On Mon, Jan 27, 2014 at 10:11:40AM +0100, Alexander Graf wrote: > > On 21.01.2014, at 10:42, Aneesh Kumar K.V <aneesh.ku...@linux.vnet.ibm.com> > wrote: > > > Liu Ping Fan <kernelf...@gmail.com> writes: > > > >> To make sure that on host, the pages marked with _PAGE_NUMA result in a > >> fault > >> when guest access them, we should force the checking when guest uses > >> hypercall > >> to setup hpte. > >> > >> Signed-off-by: Liu Ping Fan <pingf...@linux.vnet.ibm.com> > > > > Reviewed-by: Aneesh Kumar K.V <aneesh.ku...@linux.vnet.ibm.com> > > > > When we mark pte with _PAGE_NUMA we already call > > mmu_notifier_invalidate_range_start and > > mmu_notifier_invalidate_range_end, which will mark existing guest hpte > > entry as HPTE_V_ABSENT. Now we need to do that when we are inserting new > > guest hpte entries. This patch does that. > > So what happens next? We insert a page into the HTAB without HPTE_V_VALID > set, so the guest will fail to use it. If the guest does an H_READ on it it > will suddenly turn to V_VALID though? > > I might need a crash course in the use of HPTE_V_ABSENT.
HPTE_V_ABSENT means present from the point of view of the guest but not present from the host's point of view, so yes H_READ turns HPTE_V_ABSENT into HPTE_V_VALID. Paul. _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
