4.17-stable review patch. If anyone has any objections, please let me know.
------------------
From: Nicholas Piggin <npiggin@xxxxxxxxx>
commit 758380b8155f69b4e2f77f27562f8a7a466749d6 upstream.
If possible CPUs are limited (e.g., by kexec), then the kvm prefetch
workaround function can access the paca pointer for a !possible CPU.
Fixes: d2e60075a3d44 ("powerpc/64: Use array of paca pointers and allocate pacas individually")
Cc: stable@xxxxxxxxxx
Reported-by: Pridhiviraj Paidipeddi <ppaidipe@xxxxxxxxxxxxxxxxxx>
Tested-by: Pridhiviraj Paidipeddi <ppaidipe@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Nicholas Piggin <npiggin@xxxxxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/powerpc/mm/tlb-radix.c | 2 ++
1 file changed, 2 insertions(+)
--- a/arch/powerpc/mm/tlb-radix.c
+++ b/arch/powerpc/mm/tlb-radix.c
@@ -733,6 +733,8 @@ extern void radix_kvm_prefetch_workaroun
for (; sib <= cpu_last_thread_sibling(cpu) && !flush; sib++) {
if (sib == cpu)
continue;
+ if (!cpu_possible(sib))
+ continue;
if (paca_ptrs[sib]->kvm_hstate.kvm_vcpu)
flush = true;
}
