linux-kernel - Re: [PATCH v2 01/15] KVM: s390: refactor crypto initialization

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Date:   Thu, 1 Mar 2018 10:59:15 +0100
From:   Cornelia Huck <cohuck@...hat.com>
To:     Tony Krowiak <akrowiak@...ux.vnet.ibm.com>
Cc:     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,
        pmorel@...ux.vnet.ibm.com, alifm@...ux.vnet.ibm.com,
        mjrosato@...ux.vnet.ibm.com, jjherne@...ux.vnet.ibm.com,
        thuth@...hat.com, pasic@...ux.vnet.ibm.com,
        fiuczy@...ux.vnet.ibm.com, buendgen@...ibm.com
Subject: Re: [PATCH v2 01/15] KVM: s390: refactor crypto initialization

On Wed, 28 Feb 2018 16:23:29 -0500
Tony Krowiak <akrowiak@...ux.vnet.ibm.com> wrote:

> On 02/28/2018 12:37 PM, Cornelia Huck wrote:
> > On Tue, 27 Feb 2018 09:27:59 -0500
> > Tony Krowiak <akrowiak@...ux.vnet.ibm.com> wrote:

> >> diff --git a/arch/s390/kvm/kvm-ap.c b/arch/s390/kvm/kvm-ap.c
> >> new file mode 100644
> >> index 0000000..5305f4c
> >> --- /dev/null
> >> +++ b/arch/s390/kvm/kvm-ap.c
> >> @@ -0,0 +1,47 @@
> >> +/*
> >> + * Adjunct Processor (AP) configuration management for KVM guests
> >> + *
> >> + * Copyright IBM Corp. 2017
> >> + *
> >> + * Author(s): Tony Krowiak <akrowia@...ux.vnet.ibm.com>
> >> + */
> >> +
> >> +#include <asm/kvm-ap.h>
> >> +#include <asm/ap.h>
> >> +
> >> +#include "kvm-s390.h"
> >> +
> >> +static int kvm_ap_apxa_installed(void)
> >> +{
> >> +	int ret;
> >> +	struct ap_config_info config;
> >> +
> >> +	ret = ap_query_configuration(&config);  
> > Doesn't that introduce a dependency on CONFIG_ZCRYPT?  
> It does, but AFAIK zcrypt is built into the kernel. Or is that not what 
> you are asking?

It is built into the kernel (and not into a module) if CONFIG_ZCRYPT is
set. When I compile a kernel with CONFIG_KVM set and CONFIG_ZCRYPT
unset, with this patch applied I get

arch/s390/kvm/kvm-ap.o: In function `kvm_ap_apxa_installed':
/home/cohuck/git/linux/arch/s390/kvm/kvm-ap.c:19: undefined reference to `ap_query_configuration'

So I'm afraid you cannot use ap_query_configuration() in base s390 kvm
code unless you move that function to a place where it is always built
(or at least always built if either CONFIG_KVM or CONFIG_ZCRYPT are
set).