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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 EA178C433B4 for ; Wed, 7 Apr 2021 10:01:16 +0000 (UTC) Received: from smtp4.osuosl.org (smtp4.osuosl.org [140.211.166.137]) (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 5B1F46135D for ; Wed, 7 Apr 2021 10:01:16 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5B1F46135D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=8bytes.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by smtp4.osuosl.org (Postfix) with ESMTP id EB39940E82; Wed, 7 Apr 2021 10:01:15 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp4.osuosl.org ([127.0.0.1]) by localhost (smtp4.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id JGEaqp41joJs; Wed, 7 Apr 2021 10:01:15 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [IPv6:2605:bc80:3010:104::8cd3:938]) by smtp4.osuosl.org (Postfix) with ESMTP id 947B140E78; Wed, 7 Apr 2021 10:01:14 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 6314CC000C; Wed, 7 Apr 2021 10:01:14 +0000 (UTC) Received: from smtp2.osuosl.org (smtp2.osuosl.org [140.211.166.133]) by lists.linuxfoundation.org (Postfix) with ESMTP id BE881C000A for ; Wed, 7 Apr 2021 10:01:13 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp2.osuosl.org (Postfix) with ESMTP id 9C6EA405BD for ; Wed, 7 Apr 2021 10:01:13 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp2.osuosl.org ([127.0.0.1]) by localhost (smtp2.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id er1bhdKh1S5K for ; Wed, 7 Apr 2021 10:01:13 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.8.0 Received: from theia.8bytes.org (8bytes.org [81.169.241.247]) by smtp2.osuosl.org (Postfix) with ESMTPS id 0BF5C405C1 for ; Wed, 7 Apr 2021 10:01:12 +0000 (UTC) Received: by theia.8bytes.org (Postfix, from userid 1000) id 3C04A2A6; Wed, 7 Apr 2021 12:01:09 +0200 (CEST) Date: Wed, 7 Apr 2021 12:01:07 +0200 From: Joerg Roedel To: Nadav Amit Subject: Re: [PATCH] iommu/amd: page-specific invalidations for more than one page Message-ID: References: <20210323210619.513069-1-namit@vmware.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210323210619.513069-1-namit@vmware.com> Cc: Nadav Amit , iommu@lists.linux-foundation.org, Will Deacon , Jiajun Cao , linux-kernel@vger.kernel.org X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On Tue, Mar 23, 2021 at 02:06:19PM -0700, Nadav Amit wrote: > From: Nadav Amit > > Currently, IOMMU invalidations and device-IOTLB invalidations using > AMD IOMMU fall back to full address-space invalidation if more than a > single page need to be flushed. > > Full flushes are especially inefficient when the IOMMU is virtualized by > a hypervisor, since it requires the hypervisor to synchronize the entire > address-space. > > AMD IOMMUs allow to provide a mask to perform page-specific > invalidations for multiple pages that match the address. The mask is > encoded as part of the address, and the first zero bit in the address > (in bits [51:12]) indicates the mask size. > > Use this hardware feature to perform selective IOMMU and IOTLB flushes. > Combine the logic between both for better code reuse. > > The IOMMU invalidations passed a smoke-test. The device IOTLB > invalidations are untested. Have you thoroughly tested this on real hardware? I had a patch-set doing the same many years ago and it lead to data corruption under load. Back then it could have been a bug in my code of course, but it made me cautious about using targeted invalidations. Regards, Joerg _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu