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Mon, 28 Nov 2022 11:10:44 GMT Received: from b06avi18878370.portsmouth.uk.ibm.com (b06avi18878370.portsmouth.uk.ibm.com [9.149.26.194]) by ppma04ams.nl.ibm.com with ESMTP id 3m3ae9acrt-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 28 Nov 2022 11:10:44 +0000 Received: from d06av24.portsmouth.uk.ibm.com (mk.ibm.com [9.149.105.60]) by b06avi18878370.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 2ASBBNCG4522680 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 28 Nov 2022 11:11:23 GMT Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 0F0F042045; Mon, 28 Nov 2022 11:10:41 +0000 (GMT) Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 295854203F; Mon, 28 Nov 2022 11:10:40 +0000 (GMT) Received: from sig-9-145-47-38.uk.ibm.com (unknown [9.145.47.38]) by d06av24.portsmouth.uk.ibm.com (Postfix) with ESMTP; Mon, 28 Nov 2022 11:10:40 +0000 (GMT) Message-ID: <9163440eb6a47fe02730638bbdf72fda5ee5ad2c.camel@linux.ibm.com> Subject: Re: [PATCH v2 4/7] iommu: Let iommu.strict override ops->def_domain_type From: Niklas Schnelle To: Baolu Lu , Matthew Rosato , Gerd Bayer , iommu@lists.linux.dev, Joerg Roedel , Will Deacon , Robin Murphy , Jason Gunthorpe , Wenjia Zhang Cc: Pierre Morel , linux-s390@vger.kernel.org, borntraeger@linux.ibm.com, hca@linux.ibm.com, gor@linux.ibm.com, gerald.schaefer@linux.ibm.com, agordeev@linux.ibm.com, svens@linux.ibm.com, linux-kernel@vger.kernel.org, Julian Ruess Date: Mon, 28 Nov 2022 12:10:39 +0100 In-Reply-To: <33eea9bd-e101-4836-19e8-d4b191b78b00@linux.intel.com> References: <20221116171656.4128212-1-schnelle@linux.ibm.com> <20221116171656.4128212-5-schnelle@linux.ibm.com> <33eea9bd-e101-4836-19e8-d4b191b78b00@linux.intel.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.5 (3.28.5-18.el8) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: CyGuCoWUou6f4zl4TQXWvmAEwOC89LIy X-Proofpoint-ORIG-GUID: CyGuCoWUou6f4zl4TQXWvmAEwOC89LIy X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.219,Aquarius:18.0.895,Hydra:6.0.545,FMLib:17.11.122.1 definitions=2022-11-28_09,2022-11-28_01,2022-06-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 bulkscore=0 impostorscore=0 mlxlogscore=793 malwarescore=0 priorityscore=1501 spamscore=0 suspectscore=0 adultscore=0 clxscore=1011 mlxscore=0 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2210170000 definitions=main-2211280085 Precedence: bulk List-ID: X-Mailing-List: linux-s390@vger.kernel.org On Thu, 2022-11-17 at 09:55 +0800, Baolu Lu wrote: > On 2022/11/17 1:16, Niklas Schnelle wrote: > > When iommu.strict=1 is set or iommu_set_dma_strict() was called we > > should use IOMMU_DOMAIN_DMA irrespective of ops->def_domain_type. > > > > Signed-off-by: Niklas Schnelle > > --- > > drivers/iommu/iommu.c | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c > > index 65a3b3d886dc..d9bf94d198df 100644 > > --- a/drivers/iommu/iommu.c > > +++ b/drivers/iommu/iommu.c > > @@ -1562,6 +1562,9 @@ static int iommu_get_def_domain_type(struct device *dev) > > { > > const struct iommu_ops *ops = dev_iommu_ops(dev); > > > > + if (iommu_dma_strict) > > + return IOMMU_DOMAIN_DMA; > > If any quirky device must work in IOMMU identity mapping mode, this > might introduce functional regression. At least for VT-d platforms, some > devices do require IOMMU identity mapping mode for functionality. That's a good point. How about instead of unconditionally returning IOMMU_DOMAIN_DMA we just do so if the domain type returned by ops- >def_domain_type uses a flush queue (i.e. the __IOMMU_DOMAIN_DMA_FQ bit is set). That way a device that only supports identity mapping gets to set that but iommu_dma_strict at least always prevents use of an IOVA flush queue. > > > + > > if (dev_is_pci(dev) && to_pci_dev(dev)->untrusted) > > return IOMMU_DOMAIN_DMA; > > > > Best regards, > baolu