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Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.6.0 Subject: Re: [PATCH v4 4/7] s390/pci: Use dma-iommu layer Content-Language: en-US To: Niklas Schnelle , Joerg Roedel , Will Deacon , Robin Murphy , Jason Gunthorpe , Wenjia Zhang Cc: Gerd Bayer , Pierre Morel , iommu@lists.linux.dev, 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 References: <20230104120543.308933-1-schnelle@linux.ibm.com> <20230104120543.308933-5-schnelle@linux.ibm.com> <71b9e85d-960f-7403-0113-135746127f3b@linux.ibm.com> <69047c319c6cb2afd7331daeb7fc8459fdd34f80.camel@linux.ibm.com> From: Matthew Rosato In-Reply-To: <69047c319c6cb2afd7331daeb7fc8459fdd34f80.camel@linux.ibm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: MCGFh9H8R5Ex0YgjDidpBNdxwUeRVsZ- X-Proofpoint-ORIG-GUID: MCGFh9H8R5Ex0YgjDidpBNdxwUeRVsZ- X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.219,Aquarius:18.0.930,Hydra:6.0.562,FMLib:17.11.122.1 definitions=2023-01-19_09,2023-01-19_01,2022-06-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxlogscore=810 priorityscore=1501 clxscore=1015 impostorscore=0 mlxscore=0 spamscore=0 bulkscore=0 phishscore=0 adultscore=0 suspectscore=0 lowpriorityscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2212070000 definitions=main-2301190134 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 1/19/23 11:33 AM, Niklas Schnelle wrote: > On Tue, 2023-01-17 at 10:09 -0500, Matthew Rosato wrote: >> On 1/4/23 7:05 AM, Niklas Schnelle wrote: >>> While s390 already has a standard IOMMU driver and previous changes have >>> added I/O TLB flushing operations this driver is currently only used for >>> user-space PCI access such as vfio-pci. For the DMA API s390 instead >>> utilizes its own implementation in arch/s390/pci/pci_dma.c which drives >>> the same hardware and shares some code but requires a complex and >>> fragile hand over between DMA API and IOMMU API use of a device and >>> despite code sharing still leads to significant duplication and >>> maintenance effort. Let's utilize the common code DMAP API >>> implementation from drivers/iommu/dma-iommu.c instead allowing us to >>> get rid of arch/s390/pci/pci_dma.c. >>> >>> Signed-off-by: Niklas Schnelle >>> diff --git a/arch/s390/pci/pci.c b/arch/s390/pci/pci.c >>> index ef38b1514c77..6b0fe8761509 100644 >>> --- a/arch/s390/pci/pci.c >>> +++ b/arch/s390/pci/pci.c >>> @@ -124,7 +124,11 @@ int zpci_register_ioat(struct zpci_dev *zdev, u8 dmaas, >>> >>> WARN_ON_ONCE(iota & 0x3fff); >>> fib.pba = base; >>> - fib.pal = limit; >>> + /* Work around off by one in ISM virt device */ >>> + if (zdev->pft == 0x5 && limit > base) >> >> Nit: maybe a named #define for the ISM pft rather than hard-coding 0x5 here >> > > Hmm, I agree in principle but not sure where to put this #define. Maybe I would suggest pci_clp.h since the value is coming from a clp. > also important to mention that the off-by-one has actually been fixed > in current firmware but of course we still have to support broken > devices and the workaround still works with fixed ISM. +1