KVM: PPC: Book3S: fix XIVE migration of pending interrupts

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.

Fixes: 5af50993850a ("KVM: PPC: Book3S HV: Native usage of the XIVE interrupt controller")
Cc: stable@vger.kernel.org # v4.12+
Suggested-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Laurent Vivier <lvivier@redhat.com>
Tested-by: Laurent Vivier <lvivier@redhat.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/kvm/book3s_xive.c b/arch/powerpc/kvm/book3s_xive.c
index bf457843e03217b9aa02815d7791f0fce72aea2b..b5e6d227a03426125e559f234f17be0ea8d19984 100644 (file)
--- a/arch/powerpc/kvm/book3s_xive.c
+++ b/arch/powerpc/kvm/book3s_xive.c
@@ -1558,7 +1558,7 @@ static int xive_set_source(struct kvmppc_xive *xive, long irq, u64 addr)
 
        /*
         * Restore P and Q. If the interrupt was pending, we
-        * force both P and Q, which will trigger a resend.
+        * force Q and !P, which will trigger a resend.
         *
         * That means that a guest that had both an interrupt
         * pending (queued) and Q set will restore with only
@@ -1566,7 +1566,7 @@ static int xive_set_source(struct kvmppc_xive *xive, long irq, u64 addr)
         * is perfectly fine as coalescing interrupts that haven't
         * been presented yet is always allowed.
         */
-       if (val & KVM_XICS_PRESENTED || val & KVM_XICS_PENDING)
+       if (val & KVM_XICS_PRESENTED && !(val & KVM_XICS_PENDING))
                state->old_p = true;
        if (val & KVM_XICS_QUEUED || val & KVM_XICS_PENDING)
                state->old_q = true;