From: Satheesh Rajendran sathnaga@linux.vnet.ibm.com
commit b710d27bf72068b15b2f0305d825988183e2ff28 upstream.
Early secure guest boot hits the below crash while booting with vcpus numbers aligned with page boundary for PAGE size of 64k and LPPACA size of 1k i.e 64, 128 etc.
Partition configured for 64 cpus. CPU maps initialized for 1 thread per core ------------[ cut here ]------------ kernel BUG at arch/powerpc/kernel/paca.c:89! Oops: Exception in kernel mode, sig: 5 [#1] LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=2048 NUMA pSeries
This is due to the BUG_ON() for shared_lppaca_total_size equal to shared_lppaca_size. Instead the code should only BUG_ON() if we have exceeded the total_size, which indicates we've overflowed the array.
Fixes: bd104e6db6f0 ("powerpc/pseries/svm: Use shared memory for LPPACA structures") Cc: stable@vger.kernel.org # v5.4+ Signed-off-by: Satheesh Rajendran sathnaga@linux.vnet.ibm.com Reviewed-by: Laurent Dufour ldufour@linux.ibm.com Reviewed-by: Thiago Jung Bauermann bauerman@linux.ibm.com [mpe: Reword change log to clarify we're fixing not removing the check] Signed-off-by: Michael Ellerman mpe@ellerman.id.au Link: https://lore.kernel.org/r/20200619070113.16696-1-sathnaga@linux.vnet.ibm.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/powerpc/kernel/paca.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/powerpc/kernel/paca.c +++ b/arch/powerpc/kernel/paca.c @@ -86,7 +86,7 @@ static void *__init alloc_shared_lppaca( * This is very early in boot, so no harm done if the kernel crashes at * this point. */ - BUG_ON(shared_lppaca_size >= shared_lppaca_total_size); + BUG_ON(shared_lppaca_size > shared_lppaca_total_size);
return ptr; }