powerpc/64s/powernv: Fix memory corruption when saving SLB entries on MCE

This can be hit by an HPT guest running on an HPT host and bring down
the host, so it's quite important to fix.

Fixes: 7290f3b3d3e6 ("powerpc/64s/powernv: machine check dump SLB contents")
Cc: stable@vger.kernel.org # v5.4+
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Acked-by: Mahesh Salgaonkar <mahesh@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201128070728.825934-2-npiggin@gmail.com

diff --git a/arch/powerpc/platforms/powernv/setup.c b/arch/powerpc/platforms/powernv/setup.c
index 46115231a3b2b516bf27d465bf7b161095a967ab..4426a109ec2f4390044e74a62218166bd5805292 100644 (file)
--- a/arch/powerpc/platforms/powernv/setup.c
+++ b/arch/powerpc/platforms/powernv/setup.c
@@ -211,11 +211,16 @@ static void __init pnv_init(void)
                add_preferred_console("hvc", 0, NULL);
 
        if (!radix_enabled()) {
+               size_t size = sizeof(struct slb_entry) * mmu_slb_size;
                int i;
 
                /* Allocate per cpu area to save old slb contents during MCE */
-               for_each_possible_cpu(i)
-                       paca_ptrs[i]->mce_faulty_slbs = memblock_alloc_node(mmu_slb_size, __alignof__(*paca_ptrs[i]->mce_faulty_slbs), cpu_to_node(i));
+               for_each_possible_cpu(i) {
+                       paca_ptrs[i]->mce_faulty_slbs =
+                                       memblock_alloc_node(size,
+                                               __alignof__(struct slb_entry),
+                                               cpu_to_node(i));
+               }
        }
 }