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Message-ID: <7e537cfc-5d67-c188-2890-191608cb7b4f@redhat.com>
Date: Fri, 4 May 2018 09:19:45 +0200
From: David Hildenbrand <david@...hat.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, 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, 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 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
This statement is wrong. The instructions can be interpreted by SIE e.g.
if there are no devices assigned to a guest. This is e.g. the case for
!CONFIG_ZCRYPT.
Also, doesn't this directly imply that the other execution control
should also not be used ("intercept AP instuctions"). This would be bad.
Just because !CONFIG_ZCRYPT does not imply that you can't emulate AP
devices for a guest.
Why isn't it sufficient to glue CONFIG_ZCRYPT to vfio-ap? This would
make more sense in my opinion. You have no "host devices" that you can
"pass through". But you can still emulate devices or emulate an empty bus.
> 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/include/asm/ap.h b/arch/s390/include/asm/ap.h
> index c1bedb4..7773bfd 100644
> --- a/arch/s390/include/asm/ap.h
> +++ b/arch/s390/include/asm/ap.h
> @@ -120,4 +120,11 @@ struct ap_queue_status ap_queue_irq_ctrl(ap_qid_t qid,
> struct ap_qirq_ctrl qirqctrl,
> void *ind);
>
> +/**
> + * ap_instructions_installed() - Tests whether AP instructions are installed
> + *
> + * Returns 1 if the AP instructions are installed, otherwise; returns 0
> + */
> +int ap_instructions_installed(void);
> +
> #endif /* _ASM_S390_AP_H_ */
> diff --git a/arch/s390/include/asm/kvm-ap.h b/arch/s390/include/asm/kvm-ap.h
> new file mode 100644
> index 0000000..84412a9
> --- /dev/null
> +++ b/arch/s390/include/asm/kvm-ap.h
> @@ -0,0 +1,23 @@
> +// 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>
> + */
> +
> +#ifndef _ASM_KVM_AP
> +#define _ASM_KVM_AP
> +
> +/**
> + * kvm_ap_instructions_installed()
> + *
> + * Tests whether AP instructions are installed on the linux host
> + *
> + * Returns 1 if the AP instructions are installed on the host, otherwise;
> + * returns 0
> + */
> +int kvm_ap_instructions_installed(void);
> +
> +#endif /* _ASM_KVM_AP */
> diff --git a/arch/s390/kvm/Makefile b/arch/s390/kvm/Makefile
> index 05ee90a..1876bfe 100644
> --- a/arch/s390/kvm/Makefile
> +++ b/arch/s390/kvm/Makefile
> @@ -9,6 +9,6 @@ common-objs = $(KVM)/kvm_main.o $(KVM)/eventfd.o $(KVM)/async_pf.o $(KVM)/irqch
> ccflags-y := -Ivirt/kvm -Iarch/s390/kvm
>
> kvm-objs := $(common-objs) kvm-s390.o intercept.o interrupt.o priv.o sigp.o
> -kvm-objs += diag.o gaccess.o guestdbg.o vsie.o
> +kvm-objs += diag.o gaccess.o guestdbg.o vsie.o kvm-ap.o
>
> obj-$(CONFIG_KVM) += kvm.o
> 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
> + 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.
> */
>
--
Thanks,
David / dhildenb
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