[Xen-devel] [PATCH] Make ballooning work with maxmem > mem

[Glauber de Oliveira Costa <gcosta@xxxxxxxxxx>]

Trying to start a guest with maxmem > mem and then balloon up to a value
greater than mem is currently failing.

This patch fixes it.

-- 
Glauber de Oliveira Costa
Red Hat Inc.
"Free as in Freedom"

# HG changeset patch
# User gcosta@xxxxxxxxxx
# Date 1163006677 18000
# Node ID 8347687597a4da4ed323e58e640da89b25bb2c49
# Parent  20204db0891b0b7c10959822e3283656c3600500
[LINUX] Extend physical mapping to maxmem instead of mem

As currently physical mapping only reaches the initial reservation,
we're unable to balloon up to more than mem (even when maxmem > mem)
in any situation.

Signed-off-by: Glauber de Oliveira Costa <gcosta@xxxxxxxxxx>

diff -r 20204db0891b -r 8347687597a4 
linux-2.6-xen-sparse/arch/x86_64/kernel/e820-xen.c
--- a/linux-2.6-xen-sparse/arch/x86_64/kernel/e820-xen.c        Thu Nov 02 
18:52:04 2006 +0000
+++ b/linux-2.6-xen-sparse/arch/x86_64/kernel/e820-xen.c        Wed Nov 08 
12:24:37 2006 -0500
@@ -583,6 +583,7 @@ void __init setup_memory_region(void)
         * the boot process we know we have plenty slack space.
         */
        struct e820entry map[E820MAX];
+       unsigned long arg = DOMID_SELF;
 
        memmap.nr_entries = E820MAX;
        set_xen_guest_handle(memmap.buffer, map);
@@ -591,7 +592,11 @@ void __init setup_memory_region(void)
        if ( rc == -ENOSYS ) {
                memmap.nr_entries = 1;
                map[0].addr = 0ULL;
-               map[0].size = xen_start_info->nr_pages << PAGE_SHIFT;
+               rc = HYPERVISOR_memory_op(XENMEM_maximum_reservation, &arg);
+               if ( rc  < 0 )
+                       map[0].size = xen_start_info->nr_pages << PAGE_SHIFT;
+               else
+                       map[0].size = rc << PAGE_SHIFT;
                /* 8MB slack (to balance backend allocations). */
                map[0].size += 8 << 20;
                map[0].type = E820_RAM;

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