linux-kernel - Re: [PATCH v4 01/15] s390: zcrypt: externalize AP instructions available function

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Date:   Mon, 16 Apr 2018 14:11:36 +0200
From:   Cornelia Huck <cohuck@...hat.com>
To:     Pierre Morel <pmorel@...ux.vnet.ibm.com>
Cc:     Tony Krowiak <akrowiak@...ux.vnet.ibm.com>,
        linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, freude@...ibm.com, schwidefsky@...ibm.com,
        heiko.carstens@...ibm.com, borntraeger@...ibm.com,
        kwankhede@...dia.com, bjsdjshi@...ux.vnet.ibm.com,
        pbonzini@...hat.com, alex.williamson@...hat.com,
        alifm@...ux.vnet.ibm.com, mjrosato@...ux.vnet.ibm.com,
        jjherne@...ux.vnet.ibm.com, thuth@...hat.com,
        pasic@...ux.vnet.ibm.com, berrange@...hat.com,
        fiuczy@...ux.vnet.ibm.com, buendgen@...ibm.com
Subject: Re: [PATCH v4 01/15] s390: zcrypt: externalize AP instructions
 available function

On Mon, 16 Apr 2018 10:44:53 +0200
Pierre Morel <pmorel@...ux.vnet.ibm.com> wrote:

> On 15/04/2018 23:22, Tony Krowiak wrote:
> > If the AP instructions are not available on the linux host, then
> > AP devices can not be interpreted by the SIE. The AP bus has a
> > function it uses to determine if the AP instructions are
> > available. This patch provides a new function that wraps the
> > AP bus's function to externalize it for use by KVM.
> >
> > Signed-off-by: Tony Krowiak <akrowiak@...ux.vnet.ibm.com>
> > Reviewed-by: Pierre Morel <pmorel@...ux.vnet.ibm.com>
> > Reviewed-by: Harald Freudenberger <freude@...ux.vnet.ibm.com>
> > ---
> >   arch/s390/include/asm/ap.h     |    7 +++++++
> >   arch/s390/include/asm/kvm-ap.h |   23 +++++++++++++++++++++++
> >   arch/s390/kvm/Makefile         |    2 +-
> >   arch/s390/kvm/kvm-ap.c         |   21 +++++++++++++++++++++
> >   drivers/s390/crypto/ap_bus.c   |    6 ++++++
> >   5 files changed, 58 insertions(+), 1 deletions(-)
> >   create mode 100644 arch/s390/include/asm/kvm-ap.h
> >   create mode 100644 arch/s390/kvm/kvm-ap.c

> > diff --git a/arch/s390/kvm/kvm-ap.c b/arch/s390/kvm/kvm-ap.c
> > new file mode 100644
> > index 0000000..1267588
> > --- /dev/null
> > +++ b/arch/s390/kvm/kvm-ap.c
> > @@ -0,0 +1,21 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +/*
> > + * Adjunct Processor (AP) configuration management for KVM guests
> > + *
> > + * Copyright IBM Corp. 2018
> > + *
> > + * Author(s): Tony Krowiak <akrowia@...ux.vnet.ibm.com>
> > + */
> > +#include <linux/kernel.h>
> > +#include <asm/kvm-ap.h>
> > +#include <asm/ap.h>
> > +
> > +int kvm_ap_instructions_installed(void)
> > +{
> > +#ifdef CONFIG_ZCRYPT  
> 
> I did not give my R-B for this.
> please change it or suppress my R-B
> 
> I think you should review the way you wrap functions
> calling the AP interface.
> Having all of them together would simplify code and review.

I don't like the ifdeffery either (especially as there's more later).

Consolidating all functions for querying basic ap capabilities sounds
like a good idea. What about collecting them in a ap-util file and
either always building it or selecting it from both zcrypt and kvm?

> 
> > +	return ap_instructions_installed();
> > +#else
> > +	return 0;
> > +#endif
> > +}
> > +EXPORT_SYMBOL(kvm_ap_instructions_installed);
> > diff --git a/drivers/s390/crypto/ap_bus.c b/drivers/s390/crypto/ap_bus.c
> > index 35a0c2b..9d108b6 100644
> > --- a/drivers/s390/crypto/ap_bus.c
> > +++ b/drivers/s390/crypto/ap_bus.c
> > @@ -210,6 +210,12 @@ int ap_query_configuration(struct ap_config_info *info)
> >   }
> >   EXPORT_SYMBOL(ap_query_configuration);
> >
> > +int ap_instructions_installed(void)
> > +{
> > +	return (ap_instructions_available() == 0);
> > +}
> > +EXPORT_SYMBOL(ap_instructions_installed);
> > +
> >   /**
> >    * ap_init_configuration(): Allocate and query configuration array.
> >    */  
> 
>