Re: [RFC PATCH v9 4/4] s390: implementing CHSC SEI for AP config change

["Cédric Le Goater" <clg@redhat.com>]

On 5/13/25 13:38, Anthony Krowiak wrote:
> 
> 
> 
> On 5/12/25 2:02 PM, Rorie Reyes wrote:
>> Handle interception of the CHSC SEI instruction for requests
>> indicating the guest's AP configuration has changed.
>>
>> If configuring --without-default-devices, hw/s390x/ap-stub.c
>> was created to handle such circumstance. Also added the
>> following to hw/s390x/meson.build if CONFIG_VFIO_AP is
>> false, it will use the stub file.
>>
>> Signed-off-by: Rorie Reyes <rreyes@linux.ibm.com>
> 
> Reviewed-by: Anthony Krowiak <akrowiak@linux.ibm.com>
> 
>> ---
>>   MAINTAINERS           |  1 +
>>   hw/s390x/ap-stub.c    | 25 +++++++++++++++++++++++++
>>   hw/s390x/meson.build  |  1 +
>>   target/s390x/ioinst.c | 11 +++++++++--
>>   4 files changed, 36 insertions(+), 2 deletions(-)
>>   create mode 100644 hw/s390x/ap-stub.c
>>
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index 23174b4ca7..070c746c69 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -112,6 +112,7 @@ F: hw/intc/s390_flic.c
>>   F: hw/intc/s390_flic_kvm.c
>>   F: hw/s390x/
>>   F: hw/vfio/ap.c
>> +F: hw/s390x/ap-stub.c
>>   F: hw/vfio/ccw.c
>>   F: hw/watchdog/wdt_diag288.c
>>   F: include/hw/s390x/
>> diff --git a/hw/s390x/ap-stub.c b/hw/s390x/ap-stub.c
>> new file mode 100644
>> index 0000000000..e2dacff959
>> --- /dev/null
>> +++ b/hw/s390x/ap-stub.c
>> @@ -0,0 +1,25 @@
>> +/*
>> + * VFIO based AP matrix device assignment
>> + *
>> + * Copyright 2025 IBM Corp.
>> + * Author(s): Rorie Reyes <rreyes@linux.ibm.com>
>> + *
>> + * SPDX-License-Identifier: GPL-2.0-or-later
>> + *
>> + * This work is licensed under the terms of the GNU GPL, version 2 or (at
>> + * your option) any later version. See the COPYING file in the top-level
>> + * directory.

FYI, I dropped the redundent license boilerplate. See [1].

C.

[1] https://github.com/legoater/qemu/commit/8db3dbac401c56da6e865dcba1304f305555c22d

>> + */
>> +
>> +#include "qemu/osdep.h"
>> +#include "hw/s390x/ap-bridge.h"
>> +
>> +int ap_chsc_sei_nt0_get_event(void *res)
>> +{
>> +    return 0;
>> +}
>> +
>> +int ap_chsc_sei_nt0_have_event(void)
>> +{
>> +    return 0;
>> +}
>> diff --git a/hw/s390x/meson.build b/hw/s390x/meson.build
>> index 3bbebfd817..99cbcbd7d6 100644
>> --- a/hw/s390x/meson.build
>> +++ b/hw/s390x/meson.build
>> @@ -33,6 +33,7 @@ s390x_ss.add(when: 'CONFIG_S390_CCW_VIRTIO', if_true: files(
>>   ))
>>   s390x_ss.add(when: 'CONFIG_TERMINAL3270', if_true: files('3270-ccw.c'))
>>   s390x_ss.add(when: 'CONFIG_VFIO', if_true: files('s390-pci-vfio.c'))
>> +s390x_ss.add(when: 'CONFIG_VFIO_AP', if_false: files('ap-stub.c'))
>>   virtio_ss = ss.source_set()
>>   virtio_ss.add(files('virtio-ccw.c'))
>> diff --git a/target/s390x/ioinst.c b/target/s390x/ioinst.c
>> index fe62ba5b06..2320dd4c12 100644
>> --- a/target/s390x/ioinst.c
>> +++ b/target/s390x/ioinst.c
>> @@ -18,6 +18,7 @@
>>   #include "trace.h"
>>   #include "hw/s390x/s390-pci-bus.h"
>>   #include "target/s390x/kvm/pv.h"
>> +#include "hw/s390x/ap-bridge.h"
>>   /* All I/O instructions but chsc use the s format */
>>   static uint64_t get_address_from_regs(CPUS390XState *env, uint32_t ipb,
>> @@ -574,13 +575,19 @@ out:
>>   static int chsc_sei_nt0_get_event(void *res)
>>   {
>> -    /* no events yet */
>> +    if (s390_has_feat(S390_FEAT_AP)) {
>> +        return ap_chsc_sei_nt0_get_event(res);
>> +    }
>> +
>>       return 1;
>>   }
>>   static int chsc_sei_nt0_have_event(void)
>>   {
>> -    /* no events yet */
>> +    if (s390_has_feat(S390_FEAT_AP)) {
>> +        return ap_chsc_sei_nt0_have_event();
>> +    }
>> +
>>       return 0;
>>   }
>