powerpc/pseries: Add a warning in the case of cross-cpu VPA registration

The spec says it "may be problematic" if CPU x registers the VPA of
CPU y. Add a warning in case we ever do that.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/arch/powerpc/platforms/pseries/lpar.c b/arch/powerpc/platforms/pseries/lpar.c
index 6d5e932b615a..356bc75ca74f 100644
--- a/arch/powerpc/platforms/pseries/lpar.c
+++ b/arch/powerpc/platforms/pseries/lpar.c
@@ -68,6 +68,12 @@ void vpa_init(int cpu)
         struct paca_struct *pp;
         struct dtl_entry *dtl;
 
+        /*
+         * The spec says it "may be problematic" if CPU x registers the VPA of
+         * CPU y. We should never do that, but wail if we ever do.
+         */
+        WARN_ON(cpu != smp_processor_id());
+
         if (cpu_has_feature(CPU_FTR_ALTIVEC))
                 lppaca_of(cpu).vmxregs_in_use = 1;