On 31.08.2021 17:38, Jan Beulich wrote: > On 31.08.2021 17:25, Andrew Cooper wrote: >> On 31/08/2021 14:26, Jan Beulich wrote: >>> On 31.08.2021 15:16, Andrew Cooper wrote: >>>> On 30/08/2021 14:02, Jan Beulich wrote: >>>>> Further permit "access" to differ in the "executable" attribute. While >>>>> ideally only ROM regions would get mapped with X set, getting there is >>>>> quite a bit of work. Therefore, as a temporary measure, permit X to >>>>> vary. For Dom0 the more permissive of the types will be used, while for >>>>> DomU it'll be the more restrictive one. >>>> Split behaviour between dom0 and domU based on types alone cannot >>>> possibly be correct. >>> True, but what do you do. >>> >>>> DomU's need to execute ROMs too, and this looks like will malfunction if >>>> a ROM ends up in the region that HVMLoader relocated RAM from. >>>> >>>> As this is a temporary bodge emergency bugfix, don't try to be clever - >>>> just take the latest access. >>> And how do we know that that's what is going to work? >> >> Because it's the pre-existing behaviour. > > Valid point. But for the DomU case there simply has not been any > pre-existing behavior. Hence my desire to be restrictive initially > there.
Further to this: Using the last-value-set approach also puts us at risk of running into a similar issue again when the ordering of some operations changes elsewhere. Jan
