1 files changed, 81 insertions, 0 deletions

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index d669e9d89001..c9081c6671f0 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1,8 +1,12 @@
+#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
+#include <linux/bootmem.h>
+#endif
 #include <linux/cpu.h>
 #include <linux/kexec.h>
 
 #include <xen/features.h>
 #include <xen/page.h>
+#include <xen/interface/memory.h>
 
 #include <asm/xen/hypercall.h>
 #include <asm/xen/hypervisor.h>
@@ -331,3 +335,80 @@ void xen_arch_unregister_cpu(int num)
 }
 EXPORT_SYMBOL(xen_arch_unregister_cpu);
 #endif
+
+#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
+void __init arch_xen_balloon_init(struct resource *hostmem_resource)
+{
+        struct xen_memory_map memmap;
+        int rc;
+        unsigned int i, last_guest_ram;
+        phys_addr_t max_addr = PFN_PHYS(max_pfn);
+        struct e820_table *xen_e820_table;
+        const struct e820_entry *entry;
+        struct resource *res;
+
+        if (!xen_initial_domain())
+                return;
+
+        xen_e820_table = kmalloc(sizeof(*xen_e820_table), GFP_KERNEL);
+        if (!xen_e820_table)
+                return;
+
+        memmap.nr_entries = ARRAY_SIZE(xen_e820_table->entries);
+        set_xen_guest_handle(memmap.buffer, xen_e820_table->entries);
+        rc = HYPERVISOR_memory_op(XENMEM_machine_memory_map, &memmap);
+        if (rc) {
+                pr_warn("%s: Can't read host e820 (%d)\n", __func__, rc);
+                goto out;
+        }
+
+        last_guest_ram = 0;
+        for (i = 0; i < memmap.nr_entries; i++) {
+                if (xen_e820_table->entries[i].addr >= max_addr)
+                        break;
+                if (xen_e820_table->entries[i].type == E820_TYPE_RAM)
+                        last_guest_ram = i;
+        }
+
+        entry = &xen_e820_table->entries[last_guest_ram];
+        if (max_addr >= entry->addr + entry->size)
+                goto out; /* No unallocated host RAM. */
+
+        hostmem_resource->start = max_addr;
+        hostmem_resource->end = entry->addr + entry->size;
+
+        /*
+         * Mark non-RAM regions between the end of dom0 RAM and end of host RAM
+         * as unavailable. The rest of that region can be used for hotplug-based
+         * ballooning.
+         */
+        for (; i < memmap.nr_entries; i++) {
+                entry = &xen_e820_table->entries[i];
+
+                if (entry->type == E820_TYPE_RAM)
+                        continue;
+
+                if (entry->addr >= hostmem_resource->end)
+                        break;
+
+                res = kzalloc(sizeof(*res), GFP_KERNEL);
+                if (!res)
+                        goto out;
+
+                res->name = "Unavailable host RAM";
+                res->start = entry->addr;
+                res->end = (entry->addr + entry->size < hostmem_resource->end) ?
+                            entry->addr + entry->size : hostmem_resource->end;
+                rc = insert_resource(hostmem_resource, res);
+                if (rc) {
+                        pr_warn("%s: Can't insert [%llx - %llx) (%d)\n",
+                                __func__, res->start, res->end, rc);
+                        kfree(res);
+                        goto  out;
+                }
+        }
+
+ out:
+        kfree(xen_e820_table);
+}
+#endif /* CONFIG_XEN_BALLOON_MEMORY_HOTPLUG */