2 files changed, 23 insertions, 0 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 71d05f481727..766abdab94e7 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1363,6 +1363,11 @@ running once the system is up.
 
         reserve=        [KNL,BUGS] Force the kernel to ignore some iomem area
 
+        reservetop=     [IA-32]
+                        Format: nn[KMG]
+                        Reserves a hole at the top of the kernel virtual
+                        address space.
+
         resume=         [SWSUSP]
                         Specify the partition device for software suspend
 
diff --git a/arch/i386/kernel/setup.c b/arch/i386/kernel/setup.c
index 060c68004bec..16d99444cf66 100644
--- a/arch/i386/kernel/setup.c
+++ b/arch/i386/kernel/setup.c
@@ -935,6 +935,24 @@ static void __init parse_cmdline_early (char ** cmdline_p)
 }
 
 /*
+ * reservetop=size reserves a hole at the top of the kernel address space which
+ * a hypervisor can load into later.  Needed for dynamically loaded hypervisors,
+ * so relocating the fixmap can be done before paging initialization.
+ */
+static int __init parse_reservetop(char *arg)
+{
+        unsigned long address;
+
+        if (!arg)
+                return -EINVAL;
+
+        address = memparse(arg, &arg);
+        reserve_top_address(address);
+        return 0;
+}
+early_param("reservetop", parse_reservetop);
+
+/*
  * Callback for efi_memory_walk.
  */
 static int __init