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Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kIuTd-0007em-6s; Thu, 17 Sep 2020 14:01:33 +0000 Received: from foss.arm.com ([217.140.110.172]) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kIuTU-0007cI-Rj for linux-arm-kernel@lists.infradead.org; Thu, 17 Sep 2020 14:01:25 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 2851730E; Thu, 17 Sep 2020 07:01:23 -0700 (PDT) Received: from e121166-lin.cambridge.arm.com (e121166-lin.cambridge.arm.com [10.1.196.255]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id DFC2C3F718; Thu, 17 Sep 2020 07:01:21 -0700 (PDT) Date: Thu, 17 Sep 2020 15:01:16 +0100 From: Lorenzo Pieralisi To: Jason Gunthorpe Subject: Re: [PATCH] arm64: Enable PCI write-combine resources under sysfs Message-ID: <20200917140116.GA4893@e121166-lin.cambridge.arm.com> References: <2b539df4c9ec703458e46da2fc879ee3b310b31c.camel@kernel.crashing.org> <20200915101831.GA2616@e121166-lin.cambridge.arm.com> <20200915110511.GQ904879@nvidia.com> <20200915234006.GI1573713@nvidia.com> <701012f288231d0d0733bf1c2c8fdbd9caa074fd.camel@kernel.crashing.org> <20200916121226.GN1573713@nvidia.com> <28082ccc715a9fba349ae6052d5c917ae02d40fa.camel@kernel.crashing.org> <20200917102819.GA2284@e121166-lin.cambridge.arm.com> <20200917113221.GG3699@nvidia.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200917113221.GG3699@nvidia.com> User-Agent: Mutt/1.9.4 (2018-02-28) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200917_100124_938675_E0B8ECB4 X-CRM114-Status: GOOD ( 14.84 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: catalin.marinas@arm.com, Leon Romanovsky , Benjamin Herrenschmidt , Bjorn Helgaas , linux-pci@vger.kernel.org, will@kernel.org, linux-arm-kernel@lists.infradead.org, Clint Sbisa Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Sep 17, 2020 at 08:32:21AM -0300, Jason Gunthorpe wrote: > On Thu, Sep 17, 2020 at 11:28:19AM +0100, Lorenzo Pieralisi wrote: > > Unfortunately if we merge this patch we _do_ know from this thread > > that userspace will suffer from a perf regression on TX2. > > > > Either we ignore it or we write some code to prevent it > > (ie first step make arch_can_pci_mmap_wc() return 0 on TX2 - > > possibly using the arm64 errata detection mechanism). > > If anyone complains they can send the change to arch_can_pci_mmap_wc() > - I'm pretty sure nobody will complain due to mlx5 If that's the case we can go ahead and merge this patch with a reworded commit log - this thread was very useful nonetheless for my own information (and others hopefully) so thank you. For VFIO WC + "message push ioremap" - to be continued. Clint, please reword the commit and resend, not sure we can hit v5.10 but we shall try. Thanks, Lorenzo _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel