Re: [PATCH 07/10] KVM: PPC: Add PAPR hypercall code for PR mode

Alexander Graf
2011-08-12T05:38:54Z

Am 12.08.2011 um 05:35 schrieb David Gibson <david@gibson.dropbear.id.au>:

> On Tue, Aug 09, 2011 at 06:31:45PM +0200, Alexander Graf wrote:
>> When running a PAPR guest, we need to handle a few hypercalls in kernel space,
>> most prominently the page table invalidation (to sync the shadows).
>>
>> So this patch adds handling for a few PAPR hypercalls to PR mode KVM. I tried
>> to share the code with HV mode, but it ended up being a lot easier this way
>> around, as the two differ too much in those details.
>
> Are these strictly necessary, or just an optimization? Because you're
> using the space allocated by qemu for the guest hash table, it seems
> to be you could just let h_enter fall through to qemu which will put
> the right thing into the guest hash table which you can then walk in
> the kernel translation code.

Every time a PTE can be invalidated, we need to do so in kvm to keep the SPT in sync. IIRC h_enter can evict/overwrite a previous entry, so we need to handle it in kvm as well :). Removal definitely needs to happin in-kernel.

Alex

>