+{
+        /* Cannot use __dma_page_dev_to_cpu because we don't have a
+         * struct page for handle */
+
+        if (dir != DMA_TO_DEVICE)
+                outer_inv_range(handle, handle + size);
+
+        dma_cache_maint(handle & PAGE_MASK, handle & ~PAGE_MASK, size, dir, dmac_unmap_area);
+}
+
+static void __xen_dma_page_cpu_to_dev(struct device *hwdev, dma_addr_t handle,
+                size_t size, enum dma_data_direction dir)
+{
+
+        dma_cache_maint(handle & PAGE_MASK, handle & ~PAGE_MASK, size, dir, dmac_map_area);
+
+        if (dir == DMA_FROM_DEVICE) {
+                outer_inv_range(handle, handle + size);
+        } else {
+                outer_clean_range(handle, handle + size);
+        }
+}
+
+void xen_dma_unmap_page(struct device *hwdev, dma_addr_t handle,
+                size_t size, enum dma_data_direction dir,
+                struct dma_attrs *attrs)
+
+{
+        if (!__generic_dma_ops(hwdev)->unmap_page)
+                return;
+        if (dma_get_attr(DMA_ATTR_SKIP_CPU_SYNC, attrs))
+                return;
+
+        __xen_dma_page_dev_to_cpu(hwdev, handle, size, dir);
+}
+
+void xen_dma_sync_single_for_cpu(struct device *hwdev,
+                dma_addr_t handle, size_t size, enum dma_data_direction dir)
+{
+        if (!__generic_dma_ops(hwdev)->sync_single_for_cpu)
+                return;
+        __xen_dma_page_dev_to_cpu(hwdev, handle, size, dir);
+}
+
+void xen_dma_sync_single_for_device(struct device *hwdev,
+                dma_addr_t handle, size_t size, enum dma_data_direction dir)
+{
+        if (!__generic_dma_ops(hwdev)->sync_single_for_device)
+                return;
+        __xen_dma_page_cpu_to_dev(hwdev, handle, size, dir);
+}
+
+int __init xen_mm32_init(void)
+{
+        int cpu;
+
+        if (!xen_initial_domain())
+                return 0;
+
+        register_cpu_notifier(&xen_mm32_cpu_notifier);
+        get_online_cpus();
+        for_each_online_cpu(cpu) {
+                if (alloc_xen_mm32_scratch_page(cpu)) {
+                        put_online_cpus();
+                        unregister_cpu_notifier(&xen_mm32_cpu_notifier);
+                        return -ENOMEM;
+                }
+        }
+        put_online_cpus();
+
+        return 0;
+}
+arch_initcall(xen_mm32_init);
diff --git a/arch/arm/xen/p2m.c b/arch/arm/xen/p2m.c
index 97baf4427817..054857776254 100644
--- a/arch/arm/xen/p2m.c
+++ b/arch/arm/xen/p2m.c
@@ -21,14 +21,12 @@ struct xen_p2m_entry {
         unsigned long pfn;
         unsigned long mfn;
         unsigned long nr_pages;
-        struct rb_node rbnode_mach;
         struct rb_node rbnode_phys;
 };
 
 static rwlock_t p2m_lock;
 struct rb_root phys_to_mach = RB_ROOT;
 EXPORT_SYMBOL_GPL(phys_to_mach);
-static struct rb_root mach_to_phys = RB_ROOT;
 
 static int xen_add_phys_to_mach_entry(struct xen_p2m_entry *new)
 {
@@ -41,8 +39,6 @@ static int xen_add_phys_to_mach_entry(struct xen_p2m_entry *new)
                 parent = *link;
                 entry = rb_entry(parent, struct xen_p2m_entry, rbnode_phys);
 
-                if (new->mfn == entry->mfn)
-                        goto err_out;
                 if (new->pfn == entry->pfn)
                         goto err_out;
 
@@ -88,64 +84,6 @@ unsigned long __pfn_to_mfn(unsigned long pfn)
 }
 EXPORT_SYMBOL_GPL(__pfn_to_mfn);
 
-static int xen_add_mach_to_phys_entry(struct xen_p2m_entry *new)
-{
-        struct rb_node **link = &mach_to_phys.rb_node;
-        struct rb_node *parent = NULL;
-        struct xen_p2m_entry *entry;
-        int rc = 0;
-
-        while (*link) {
-                parent = *link;
-                entry = rb_entry(parent, struct xen_p2m_entry, rbnode_mach);
-
-                if (new->mfn == entry->mfn)
-                        goto err_out;
-                if (new->pfn == entry->pfn)
-                        goto err_out;
-
-                if (new->mfn < entry->mfn)
-                        link = &(*link)->rb_left;
-                else
-                        link = &(*link)->rb_right;
-        }
-        rb_link_node(&new->rbnode_mach, parent, link);
-        rb_insert_color(&new->rbnode_mach, &mach_to_phys);
-        goto out;
-
-err_out:
-        rc = -EINVAL;
-        pr_warn("%s: cannot add pfn=%pa -> mfn=%pa: pfn=%pa -> mfn=%pa already exists\n",
-                        __func__, &new->pfn, &new->mfn, &entry->pfn, &entry->mfn);
-out:
-        return rc;
-}
-
-unsigned long __mfn_to_pfn(unsigned long mfn)
-{
-        struct rb_node *n = mach_to_phys.rb_node;
-        struct xen_p2m_entry *entry;
-        unsigned long irqflags;
-
-        read_lock_irqsave(&p2m_lock, irqflags);
-        while (n) {
-                entry = rb_entry(n, struct xen_p2m_entry, rbnode_mach);
-                if (entry->mfn <= mfn &&
-                                entry->mfn + entry->nr_pages > mfn) {
-                        read_unlock_irqrestore(&p2m_lock, irqflags);
-                        return entry->pfn + (mfn - entry->mfn);
-                }
-                if (mfn < entry->mfn)
-                        n = n->rb_left;
-                else
-                        n = n->rb_right;
-        }
-        read_unlock_irqrestore(&p2m_lock, irqflags);
-
-        return INVALID_P2M_ENTRY;
-}
-EXPORT_SYMBOL_GPL(__mfn_to_pfn);
-
 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)
@@ -192,7 +130,6 @@ bool __set_phys_to_machine_multi(unsigned long pfn,
                         p2m_entry = rb_entry(n, struct xen_p2m_entry, rbnode_phys);
                         if (p2m_entry->pfn <= pfn &&
                                         p2m_entry->pfn + p2m_entry->nr_pages > pfn) {
-                                rb_erase(&p2m_entry->rbnode_mach, &mach_to_phys);
                                 rb_erase(&p2m_entry->rbnode_phys, &phys_to_mach);
                                 write_unlock_irqrestore(&p2m_lock, irqflags);
                                 kfree(p2m_entry);
@@ -217,8 +154,7 @@ bool __set_phys_to_machine_multi(unsigned long pfn,
         p2m_entry->mfn = mfn;
 
         write_lock_irqsave(&p2m_lock, irqflags);
-        if ((rc = xen_add_phys_to_mach_entry(p2m_entry) < 0) ||
-                (rc = xen_add_mach_to_phys_entry(p2m_entry) < 0)) {
+        if ((rc = xen_add_phys_to_mach_entry(p2m_entry)) < 0) {
                 write_unlock_irqrestore(&p2m_lock, irqflags);
                 return false;
         }