xen: support large numbers of CPUs with vcpu info placement
When vcpu info placement is supported, we're not limited to MAX_VIRT_CPUS
vcpus. However, if it isn't supported, then ignore any excess vcpus.
Signed-off-by: Mukesh Rathor <mukesh.rathor@oracle.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index fef034a..90a3e80 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -97,6 +97,14 @@
*/
static int have_vcpu_info_placement = 1;
+static void clamp_max_cpus(void)
+{
+#ifdef CONFIG_SMP
+ if (setup_max_cpus > MAX_VIRT_CPUS)
+ setup_max_cpus = MAX_VIRT_CPUS;
+#endif
+}
+
static void xen_vcpu_setup(int cpu)
{
struct vcpu_register_vcpu_info info;
@@ -104,13 +112,17 @@
struct vcpu_info *vcpup;
BUG_ON(HYPERVISOR_shared_info == &xen_dummy_shared_info);
- per_cpu(xen_vcpu, cpu) = &HYPERVISOR_shared_info->vcpu_info[cpu];
- if (!have_vcpu_info_placement)
- return; /* already tested, not available */
+ if (cpu < MAX_VIRT_CPUS)
+ per_cpu(xen_vcpu,cpu) = &HYPERVISOR_shared_info->vcpu_info[cpu];
+
+ if (!have_vcpu_info_placement) {
+ if (cpu >= MAX_VIRT_CPUS)
+ clamp_max_cpus();
+ return;
+ }
vcpup = &per_cpu(xen_vcpu_info, cpu);
-
info.mfn = arbitrary_virt_to_mfn(vcpup);
info.offset = offset_in_page(vcpup);
@@ -125,6 +137,7 @@
if (err) {
printk(KERN_DEBUG "register_vcpu_info failed: err=%d\n", err);
have_vcpu_info_placement = 0;
+ clamp_max_cpus();
} else {
/* This cpu is using the registered vcpu info, even if
later ones fail to. */
