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

[Cornelia Huck <cohuck@redhat.com>]

On Tue, 27 Feb 2018 09:27:59 -0500
Tony Krowiak <akrowiak@linux.vnet.ibm.com> wrote:

> The crypto control block designation (CRYCBD) is a 32-bit
> field in the KVM guest's SIE state description. The
> contents of bits 1-28 of this field, with three zero bits
> appended on the right, designate the host real 31-bit
> address of a crypto control block (CRYCB). Bits 30-31
> specify the format of the CRYCB. In the current
> implementation, the address of the CRYCB is stored in
> the CRYCBD only if the Message-Security-Assist extension
> 3 (MSA3) facility is installed. Virtualization of AP
> facilities, however, requires that a CRYCB of the
> appropriate format be made available to SIE regardless
> of whether MSA3 is installed or not.
> 
> This patch introduces a new compilation unit to provide
> all interfaces related to configuration of AP facilities.
> Let's start by moving the function for setting the CRYCB
> format from arch/s390/kvm/kvm-s390 to this new AP
> configuration interface.

Hm, I would tweak this patch description a bit. First, you talk about
what the crycbd is; then, what needs to be done for vfio-ap support;
then you simply state that you move some interfaces to a new file. I'd
like to see a connection between those parts :)

[It sounds a bit like you'd just introduce a new file and move some
functions, while you do have more changes in there.]

> 
> Signed-off-by: Tony Krowiak <akrowiak@linux.vnet.ibm.com>
> ---
>  MAINTAINERS                      |   10 ++++++
>  arch/s390/include/asm/kvm-ap.h   |   16 ++++++++++
>  arch/s390/include/asm/kvm_host.h |    1 +
>  arch/s390/kvm/Makefile           |    2 +-
>  arch/s390/kvm/kvm-ap.c           |   47 ++++++++++++++++++++++++++++
>  arch/s390/kvm/kvm-s390.c         |   62 +++++---------------------------------
>  6 files changed, 83 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..4acf7c2 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@linux.vnet.ibm.com>
> +M:	Christian BornTraeger <borntraeger@de.ibm.com>

Typo.

> +M:	Martin Schwidefsky <schwidefsky@de.ibm.com>
> +L:	linux-s390@vger.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@linux.vnet.ibm.com>
>  M:	Benjamin Block <bblock@linux.vnet.ibm.com>

(...)

> 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@linux.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?

> +	if (ret)
> +		return 0;
> +
> +	return (config.apxa == 1);
> +}
> +
> +/**
> + * kvm_ap_set_crycb_format
> + *
> + * Set the CRYCB format in the CRYCBD for the KVM guest.

Spell out "crypto control block" somewhere?

> + *
> + * @kvm:	the KVM guest
> + * @crycbd:	the CRYCB descriptor
> + */
> +void kvm_ap_set_crycb_format(struct kvm *kvm, __u32 *crycbd)
> +{
> +	*crycbd = (__u32)(unsigned long) kvm->arch.crypto.crycb;
> +
> +	*crycbd &= ~(CRYCB_FORMAT_MASK);
> +
> +	/* If the MSAX3 is installed */

/* check whether MSAX3 is installed */ ?

> +	if (test_kvm_facility(kvm, 76)) {
> +		if (kvm_ap_apxa_installed())
> +			*crycbd |= CRYCB_FORMAT2;
> +		else
> +			*crycbd |= CRYCB_FORMAT1;
> +	}
> +}
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index 5f5a4cb..de1e299 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c

> @@ -1913,12 +1866,13 @@ static u64 kvm_s390_get_initial_cpuid(void)
>  
>  static void kvm_s390_crypto_init(struct kvm *kvm)
>  {
> +	kvm->arch.crypto.crycb = &kvm->arch.sie_page2->crycb;
> +	kvm->arch.crypto.crycbd = (__u32)(unsigned long) kvm->arch.crypto.crycb;
> +	kvm_ap_set_crycb_format(kvm, &kvm->arch.crypto.crycbd);

Doesn't kvm_ap_set_crycb_format() already initialize its second
parameter?

Would it make sense to do

kvm->arch.crypto.crycbd = kvm_ap_build_crycbd(kvm);

or so instead?

> +
>  	if (!test_kvm_facility(kvm, 76))
>  		return;
>  
> -	kvm->arch.crypto.crycb = &kvm->arch.sie_page2->crycb;
> -	kvm_s390_set_crycb_format(kvm);
> -
>  	/* Enable AES/DEA protected key functions by default */
>  	kvm->arch.crypto.aes_kw = 1;
>  	kvm->arch.crypto.dea_kw = 1;