Re: [PATCH] arm64: cpufeature: Enable Qualcomm erratas

Bjorn Andersson
2019-10-29T17:06:39Z

On Tue 29 Oct 05:04 PDT 2019, Suzuki K Poulose wrote:

> On 10/29/2019 11:39 AM, Will Deacon wrote:
> > On Mon, Oct 28, 2019 at 11:04:32PM -0700, Bjorn Andersson wrote:
> > > With the introduction of 'cce360b54ce6 ("arm64: capabilities: Filter the
> > > entries based on a given mask")' the Qualcomm erratas are no long
> > > applied.
> > >
> > > The result of not applying errata 1003 is that MSM8996 runs into various
> > > RCU stalls and fails to boot most of the times.
> > >
> > > Give both 1003 and 1009 a "type" to ensure they are not filtered out in
> > > update_cpu_capabilities().
> >
> > Oh nasty. Thanks for debugging and fixing this.
> >
> > > Fixes: cce360b54ce6 ("arm64: capabilities: Filter the entries based on a given mask")
> > > Cc: stable@vger.kernel.org
> > > Reported-by: Mark Brown <broonie@kernel.org>
> > > Suggested-by: Will Deacon <will@kernel.org>
> > > Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
> > > ---
> > > arch/arm64/kernel/cpu_errata.c | 2 ++
> > > 1 file changed, 2 insertions(+)
> > >
> > > diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
> > > index df9465120e2f..cdd8df033536 100644
> > > --- a/arch/arm64/kernel/cpu_errata.c
> > > +++ b/arch/arm64/kernel/cpu_errata.c
> > > @@ -780,6 +780,7 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
> > > {
> > > .desc = "Qualcomm Technologies Falkor/Kryo erratum 1003",
> > > .capability = ARM64_WORKAROUND_QCOM_FALKOR_E1003,
> > > + .type = ARM64_CPUCAP_SCOPE_LOCAL_CPU,
> > > .matches = cpucap_multi_entry_cap_matches,
> >
> > This should probably be ARM64_CPUCAP_LOCAL_CPU_ERRATUM instead, but I'll
> > want Suzuki's ack before I take the change.
>
> Yes, it must be ARM64_CPUCAP_LOCAL_CPU_ERRATUM.
>

Thanks, will fix.

> It may be a good idea to stick in a check to make sure that the scope is
> set for all the capabilities in a separate patch. e.g,
>
> diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
> index d260e3bdf07b..51a79b4a44eb 100644
> --- a/arch/arm64/kernel/cpufeature.c
> +++ b/arch/arm64/kernel/cpufeature.c
> @@ -546,6 +546,8 @@ static void __init
> init_cpu_hwcaps_indirect_list_from_array(const struct
> arm64_cpu_capabilities *caps)
> {
> for (; caps->matches; caps++) {
> + WARN(!cpucap_default_scope(caps),
> + "Invalid scope for capability %d\n", caps->capability);
> if (WARN(caps->capability >= ARM64_NCAPS,
> "Invalid capability %d\n", caps->capability))
> continue;

In hindsight this would have saved me a considerable amount of time, so
I like this proposal!

Regards,
Bjorn

>
> Otherwise looks good to me.
>
> > > .match_list = qcom_erratum_1003_list,
> > > },
> > > @@ -788,6 +789,7 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
> > > {
> > > .desc = "Qualcomm erratum 1009, ARM erratum 1286807",
> > > .capability = ARM64_WORKAROUND_REPEAT_TLBI,
> > > + .type = ARM64_CPUCAP_SCOPE_LOCAL_CPU,
> > > ERRATA_MIDR_RANGE_LIST(arm64_repeat_tlbi_cpus),
> >
> > ERRATA_MIDR_RANGE_LIST sets the type already, so I think this is redundant.
> >
> > Will
> >
>
>
>
> Cheers
> Suzuki