From: Matthew Rosato <mjrosato@linux.ibm.com>
To: Thomas Huth <thuth@redhat.com>, Cornelia Huck <cohuck@redhat.com>,
Christian Borntraeger <borntraeger@de.ibm.com>,
qemu-devel@nongnu.org
Cc: Halil Pasic <pasic@linux.ibm.com>,
qemu-s390x@nongnu.org, David Hildenbrand <david@redhat.com>
Subject: Re: [PATCH] target/s390x/kvm: Enable adapter interruption suppression again
Date: Thu, 16 Jan 2020 15:19:13 -0500 [thread overview]
Message-ID: <ad421fc1-8241-3c73-e597-aebb3fc8a309@linux.ibm.com> (raw)
In-Reply-To: <20200116122026.5804-1-thuth@redhat.com>
On 1/16/20 7:20 AM, Thomas Huth wrote:
> 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 for the new s390-ccw-virtio-5.0 machine now.
>
> Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1756946
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
> hw/s390x/s390-virtio-ccw.c | 4 ++++
> include/hw/s390x/s390-virtio-ccw.h | 4 ++++
> target/s390x/kvm.c | 11 ++++++++---
> 3 files changed, 16 insertions(+), 3 deletions(-)
>
> diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
> index e7eadd14e8..6f43136396 100644
> --- a/hw/s390x/s390-virtio-ccw.c
> +++ b/hw/s390x/s390-virtio-ccw.c
> @@ -456,6 +456,7 @@ static void ccw_machine_class_init(ObjectClass *oc, void *data)
> s390mc->cpu_model_allowed = true;
> s390mc->css_migration_enabled = true;
> s390mc->hpage_1m_allowed = true;
> + s390mc->kvm_ais_allowed = true;
> mc->init = ccw_init;
> mc->reset = s390_machine_reset;
> mc->hot_add_cpu = s390_hot_add_cpu;
> @@ -662,6 +663,9 @@ static void ccw_machine_4_2_instance_options(MachineState *machine)
>
> static void ccw_machine_4_2_class_options(MachineClass *mc)
> {
> + S390CcwMachineClass *s390mc = S390_MACHINE_CLASS(mc);
> +
> + s390mc->kvm_ais_allowed = false;
> ccw_machine_5_0_class_options(mc);
> compat_props_add(mc->compat_props, hw_compat_4_2, hw_compat_4_2_len);
> }
> diff --git a/include/hw/s390x/s390-virtio-ccw.h b/include/hw/s390x/s390-virtio-ccw.h
> index 8aa27199c9..f142d379c6 100644
> --- a/include/hw/s390x/s390-virtio-ccw.h
> +++ b/include/hw/s390x/s390-virtio-ccw.h
> @@ -21,6 +21,9 @@
> #define S390_MACHINE_CLASS(klass) \
> OBJECT_CLASS_CHECK(S390CcwMachineClass, (klass), TYPE_S390_CCW_MACHINE)
>
> +#define S390_CCW_MACHINE_OBJ_GET_CLASS(obj) \
> + OBJECT_GET_CLASS(S390CcwMachineClass, obj, TYPE_S390_CCW_MACHINE)
> +
> typedef struct S390CcwMachineState {
> /*< private >*/
> MachineState parent_obj;
> @@ -40,6 +43,7 @@ typedef struct S390CcwMachineClass {
> bool cpu_model_allowed;
> bool css_migration_enabled;
> bool hpage_1m_allowed;
> + bool kvm_ais_allowed;
> } S390CcwMachineClass;
>
> /* runtime-instrumentation allowed by the machine */
> diff --git a/target/s390x/kvm.c b/target/s390x/kvm.c
> index 15260aeb9a..4c1c8c0208 100644
> --- a/target/s390x/kvm.c
> +++ b/target/s390x/kvm.c
> @@ -329,6 +329,8 @@ static void ccw_machine_class_foreach(ObjectClass *oc, void *opaque)
>
> int kvm_arch_init(MachineState *ms, KVMState *s)
> {
> + S390CcwMachineClass *smc = S390_CCW_MACHINE_OBJ_GET_CLASS(ms);
> +
I still can't run a proper test due to unavailable hw but in the
meantime I tried to virsh define a libvirt guest pointed at qemu (master
+ this patch). Regardless of machine type (s390-ccw-virtio-5.0 or
s390-ccw-virtio-4.2) I get:
virsh define guest.xml
error: Failed to define domain from /path/to/guest.xml
error: invalid argument: could not find capabilities for arch=s390x
domaintype=kvm
Similarly:
virsh domcapabilities
error: failed to get emulator capabilities
error: invalid argument: unable to find any emulator to serve 's390x'
architecture
Rolling back to qemu master, the define and domcapabilities work (with
no ais of course).
So: there is some incompatibility between the way libvirt invokes qemu
to detect capabilities and this code. The above line seems to be the
root problem - if I take your patch and remove 'smc' then libvirt works
as expected and I can see ais in the domcapabilities.
Looking at those wrappers David mentioned... I suspect you need this
for the 'none' machine case. I tried a quick hack with the following:
bool ais_allowed(void)
{
/* for "none" machine this results in true */
return get_machine_class()->kvm_ais_allowed;
}
and
if (ais_allowed() &&
kvm_check_extension(s, KVM_CAP_S390_AIS_MIGRATION)) {
kvm_vm_enable_cap(s, KVM_CAP_S390_AIS, 0);
}
This works and doesn't break libvirt compatibility detection.
> object_class_foreach(ccw_machine_class_foreach, TYPE_S390_CCW_MACHINE,
> false, NULL);
>
> @@ -365,10 +367,13 @@ 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 enable this for newer
> + * machine types and if KVM_CAP_S390_AIS_MIGRATION is available.
> */
> - /* kvm_vm_enable_cap(s, KVM_CAP_S390_AIS, 0); */
> + if (smc->kvm_ais_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;
>
next prev parent reply other threads:[~2020-01-16 20:20 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-16 12:20 [PATCH] target/s390x/kvm: Enable adapter interruption suppression again Thomas Huth
2020-01-16 12:23 ` David Hildenbrand
2020-01-16 12:26 ` Thomas Huth
2020-01-16 12:28 ` David Hildenbrand
2020-01-16 12:38 ` Thomas Huth
2020-01-16 12:50 ` Cornelia Huck
2020-01-16 12:55 ` Thomas Huth
2020-01-16 13:22 ` Christian Borntraeger
2020-01-16 14:22 ` Cornelia Huck
2020-01-16 14:51 ` Matthew Rosato
2020-01-16 20:19 ` Matthew Rosato [this message]
2020-01-16 20:26 ` Cornelia Huck
2020-01-17 10:38 ` Thomas Huth
2020-01-17 11:05 ` Christian Borntraeger
2020-01-17 15:38 ` Thomas Huth
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