From c4fe37ae6d75ed72e6a3bde01fea053eb508274c Mon Sep 17 00:00:00 2001
From: Thomas Huth <thuth@redhat.com>
Date: Fri, 5 Jun 2020 07:41:11 -0400
Subject: [PATCH 41/42] target/s390x/kvm: Enable adapter interruption
 suppression again
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RH-Author: Thomas Huth <thuth@redhat.com>
Message-id: <20200605074111.2185-4-thuth@redhat.com>
Patchwork-id: 97370
O-Subject: [RHEL-8.3.0 qemu-kvm PATCH 3/3] target/s390x/kvm: Enable adapter interruption suppression again
Bugzilla: 1756946
RH-Acked-by: Philippe Mathieu-Daudé <philmd@redhat.com>
RH-Acked-by: Cornelia Huck <cohuck@redhat.com>
RH-Acked-by: David Hildenbrand <david@redhat.com>

The AIS feature has been disabled late in the v2.10 development cycle since
there were some issues with migration (see commit 3f2d07b3b01ea61126b -
"s390x/ais: for 2.10 stable: disable ais facility"). We originally wanted
to enable it again for newer machine types, but apparently we forgot to do
this so far. Let's do it now for the machines that support proper CPU models.

Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1756946
Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20200122101437.5069-1-thuth@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Tested-by: Matthew Rosato <mjrosato@linux.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
(cherry picked from commit a5c8617af6919515b84256978452edf07401c45e)
Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
---
 target/s390x/kvm.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/target/s390x/kvm.c b/target/s390x/kvm.c
index c589ef9034..0bbf8f81b0 100644
--- a/target/s390x/kvm.c
+++ b/target/s390x/kvm.c
@@ -377,10 +377,13 @@ int kvm_arch_init(MachineState *ms, KVMState *s)
     /*
      * The migration interface for ais was introduced with kernel 4.13
      * but the capability itself had been active since 4.12. As migration
-     * support is considered necessary let's disable ais in the 2.10
-     * machine.
+     * support is considered necessary, we only try to enable this for
+     * newer machine types if KVM_CAP_S390_AIS_MIGRATION is available.
      */
-    /* kvm_vm_enable_cap(s, KVM_CAP_S390_AIS, 0); */
+    if (cpu_model_allowed() && kvm_kernel_irqchip_allowed() &&
+        kvm_check_extension(s, KVM_CAP_S390_AIS_MIGRATION)) {
+        kvm_vm_enable_cap(s, KVM_CAP_S390_AIS, 0);
+    }
 
     kvm_set_max_memslot_size(KVM_SLOT_MAX_BYTES);
     return 0;
-- 
2.27.0

