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=1.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,URI_WP_DIRINDEX,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 411B6C2BA19 for ; Mon, 6 Apr 2020 10:31:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0D49F206F5 for ; Mon, 6 Apr 2020 10:31:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="JZOJ5C+K" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726948AbgDFKbP (ORCPT ); Mon, 6 Apr 2020 06:31:15 -0400 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:39880 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726675AbgDFKbO (ORCPT ); Mon, 6 Apr 2020 06:31:14 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1586169073; 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=Frr3U9FewSH3rwJWC1POGOuw/i/P/MIPEW7fR+tNJOo=; b=JZOJ5C+K2Vtfscy4FB/znZTOktwU/ZUk0ffxXCm//Qyo6sNG7Sl+MGXFKUEHsPqcmUMJVp JTnR3iZMP2czs3eGGsx2ICg3peec3aIttOmxp8k84URzDwh7Ii4V1FnhmnKLMKsdr62dtg KoYRfmsb7jfozNU9hJXl4j/SWQtgZPI= 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-293-p-t34X7RPyeNPqCCGcDabQ-1; Mon, 06 Apr 2020 06:30:47 -0400 X-MC-Unique: p-t34X7RPyeNPqCCGcDabQ-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id CE647113784E; Mon, 6 Apr 2020 10:30:45 +0000 (UTC) Received: from [10.36.112.58] (ovpn-112-58.ams2.redhat.com [10.36.112.58]) by smtp.corp.redhat.com (Postfix) with ESMTPS id B5D8A60BF1; Mon, 6 Apr 2020 10:30:41 +0000 (UTC) Subject: Re: [PATCH v2 04/22] hw/iommu: introduce HostIOMMUContext To: "Liu, Yi L" , "qemu-devel@nongnu.org" , "alex.williamson@redhat.com" , "peterx@redhat.com" Cc: "pbonzini@redhat.com" , "mst@redhat.com" , "david@gibson.dropbear.id.au" , "Tian, Kevin" , "Tian, Jun J" , "Sun, Yi Y" , "kvm@vger.kernel.org" , "Wu, Hao" , "jean-philippe@linaro.org" , Jacob Pan , Yi Sun References: <1585542301-84087-1-git-send-email-yi.l.liu@intel.com> <1585542301-84087-5-git-send-email-yi.l.liu@intel.com> From: Auger Eric Message-ID: <338937be-9b1e-163f-90ef-2cf0c437c3e8@redhat.com> Date: Mon, 6 Apr 2020 12:30:39 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Hi Yi, On 4/6/20 10:04 AM, Liu, Yi L wrote: > Hi Eric, > >> From: Auger Eric < eric.auger@redhat.com> >> Sent: Tuesday, March 31, 2020 1:23 AM >> To: Liu, Yi L ; qemu-devel@nongnu.org; >> Subject: Re: [PATCH v2 04/22] hw/iommu: introduce HostIOMMUContext >> >> Yi, >> >> On 3/30/20 6:24 AM, Liu Yi L wrote: >>> Currently, many platform vendors provide the capability of dual stage >>> DMA address translation in hardware. For example, nested translation >>> on Intel VT-d scalable mode, nested stage translation on ARM SMMUv3, >>> and etc. In dual stage DMA address translation, there are two stages >>> address translation, stage-1 (a.k.a first-level) and stage-2 (a.k.a >>> second-level) translation structures. Stage-1 translation results are >>> also subjected to stage-2 translation structures. Take vSVA (Virtual >>> Shared Virtual Addressing) as an example, guest IOMMU driver owns >>> stage-1 translation structures (covers GVA->GPA translation), and host >>> IOMMU driver owns stage-2 translation structures (covers GPA->HPA >>> translation). VMM is responsible to bind stage-1 translation structures >>> to host, thus hardware could achieve GVA->GPA and then GPA->HPA >>> translation. For more background on SVA, refer the below links. >>> - https://www.youtube.com/watch?v=Kq_nfGK5MwQ >>> - https://events19.lfasiallc.com/wp-content/uploads/2017/11/\ >>> Shared-Virtual-Memory-in-KVM_Yi-Liu.pdf >>> > [...] >>> +void host_iommu_ctx_init(void *_iommu_ctx, size_t instance_size, >>> + const char *mrtypename, >>> + uint64_t flags) >>> +{ >>> + HostIOMMUContext *iommu_ctx; >>> + >>> + object_initialize(_iommu_ctx, instance_size, mrtypename); >>> + iommu_ctx = HOST_IOMMU_CONTEXT(_iommu_ctx); >>> + iommu_ctx->flags = flags; >>> + iommu_ctx->initialized = true; >>> +} >>> + >>> +static const TypeInfo host_iommu_context_info = { >>> + .parent = TYPE_OBJECT, >>> + .name = TYPE_HOST_IOMMU_CONTEXT, >>> + .class_size = sizeof(HostIOMMUContextClass), >>> + .instance_size = sizeof(HostIOMMUContext), >>> + .abstract = true, >> Can't we use the usual .instance_init and .instance_finalize? > sorry, I somehow missed this comment. In prior patch, .instace_init > was used, but the current major init method is via host_iommu_ctx_init(), > so .instance_init is not really necessary. > https://www.spinics.net/lists/kvm/msg210878.html OK globally what disturbs me is you introduced a QOM object but globally the inheritance schema is not totally clear to me (only a VFIO derived is created and I do not understand what other backend would be able to use it) and this does not really have the look & feel of standard QOM objects. I tried to compare its usage/implementation version MemoryRegion for instance. Thanks Eric > Regards, > Yi Liu >