| Message ID | 20200214001905.20065-1-desnesn@linux.ibm.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | powerpc: fix hardware PMU exception bug on PowerVM compatibility mode systems | expand |
| Context | Check | Description |
|---|---|---|
| snowpatch_ozlabs/apply_patch | success | Successfully applied on branch powerpc/merge (a5bc6e124219546a81ce334dc9b16483d55e9abf) |
| snowpatch_ozlabs/build-ppc64le | success | Build succeeded |
| snowpatch_ozlabs/build-ppc64be | success | Build succeeded |
| snowpatch_ozlabs/build-ppc64e | success | Build succeeded |
| snowpatch_ozlabs/build-pmac32 | success | Build succeeded |
| snowpatch_ozlabs/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 8 lines checked |
| snowpatch_ozlabs/needsstable | warning | Please consider tagging this patch for stable! |
Hello Desnes, thanks for the patch. On Thu, 2020-02-13 at 21:19 -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 <desnesn@linux.ibm.com> > --- > arch/powerpc/kernel/cputable.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/arch/powerpc/kernel/cputable.c b/arch/powerpc/kernel/cputable.c > index e745abc5457a..5bfef6263dfb 100644 > --- a/arch/powerpc/kernel/cputable.c > +++ b/arch/powerpc/kernel/cputable.c > @@ -2198,6 +2198,8 @@ static struct cpu_spec * __init setup_cpu_spec(unsigned long offset, > if (old.oprofile_cpu_type != NULL) { > t->oprofile_cpu_type = old.oprofile_cpu_type; > t->oprofile_type = old.oprofile_type; > + if (old.cpu_features & CPU_FTR_PMAO_BUG) > + t->cpu_features |= CPU_FTR_PMAO_BUG; > } > } > What are your thoughts about doing: t->cpu_features |= old.cpu_features & CPU_FTR_PMAO_BUG; Also, I would recommend adding a short comment on top of the added lines explaining why it is needed. Best regards, Leonardo Bras
diff --git a/arch/powerpc/kernel/cputable.c b/arch/powerpc/kernel/cputable.c index e745abc5457a..5bfef6263dfb 100644 --- a/arch/powerpc/kernel/cputable.c +++ b/arch/powerpc/kernel/cputable.c @@ -2198,6 +2198,8 @@ static struct cpu_spec * __init setup_cpu_spec(unsigned long offset, if (old.oprofile_cpu_type != NULL) { t->oprofile_cpu_type = old.oprofile_cpu_type; t->oprofile_type = old.oprofile_type; + if (old.cpu_features & CPU_FTR_PMAO_BUG) + t->cpu_features |= CPU_FTR_PMAO_BUG; } }
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 <desnesn@linux.ibm.com> --- arch/powerpc/kernel/cputable.c | 2 ++ 1 file changed, 2 insertions(+)