linux-kernel - Re: [PATCH v3 01/14] KVM: s390: refactor crypto initialization

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Message-Id: <3227b02e-4a16-295d-9a01-043702cf149d@linux.vnet.ibm.com>
Date:   Thu, 15 Mar 2018 15:55:39 +0100
From:   Pierre Morel <pmorel@...ux.vnet.ibm.com>
To:     Tony Krowiak <akrowiak@...ux.vnet.ibm.com>,
        linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Cc:     freude@...ibm.com, schwidefsky@...ibm.com,
        heiko.carstens@...ibm.com, borntraeger@...ibm.com,
        cohuck@...hat.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 v3 01/14] KVM: s390: refactor crypto initialization

On 15/03/2018 15:48, Tony Krowiak wrote:
> On 03/15/2018 08:26 AM, Pierre Morel wrote:
>> On 14/03/2018 19:25, Tony Krowiak wrote:
>>> This patch refactors the code that initializes the crypto
>>> configuration for a guest. The crypto configuration is contained in
>>> a crypto control block (CRYCB) which is a satellite control block to
>>> our main hardware virtualization control block. The CRYCB is
>>> attached to the main virtualization control block via a CRYCB
>>> designation (CRYCBD) designation field containing the address of
>>> the CRYCB as well as its format.
>>>
>>> Prior to the introduction of AP device virtualization, there was
>>> no need to provide access to or specify the format of the CRYCB for
>>> a guest unless the MSA extension 3 (MSAX3) facility was installed
>>> on the host system. With the introduction of AP device virtualization,
>>> the CRYCB and its format must be made accessible to the guest
>>> regardless of the presence of the MSAX3 facility.
>>>
>>> The crypto initialization code is restructured as follows:
>>>
>>> * A new compilation unit is introduced to contain all interfaces
>>>    and data structures related to configuring a guest's CRYCB for
>>>    both the refactoring of crypto initialization as well as all
>>>    subsequent patches introducing AP virtualization support.
>>>
>>> * Currently, the asm code for querying the AP configuration is
>>>    duplicated in the AP bus as well as in KVM. Since the KVM
>>>    code was introduced, the AP bus has externalized the interface
>>>    for querying the AP configuration. The KVM interface will be
>>>    replaced with a call to the AP bus interface. Of course, this
>>>    will be moved to the new compilation unit mentioned above.
>>>
>>> * An interface to format the CRYCBD field will be provided via
>>>    the new compilation unit and called from the KVM vm
>>>    initialization.
>>>
>>> Signed-off-by: Tony Krowiak <akrowiak@...ux.vnet.ibm.com>
>>> ---
>>>   MAINTAINERS                      |   10 ++++++
>>>   arch/s390/include/asm/kvm-ap.h   |   16 ++++++++++
>>>   arch/s390/include/asm/kvm_host.h |    1 +
>>>   arch/s390/kvm/Kconfig            |    1 +
>>>   arch/s390/kvm/Makefile           |    2 +-
>>>   arch/s390/kvm/kvm-ap.c           |   48 +++++++++++++++++++++++++++++
>>>   arch/s390/kvm/kvm-s390.c         |   61 
>>> ++++---------------------------------
>>>   7 files changed, 84 insertions(+), 55 deletions(-)
>>>   create mode 100644 arch/s390/include/asm/kvm-ap.h
>>>   create mode 100644 arch/s390/kvm/kvm-ap.c
>>>
>>> diff --git a/MAINTAINERS b/MAINTAINERS
>>> index 0ec5881..72742d5 100644
>>> --- a/MAINTAINERS
>>> +++ b/MAINTAINERS
>>> @@ -11875,6 +11875,16 @@ W: 
>>> http://www.ibm.com/developerworks/linux/linux390/
>>>   S:    Supported
>>>   F:    drivers/s390/crypto/
>>>
>>> +S390 VFIO AP DRIVER
>>> +M:    Tony Krowiak <akrowiak@...ux.vnet.ibm.com>
>>> +M:    Christian Borntraeger <borntraeger@...ibm.com>
>>> +M:    Martin Schwidefsky <schwidefsky@...ibm.com>
>>> +L:    linux-s390@...r.kernel.org
>>> +W:    http://www.ibm.com/developerworks/linux/linux390/
>>> +S:    Supported
>>> +F:    arch/s390/include/asm/kvm/kvm-ap.h
>>> +F:    arch/s390/kvm/kvm-ap.c
>>> +
>>>   S390 ZFCP DRIVER
>>>   M:    Steffen Maier <maier@...ux.vnet.ibm.com>
>>>   M:    Benjamin Block <bblock@...ux.vnet.ibm.com>
>>> diff --git a/arch/s390/include/asm/kvm-ap.h 
>>> b/arch/s390/include/asm/kvm-ap.h
>>> new file mode 100644
>>> index 0000000..362846c
>>> --- /dev/null
>>> +++ b/arch/s390/include/asm/kvm-ap.h
>>> @@ -0,0 +1,16 @@
>>> +/*
>>> + * Adjunct Processor (AP) configuration management for KVM guests
>>> + *
>>> + * Copyright IBM Corp. 2017
>>> + *
>>> + * Author(s): Tony Krowiak <akrowia@...ux.vnet.ibm.com>
>>> + */
>>> +
>>> +#ifndef _ASM_KVM_AP
>>> +#define _ASM_KVM_AP
>>> +#include <linux/types.h>
>>> +#include <linux/kvm_host.h>
>>> +
>>> +void kvm_ap_build_crycbd(struct kvm *kvm);
>>> +
>>> +#endif /* _ASM_KVM_AP */
>>> diff --git a/arch/s390/include/asm/kvm_host.h 
>>> b/arch/s390/include/asm/kvm_host.h
>>> index 34c9b5b..65a944e 100644
>>> --- a/arch/s390/include/asm/kvm_host.h
>>> +++ b/arch/s390/include/asm/kvm_host.h
>>> @@ -257,6 +257,7 @@ struct kvm_s390_sie_block {
>>>       __u8    reservedf0[12];        /* 0x00f0 */
>>>   #define CRYCB_FORMAT1 0x00000001
>>>   #define CRYCB_FORMAT2 0x00000003
>>> +#define CRYCB_FORMAT_MASK 0x00000003
>>>       __u32    crycbd;            /* 0x00fc */
>>>       __u64    gcr[16];        /* 0x0100 */
>>>       __u64    gbea;            /* 0x0180 */
>>> diff --git a/arch/s390/kvm/Kconfig b/arch/s390/kvm/Kconfig
>>> index a3dbd45..4ca9077 100644
>>> --- a/arch/s390/kvm/Kconfig
>>> +++ b/arch/s390/kvm/Kconfig
>>> @@ -33,6 +33,7 @@ config KVM
>>>       select HAVE_KVM_INVALID_WAKEUPS
>>>       select SRCU
>>>       select KVM_VFIO
>>> +    select ZCRYPT
>>
>> I do not think it is a good solution to *always* enable ZCRYPT
>> when we have KVM.
> If CONFIG_ZCRYPT is not selected, then the kvm_ap_apxa_installed() 
> function will not compile
> because it calls a zcrypt interface. How would you suggest we make 
> sure zcrypt interfaces
> used in KVM are built if CONFIG_ZCRYPT is not selected?

if zcrypt is not configured, I suppose that the KVM code initializaing CRYCB
has no use but the function will be called from KVM.
So I would do something like:

#ifdef ZCRYPT
external definitions.
#else
stubs returning error -ENOZCRYPT (or whatever)
#endif



>>
>> Pierre
>>
>>
>

-- 
Pierre Morel
Linux/KVM/QEMU in Böblingen - Germany