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=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 A7564CA9EC7 for ; Wed, 30 Oct 2019 21:41:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6CDA12067D for ; Wed, 30 Oct 2019 21:41:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="uEYvzQ1n" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727351AbfJ3Vln (ORCPT ); Wed, 30 Oct 2019 17:41:43 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:38922 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726171AbfJ3Vln (ORCPT ); Wed, 30 Oct 2019 17:41:43 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=RjClCXbIwBQLkxNlWfstc40OfJNOOeU+sDESejAVB2Q=; b=uEYvzQ1nc3dk6wMfF5V6miAgo Dkirmio0pEoS9DinmkrCztgl5Na8Evqct0LleL21apd0iabo4P9B3KbbmMDP3o/xndED4gtxctkvs 28Qj52OIYqR/Dh4hmObviIYooPZdmPIvquPzWtQU7QFJddYbJDVJSY2MqoexYALVqErggcziqLXWA iHtvXIhX/PD9qmfE+LLqlCrPwSLChbAaoGX+J0gYQh8Rp4baHCraZcGfUgxcTrW+eldc/s5iia8Oi Je/Gw3aK7RPlhAfWgf1Zmc/Ao1Ya32dA6O7bBrWud74vKKjb7fjN4PEnfNeeZXizDojP6GoCpgCAu gO+r5sQ4w==; Received: from hch by bombadil.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1iPvim-00020g-Ao; Wed, 30 Oct 2019 21:41:40 +0000 Date: Wed, 30 Oct 2019 14:41:40 -0700 From: Christoph Hellwig To: Nicolas Saenz Julienne Cc: rubini@gnudd.com, hch@infradead.org, linux-kernel@vger.kernel.org, Marek Szyprowski , Robin Murphy , helgaas@kernel.org, iommu@lists.linux-foundation.org Subject: Re: [PATCH v2 1/2] dma-direct: check for overflows on 32 bit DMA addresses Message-ID: <20191030214140.GB25515@infradead.org> References: <20191018110044.22062-1-nsaenzjulienne@suse.de> <20191018110044.22062-2-nsaenzjulienne@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191018110044.22062-2-nsaenzjulienne@suse.de> User-Agent: Mutt/1.12.1 (2019-06-15) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 18, 2019 at 01:00:43PM +0200, Nicolas Saenz Julienne wrote: > +#ifndef CONFIG_ARCH_DMA_ADDR_T_64BIT > + /* Check if DMA address overflowed */ > + if (min(addr, addr + size - 1) < > + __phys_to_dma(dev, (phys_addr_t)(min_low_pfn << PAGE_SHIFT))) > + return false; > +#endif Would be nice to use IS_ENABLED and PFN_PHYS here, and I also think we need to use phys_to_dma to take care of the encryption bit. If you then also introduce an end variable we can make the whole thing actually look nice: static inline bool dma_capable(struct device *dev, dma_addr_t addr, size_t size) { dma_addr_t end = addr + size - 1; if (!dev->dma_mask) return false; if (!IS_ENABLED(CONFIG_ARCH_DMA_ADDR_T_64BIT) && min(addr, end) < phys_to_dma(dev, PFN_PHYS(min_low_pfn))) return false; return end <= min_not_zero(*dev->dma_mask, dev->bus_dma_mask); } Otherwise this looks sensible to me.