[PATCH v3] powerpc: kvm: make _PAGE_NUMA take effect

Alexander Graf agraf at suse.de
Sat Apr 12 00:03:09 EST 2014

On 11.04.2014, at 13:45, Liu Ping Fan <pingfank at linux.vnet.ibm.com> wrote:

> 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.

What happens when we don't? Why do we need the check? Why isn't it done implicitly? What happens when we treat a NUMA marked page as non-present? Why does it work out for us?

Assume you have no idea what PAGE_NUMA is, but try to figure out what this patch does and whether you need to cherry-pick it into your downstream kernel. The description as is still is not very helpful for that. It doesn't even explain what really changes with this patch applied.

> 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>
> ---
> v3:
>  rebased onto Alex's tree, branch kvm-ppc-next
>  substitue commit log with the more clear description in Aneesh's reply (thanks, Aneesh)
> ---
> arch/powerpc/kvm/book3s_hv_rm_mmu.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
> diff --git a/arch/powerpc/kvm/book3s_hv_rm_mmu.c b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
> index 1d6c56a..1117525 100644
> --- a/arch/powerpc/kvm/book3s_hv_rm_mmu.c
> +++ b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
> @@ -234,7 +234,7 @@ long kvmppc_do_h_enter(struct kvm *kvm, unsigned long flags,
> 		pte_size = psize;
> 		pte = lookup_linux_pte_and_update(pgdir, hva, writing,
> 						  &pte_size);
> -		if (pte_present(pte)) {
> +		if (pte_present(pte)&&!pte_numa(pte)) {

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