On 28/01/2020 17:16, Roger Pau Monné wrote: >>>> OOI why isn't tlb_clk_enabled set to false when Xen determines to use L0 >>>> assisted flush? >>> L0 assisted flush can fail (ie: return an error), and in that case Xen >>> would be better to continue using the timestamped tlb, as it could >>> avoid some flushes. >> Do you need to set tlb_clk_enabled in that case? > AFAICT it's safe to enable the TLB timestamps after being disabled, > but hypervisor_flush_tlb could fail intermittently with EBUSY in the > Xen implementation, and I don't really want that to cause spurious > enabling of the timestamps periodically.
What causes -EBUSY? I don't think it is reasonable for the hypercall to fail like that. There is no circumstance ever where a TLB flush is wanted, and it is able to be deferred. Forcing all callers to loop while busy is a terrible interface. ~Andrew _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
