[PATCH v2] powernv: kvm: make _PAGE_NUMA take effect

[Alexander Graf]

On 21.01.2014, at 10:42, Aneesh Kumar K.V <aneesh.kumar at linux.vnet.ibm.com> wrote:

> Liu Ping Fan <kernelfans at 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 <pingfank at linux.vnet.ibm.com>
> 
> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar at 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.


Alex