Messages in this thread | | | Subject | Re: [PATCH v4 01/15] s390: zcrypt: externalize AP instructions available function | From | Tony Krowiak <> | Date | Tue, 17 Apr 2018 09:31:00 -0400 |
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On 04/16/2018 08:11 AM, Cornelia Huck wrote: > On Mon, 16 Apr 2018 10:44:53 +0200 > Pierre Morel <pmorel@linux.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@linux.vnet.ibm.com> >>> Reviewed-by: Pierre Morel <pmorel@linux.vnet.ibm.com> >>> Reviewed-by: Harald Freudenberger <freude@linux.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@linux.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).
I'm not crazy about it myself (see below)
> > 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?
My preference would be one of the following:
1. All of the interfaces defined in arch/s390/include/asm/ap.h are implemented in a file that is built whether ZCRYPT is built or not.
2. The drivers/s390/crypto/ap_asm.h file containing the functions that execute the AP instructions are made available outside of the AP bus, for example; arch/s390/include/asm
I requested this from the maintainer but was told we don't want to have any crypto adapter support when the host AP functionality is disabled (CONFIG_ZCRYPT=n). This makes sense, however; I think it is a bit confusing to have a header file (arch/s390/include/asm/ap.h) with interfaces that are conditionally built.
This is why I chose the ifdeffery (as you call it) approach. The only other solution I can conjure is to duplicate the asm code for the AP instructions needed in KVM and bypass using the AP bus interfaces.
> >>> + 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. >>> */ >>
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