>>> On 04.04.19 at 15:09, <ta...@tklengyel.com> wrote: > I agree that it is confusing. It would be fine to UNSHARE here as well > to keep things consistent but otherwise it's not really an issue as > the entry type is checked later to ensure that this is a p2m_ram_rw > entry. We are simply trying to keep mem_sharing and _modified_ altp2m > entries exclusive. So it is fine to have mem_shared entries in the > hostp2m and have those entries be copied into altp2m tables lazily, > but for altp2m entries that have changed mem_access permissions or are > remapped we want the entries in the hostp2m to be of regular type. > This is not necessarily a technical requirement, it's mostly just to > reduce complexity. So it would be fine to add UNSHARE here as well, I > guess the only reason why I haven't done that is because I already > trigger the unshare and copy-to-altp2m before remapping by setting > dummy mem_access permission on the entries.
I'm afraid I don't agree with this justification: mem-sharing is about contents of pages, whereas altp2m is about meta data (permissions etc). I don't see why one would want to unshare because of a meta data adjustment other than a page becoming non-CoW-writable. Eagerly un-sharing in the end undermines the intentions of sharing. Jan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
