Re: [PATCH v4] powerpc: kvm: make _PAGE_NUMA take effect

[Alexander Graf <agraf@suse.de>]

On 15.04.14 10:33, Liu Ping Fan wrote:
> Numa fault is a method which help to achieve auto numa balancing.
> When such a page fault takes place, the page fault handler will check
> whether the page is placed correctly. If not, migration should be
> involved to cut down the distance between the cpu and pages.
>
> A pte with _PAGE_NUMA help to implement numa fault. It means not to
> allow the MMU to access the page directly. So a page fault is triggered
> and numa fault handler gets the opportunity to run checker.
>
> As for the access of MMU, we need special handling for the powernv's guest.
> When we mark a pte with _PAGE_NUMA, we already call mmu_notifier to
> invalidate it in guest's htab, but when we tried to re-insert them,
> we firstly try to map it in real-mode. Only after this fails, we fallback
> to virt mode, and most of important, we run numa fault handler in virt
> mode.  This patch guards the way of real-mode to ensure that if a pte is
> marked with _PAGE_NUMA, it will NOT be mapped in real mode, instead, it will
> be mapped in virt mode and have the opportunity to be checked with placement.
>
> Signed-off-by: Liu Ping Fan <pingfank@linux.vnet.ibm.com>
> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

Thanks, applied to for-3.15.


Alex