[PATCH] KVM: PPC: Book3S: fix XIVE migration of pending interrupts

[Michael Ellerman]

Paul Mackerras <paulus at ozlabs.org> writes:

> On Fri, Dec 22, 2017 at 03:34:20PM +1100, Michael Ellerman wrote:
>> Laurent Vivier <lvivier at redhat.com> writes:
>> 
>> > On 12/12/2017 13:02, Cédric Le Goater wrote:
>> >> When restoring a pending interrupt, we are setting the Q bit to force
>> >> a retrigger in xive_finish_unmask(). But we also need to force an EOI
>> >> in this case to reach the same initial state : P=1, Q=0.
>> >> 
>> >> This can be done by not setting 'old_p' for pending interrupts which
>> >> will inform xive_finish_unmask() that an EOI needs to be sent.
>> >> 
>> >> Suggested-by: Benjamin Herrenschmidt <benh at kernel.crashing.org>
>> >> Signed-off-by: Cédric Le Goater <clg at kaod.org>
>> >> ---
>> >> 
>> >>  Tested with a guest running iozone.
>> >> 
>> >>  arch/powerpc/kvm/book3s_xive.c | 4 ++--
>> >>  1 file changed, 2 insertions(+), 2 deletions(-)
>> >
>> > We really need this patch to fix VM migration on POWER9.
>> > When will it be merged?
>> 
>> Paul is away, so I'll merge it via the powerpc tree.
>> 
>> I'll mark it:
>> 
>>   Fixes: 5af50993850a ("KVM: PPC: Book3S HV: Native usage of the XIVE interrupt controller")
>>   Cc: stable at vger.kernel.org # v4.12+
>
> Thanks for doing that.
>
> If you felt like merging Alexey's patch "KVM: PPC: Book3S PR: Fix WIMG
> handling under pHyp" with my acked-by, that would be fine too.  The
> commit message needs a little work - the reason for using HPTE_R_M is
> not just because it seems to work, but because current POWER
> processors require M set on mappings for normal pages, and pHyp
> enforces that.

OK. I saw this too late, but I'll pick that one up next week. If someone
sends me an updated change log I will merge all of their patches for
ever.

cheers