Messages in this thread | | | Date | Tue, 30 Mar 2021 15:00:16 +0100 | From | Marc Zyngier <> | Subject | Re: [PATCH v5 07/19] arm64: kvm: Enable access to TRBE support for host |
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On Tue, 30 Mar 2021 14:34:23 +0100, Suzuki K Poulose <suzuki.poulose@arm.com> wrote: > > On 30/03/2021 13:15, Marc Zyngier wrote: > > On Tue, 30 Mar 2021 12:12:49 +0100, > > Suzuki K Poulose <suzuki.poulose@arm.com> wrote:
[...]
> >> May be we could do this check at kvm_arch_vcpu_load()/put() ? > > > > That would extend the tracing blackout period enormously, wouldn't it? > > I'm not sure that's the best thing to do... > > Sorry for not making this clear. We could check if the SPE/TRBE is > available on this CPU (including the PMB/TRB_IDR bits and a set a flag > in the VCPU on every kvm_arch_vcpu_load() and cleared on put. > The actual switching code could check this flag and check if the unit > is enabled and then do the actual save/restore as we do below. > (We may be able to even check if unit is enabled there, need to double > check this.)
Ah, gotcha. Yes, this seems like a reasonable thing to do. We have the per-vcpu debug flags already, and you could piggy-back on that.
Thanks,
M.
-- Without deviation from the norm, progress is not possible.
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