From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:46878) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eJLHK-0005NZ-Qd for qemu-devel@nongnu.org; Mon, 27 Nov 2017 10:25:06 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eJLHH-0008Nb-Eh for qemu-devel@nongnu.org; Mon, 27 Nov 2017 10:25:02 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:33658 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 1eJLHH-0008NP-8d for qemu-devel@nongnu.org; Mon, 27 Nov 2017 10:24:59 -0500 Received: from pps.filterd (m0098419.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id vARFOs5c033515 for ; Mon, 27 Nov 2017 10:24:56 -0500 Received: from e06smtp13.uk.ibm.com (e06smtp13.uk.ibm.com [195.75.94.109]) by mx0b-001b2d01.pphosted.com with ESMTP id 2egkp8w8sx-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Mon, 27 Nov 2017 10:24:55 -0500 Received: from localhost by e06smtp13.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 27 Nov 2017 15:24:12 -0000 References: <1511388334-16347-1-git-send-email-pmorel@linux.vnet.ibm.com> <1511388334-16347-2-git-send-email-pmorel@linux.vnet.ibm.com> <3acc6fdb-5638-97b2-2dc7-bce34d22cd1f@redhat.com> <20171123104903.24424b40.cohuck@redhat.com> <20171123110844.4649f3b1.cohuck@redhat.com> <58a08c1d-3935-42e7-cdc0-7bc45c08d2d3@redhat.com> <20171123113326.3b2c5281.cohuck@redhat.com> <6ab0d29e-1af0-888a-c932-a0a294ea225d@linux.vnet.ibm.com> <4000596f-d2a0-c32e-7683-7e074e8132e2@linux.vnet.ibm.com> <37aa6eb3-cbdf-39af-2068-7d0e5949e601@linux.vnet.ibm.com> <2ab76ab0-b20a-9eaf-cafb-195e1621edd6@redhat.com> <20171127120255.2d36c8f3.cohuck@redhat.com> <20171127153436.200a01c7.cohuck@redhat.com> From: Pierre Morel Date: Mon, 27 Nov 2017 16:24:08 +0100 MIME-Version: 1.0 In-Reply-To: <20171127153436.200a01c7.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] [qemu-s390x] [PATCH v3 1/7] s390x/pci: factor out endianess conversion List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Cornelia Huck , Thomas Huth Cc: Yi Min Zhao , pasic@linux.vnet.ibm.com, qemu-devel@nongnu.org, agraf@suse.de, borntraeger@de.ibm.com, Qemu-s390x list On 27/11/2017 15:34, Cornelia Huck wrote: > On Mon, 27 Nov 2017 12:02:55 +0100 > Cornelia Huck wrote: >=20 >> On Mon, 27 Nov 2017 07:59:36 +0100 >> Thomas Huth wrote: >> >>> On 25.11.2017 14:49, Pierre Morel wrote: >>>> On 24/11/2017 07:19, Yi Min Zhao wrote: >>>>> >>>>> >>>>> =E5=9C=A8 2017/11/23 =E4=B8=8B=E5=8D=888:18, Thomas Huth =E5=86=99=E9= =81=93: >>>>>> On 23.11.2017 13:07, Yi Min Zhao wrote: >> >>>>>>> Another question, does 'cpu' in cpu_to_le**() or le**_to_cpu() me= an the >>>>>>> host endianess? >>>>>> Yes, the "cpu" in cpu_to_le or le_to_cpu means the host, indeed. I= t's >>>>>> confusing :-/ >>>>>> =20 >>>>>>> If the answers to upper two questions are yes, we actually need h= andle >>>>>>> two cases. >>>>>>> 1) For pcilg, we need to translate the data to little-endian, thu= s >>>>>>> cpu_to_le**(). >>>>>>> 2) For pcistg, we need to translate the data to host endianess, t= hus >>>>>>> le**_to_cpu(). >>>>>> I think we've got to byte-swap if the host is big endian (s390x), = but >>>>>> not if the host is little endian (x86 with TCG). >>>> >>>> Here is my comprehension of this funny swapping: >>>> >>>> - TCG for a BE guest and a le host swap bytes because if we do (regi= ster >>>> & 0x01) in the zPCI interception code it must work what ever the >>>> endianess is. >>> >>> Uhhh, I might have missed that the value has already been byte-swappe= d >>> once by TCG for env->regs[r1] ... >>> Now I'm pretty much completely confused ... sorry for the noise if I = was >>> wrong... I think it's best you ignore my comment for now (i.e. go wit= h >>> bswapXX() instead of le_to_cpuXX()), and if we later wire up zPCI wit= h >>> TCG, we still can fix this if necessary. >> >> I'll try my current pci/tcg patches on LPAR with this (or a v4) on top. >> If it works there (it doesn't yet on my laptop), we do have a >> endianness issue... (unfortunately, the reverse isn't true.) >=20 > It does not look too bad: I can get a nice enP1p0s0 device from a > virtio-net-pci with my tcg patches on my laptop (with these patches as > well, of course). So, endianness is likely mostly fine. On the Lpar and on the Laptop or only on the Lpar ? >=20 >> >> I'll post my pci/tcg patches once I get it mostly working (and it does >> not look like a horror from the crypt anymore). >=20 > Time to get out the make up kit for these. >=20 --=20 Pierre Morel Linux/KVM/QEMU in B=C3=B6blingen - Germany