xen: ask the hypervisor how much space it needs reserved
Ask the hypervisor how much space it needs reserved, since 32-on-64
doesn't need any space, and it may change in future.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 4186cb6..bc7bf5f 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1112,6 +1112,17 @@
};
+static void __init xen_reserve_top(void)
+{
+ unsigned long top = HYPERVISOR_VIRT_START;
+ struct xen_platform_parameters pp;
+
+ if (HYPERVISOR_xen_version(XENVER_platform_parameters, &pp) == 0)
+ top = pp.virt_start;
+
+ reserve_top_address(-top + 2 * PAGE_SIZE);
+}
+
/* First C function to be called on Xen boot */
asmlinkage void __init xen_start_kernel(void)
{
@@ -1169,7 +1180,7 @@
pv_info.kernel_rpl = 0;
/* set the limit of our address space */
- reserve_top_address(-HYPERVISOR_VIRT_START + 2 * PAGE_SIZE);
+ xen_reserve_top();
/* set up basic CPUID stuff */
cpu_detect(&new_cpu_data);