Re: [PATCH v7 11/15] KVM: s390: add functions to (un)register GISC with GISA

Cornelia Huck
2019-01-31T17:41:13Z

On Thu, 31 Jan 2019 09:52:42 +0100
Michael Mueller <mimu@linux.ibm.com> wrote:

> Add the Interruption Alert Mask (IAM) to the architecture specific
> kvm struct. This mask in the GISA is used to define for which ISC
> a GIB alert will be issued.
>
> The functions kvm_s390_gisc_register() and kvm_s390_gisc_unregister()
> are used to (un)register a GISC (guest ISC) with a virtual machine and
> its GISA.
>
> Upon successful completion, kvm_s390_gisc_register() returns the
> ISC to be used for GIB alert interruptions. A negative return code
> indicates an error during registration.
>
> Theses functions will be used by other adapter types like AP and PCI to
> request pass-through interruption support.
>
> Signed-off-by: Michael Mueller <mimu@linux.ibm.com>
> Acked-by: Pierre Morel <pmorel@linux.ibm.com>
> Acked-by: Halil Pasic <pasic@linux.ibm.com>
> ---
> arch/s390/include/asm/kvm_host.h | 13 +++++
> arch/s390/kvm/interrupt.c | 112 +++++++++++++++++++++++++++++++++++++++
> 2 files changed, 125 insertions(+)

> +/**
> + * kvm_s390_gisc_register - register a guest ISC
> + *
> + * @kvm: the kernel vm to work with
> + * @gisc: the guest interruption sub class to register
> + *
> + * The function extends the vm specific alert mask to use.
> + * The effectve IAM mask in the GISA is updated as well

Typo: s/effectve/effective/

> + * in case the GISA is not part of the GIB alert list.
> + * It will be updated latest when the IAM gets restored
> + * by gisa_get_ipm_or_restore_iam().
> + *
> + * Returns: the nonspecific ISC (NISC) the gib alert mechanism
> + * has registered with the channel subsystem.
> + * -ENODEV in case the vm uses no GISA
> + * -ERANGE in case the guest ISC is invalid
> + */
> +int kvm_s390_gisc_register(struct kvm *kvm, u32 gisc)
> +{
> + struct kvm_s390_gisa_interrupt *gi = &kvm->arch.gisa_int;
> +
> + if (!gi->origin)
> + return -ENODEV;
> + if (gisc > MAX_ISC)
> + return -ERANGE;
> +
> + spin_lock(&gi->alert.ref_lock);
> + gi->alert.ref_count[gisc]++;
> + if (gi->alert.ref_count[gisc] == 1) {
> + gi->alert.mask |= 0x80 >> gisc;
> + gisa_set_iam(gi->origin, gi->alert.mask);
> + }
> + spin_unlock(&gi->alert.ref_lock);
> +
> + return gib->nisc;
> +}
> +EXPORT_SYMBOL_GPL(kvm_s390_gisc_register);
> +
> +/**
> + * kvm_s390_gisc_unregister - unregister a guest ISC
> + *
> + * @kvm: the kernel vm to work with
> + * @gisc: the guest interruption sub class to register
> + *
> + * The function reduces the vm specific alert mask to use.
> + * The effectve IAM mask in the GISA is updated as well

Same here.

> + * in case the GISA is not part of the GIB alert list.
> + * It will be updated latest when the IAM gets restored
> + * by gisa_get_ipm_or_restore_iam().
> + *
> + * Returns: the nonspecific ISC (NISC) the gib alert mechanism
> + * has registered with the channel subsystem.
> + * -ENODEV in case the vm uses no GISA
> + * -ERANGE in case the guest ISC is invalid
> + * -EINVAL in case the guest ISC is not registered
> + */
> +int kvm_s390_gisc_unregister(struct kvm *kvm, u32 gisc)
> +{
> + struct kvm_s390_gisa_interrupt *gi = &kvm->arch.gisa_int;
> + int rc = 0;
> +
> + if (!gi->origin)
> + return -ENODEV;
> + if (gisc > MAX_ISC)
> + return -ERANGE;
> +
> + spin_lock(&gi->alert.ref_lock);
> + if (gi->alert.ref_count[gisc] == 0) {
> + rc = -EINVAL;
> + goto out;
> + }
> + gi->alert.ref_count[gisc]--;
> + if (gi->alert.ref_count[gisc] == 0) {
> + gi->alert.mask &= ~(0x80 >> gisc);
> + gisa_set_iam(gi->origin, gi->alert.mask);
> + }
> +out:
> + spin_unlock(&gi->alert.ref_lock);
> +
> + return rc;
> +}
> +EXPORT_SYMBOL_GPL(kvm_s390_gisc_unregister);
> +
> void kvm_s390_gib_destroy(void)
> {
> if (!gib)

Otherwise, looks good AFAICS.

Reviewed-by: Cornelia Huck <cohuck@redhat.com>