From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753271AbdA0Bnk (ORCPT ); Thu, 26 Jan 2017 20:43:40 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:48560 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750784AbdA0Bni (ORCPT ); Thu, 26 Jan 2017 20:43:38 -0500 Subject: Re: ibmvtpm byteswapping inconsistency To: =?UTF-8?Q?Michal_Such=c3=a1nek?= , Ashley Lai , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Peter Huewe , Marcel Selhorst , Jarkko Sakkinen , Jason Gunthorpe , tpmdd-devel@lists.sourceforge.net, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org References: <20170126212248.3f3e9103@kitsune.suse.cz> From: Tyrel Datwyler Date: Thu, 26 Jan 2017 17:42:29 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.5.1 MIME-Version: 1.0 In-Reply-To: <20170126212248.3f3e9103@kitsune.suse.cz> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Content-Scanned: Fidelis XPS MAILER x-cbid: 17012701-0044-0000-0000-00000263C329 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00006505; HX=3.00000240; KW=3.00000007; PH=3.00000004; SC=3.00000200; SDB=6.00813217; UDB=6.00396686; IPR=6.00590633; BA=6.00005091; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00014063; XFM=3.00000011; UTC=2017-01-27 01:42:35 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17012701-0045-0000-0000-00000690C3C3 Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-01-26_16:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1612050000 definitions=main-1701270014 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/26/2017 12:22 PM, Michal Suchánek wrote: > Hello, > > building ibmvtpm I noticed gcc warning complaining that second word of > struct ibmvtpm_crq in tpm_ibmvtpm_suspend is uninitialized. > > The structure is defined as > > struct ibmvtpm_crq { > u8 valid; > u8 msg; > __be16 len; > __be32 data; > __be64 reserved; > } __attribute__((packed, aligned(8))); > > initialized as > > struct ibmvtpm_crq crq; > u64 *buf = (u64 *) &crq; > ... > crq.valid = (u8)IBMVTPM_VALID_CMD; > crq.msg = (u8)VTPM_PREPARE_TO_SUSPEND; > > and submitted with > > rc = ibmvtpm_send_crq(ibmvtpm->vdev, cpu_to_be64(buf[0]), > cpu_to_be64(buf[1])); These should be be64_to_cpu() here. The underlying hcall made by ibmvtpm_send_crq() requires parameters to be in cpu endian unlike the RTAS interface which requires data in BE. > > which means that the second word indeed contains purely garbage. > > This is repeated a few times in the driver so I added memset to quiet > gcc and make behavior deterministic in case the unused fields get some > meaning in the future. > > However, in tpm_ibmvtpm_send the structure is initialized as > > struct ibmvtpm_crq crq; > __be64 *word = (__be64 *)&crq; > ... > crq.valid = (u8)IBMVTPM_VALID_CMD; > crq.msg = (u8)VTPM_TPM_COMMAND; > crq.len = cpu_to_be16(count); > crq.data = cpu_to_be32(ibmvtpm->rtce_dma_handle); > > and submitted with > > rc = ibmvtpm_send_crq(ibmvtpm->vdev, be64_to_cpu(word[0]), > be64_to_cpu(word[1])); > meaning it is swapped twice. > > > Where is the interface defined? Are the command arguments passed as BE > subfields (the second case was correct before adding the extra whole > word swap) or BE words (the first case doing whole word swap is > correct)? The interface is defined in PAPR. The crq format is defined in BE terms. However, when we break the crq apart into high and low words they need to be in cpu endian as mentioned above. -Tyrel > > Thanks > > Michal >