Messages in this thread | | | Date | Wed, 11 Nov 2020 13:29:29 +0000 | From | Marc Zyngier <> | Subject | Re: [PATCH v1 07/24] kvm: arm64: Create nVHE copy of cpu_logical_map |
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On 2020-11-11 13:03, David Brazdil wrote: >> > +/* >> > + * nVHE copy of data structures tracking available CPU cores. >> > + * Only entries for CPUs that were online at KVM init are populated. >> > + * Other CPUs should not be allowed to boot because their features were >> > + * not checked against the finalized system capabilities. >> > + */ >> > +u64 __ro_after_init __cpu_logical_map[NR_CPUS] = { [0 ... NR_CPUS-1] >> > = INVALID_HWID }; >> >> I'm not sure what __ro_after_init means once we get S2 isolation. > > It is stretching the definition of 'init' a bit, I know, but I don't > see what > your worry is about S2? The intention is to mark this read-only for > .hyp.text > at runtime. With S2, the host won't be able to write to it after KVM > init. > Obviously that's currently not the case.
More importantly, EL2 can write to it at any time, which is the bit I'm worried about, as it makes the annotation misleading.
> One thing we might change in the future is marking it RW for some > initial > setup in a HVC handler, then marking it RO for the rest of uptime.
That'd be a desirable outcome, and it would be consistent with the rest of the kernel.
> >> >> > + >> > +u64 cpu_logical_map(int cpu) >> >> nit: is there any reason why "cpu" cannot be unsigned? The thought >> of a negative CPU number makes me shiver... > > Same here. That's how it's defined in kernel proper, so I went with > that.
I'm happy to deviate from the kernel (give the function a different name if this clashes with existing include files).
We can also fix the rest of the kernel (I've just written the trivial patch).
>> >> > +{ >> > + if (cpu < 0 || cpu >= ARRAY_SIZE(__cpu_logical_map)) >> > + hyp_panic(); >> > + >> > + return __cpu_logical_map[cpu]; >> > +} >> > + >> > unsigned long __hyp_per_cpu_offset(unsigned int cpu) >> > { >> > unsigned long *cpu_base_array; >> >> Overall, this patch would make more sense closer it its use case >> (in patch 19). I also don't understand why this lives in percpu.c... > > I didn't think it called for adding another C file for this. How about > we > rename this file to smp.c? Would that make sense for both?
Make that hyp-smp.c, please!
M. -- Jazz is not dead. It just smells funny...
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