From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pierre Morel Subject: Re: [PATCH 1/3] vfio-ccw: add capabilities chain Date: Fri, 23 Nov 2018 14:26:50 +0100 Message-ID: References: <20181122165432.4437-1-cohuck@redhat.com> <20181122165432.4437-2-cohuck@redhat.com> <853a8421-af17-5130-51b7-3242cc10b989@linux.ibm.com> <20181123134517.0b21c263.cohuck@redhat.com> Reply-To: pmorel@linux.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <20181123134517.0b21c263.cohuck@redhat.com> Content-Language: en-US List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+gceq-qemu-devel2=m.gmane.org@nongnu.org Sender: "Qemu-devel" List-Archive: List-Post: To: Cornelia Huck Cc: linux-s390@vger.kernel.org, Eric Farman , Alex Williamson , kvm@vger.kernel.org, Farhan Ali , qemu-devel@nongnu.org, Halil Pasic , qemu-s390x@nongnu.org List-ID: On 23/11/2018 13:45, Cornelia Huck wrote: > On Fri, 23 Nov 2018 13:28:25 +0100 > Pierre Morel wrote: >=20 >> On 22/11/2018 17:54, Cornelia Huck wrote: >>> Allow to extend the regions used by vfio-ccw. The first user will be >>> handling of halt and clear subchannel. >>> >>> Signed-off-by: Cornelia Huck >>> --- >>> drivers/s390/cio/vfio_ccw_ops.c | 182 ++++++++++++++++++++++++= ---- >>> drivers/s390/cio/vfio_ccw_private.h | 38 ++++++ >>> include/uapi/linux/vfio.h | 1 + >>> 3 files changed, 195 insertions(+), 26 deletions(-) >>> =20 >> >> Halt and clear have no parameters (the sub-channel ID is obviously the >> one of the mediated device). >> >> Isn't adding a new sub-region for the purpose of handling halt and cle= ar >> superfluous? >> >> What is the reason not to use simple ioctls ? >=20 > Should it turn out that we missed something and need an enhanced > interface, we can simply stop providing this subregion and add a new > subregion, without breaking existing userspace. We can't do that with > ioctls. OK, it is a good reason, took me a while but I get the interest of=20 capabilities for regions too. >=20 > And moreover, this is only the first user of this infrastructure. > There's also that path handling series that Dong Jia had posted early > this year -- that would be an obvious user as well. >=20 right. Thanks. Regards, Pierre --=20 Pierre Morel Linux/KVM/QEMU in B=C3=B6blingen - Germany