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Tue, 28 May 2024 15:13:39 GMT Received: from smtpav04.wdc07v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 457B25805F; Tue, 28 May 2024 15:13:37 +0000 (GMT) Received: from smtpav04.wdc07v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id C122C58050; Tue, 28 May 2024 15:13:35 +0000 (GMT) Received: from [9.61.37.147] (unknown [9.61.37.147]) by smtpav04.wdc07v.mail.ibm.com (Postfix) with ESMTP; Tue, 28 May 2024 15:13:35 +0000 (GMT) Message-ID: <67fb5c3d-a53f-4ef3-93de-a307777ec044@linux.ibm.com> Date: Tue, 28 May 2024 11:13:35 -0400 Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 2/3] vfio/pci: Tolerate oversized BARs by disallowing mmap To: Niklas Schnelle , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Alex Williamson , Gerd Bayer , Jason Gunthorpe Cc: linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org References: <20240523-vfio_pci_mmap-v2-0-0dc6c139a4f1@linux.ibm.com> <20240523-vfio_pci_mmap-v2-2-0dc6c139a4f1@linux.ibm.com> Content-Language: en-US From: Matthew Rosato In-Reply-To: <20240523-vfio_pci_mmap-v2-2-0dc6c139a4f1@linux.ibm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: 1TMO_DwrdKXKL-FGAcPwUpCYKZuyh9d- X-Proofpoint-GUID: YViOe4KNdkMX-dMiwr9B6EZb5UU2L43m X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1039,Hydra:6.0.650,FMLib:17.12.28.16 definitions=2024-05-28_11,2024-05-28_01,2024-05-17_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 mlxlogscore=909 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 mlxscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2405010000 definitions=main-2405280113 On 5/23/24 7:10 AM, Niklas Schnelle wrote: > On s390 there is a virtual PCI device called ISM which has a few rather > annoying oddities. For one it claims to have a 256 TiB PCI BAR (not > a typo) which leads to any attempt to mmap() it failing during vmap. > > Even if one tried to map this "BAR" only partially the mapping would not > be usable on systems with MIO support enabled however. This is because > of another oddity in that this virtual PCI device does not support the > newer memory I/O (MIO) PCI instructions and legacy PCI instructions are > not accessible by user-space when MIO is in use. If this device needs to > be accessed by user-space it will thus need a vfio-pci variant driver. > Until then work around both issues by excluding resources which don't > fit between IOREMAP_START and IOREMAP_END in vfio_pci_probe_mmaps(). > > Reviewed-by: Jason Gunthorpe > Signed-off-by: Niklas Schnelle > --- Reviewed-by: Matthew Rosato