xen/smp/pvhvm: Don't point per_cpu(xen_vpcu, 33 and larger) to shared_info

As it will point to some data, but not event channel data (the
shared_info has an array limited to 32).

This means that for PVHVM guests with more than 32 VCPUs without
the usage of VCPUOP_register_info any interrupts to VCPUs
larger than 32 would have gone unnoticed during early bootup.

That is OK, as during early bootup, in smp_init we end up calling
the hotplug mechanism (xen_hvm_cpu_notify) which makes the
VCPUOP_register_vcpu_info call for all VCPUs and we can receive
interrupts on VCPUs 33 and further.

This is just a cleanup.

Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index a2babdb..31e19f9 100644 (file)
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1646,6 +1646,9 @@ void __ref xen_hvm_init_shared_info(void)
         * online but xen_hvm_init_shared_info is run at resume time too and
         * in that case multiple vcpus might be online. */
        for_each_online_cpu(cpu) {
+               /* Leave it to be NULL. */
+               if (cpu >= MAX_VIRT_CPUS)
+                       continue;
                per_cpu(xen_vcpu, cpu) = &HYPERVISOR_shared_info->vcpu_info[cpu];
        }
 }