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

["Cédric Le Goater" <clg@redhat.com>]

On 5/12/25 20:02, 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>
> ---
>   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



Reviewed-by: Cédric Le Goater <clg@redhat.com>

Thanks,

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.
> + */
> +
> +#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;
>   }
>