1 files changed, 52 insertions, 0 deletions

diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
index 7201800e55a..54d93791ddb 100644
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -143,12 +143,55 @@ static unsigned long __init xen_return_unused_memory(unsigned long max_pfn,
         return released;
 }
 
+static unsigned long __init xen_set_identity(const struct e820entry *list,
+                                             ssize_t map_size)
+{
+        phys_addr_t last = xen_initial_domain() ? 0 : ISA_END_ADDRESS;
+        phys_addr_t start_pci = last;
+        const struct e820entry *entry;
+        unsigned long identity = 0;
+        int i;
+
+        for (i = 0, entry = list; i < map_size; i++, entry++) {
+                phys_addr_t start = entry->addr;
+                phys_addr_t end = start + entry->size;
+
+                if (start < last)
+                        start = last;
+
+                if (end <= start)
+                        continue;
+
+                /* Skip over the 1MB region. */
+                if (last > end)
+                        continue;
+
+                if (entry->type == E820_RAM) {
+                        if (start > start_pci)
+                                identity += set_phys_range_identity(
+                                                PFN_UP(start_pci), PFN_DOWN(start));
+
+                        /* Without saving 'last' we would gooble RAM too
+                         * at the end of the loop. */
+                        last = end;
+                        start_pci = end;
+                        continue;
+                }
+                start_pci = min(start, start_pci);
+                last = end;
+        }
+        if (last > start_pci)
+                identity += set_phys_range_identity(
+                                        PFN_UP(start_pci), PFN_DOWN(last));
+        return identity;
+}
 /**
  * machine_specific_memory_setup - Hook for machine specific memory setup.
  **/
 char * __init xen_memory_setup(void)
 {
         static struct e820entry map[E820MAX] __initdata;
+        static struct e820entry map_raw[E820MAX] __initdata;
 
         unsigned long max_pfn = xen_start_info->nr_pages;
         unsigned long long mem_end;
@@ -156,6 +199,7 @@ char * __init xen_memory_setup(void)
         struct xen_memory_map memmap;
         unsigned long extra_pages = 0;
         unsigned long extra_limit;
+        unsigned long identity_pages = 0;
         int i;
         int op;
 
@@ -181,6 +225,7 @@ char * __init xen_memory_setup(void)
         }
         BUG_ON(rc);
 
+        memcpy(map_raw, map, sizeof(map));
         e820.nr_map = 0;
         xen_extra_mem_start = mem_end;
         for (i = 0; i < memmap.nr_entries; i++) {
@@ -251,6 +296,13 @@ char * __init xen_memory_setup(void)
 
         xen_add_extra_mem(extra_pages);
 
+        /*
+         * Set P2M for all non-RAM pages and E820 gaps to be identity
+         * type PFNs. We supply it with the non-sanitized version
+         * of the E820.
+         */
+        identity_pages = xen_set_identity(map_raw, memmap.nr_entries);
+        printk(KERN_INFO "Set %ld page(s) to 1-1 mapping.\n", identity_pages);
         return "Xen";
 }