Laurent Vivier [off-list ref] writes:

On 12/12/2017 13:02, C=C3=A9dric Le Goater wrote:

quoted

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=3D1, Q=3D0.
=20
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.
=20
Suggested-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: C=C3=A9dric Le Goater <clg@kaod.org>
---
=20
 Tested with a guest running iozone.
=20
 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 inter=
rupt controller")
  Cc: stable@vger.kernel.org # v4.12+

cheers