4.17-stable review patch. If anyone has any objections, please let me know.
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From: Nicholas Piggin npiggin@gmail.com
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@kernel.org Reported-by: Pridhiviraj Paidipeddi ppaidipe@linux.vnet.ibm.com Tested-by: Pridhiviraj Paidipeddi ppaidipe@linux.vnet.ibm.com Signed-off-by: Nicholas Piggin npiggin@gmail.com Signed-off-by: Michael Ellerman mpe@ellerman.id.au Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- 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; }