Ping: [PATCH 4/5] x86/PV: restrict TLB flushing after mod_l[234]_entry()

[Jan Beulich <jbeulich@suse.com>]

On 11.01.2021 14:22, Jan Beulich wrote:
> On 11.01.2021 14:00, Roger Pau Monné wrote:
>> On Tue, Nov 03, 2020 at 11:57:33AM +0100, Jan Beulich wrote:
>>> Just like we avoid to invoke remote root pt flushes when all uses of an
>>> L4 table can be accounted for locally, the same can be done for all of
>>> L[234] for the linear pt flush when the table is a "free floating" one,
>>> i.e. it is pinned but not hooked up anywhere. While this situation
>>> doesn't occur very often, it can be observed.
>>>
>>> Since this breaks one of the implications of the XSA-286 fix, drop the
>>> flush_root_pt_local variable again and set ->root_pgt_changed directly,
>>> just like it was before that change.
>>>
>>> Signed-off-by: Jan Beulich <jbeulich@suse.com>
>>
>> LGTM, so:
>>
>> Acked-by: Roger Pau Monné <roger.pau@citrix.com>
> 
> Thanks.
> 
>> It would be good however if Andrew can give is opinion also, since he
>> was the one to introduce such logic, and it's not trivial.
> 
> I can certainly wait some, also to hopefully get a comment on
> 
>>> ---
>>> While adjusting the big comment that was added for XSA-286 I wondered
>>> why it talks about the "construction of 32bit PV guests". How are 64-bit
>>> PV guests different in this regard?
> 
> ... this, but his email troubles make it hard to judge for how
> long to wait.

About like for the other one just pinged, I intend to commit this
one together with the other two still pending ones in this series
once the tree is fully open again, unless I hear otherwise by then.
All three have been acked by Roger.

Jan