Re: [PATCH v4 20/36] KVM: s390/mm: handle guest unpin events

Cornelia Huck
2020-02-25T14:30:38Z

On Tue, 25 Feb 2020 15:21:42 +0100
Christian Borntraeger <borntraeger@de.ibm.com> wrote:

> On 25.02.20 13:18, Cornelia Huck wrote:
> > On Mon, 24 Feb 2020 06:40:51 -0500
> > Christian Borntraeger <borntraeger@de.ibm.com> wrote:
> >
> >> From: Claudio Imbrenda <imbrenda@linux.ibm.com>
> >>
> >> The current code tries to first pin shared pages, if that fails (e.g.
> >> because the page is not shared) it will export them. For shared pages
> >> this means that we get a new intercept telling us that the guest is
> >> unsharing that page. We will make the page secure at that point in time
> >> and revoke the host access. This is synchronized with other host events,
> >> e.g. the code will wait until host I/O has finished.
> >>
> >> Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
> >> Acked-by: David Hildenbrand <david@redhat.com>
> >> [borntraeger@de.ibm.com: patch merging, splitting, fixing]
> >> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> >> ---
> >> arch/s390/kvm/intercept.c | 24 ++++++++++++++++++++++++
> >> 1 file changed, 24 insertions(+)

> I will also fixup the misleading patch description:
>
> The current code tries to first pin shared pages, if that fails (e.g.
> because the page is not shared) it will export them. For shared pages
> this means that we get a new intercept telling us that the guest is
> unsharing that page. We will unpin the page at that point in time,
> following the same rules as for make secure. (wait for writeback, no
> elevated page refs etc).

I'd suggest:

"...as for making a page secure (i.e. waiting for writeback, no
elevated page references, etc.)"

With the touchups,

Reviewed-by: Cornelia Huck <cohuck@redhat.com>