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authorBoris Ostrovsky <boris.ostrovsky@oracle.com>2016-10-05 13:09:33 -0400
committerDavid Vrabel <david.vrabel@citrix.com>2016-10-06 11:47:05 +0100
commita6a198bc60e6c980a56eca24d33dc7f29139f8ea (patch)
treee2a4adc45aabc5a1cc0e5529166ab9ca15cd7fee
parent565fdc6a2afeb14e654a8d9ebc792afb9d2c0019 (diff)
downloadlinux-a6a198bc60e6c980a56eca24d33dc7f29139f8ea.tar.bz2
xen/x86: Update topology map for PV VCPUs
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> Cc: stable@vger.kernel.org Signed-off-by: David Vrabel <david.vrabel@citrix.com>
-rw-r--r--arch/x86/xen/smp.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
index 311acad7dad2..9fa27ceeecfd 100644
--- 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);