On Thu, 2020-02-27 at 10:47 -0300, Desnes A. Nunes do Rosario wrote:
> PowerVM systems running compatibility mode on a few Power8 revisions are
> still vulnerable to the hardware defect that loses PMU exceptions arriving
> prior to a context switch.
>
> The software fix for this issue is enabled through the CPU_FTR_PMAO_BUG
> cpu_feature bit, nevertheless this bit also needs to be set for PowerVM
> compatibility mode systems.
>
> Fixes: 68f2f0d431d9ea4 ("powerpc: Add a cpu feature CPU_FTR_PMAO_BUG")
> Signed-off-by: Desnes A. Nunes do Rosario <desn...@linux.ibm.com>
> ---
> arch/powerpc/kernel/cputable.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/kernel/cputable.c b/arch/powerpc/kernel/cputable.c
> index e745abc5457a..245be4fafe13 100644
> --- a/arch/powerpc/kernel/cputable.c
> +++ b/arch/powerpc/kernel/cputable.c
> @@ -2193,11 +2193,13 @@ static struct cpu_spec * __init
> setup_cpu_spec(unsigned long offset,
> * oprofile_cpu_type already has a value, then we are
> * possibly overriding a real PVR with a logical one,
> * and, in that case, keep the current value for
> - * oprofile_cpu_type.
> + * oprofile_cpu_type. Futhermore, let's ensure that the
> + * fix for the PMAO bug is enabled on compatibility mode.
> */
> if (old.oprofile_cpu_type != NULL) {
> t->oprofile_cpu_type = old.oprofile_cpu_type;
> t->oprofile_type = old.oprofile_type;
> + t->cpu_features |= old.cpu_features & CPU_FTR_PMAO_BUG;
> }
> }
> Looks good to me. Reviewed-by: Leonardo Bras <leona...@linux.ibm.com>
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