From: Paul Burton paul.burton@imgtec.com
[ Upstream commit 5570ba2ee920de4e7760a2802b842771845b2c32 ]
Systems using the MIPS Coherence Manager (CM) cannot support multi-core SMP with dcache aliasing. This is because CPU caches are VIPT, but interventions in CM-based systems provide only the physical address to remote caches. This means that interventions may behave incorrectly in the presence of an aliasing dcache, since the physical address used when handling an intervention may lead to operation on an aliased cache line rather than the correct line.
Prevent us from running into this issue by refusing to boot secondary cores in systems where dcache aliasing may occur.
Signed-off-by: Paul Burton paul.burton@imgtec.com Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/16196/ Signed-off-by: Ralf Baechle ralf@linux-mips.org Signed-off-by: Sasha Levin alexander.levin@microsoft.com --- arch/mips/kernel/smp-cps.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/arch/mips/kernel/smp-cps.c b/arch/mips/kernel/smp-cps.c index e04c8057b882..ff0993dfeb08 100644 --- a/arch/mips/kernel/smp-cps.c +++ b/arch/mips/kernel/smp-cps.c @@ -122,9 +122,11 @@ static void __init cps_prepare_cpus(unsigned int max_cpus)
/* Warn the user if the CCA prevents multi-core */ ncores = mips_cm_numcores(); - if (cca_unsuitable && ncores > 1) { - pr_warn("Using only one core due to unsuitable CCA 0x%x\n", - cca); + if ((cca_unsuitable || cpu_has_dc_aliases) && ncores > 1) { + pr_warn("Using only one core due to %s%s%s\n", + cca_unsuitable ? "unsuitable CCA" : "", + (cca_unsuitable && cpu_has_dc_aliases) ? " & " : "", + cpu_has_dc_aliases ? "dcache aliasing" : "");
for_each_present_cpu(c) { if (cpu_data[c].core)