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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6188CCCA47B for ; Wed, 8 Jun 2022 17:28:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232738AbiFHR2V (ORCPT ); Wed, 8 Jun 2022 13:28:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58338 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231459AbiFHR2J (ORCPT ); Wed, 8 Jun 2022 13:28:09 -0400 Received: from mail-pg1-f181.google.com (mail-pg1-f181.google.com [209.85.215.181]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AA8213586C; Wed, 8 Jun 2022 10:26:43 -0700 (PDT) Received: by mail-pg1-f181.google.com with SMTP id f65so9329940pgc.7; Wed, 08 Jun 2022 10:26:43 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:to:cc:references:from:in-reply-to :content-transfer-encoding; bh=vdq4x2cK2Kxb7bPLAXT0rRqzYQf9uH8WQ9IJlchFrLc=; b=jRFKiT1kHAmJTYJo2KyTn5ixFFyDjuFa6fxsl1WNSKLzhgNMDMOAi6WTiuKex7secK O6Gd/25v/L9ZGBaw3PJHmWaOZoWfKq+6z4Y4gU25o8vz/XIQuPEIbTs2oah4IP/+Xs3R mwe7tNnruEIRRzH/xAjbSaS5DU8a0x31WFh2UbNKZBYusnp4byTSIq9wyGmli/T/gtEr md6BytTdEaK8ss4WC5+529einlHqxdK3qCO3RZgBqIOIpT3l8DZlqZ1kcB04U3kQEwH7 RbBsHsMxATaWjuqn/fSKEuF6rXGwgvzl9ZYMD628qvcYgL1bJrP9wcEUAP4VmnyPsSqV 5Lqw== X-Gm-Message-State: AOAM531RTOV1FyEIOHqez0JU1MEJTzS2fW5eq5woT6oYsPjKhMfviyVQ /VcVzxXcJsYH9w0Mzd3z5/0= X-Google-Smtp-Source: ABdhPJy2XkL1wjH+iK3e6e2Hx2QMmfgjTy/wyGK/xCsPzQDJHM5fZRi20ssFAqNOW/TkC9QwcpHNxQ== X-Received: by 2002:a05:6a00:1344:b0:51b:ed0d:dbbd with SMTP id k4-20020a056a00134400b0051bed0ddbbdmr26197497pfu.45.1654709202923; Wed, 08 Jun 2022 10:26:42 -0700 (PDT) Received: from ?IPV6:2620:15c:211:201:1cb7:9e5d:5ca4:2a39? ([2620:15c:211:201:1cb7:9e5d:5ca4:2a39]) by smtp.gmail.com with ESMTPSA id p5-20020a62d005000000b0050dc762813csm3282490pfg.22.2022.06.08.10.26.41 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 08 Jun 2022 10:26:42 -0700 (PDT) Message-ID: Date: Wed, 8 Jun 2022 10:26:40 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.8.0 Subject: Re: [PATCH v3 2/4] dma-iommu: Add iommu_dma_opt_mapping_size() Content-Language: en-US To: John Garry , damien.lemoal@opensource.wdc.com, joro@8bytes.org, will@kernel.org, jejb@linux.ibm.com, martin.petersen@oracle.com, hch@lst.de, m.szyprowski@samsung.com, robin.murphy@arm.com Cc: linux-scsi@vger.kernel.org, linux-doc@vger.kernel.org, liyihang6@hisilicon.com, linux-kernel@vger.kernel.org, linux-ide@vger.kernel.org, iommu@lists.linux-foundation.org References: <1654507822-168026-1-git-send-email-john.garry@huawei.com> <1654507822-168026-3-git-send-email-john.garry@huawei.com> From: Bart Van Assche In-Reply-To: <1654507822-168026-3-git-send-email-john.garry@huawei.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org On 6/6/22 02:30, John Garry via iommu wrote: > +unsigned long iova_rcache_range(void) > +{ > + return PAGE_SIZE << (IOVA_RANGE_CACHE_MAX_SIZE - 1); > +} My understanding is that iova cache entries may be smaller than IOVA_RANGE_CACHE_MAX_SIZE and hence that even if code that uses the DMA mapping API respects this limit that a cache miss can still happen. Thanks, Bart.