| Message ID | 20200301111717.22236-1-mpe@ellerman.id.au (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | [1/2] powerpc: fix hardware PMU exception bug on PowerVM compatibility mode systems | expand |
Michael Ellerman <mpe@ellerman.id.au> writes: > From: "Desnes A. Nunes do Rosario" <desnesn@linux.ibm.com> > > 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> > Reviewed-by: Leonardo Bras <leonardo@linux.ibm.com> > Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> > Link: https://lore.kernel.org/r/20200227134715.9715-1-desnesn@linux.ibm.com > --- > arch/powerpc/kernel/cputable.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) Ignore, PEBKAC. Don't try to operate git-send-email after 10pm. cheers > 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; > } > } > > -- > 2.21.1
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; } }