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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 864A2C30653 for ; Thu, 4 Jul 2024 15:24:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=u+aHfEX8o0rhywophaRE/rYg5Icyqncq4KrEqzyoFgE=; b=ghmvj/K5DvmDfGphNKF5xhMLzk TSmihLgqtm/2R1CjUJPIxlLVV5YngTjQ1xh7faEKEsHxDi+liJoMM0LwOVXWTY3cxaNuU+dCDNCjz brTRnkqo6CoHUq8tVdVtjCrK4bFAd5jNUS8i8gwll8Um/J7zHk7LjxnJeWD9u/wT5+ignGvPDB0hz BUX1fuZVMkFkavc+zW8koRZCjNmUm6MT4tb9ReHnakiBmCsygLaydXFFUcfgzGQ0CMs0D64kgCr7z sTXDDV603+9vye7iCaUurvFfLeueET40y8kyRO+QPQ9iHv+BVwtroLrsZJ7WEXMFU5u3amIKcr5Oa BgZS+E/w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1sPOJW-0000000Dgju-0xhe; Thu, 04 Jul 2024 15:24:02 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1sPOJP-0000000Dggk-2Pps for linux-nvme@lists.infradead.org; Thu, 04 Jul 2024 15:23:57 +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 EA206367; Thu, 4 Jul 2024 08:24:18 -0700 (PDT) Received: from [10.1.196.40] (e121345-lin.cambridge.arm.com [10.1.196.40]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 2E2F73F766; Thu, 4 Jul 2024 08:23:50 -0700 (PDT) Message-ID: <249ec228-4ffd-4121-bd51-f4a19275fee1@arm.com> Date: Thu, 4 Jul 2024 16:23:47 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH v1 18/18] nvme-pci: use new dma API To: Leon Romanovsky , Jens Axboe , Jason Gunthorpe , Joerg Roedel , Will Deacon , Keith Busch , Christoph Hellwig , "Zeng, Oak" , Chaitanya Kulkarni Cc: Sagi Grimberg , Bjorn Helgaas , Logan Gunthorpe , Yishai Hadas , Shameer Kolothum , Kevin Tian , Alex Williamson , Marek Szyprowski , =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , Andrew Morton , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-rdma@vger.kernel.org, iommu@lists.linux.dev, linux-nvme@lists.infradead.org, linux-pci@vger.kernel.org, kvm@vger.kernel.org, linux-mm@kvack.org References: <47eb0510b0a6aa52d9f5665d75fa7093dd6af53f.1719909395.git.leon@kernel.org> From: Robin Murphy Content-Language: en-GB In-Reply-To: <47eb0510b0a6aa52d9f5665d75fa7093dd6af53f.1719909395.git.leon@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240704_082355_701477_3A1C9A12 X-CRM114-Status: GOOD ( 10.29 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On 02/07/2024 10:09 am, Leon Romanovsky wrote: [...] > +static inline dma_addr_t nvme_dma_link_page(struct page *page, > + unsigned int poffset, > + unsigned int len, > + struct nvme_iod *iod) > { > - int i; > - struct scatterlist *sg; > + struct dma_iova_attrs *iova = &iod->dma_map->iova; > + struct dma_iova_state *state = &iod->dma_map->state; > + dma_addr_t dma_addr; > + int ret; > + > + if (iod->dma_map->use_iova) { > + phys_addr_t phys = page_to_phys(page) + poffset; Yeah, there's no way this can possibly work. You can't do the dev_use_swiotlb() check up-front based on some overall DMA operation size, but then build that operation out of arbitrarily small fragments of different physical pages that *could* individually need bouncing to not break coherency. Thanks, Robin. > + > + dma_addr = state->iova->addr + state->range_size; > + ret = dma_link_range(&iod->dma_map->state, phys, len); > + if (ret) > + return DMA_MAPPING_ERROR; > + } else { > + dma_addr = dma_map_page_attrs(iova->dev, page, poffset, len, > + iova->dir, iova->attrs); > + } > + return dma_addr; > +}