| From a6a198bc60e6c980a56eca24d33dc7f29139f8ea Mon Sep 17 00:00:00 2001 |
| From: Boris Ostrovsky <boris.ostrovsky@oracle.com> |
| Date: Wed, 5 Oct 2016 13:09:33 -0400 |
| Subject: xen/x86: Update topology map for PV VCPUs |
| |
| From: Boris Ostrovsky <boris.ostrovsky@oracle.com> |
| |
| commit a6a198bc60e6c980a56eca24d33dc7f29139f8ea upstream. |
| |
| Early during boot topology_update_package_map() computes |
| logical_pkg_ids for all present processors. |
| |
| Later, when processors are brought up, identify_cpu() updates |
| these values based on phys_pkg_id which is a function of |
| initial_apicid. On PV guests the latter may point to a |
| non-existing node, causing logical_pkg_ids to be set to -1. |
| |
| Intel's RAPL uses logical_pkg_id (as topology_logical_package_id()) |
| to index its arrays and therefore in this case will point to index |
| 65535 (since logical_pkg_id is a u16). This could lead to either a |
| crash or may actually access random memory location. |
| |
| As a workaround, we recompute topology during CPU bringup to reset |
| logical_pkg_id to a valid value. |
| |
| (The reason for initial_apicid being bogus is because it is |
| initial_apicid of the processor from which the guest is launched. |
| This value is CPUID(1).EBX[31:24]) |
| |
| Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> |
| Signed-off-by: David Vrabel <david.vrabel@citrix.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| arch/x86/xen/smp.c | 6 ++++++ |
| 1 file changed, 6 insertions(+) |
| |
| --- a/arch/x86/xen/smp.c |
| +++ b/arch/x86/xen/smp.c |
| @@ -87,6 +87,12 @@ static void cpu_bringup(void) |
| cpu_data(cpu).x86_max_cores = 1; |
| set_cpu_sibling_map(cpu); |
| |
| + /* |
| + * identify_cpu() may have set logical_pkg_id to -1 due |
| + * to incorrect phys_proc_id. Let's re-comupte it. |
| + */ |
| + topology_update_package_map(apic->cpu_present_to_apicid(cpu), cpu); |
| + |
| xen_setup_cpu_clockevents(); |
| |
| notify_cpu_starting(cpu); |
