1 files changed, 112 insertions, 4 deletions

diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
index 7b0ab77b8479..710af36e6dfb 100644
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -26,7 +26,6 @@
 #include <xen/interface/memory.h>
 #include <xen/interface/physdev.h>
 #include <xen/features.h>
-
 #include "xen-ops.h"
 #include "vdso.h"
 
@@ -120,7 +119,105 @@ static unsigned long __init xen_release_chunk(unsigned long start,
 
         return len;
 }
+static unsigned long __init xen_populate_physmap(unsigned long start,
+                                                 unsigned long end)
+{
+        struct xen_memory_reservation reservation = {
+                .address_bits = 0,
+                .extent_order = 0,
+                .domid        = DOMID_SELF
+        };
+        unsigned long len = 0;
+        int ret;
+
+        for (pfn = start; pfn < end; pfn++) {
+                unsigned long frame;
+
+                /* Make sure pfn does not exists to start with */
+                if (pfn_to_mfn(pfn) != INVALID_P2M_ENTRY)
+                        continue;
 
+                frame = pfn;
+                set_xen_guest_handle(reservation.extent_start, &frame);
+                reservation.nr_extents = 1;
+
+                ret = HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation);
+                WARN(ret != 1, "Failed to populate pfn %lx err=%d\n", pfn, ret);
+                if (ret == 1) {
+                        if (!early_set_phys_to_machine(pfn, frame)) {
+                                set_xen_guest_handle(reservation.extent_start, &frame);
+                                reservation.nr_extents = 1;
+                                ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation,
+                                                        &reservation);
+                                break;
+                        }
+                        len++;
+                } else
+                        break;
+        }
+        if (len)
+                printk(KERN_INFO "Populated %lx-%lx pfn range: %lu pages added\n",
+                       start, end, len);
+        return len;
+}
+static unsigned long __init xen_populate_chunk(
+        const struct e820entry *list, size_t map_size,
+        unsigned long max_pfn, unsigned long *last_pfn,
+        unsigned long credits_left)
+{
+        const struct e820entry *entry;
+        unsigned int i;
+        unsigned long done = 0;
+        unsigned long dest_pfn;
+
+        for (i = 0, entry = list; i < map_size; i++, entry++) {
+                unsigned long credits = credits_left;
+                unsigned long s_pfn;
+                unsigned long e_pfn;
+                unsigned long pfns;
+                long capacity;
+
+                if (credits <= 0)
+                        break;
+
+                if (entry->type != E820_RAM)
+                        continue;
+
+                e_pfn = PFN_UP(entry->addr + entry->size);
+
+                /* We only care about E820 after the xen_start_info->nr_pages */
+                if (e_pfn <= max_pfn)
+                        continue;
+
+                s_pfn = PFN_DOWN(entry->addr);
+                /* If the E820 falls within the nr_pages, we want to start
+                 * at the nr_pages PFN.
+                 * If that would mean going past the E820 entry, skip it
+                 */
+                if (s_pfn <= max_pfn) {
+                        capacity = e_pfn - max_pfn;
+                        dest_pfn = max_pfn;
+                } else {
+                        /* last_pfn MUST be within E820_RAM regions */
+                        if (*last_pfn && e_pfn >= *last_pfn)
+                                s_pfn = *last_pfn;
+                        capacity = e_pfn - s_pfn;
+                        dest_pfn = s_pfn;
+                }
+                /* If we had filled this E820_RAM entry, go to the next one. */
+                if (capacity <= 0)
+                        continue;
+
+                if (credits > capacity)
+                        credits = capacity;
+
+                pfns = xen_populate_physmap(dest_pfn, dest_pfn + credits);
+                done += pfns;
+                credits_left -= pfns;
+                *last_pfn = (dest_pfn + pfns);
+        }
+        return done;
+}
 static unsigned long __init xen_set_identity_and_release(
         const struct e820entry *list, size_t map_size, unsigned long nr_pages)
 {
@@ -143,7 +240,6 @@ static unsigned long __init xen_set_identity_and_release(
          */
         for (i = 0, entry = list; i < map_size; i++, entry++) {
                 phys_addr_t end = entry->addr + entry->size;
-
                 if (entry->type == E820_RAM || i == map_size - 1) {
                         unsigned long start_pfn = PFN_DOWN(start);
                         unsigned long end_pfn = PFN_UP(end);
@@ -220,7 +316,9 @@ char * __init xen_memory_setup(void)
         int rc;
         struct xen_memory_map memmap;
         unsigned long max_pages;
+        unsigned long last_pfn = 0;
         unsigned long extra_pages = 0;
+        unsigned long populated;
         int i;
         int op;
 
@@ -260,9 +358,20 @@ char * __init xen_memory_setup(void)
          */
         xen_released_pages = xen_set_identity_and_release(
                 map, memmap.nr_entries, max_pfn);
-        extra_pages += xen_released_pages;
 
         /*
+         * Populate back the non-RAM pages and E820 gaps that had been
+         * released. */
+        populated = xen_populate_chunk(map, memmap.nr_entries,
+                        max_pfn, &last_pfn, xen_released_pages);
+
+        extra_pages += (xen_released_pages - populated);
+
+        if (last_pfn > max_pfn) {
+                max_pfn = min(MAX_DOMAIN_PAGES, last_pfn);
+                mem_end = PFN_PHYS(max_pfn);
+        }
+        /*
          * Clamp the amount of extra memory to a EXTRA_MEM_RATIO
          * factor the base size.  On non-highmem systems, the base
          * size is the full initial memory allocation; on highmem it
@@ -275,7 +384,6 @@ char * __init xen_memory_setup(void)
          */
         extra_pages = min(EXTRA_MEM_RATIO * min(max_pfn, PFN_DOWN(MAXMEM)),
                           extra_pages);
-
         i = 0;
         while (i < memmap.nr_entries) {
                 u64 addr = map[i].addr;