From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0b-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D63FF1FAC42; Thu, 13 Feb 2025 10:06:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=148.163.158.5 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739441215; cv=none; b=FonxUGUIhMClimY+ul3z2lZZZ7CY3nyGvcn5V8efAROEp07GW1HjT6pW891Yd/RZdKRfagpbt7BdzASJ5DqI+2xwwhx6nIV3XB/K5pjFa1Yf95nTNR034b9kXg7XfhF/XRU7h6fYqsDBtmYdC7meIIYfH5otvEc7kNoUbwQrqig= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739441215; c=relaxed/simple; bh=ko837iq1ve/8hqP2/4ukx7/LfNVkESiB7v53Gzu9/xM=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=G91pGNRD6rATsoFGbBM5doGqE/WRAOnbCsEvBJiSgTu+RwuiwGUkY8kUMuyVVcVHTYSj0P6tqUA4sbtCYNLn0nF3poFXeRnccFDbcj1H3AzIF/Yj/Hy0onu7jcQ3BDPh7kSrTfF9NEMsq2glEFGX8L6sdRS5J4RxdooOlDc5+x8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com; spf=pass smtp.mailfrom=linux.ibm.com; dkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b=CnZFkRLV; arc=none smtp.client-ip=148.163.158.5 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.ibm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b="CnZFkRLV" Received: from pps.filterd (m0356516.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.18.1.2/8.18.1.2) with ESMTP id 51D7YHwL017386; Thu, 13 Feb 2025 10:06:38 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=cc :content-transfer-encoding:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to; s=pp1; bh=+uEW0T cugeSxMGhadSCJPH9+qLh2x0/3ZL4KmjvKuyg=; b=CnZFkRLV0r/+LxHWU9sCb9 Mg+pYguRwrXskPrlsmAQUc1aOS+elsmezqSYMeDhbDDH0QW77lLon2QLj3055tGQ xi/gQYD+6/DIfl4V6EtSMZj0zlTUvvmRro9MfFLAfFoiPM5Wq4vaCEmhHHktlNSK axSgwgL2Lx9jakRoMBqkIXG12qlHl0zymY4Ch0le3iklIpCRB90SwK1pCBoAPNLv kcRyNoNK0ejVwd9m0BbV4F2y7g5TpF7dYI8rJ+mUKKDl7Z87u+58isxkHmXkSoKr qEgseve+UNnjRBXKNM2N56cyyE4AGeysxNcUP/e6/8d8voQ8oVvr7UoeUbFtKxdA == Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 44rxfu4tke-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 13 Feb 2025 10:06:37 +0000 (GMT) Received: from m0356516.ppops.net (m0356516.ppops.net [127.0.0.1]) by pps.reinject (8.18.0.8/8.18.0.8) with ESMTP id 51DA3a75020734; Thu, 13 Feb 2025 10:06:37 GMT Received: from ppma21.wdc07v.mail.ibm.com (5b.69.3da9.ip4.static.sl-reverse.com [169.61.105.91]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 44rxfu4tka-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 13 Feb 2025 10:06:36 +0000 (GMT) Received: from pps.filterd (ppma21.wdc07v.mail.ibm.com [127.0.0.1]) by ppma21.wdc07v.mail.ibm.com (8.18.1.2/8.18.1.2) with ESMTP id 51D81TZx001355; Thu, 13 Feb 2025 10:06:36 GMT Received: from smtprelay06.wdc07v.mail.ibm.com ([172.16.1.73]) by ppma21.wdc07v.mail.ibm.com (PPS) with ESMTPS id 44pjkndnvs-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 13 Feb 2025 10:06:36 +0000 Received: from smtpav05.wdc07v.mail.ibm.com (smtpav05.wdc07v.mail.ibm.com [10.39.53.232]) by smtprelay06.wdc07v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 51DA6Z6v32965246 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 13 Feb 2025 10:06:35 GMT Received: from smtpav05.wdc07v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 26E2558059; Thu, 13 Feb 2025 10:06:35 +0000 (GMT) Received: from smtpav05.wdc07v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 47E2B58043; Thu, 13 Feb 2025 10:06:31 +0000 (GMT) Received: from [9.171.82.253] (unknown [9.171.82.253]) by smtpav05.wdc07v.mail.ibm.com (Postfix) with ESMTP; Thu, 13 Feb 2025 10:06:31 +0000 (GMT) Message-ID: <8f1a62e93bde37708a47b7db70767d1e14c608e0.camel@linux.ibm.com> Subject: Re: [PATCH v5 2/2] PCI: s390: Support mmap() of BARs and replace VFIO_PCI_MMAP by a device flag From: Niklas Schnelle To: Alex Williamson Cc: Bjorn Helgaas , Christoph Hellwig , Alexandra Winter , Gerd Bayer , Matthew Rosato , Jason Gunthorpe , Thorsten Winkler , Bjorn Helgaas , Julian Ruess , Halil Pasic , Christian Borntraeger , Sven Schnelle , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-pci@vger.kernel.org Date: Thu, 13 Feb 2025 11:06:30 +0100 In-Reply-To: <20250212132808.08dcf03c.alex.williamson@redhat.com> References: <20250212-vfio_pci_mmap-v5-0-633ca5e056da@linux.ibm.com> <20250212-vfio_pci_mmap-v5-2-633ca5e056da@linux.ibm.com> <20250212132808.08dcf03c.alex.williamson@redhat.com> Autocrypt: addr=schnelle@linux.ibm.com; prefer-encrypt=mutual; keydata=mQINBGHm3M8BEAC+MIQkfoPIAKdjjk84OSQ8erd2OICj98+GdhMQpIjHXn/RJdCZLa58k /ay5x0xIHkWzx1JJOm4Lki7WEzRbYDexQEJP0xUia0U+4Yg7PJL4Dg/W4Ho28dRBROoJjgJSLSHwc 3/1pjpNlSaX/qg3ZM8+/EiSGc7uEPklLYu3gRGxcWV/944HdUyLcnjrZwCn2+gg9ncVJjsimS0ro/ 2wU2RPE4ju6NMBn5Go26sAj1owdYQQv9t0d71CmZS9Bh+2+cLjC7HvyTHKFxVGOznUL+j1a45VrVS XQ+nhTVjvgvXR84z10bOvLiwxJZ/00pwNi7uCdSYnZFLQ4S/JGMs4lhOiCGJhJ/9FR7JVw/1t1G9a UlqVp23AXwzbcoV2fxyE/CsVpHcyOWGDahGLcH7QeitN6cjltf9ymw2spBzpRnfFn80nVxgSYVG1d w75ksBAuQ/3e+oTQk4GAa2ShoNVsvR9GYn7rnsDN5pVILDhdPO3J2PGIXa5ipQnvwb3EHvPXyzakY tK50fBUPKk3XnkRwRYEbbPEB7YT+ccF/HioCryqDPWUivXF8qf6Jw5T1mhwukUV1i+QyJzJxGPh19 /N2/GK7/yS5wrt0Lwxzevc5g+jX8RyjzywOZGHTVu9KIQiG8Pqx33UxZvykjaqTMjo7kaAdGEkrHZ dVHqoPZwhCsgQARAQABtChOaWtsYXMgU2NobmVsbGUgPHNjaG5lbGxlQGxpbnV4LmlibS5jb20+iQ JXBBMBCABBAhsBBQsJCAcCBhUKCQgLAgQWAgMBAh4BAheAAhkBFiEEnbAAstJ1IDCl9y3cr+Q/Fej CYJAFAmesutgFCQenEYkACgkQr+Q/FejCYJDIzA//W5h3t+anRaztihE8ID1c6ifS7lNUtXr0wEKx Qm6EpDQKqFNP+n3R4A5w4gFqKv2JpYQ6UJAAlaXIRTeT/9XdqxQlHlA20QWI7yrJmoYaF74ZI9s/C 8aAxEzQZ64NjHrmrZ/N9q8JCTlyhk5ZEV1Py12I2UH7moLFgBFZsPlPWAjK2NO/ns5UJREAJ04pR9 XQFSBm55gsqkPp028cdoFUD+IajGtW7jMIsx/AZfYMZAd30LfmSIpaPAi9EzgxWz5habO1ZM2++9e W6tSJ7KHO0ZkWkwLKicrqpPvA928eNPxYtjkLB2XipdVltw5ydH9SLq0Oftsc4+wDR8TqhmaUi8qD Fa2I/0NGwIF8hjwSZXtgJQqOTdQA5/6voIPheQIi0NBfUr0MwboUIVZp7Nm3w0QF9SSyTISrYJH6X qLp17NwnGQ9KJSlDYCMCBJ+JGVmlcMqzosnLli6JszAcRmZ1+sd/f/k47Fxy1i6o14z9Aexhq/UgI 5InZ4NUYhf5pWflV41KNupkS281NhBEpChoukw25iZk0AsrukpJ74x69MJQQO+/7PpMXFkt0Pexds XQrtsXYxLDQk8mgjlgsvWl0xlk7k7rddN1+O/alcv0yBOdvlruirtnxDhbjBqYNl8PCbfVwJZnyQ4 SAX2S9XiGeNtWfZ5s2qGReyAcd2nBna0KU5pa2xhcyBTY2huZWxsZSA8bmlrbGFzLnNjaG5lbGxlQ GlibS5jb20+iQJUBBMBCAA+AhsBBQsJCAcCBhUKCQgLAgQWAgMBAh4BAheAFiEEnbAAstJ1IDCl9y 3cr+Q/FejCYJAFAmesuuEFCQenEYkACgkQr+Q/FejCYJCosA/9GCtbN8lLQkW71n/CHR58BAA5ct1 KRYiZNPnNNAiAzjvSb0ezuRVt9H0bk/tnj6pPj0zdyU2bUj9Ok3lgocWhsF2WieWbG4dox5/L1K28 qRf3p+vdPfu7fKkA1yLE5GXffYG3OJnqR7OZmxTnoutj81u/tXO95JBuCSJn5oc5xMQvUUFzLQSbh prIWxcnzQa8AHJ+7nAbSiIft/+64EyEhFqncksmzI5jiJ5edABiriV7bcNkK2d8KviUPWKQzVlQ3p LjRJcJJHUAFzsZlrsgsXyZLztAM7HpIA44yo+AVVmcOlmgPMUy+A9n+0GTAf9W3y36JYjTS+ZcfHU KP+y1TRGRzPrFgDKWXtsl1N7sR4tRXrEuNhbsCJJMvcFgHsfni/f4pilabXO1c5Pf8fiXndCz04V8 ngKuz0aG4EdLQGwZ2MFnZdyf3QbG3vjvx7XDlrdzH0wUgExhd2fHQ2EegnNS4gNHjq82uLPU0hfcr obuI1D74nV0BPDtr7PKd2ryb3JgjUHKRKwok6IvlF2ZHMMXDxYoEvWlDpM1Y7g81NcKoY0BQ3ClXi a7vCaqAAuyD0zeFVGcWkfvxYKGqpj8qaI/mA8G5iRMTWUUUROy7rKJp/y2ioINrCul4NUJUujfx4k 7wFU11/YNAzRhQG4MwoO5e+VY66XnAd+XPyBIlvy0K05pa2xhcyBTY2huZWxsZSA8bmlrbGFzLnNj aG5lbGxlQGdtYWlsLmNvbT6JAlQEEwEIAD4CGwEFCwkIBwIGFQoJCAsCBBYCAwECHgECF4AWIQSds ACy0nUgMKX3Ldyv5D8V6MJgkAUCZ6y64QUJB6cRiQAKCRCv5D8V6MJgkEr/D/9iaYSYYwlmTJELv+ +EjsIxXtneKYpjXEgNnPwpKEXNIpuU/9dcVDcJ10MfvWBPi3sFbIzO9ETIRyZSgrjQxCGSIhlbom4 D8jVzTA698tl9id0FJKAi6T0AnBF7CxyqofPUzAEMSj9ynEJI/Qu8pHWkVp97FdJcbsho6HNMthBl +Qgj9l7/Gm1UW3ZPvGYgU75uB/mkaYtEv0vYrSZ+7fC2Sr/O5SM2SrNk+uInnkMBahVzCHcoAI+6O Enbag+hHIeFbqVuUJquziiB/J4Z2yT/3Ps/xrWAvDvDgdAEr7Kn697LLMRWBhGbdsxdHZ4ReAhc8M 8DOcSWX7UwjzUYq7pFFil1KPhIkHctpHj2Wvdnt+u1F9fN4e3C6lckUGfTVd7faZ2uDoCCkJAgpWR 10V1Q1Cgl09VVaoi6LcGFPnLZfmPrGYiDhM4gyDDQJvTmkB+eMEH8u8V1X30nCFP2dVvOpevmV5Uk onTsTwIuiAkoTNW4+lRCFfJskuTOQqz1F8xVae8KaLrUt2524anQ9x0fauJkl3XdsVcNt2wYTAQ/V nKUNgSuQozzfXLf+cOEbV+FBso/1qtXNdmAuHe76ptwjEfBhfg8L+9gMUthoCR94V0y2+GEzR5nlD 5kfu8ivV/gZvij+Xq3KijIxnOF6pd0QzliKadaFNgGw4FoUeZo0rQhTmlrbGFzIFNjaG5lbGxlIDx uaWtzQGtlcm5lbC5vcmc+iQJUBBMBCAA+AhsBBQsJCAcCBhUKCQgLAgQWAgMBAh4BAheAFiEEnbAA stJ1IDCl9y3cr+Q/FejCYJAFAmesuuEFCQenEYkACgkQr+Q/FejCYJC6yxAAiQQ5NAbWYKpkxxjP/ AajXheMUW8EtK7EMJEKxyemj40laEs0wz9owu8ZDfQl4SPqjjtcRzUW6vE6JvfEiyCLd8gUFXIDMS l2hzuNot3sEMlER9kyVIvemtV9r8Sw1NHvvCjxOMReBmrtg9ooeboFL6rUqbXHW+yb4GK+1z7dy+Q 9DMlkOmwHFDzqvsP7eGJN0xD8MGJmf0L5LkR9LBc+jR78L+2ZpKA6P4jL53rL8zO2mtNQkoUO+4J6 0YTknHtZrqX3SitKEmXE2Is0Efz8JaDRW41M43cE9b+VJnNXYCKFzjiqt/rnqrhLIYuoWCNzSJ49W vt4hxfqh/v2OUcQCIzuzcvHvASmt049ZyGmLvEz/+7vF/Y2080nOuzE2lcxXF1Qr0gAuI+wGoN4gG lSQz9pBrxISX9jQyt3ztXHmH7EHr1B5oPus3l/zkc2Ajf5bQ0SE7XMlo7Pl0Xa1mi6BX6I98CuvPK SA1sQPmo+1dQYCWmdQ+OIovHP9Nx8NP1RB2eELP5MoEW9eBXoiVQTsS6g6OD3rH7xIRxRmuu42Z5e 0EtzF51BjzRPWrKSq/mXIbl5nVW/wD+nJ7U7elW9BoJQVky03G0DhEF6fMJs08DGG3XoKw/CpGtMe 2V1z/FRotP5Fkf5VD3IQGtkxSnO/awtxjlhytigylgrZ4wDpSE= Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.54.3 (3.54.3-1.fc41) Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: m-TpfZyWbtPLrVmCPbTe1NiQnFbLIm8- X-Proofpoint-GUID: hEYqtllOeUmpjoh9AXKXLcdtFhnuBX-s X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1057,Hydra:6.0.680,FMLib:17.12.68.34 definitions=2025-02-13_03,2025-02-13_01,2024-11-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 mlxscore=0 clxscore=1015 adultscore=0 mlxlogscore=999 phishscore=0 bulkscore=0 suspectscore=0 spamscore=0 impostorscore=0 malwarescore=0 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2501170000 definitions=main-2502130076 On Wed, 2025-02-12 at 13:28 -0700, Alex Williamson wrote: > On Wed, 12 Feb 2025 16:28:32 +0100 > Niklas Schnelle wrote: >=20 > > On s390 there is a virtual PCI device called ISM which has a few > > peculiarities. For one, it presents a 256 TiB PCI BAR whose size leads > > to any attempt to ioremap() the whole BAR failing. This is problematic > > since mapping the whole BAR is the default behavior of for example > > vfio-pci in combination with QEMU and VFIO_PCI_MMAP enabled. > >=20 > > Even if one tried to map this BAR only partially, the mapping would not > > be usable without extra precautions on systems with MIO support enabled= . > > 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 through writeq()/readq() when MIO is in > > use. > >=20 > > In short the ISM device's BAR is not accessible through memory mappings= . > > Indicate this by introducing a new non_mappable_bars flag for the ISM > > device and set it using a PCI quirk. Use this flag instead of the > > VFIO_PCI_MMAP Kconfig option to block mapping with vfio-pci. This was > > the only use of the Kconfig option so remove it. Note that there are no > > PCI resource sysfs files on s390x already as HAVE_PCI_MMAP is currently > > not set. If this were to be set in the future pdev->non_mappable_bars > > can be used to prevent unusable resource files for ISM from being > > created. >=20 > I think we should also look at it from the opposite side, not just > s390x maybe adding HAVE_PCI_MMAP in the future, but the fact that we're > currently adding a generic PCI device flag which isn't honored by the > one mechanism that PCI core provides to mmap MMIO BARs to userspace. > It seems easier to implement it in pci_mmap_resource() now rather than > someone later discovering there's no enforcement outside of the very > narrow s390x use case. Thanks, >=20 > Alex That is a very good point! I did try enabling HAVE_PCI_MMAP for s390 a while back and I believe that ran into trouble with ISM devices too. So I just did a quick test of enabling HAVE_PCI_MMAP with ARCH_GENERIC_PCI_MMAP_RESOURCE for s390. Then added a check for=C2=A0 pdev->non_mappable_bars to pci_create_resource_files() and proc_bus_pci_mmap(). I pondered adding it to pci_mmap_resource() too but felt like not showing the resource at all, like we do now with !HAVE_PCI_MMAP is cleaner. Using a little test program that just mmap()s BAR 0 of an NVMe and reads the NVMe version at offset 8 using our PCI MIO load instruction works. Also, as expected I don't get resourceX files for ISM devices with the added check.=C2=A0 I still have to test the /proc/bus/pci based mmap() but would expect that to work too. So I'd be open to adding another patch which adds HAVE_PCI_MMAP for s390, if we see too much risk with that, we could alternatively add just the pdev->non_mappable_bars but then they would be untested, still better than hoping that someone remembers to add that in the future. Thanks, Niklas