From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45507) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gQBU8-0005D7-Tt for qemu-devel@nongnu.org; Fri, 23 Nov 2018 08:27:05 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gQBU5-0005dr-LZ for qemu-devel@nongnu.org; Fri, 23 Nov 2018 08:27:04 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:58508 helo=mx0a-001b2d01.pphosted.com) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gQBU3-0005Yl-Qi for qemu-devel@nongnu.org; Fri, 23 Nov 2018 08:27:00 -0500 Received: from pps.filterd (m0098420.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id wANDIdjl072109 for ; Fri, 23 Nov 2018 08:26:57 -0500 Received: from e06smtp02.uk.ibm.com (e06smtp02.uk.ibm.com [195.75.94.98]) by mx0b-001b2d01.pphosted.com with ESMTP id 2nxg8vnw2b-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Fri, 23 Nov 2018 08:26:57 -0500 Received: from localhost by e06smtp02.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 23 Nov 2018 13:26:55 -0000 Reply-To: pmorel@linux.ibm.com 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> From: Pierre Morel Date: Fri, 23 Nov 2018 14:26:50 +0100 MIME-Version: 1.0 In-Reply-To: <20181123134517.0b21c263.cohuck@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Message-Id: Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH 1/3] vfio-ccw: add capabilities chain List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Cornelia Huck Cc: Halil Pasic , Eric Farman , Farhan Ali , linux-s390@vger.kernel.org, kvm@vger.kernel.org, qemu-s390x@nongnu.org, qemu-devel@nongnu.org, Alex Williamson 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