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=-7.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, 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 6C23DC433ED for ; Thu, 8 Apr 2021 07:28:39 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (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 65FFA60FF1 for ; Thu, 8 Apr 2021 07:28:38 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 65FFA60FF1 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:54160 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lUP5h-0005sn-3b for qemu-devel@archiver.kernel.org; Thu, 08 Apr 2021 03:28:37 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:60228) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lUP4z-0005Li-DU for qemu-devel@nongnu.org; Thu, 08 Apr 2021 03:27:54 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:46109) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lUP4v-0003it-J0 for qemu-devel@nongnu.org; Thu, 08 Apr 2021 03:27:53 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1617866867; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=qNj70kud8fNI4ZH8HL0d7dCtnVhpt46oZF7wMQg9hWo=; b=EYgdNPsYVaPdSTGWzbKTZ0KxZMf2m7d0M/aHEQFbfXQv4kijKYH29OMRcsv5LVGLzX7dyt e8pdhmdL7STLMZ/aT63KdPXGTKFGqgoWm3r/9mUO+ME8P55Yed2dKVUwO9obALz/8nt+Z6 y/JFMpVlmyuPg94GGQeFFzfQqI/41io= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-502-LkKIH64dPeyi2jX5P54Ruw-1; Thu, 08 Apr 2021 03:27:42 -0400 X-MC-Unique: LkKIH64dPeyi2jX5P54Ruw-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id DE126107ACC7; Thu, 8 Apr 2021 07:27:40 +0000 (UTC) Received: from [10.36.113.184] (ovpn-113-184.ams2.redhat.com [10.36.113.184]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 7D8191724D; Thu, 8 Apr 2021 07:27:38 +0000 (UTC) Subject: Re: A question about the translation granule size supported by the vSMMU To: Kunkun Jiang , Peter Maydell , linuc.decode@gmail.com References: <4886d8d0-cca6-d4b2-4139-29ad52020f79@redhat.com> From: Auger Eric Message-ID: <0a3ae73c-af3a-9d80-2f30-55424a07d104@redhat.com> Date: Thu, 8 Apr 2021 09:27:36 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=eric.auger@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=63.128.21.124; envelope-from=eric.auger@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Zenghui Yu , "wanghaibin.wang@huawei.com" , "open list:ARM SMMU" , Keqian Zhu , "open list:All patches CC here" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Hi Kunkun, On 4/7/21 11:26 AM, Kunkun Jiang wrote: > Hi Eric, > > On 2021/4/7 3:50, Auger Eric wrote: >> Hi Kunkun, >> >> On 3/27/21 3:24 AM, Kunkun Jiang wrote: >>> Hi all, >>> >>> Recently, I did some tests on SMMU nested mode. Here is >>> a question about the translation granule size supported by >>> vSMMU. >>> >>> There is such a code in SMMUv3_init_regs(): >>> >>>>     /* 4K and 64K granule support */ >>>>      s->idr[5] = FIELD_DP32(s->idr[5], IDR5, GRAN4K, 1); >>>>      s->idr[5] = FIELD_DP32(s->idr[5], IDR5, GRAN64K, 1); >>>>      s->idr[5] = FIELD_DP32(s->idr[5], IDR5, OAS, SMMU_IDR5_OAS); /* 44 >>>> bits */ >>> Why is the 16K granule not supported? I modified the code >>> to support it and did not encounter any problems in the >>> test. Although 4K and 64K minimal granules are "strongly >>> recommended", I think vSMMU should still support 16K.😉 >>> Are there other reasons why 16K is not supported here? >> no there aren't any. The main reasons were 16KB support is optional and >> supporting it increases the test matrix. Also it seems quite a few >> machines I have access to do support 16KB granule. On the others I get >> >> "EFI stub: ERROR: This 16 KB granular kernel is not supported by your >> CPU". >> >> Nevertheless I am not opposed to support it as it seems to work without >> trouble. Just need to have an extra look at implied validity checks but >> there shouldn't be much. >> >> Thanks >> >> Eric > Yes, you are right. In my opinion, it is necessary to check whether pSMMU > supports 16K to avoid the situation I mentioned below. > In SMMU nested mode, if vSMMU supports 16K and set pasid table to > pSMMU, it may get errors when pSMMU does translation table walk if > pSMMU doesn't support 16K (not tested). Do you think we need to add > an interface to get some pSMMU info?> > Maybe my consideration was superfluous.😁 No it is not. At qemu level we have memory_region_iommu_set_page_size_mask() that is called from the VFIO device. It allows to pass such info to the IOMMU device (qemu b91774984249). iommu_set_page_size_mask() cb needs to be implemented at SMMU QEMU device level. Also [PATCH 0/2] Domain nesting info for arm-smmu may allow to return other constraints from the pSMMU. Thanks Eric > > Thanks, > Kunkun Jiang >>> When in SMMU nested mode, it may get errors if pSMMU >>> doesn't support 16K but vSMMU supports 16K. But we >>> can get some settings of pSMMU to avoid this situation. >>> I found some discussions between Eric and Linu about >>> this [1], but this idea does not seem to be implemented. >>> >>> [1] https://lists.gnu.org/archive/html/qemu-arm/2017-09/msg00149.html >>> >>> Best regards, >>> Kunkun Jiang >>> >> >> . > >