Re: [RFC PATCH] kvm: Use huge pages for DAX-backed files

[Paolo Bonzini]

On 02/11/2018 21:32, Barret Rhoden wrote:
> One of the other things I noticed was some places in KVM make a
> distinction between kvm_is_reserved_pfn and PageReserved:
> 
> void kvm_set_pfn_dirty(kvm_pfn_t pfn)
> {
>         if (!kvm_is_reserved_pfn(pfn)) {
>                 struct page *page = pfn_to_page(pfn);
> 
>                 if (!PageReserved(page))
>                         SetPageDirty(page);
>         }
> }
> 
> I think we want to SetPageDirty for DAX, so making PageReserved be true
> for DAX seems like the way to go, or we'll need more KVM-specific
> changes.  Apologies is this was discussed in the previous thread on this
> topic and is redundant.

Isn't it the opposite?  We want SetPageDirty, so PageReserved must _not_
be true.

Paolo