Messages in this thread | | | Subject | Re: [PATCH] arm64: Run enable method for errata work arounds on late CPUs | From | Suzuki K Poulose <> | Date | Wed, 17 Jan 2018 14:04:38 +0000 |
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On 17/01/18 13:43, Robin Murphy wrote: > On 17/01/18 13:31, Suzuki K Poulose wrote: >> On 17/01/18 13:20, Robin Murphy wrote: >>> On 17/01/18 12:25, Dave Martin wrote: >>>> On Wed, Jan 17, 2018 at 10:05:56AM +0000, Suzuki K Poulose wrote: >>>>> When a CPU is brought up after we have finalised the system >>>>> wide capabilities (i.e, features and errata), we make sure the >>>>> new CPU doesn't need a new errata work around which has not been >>>>> detected already. However we don't run enable() method on the new >>>>> CPU for the errata work arounds already detected. This could >>>>> cause the new CPU running without potential work arounds. >>>>> It is upto the "enable()" method to decide if this CPU should >>>>> do something about the errata. >>>>> >>>>> Fixes: commit 6a6efbb45b7d95c84 ("arm64: Verify CPU errata work arounds on hotplugged CPU") >>>>> Cc: Will Deacon <will.deacon@arm.com> >>>>> Cc: Mark Rutland <mark.rutland@arm.com> >>>>> Cc: Andre Przywara <andre.przywara@arm.com> >>>>> Cc: Catalin Marinas <catalin.marinas@arm.com> >>>>> Cc: Dave Martin <dave.martin@arm.com> >>>>> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> >>>>> --- >>>>> arch/arm64/kernel/cpu_errata.c | 9 ++++++--- >>>>> 1 file changed, 6 insertions(+), 3 deletions(-) >>>>> >>>>> diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c >>>>> index 90a9e465339c..54e41dfe41f6 100644 >>>>> --- a/arch/arm64/kernel/cpu_errata.c >>>>> +++ b/arch/arm64/kernel/cpu_errata.c >>>>> @@ -373,15 +373,18 @@ void verify_local_cpu_errata_workarounds(void) >>>>> { >>>>> const struct arm64_cpu_capabilities *caps = arm64_errata; >>>>> - for (; caps->matches; caps++) >>>>> - if (!cpus_have_cap(caps->capability) && >>>>> - caps->matches(caps, SCOPE_LOCAL_CPU)) { >>>>> + for (; caps->matches; caps++) { >>>>> + if (cpus_have_cap(caps->capability)) { >>>>> + if (caps->enable) >>>>> + caps->enable((void *)caps); >>>> >>>> Do we really need this cast? >>> >>> Seems to me like the prototype for .enable needs updating. If any existing callback was actually using the (non-const) void* for some purpose (thankfully nothing seems to be), then passing the capability pointer into that would be unlikely to end well anyway. >> >> I agree. This was initially written such that we could call it via on_each_cpu(). >> But then we later switched to stop_machine(). And we weren't using the argument until >> very recently with the introduction of multiple entries for the same capability. >> >> I will try to clean this up in a separate series, which would involve cleaning up >> all the enable(), quite invasive. I would like this to go in for 4.16, as it is>> needed for things like KPTI and some of the existing caps.
Correction, s/KPTI/bp hardening/
> > OK, sounds good. For the sake of the immediate fix, perhaps it's cleaner to just pass NULL here if the current callbacks ignore it?
As I said above, we have some users at the moment, so we cant do that.
Suzuki
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