From: Desnes A. Nunes do Rosario Date: Thu, 27 Feb 2020 13:47:15 +0000 (-0300) Subject: powerpc: fix hardware PMU exception bug on PowerVM compatibility mode systems X-Git-Tag: v5.6-rc5~12^2~1 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=fc37a1632d40c80c067eb1bc235139f5867a2667;p=thirdparty%2Fkernel%2Flinux.git powerpc: fix hardware PMU exception bug on PowerVM compatibility mode systems 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 Reviewed-by: Leonardo Bras Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20200227134715.9715-1-desnesn@linux.ibm.com --- diff --git a/arch/powerpc/kernel/cputable.c b/arch/powerpc/kernel/cputable.c index e745abc5457a0..245be4fafe134 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; } }