On 2018/2/1 16:53, Marc Zyngier wrote: [...] >>>> ... and actually, perhaps it makes sense for the >>>> SMCCC_ARCH_WORKAROUND_1 check to be completely independent of MIDR >>>> based errata matching? >>>> >>>> I.e., if SMCCC v1.1 and SMCCC_ARCH_WORKAROUND_1 are both implemented, >>>> we should probably invoke it even if the MIDR is not known to belong >>>> to an affected implementation. >>> >>> This would have an impact on big-little systems, for which there is >>> often a bunch of unaffected CPUs. >> >> I think it's what we are doing now, SMCCC v1.1 didn't provide the ability >> to report per-cpu SMCCC_ARCH_WORKAROUND_1, and it said: >> - The discovery call must return the same result on all PEs in the system. >> - In heterogeneous systems with some PEs that require mitigation and others >> that do not, the firmware must provide a safe implementation of this >> function on all PEs. >> >> So from the spec that it's the firmware to take care of unaffected CPUs, >> to the kernel it's the same. > > The spec makes it safe. The MIDR list makes it fast. Got it, thank you for clarifying this. Thanks Hanjun _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
