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Thu, 23 May 2024 21:52:53 +0000 Message-ID: Date: Thu, 23 May 2024 14:52:50 -0700 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 2/3] vfio/pci: Support 8-byte PCI loads and stores From: Ramesh Thomas To: "Tian, Kevin" , Gerd Bayer , Alex Williamson , Jason Gunthorpe , Niklas Schnelle CC: "kvm@vger.kernel.org" , "linux-s390@vger.kernel.org" , Ankit Agrawal , Yishai Hadas , Halil Pasic , Julian Ruess , Ben Segal References: <20240425165604.899447-1-gbayer@linux.ibm.com> <20240425165604.899447-3-gbayer@linux.ibm.com> Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-ClientProxiedBy: MW3PR06CA0002.namprd06.prod.outlook.com (2603:10b6:303:2a::7) To BYAPR11MB2535.namprd11.prod.outlook.com (2603:10b6:a02:be::32) Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BYAPR11MB2535:EE_|LV8PR11MB8486:EE_ X-MS-Office365-Filtering-Correlation-Id: c75218ed-aacd-4548-5dd7-08dc7b72b2e8 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230031|366007|7416005|376005|1800799015; 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>>>> >>>> +#if defined(ioread64) && defined(iowrite64) >>> >>> Can we check for #ifdef CONFIG_64BIT instead? In x86, ioread64 and >>> iowrite64 get declared as extern functions if CONFIG_GENERIC_IOMAP is >>> defined and this check always fails. In include/asm-generic/io.h, >>> asm-generic/iomap.h gets included which declares them as extern >>> functions. >>> >>> One more thing to consider io-64-nonatomic-hi-lo.h and >>> io-64-nonatomic-lo-hi.h, if included would define it as a macro that >>> calls a function that rw 32 bits back to back. >> >> I don't see the problem here. when the defined check fails it falls >> back to back-to-back vfio_pci_core_iordwr32(). there is no need to >> do it in an indirect way via including io-64-nonatomic-hi-lo.h. > > The issue is iowrite64 and iowrite64 was not getting defined when > CONFIG_GENERIC_IOMAP was not defined, even though the architecture Sorry, I meant they were not getting defined when CONFIG_GENERIC_IOMAP *was defined*. The only definitions of ioread64 and iowrite64 in the code path are in asm/io.h where they are surrounded by #ifndef CONFIG_GENERIC_IOMAP > implemented the 64 bit rw functions readq and writeq. > io-64-nonatomic-hi-lo.h and io-64-nonatomic-lo-hi.h define them and map > them to generic implementations in lib/iomap.c. The implementation calls > the 64 bit rw functions if present, otherwise does 32 bit back to back > rw. Besides it also has sanity checks for port numbers in the iomap > path. I think it is better to rely on this existing generic method than > implementing the checks at places where iowrite64 and ioread64 get > called, at least in the IOMAP path.