From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 96DCDC433DB for ; Wed, 13 Jan 2021 11:56:09 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id A0BCF22CE3 for ; Wed, 13 Jan 2021 11:56:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A0BCF22CE3 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from bilbo.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 4DG5W65yNGzDqCX for ; Wed, 13 Jan 2021 22:56:02 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=none (no SPF record) smtp.mailfrom=lst.de (client-ip=213.95.11.211; helo=verein.lst.de; envelope-from=hch@lst.de; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=lst.de Received: from verein.lst.de (verein.lst.de [213.95.11.211]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4DG5P94n1MzDrSq for ; Wed, 13 Jan 2021 22:50:38 +1100 (AEDT) Received: by verein.lst.de (Postfix, from userid 2407) id AA26B68AFE; Wed, 13 Jan 2021 12:50:31 +0100 (CET) Date: Wed, 13 Jan 2021 12:50:31 +0100 From: Christoph Hellwig To: Claire Chang Subject: Re: [RFC PATCH v3 1/6] swiotlb: Add io_tlb_mem struct Message-ID: <20210113115031.GA29376@lst.de> References: <20210106034124.30560-1-tientzu@chromium.org> <20210106034124.30560-2-tientzu@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210106034124.30560-2-tientzu@chromium.org> User-Agent: Mutt/1.5.17 (2007-11-01) X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: heikki.krogerus@linux.intel.com, peterz@infradead.org, grant.likely@arm.com, paulus@samba.org, frowand.list@gmail.com, mingo@kernel.org, m.szyprowski@samsung.com, sstabellini@kernel.org, saravanak@google.com, joro@8bytes.org, rafael.j.wysocki@intel.com, hch@lst.de, bgolaszewski@baylibre.com, xen-devel@lists.xenproject.org, treding@nvidia.com, devicetree@vger.kernel.org, will@kernel.org, konrad.wilk@oracle.com, dan.j.williams@intel.com, linuxppc-dev@lists.ozlabs.org, robh+dt@kernel.org, boris.ostrovsky@oracle.com, andriy.shevchenko@linux.intel.com, jgross@suse.com, drinkcat@chromium.org, gregkh@linuxfoundation.org, rdunlap@infradead.org, linux-kernel@vger.kernel.org, tfiga@chromium.org, iommu@lists.linux-foundation.org, xypron.glpk@gmx.de, robin.murphy@arm.com, bauerman@linux.ibm.com Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Wed, Jan 06, 2021 at 11:41:19AM +0800, Claire Chang wrote: > Added a new struct, io_tlb_mem, as the IO TLB memory pool descriptor and > moved relevant global variables into that struct. > This will be useful later to allow for restricted DMA pool. I like where this is going, but a few comments. Mostly I'd love to be able to entirely hide io_tlb_default_mem and struct io_tlb_mem inside of swiotlb.c. > --- a/arch/powerpc/platforms/pseries/svm.c > +++ b/arch/powerpc/platforms/pseries/svm.c > @@ -55,8 +55,8 @@ void __init svm_swiotlb_init(void) > if (vstart && !swiotlb_init_with_tbl(vstart, io_tlb_nslabs, false)) > return; > > - if (io_tlb_start) > - memblock_free_early(io_tlb_start, > + if (io_tlb_default_mem.start) > + memblock_free_early(io_tlb_default_mem.start, > PAGE_ALIGN(io_tlb_nslabs << IO_TLB_SHIFT)); I think this should switch to use the local vstart variable in prep patch. > panic("SVM: Cannot allocate SWIOTLB buffer"); > } > diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c > index 2b385c1b4a99..4d17dff7ffd2 100644 > --- a/drivers/xen/swiotlb-xen.c > +++ b/drivers/xen/swiotlb-xen.c > @@ -192,8 +192,8 @@ int __ref xen_swiotlb_init(int verbose, bool early) > /* > * IO TLB memory already allocated. Just use it. > */ > - if (io_tlb_start != 0) { > - xen_io_tlb_start = phys_to_virt(io_tlb_start); > + if (io_tlb_default_mem.start != 0) { > + xen_io_tlb_start = phys_to_virt(io_tlb_default_mem.start); > goto end; xen_io_tlb_start is interesting. It is used only in two functions: 1) is_xen_swiotlb_buffer, where I think we should be able to just use is_swiotlb_buffer instead of open coding it with the extra phys_to_virt/virt_to_phys cycle. 2) xen_swiotlb_init, where except for the assignment it only is used locally for the case not touched above and could this be replaced with a local variable. Konrad, does this make sense to you? > static inline bool is_swiotlb_buffer(phys_addr_t paddr) > { > - return paddr >= io_tlb_start && paddr < io_tlb_end; > + struct io_tlb_mem *mem = &io_tlb_default_mem; > + > + return paddr >= mem->start && paddr < mem->end; We'd then have to move this out of line as well.