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

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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>
This commit is contained in:
Nico Boehr 2022-10-12 14:32:29 +02:00 committed by Thomas Huth
parent d001a81256
commit 38621181ae
1 changed files with 9 additions and 0 deletions
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9
hw/s390x/tod-kvm.c
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@ -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);