Re: [PATCH 3/3] arm, arm64: KVM: handle potential incoherency of readonly memslots

Christoffer Dall
2014-11-21T11:19:10Z

Hi Mario,

On Wed, Nov 19, 2014 at 03:32:31PM -0800, Mario Smarduch wrote:
> Hi Laszlo,
>
> couple observations.
>
> I'm wondering if access from qemu and guest won't
> result in mixed memory attributes and if that's acceptable
> to the CPU.
>
> Also is if you update memory from qemu you may break
> dirty page logging/migration. Unless there is some other way
> you keep track. Of course it may not be applicable in your
> case (i.e. flash unused after boot).
>
I'm not concerned about this particular case; dirty page logging exists
so KVM can inform userspace when a page may have been dirtied. If
userspace directly dirties (is that a verb?) a page, then it already
knows that it needs to migrate that page and deal with it accordingly.

Or did I miss some more subtle point here?

-Christoffer