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

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Date:   Thu, 31 Jan 2019 18:41:13 +0100
From:   Cornelia Huck <cohuck@...hat.com>
To:     Michael Mueller <mimu@...ux.ibm.com>
Cc:     KVM Mailing List <kvm@...r.kernel.org>,
        Linux-S390 Mailing List <linux-s390@...r.kernel.org>,
        linux-kernel@...r.kernel.org,
        Martin Schwidefsky <schwidefsky@...ibm.com>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        Janosch Frank <frankja@...ux.ibm.com>,
        David Hildenbrand <david@...hat.com>,
        Halil Pasic <pasic@...ux.ibm.com>,
        Pierre Morel <pmorel@...ux.ibm.com>
Subject: Re: [PATCH v7 11/15] KVM: s390: add functions to (un)register GISC
 with GISA

On Thu, 31 Jan 2019 09:52:42 +0100
Michael Mueller <mimu@...ux.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@...ux.ibm.com>
> Acked-by: Pierre Morel <pmorel@...ux.ibm.com>
> Acked-by: Halil Pasic <pasic@...ux.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@...hat.com>