linux-kernel - Re: [PATCH 3/3] s390/vfio-ap: r/w lock for PQAP interception handler function pointer

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20210611170610.GV1002214@nvidia.com>
Date:   Fri, 11 Jun 2021 14:06:10 -0300
From:   Jason Gunthorpe <jgg@...dia.com>
To:     Tony Krowiak <akrowiak@...ux.ibm.com>
Cc:     linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
        borntraeger@...ibm.com, cohuck@...hat.com,
        pasic@...ux.vnet.ibm.com, jjherne@...ux.ibm.com,
        alex.williamson@...hat.com, kwankhede@...dia.com,
        frankja@...ux.ibm.com, david@...hat.com, imbrenda@...ux.ibm.com,
        hca@...ux.ibm.com
Subject: Re: [PATCH 3/3] s390/vfio-ap: r/w lock for PQAP interception handler
 function pointer

On Wed, Jun 09, 2021 at 06:46:34PM -0400, Tony Krowiak wrote:
> The function pointer to the interception handler for the PQAP instruction
> can get changed during the interception process. Let's add a
> semaphore to struct kvm_s390_crypto to control read/write access to the
> function pointer contained therein.
> 
> The semaphore must be locked for write access by the vfio_ap device driver
> when notified that the KVM pointer has been set or cleared. It must be
> locked for read access by the interception framework when the PQAP
> instruction is intercepted.
> 
> Signed-off-by: Tony Krowiak <akrowiak@...ux.ibm.com>
> ---
>  arch/s390/include/asm/kvm_host.h      |  6 +++---
>  arch/s390/kvm/kvm-s390.c              |  1 +
>  arch/s390/kvm/priv.c                  |  6 +++---
>  drivers/s390/crypto/vfio_ap_ops.c     | 14 ++++++++++----
>  drivers/s390/crypto/vfio_ap_private.h |  2 +-
>  5 files changed, 18 insertions(+), 11 deletions(-)

This is alot better than the try_module_get!

Reviewed-by: Jason Gunthorpe <jgg@...dia.com>

Jason