From: Nico Boehr <nrb@linux.ibm.com>

Date: Wed, 12 Oct 2022 14:32:29 +0200

Subject: s390x/tod-kvm: don't save/restore the TOD in PV guests

Under PV, the guest's TOD clock is under control of the ultravisor and the

hypervisor cannot change it.

With upcoming kernel changes[1], the Linux kernel will reject QEMU's

request to adjust the guest's clock in this case, so don't attempt to set

the clock.

This avoids the following warning message on save/restore of a PV guest:

warning: Unable to set KVM guest TOD clock: Operation not supported

[1] https://lore.kernel.org/all/20221011160712.928239-2-nrb@linux.ibm.com/

Fixes: c3347ed0d2ee ("s390x: protvirt: Support unpack facility")

Signed-off-by: Nico Boehr <nrb@linux.ibm.com>

Message-Id: <20221012123229.1196007-1-nrb@linux.ibm.com>

[thuth: Add curly braces]

Signed-off-by: Thomas Huth <thuth@redhat.com>

(cherry picked from commit 38621181ae3cbec62e3490fbc14f6ac01642d07a)

Resolves: bsc#1206527

Signed-off-by: Dario Faggioli <dfaggioli@suse.com>

---

 hw/s390x/tod-kvm.c | 9 +++++++++

 1 file changed, 9 insertions(+)

diff --git a/hw/s390x/tod-kvm.c b/hw/s390x/tod-kvm.c

index 9d0cbfbce2bf56b3593d712bd082..e2202dae2dc203a2848a3d0faaaf 100644

--- a/hw/s390x/tod-kvm.c

+++ b/hw/s390x/tod-kvm.c

@@ -13,6 +13,7 @@

 #include "qemu/module.h"

 #include "sysemu/runstate.h"

 #include "hw/s390x/tod.h"

+#include "hw/s390x/pv.h"

 #include "kvm/kvm_s390x.h"

 static void kvm_s390_get_tod_raw(S390TOD *tod, Error **errp)

@@ -84,6 +85,14 @@ static void kvm_s390_tod_vm_state_change(void *opaque, bool running,

     S390TODState *td = opaque;

     Error *local_err = NULL;

+    /*

+     * Under PV, the clock is under ultravisor control, hence we cannot restore

+     * it on resume.

+     */

+    if (s390_is_pv()) {

+        return;

+    }

+

     if (running && td->stopped) {

         /* Set the old TOD when running the VM - start the TOD clock. */

         kvm_s390_set_tod_raw(&td->base, &local_err);