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=-0.5 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, 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 40041C47247 for ; Thu, 30 Apr 2020 19:34:37 +0000 (UTC) Received: from silver.osuosl.org (smtp3.osuosl.org [140.211.166.136]) (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 0688920656 for ; Thu, 30 Apr 2020 19:34:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Nx/SPKJc" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0688920656 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by silver.osuosl.org (Postfix) with ESMTP id A59AE204D5; Thu, 30 Apr 2020 19:34:36 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from silver.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id u7zJ1hyw0XXg; Thu, 30 Apr 2020 19:34:35 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by silver.osuosl.org (Postfix) with ESMTP id A5A1A20465; Thu, 30 Apr 2020 19:34:35 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 786D2C0889; Thu, 30 Apr 2020 19:34:35 +0000 (UTC) Received: from silver.osuosl.org (smtp3.osuosl.org [140.211.166.136]) by lists.linuxfoundation.org (Postfix) with ESMTP id 16347C016F for ; Thu, 30 Apr 2020 19:34:34 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by silver.osuosl.org (Postfix) with ESMTP id E26EB204AD for ; Thu, 30 Apr 2020 19:34:33 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from silver.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id G6nwazNt2tbE for ; Thu, 30 Apr 2020 19:34:32 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from us-smtp-delivery-1.mimecast.com (us-smtp-1.mimecast.com [207.211.31.81]) by silver.osuosl.org (Postfix) with ESMTPS id B7BFE20465 for ; Thu, 30 Apr 2020 19:34:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1588275271; 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: in-reply-to:in-reply-to:references:references; bh=sS8AddF4WlY4FM3AJEU8Vr5dd3INR3Y9YVDuw7T/d9Y=; b=Nx/SPKJc966HF0Nvun8X9o49ex3kFrtReHyeUHX/DpadYOYO5NQeJKvRub5Z4uuWldQ/Ku lnPyWsTFw6EAPfB3o0j5VMIlmZHlSZerr1HraWm4qnV4h7zpyxRQalq/pEtqAJO+cCui4E 16whihZa6Dwviw6VzBxQz/SY0JCY8pM= Received: from mail-wr1-f70.google.com (mail-wr1-f70.google.com [209.85.221.70]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-149-425PqBcLNvC4UN3ztSq8gQ-1; Thu, 30 Apr 2020 15:34:29 -0400 X-MC-Unique: 425PqBcLNvC4UN3ztSq8gQ-1 Received: by mail-wr1-f70.google.com with SMTP id j16so4379686wrw.20 for ; Thu, 30 Apr 2020 12:34:29 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=sS8AddF4WlY4FM3AJEU8Vr5dd3INR3Y9YVDuw7T/d9Y=; b=JE+040OSo59TlMxmvY44/9cyCSGPiddr53E/6LX078H1sxOxpogV6F07X+zuQKL+vg ssv/YeeWoZ5RbyizrboEZDHFX6OF3Dr7pPwd+oB/PwloLZ9HoAKOAFSGovO8Eh2VIPJN Qwc+IcDO3hLSUKI5WKA1zgZC2fNzfO6lJBCdLRtrolsYyI+6EvbFPDro+GNtsgj8E7rR +6ttwIIIjgTSjMP/sDYcylQmj5fETNW+COR6Fg4NzkH9NZLJ41tlsBlDYDEsRVRugZVD tDcGndN5E4vzh2R2lFe9dXj1lVhKWyDU6SLsyb1uRbRRqYpKSJ9GMMlwLlNnWpVJ18bJ UJmg== X-Gm-Message-State: AGi0Pub+H0iUWlF50d7bMJS4L0RUOeG3ZSn0UKY+I7jAtEsMRLerHY9O H80lEyIhSG2iBiLE3Xt0YtLxQ6BeDiOPgg6bgGu6yljofgZ/Iixk06Y0Yt0xciqLNyr+i1czyj6 qFUfPbAAOipQ2adXFNx+cuQOVqPAqlA== X-Received: by 2002:a1c:4d17:: with SMTP id o23mr147554wmh.47.1588275268441; Thu, 30 Apr 2020 12:34:28 -0700 (PDT) X-Google-Smtp-Source: APiQypIErEi2OKs7eqnsETBaKuMVCIu+8B3dc0io3m7kIhj79uNOeJtHgco9xaP2TdUr4Pnz00osWA== X-Received: by 2002:a1c:4d17:: with SMTP id o23mr147527wmh.47.1588275268199; Thu, 30 Apr 2020 12:34:28 -0700 (PDT) Received: from redhat.com (bzq-109-66-7-121.red.bezeqint.net. [109.66.7.121]) by smtp.gmail.com with ESMTPSA id n6sm831929wmc.28.2020.04.30.12.34.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 30 Apr 2020 12:34:27 -0700 (PDT) Date: Thu, 30 Apr 2020 15:34:24 -0400 From: "Michael S. Tsirkin" To: Srivatsa Vaddagiri Subject: Re: [RFC/PATCH 1/1] virtio: Introduce MMIO ops Message-ID: <20200430152808-mutt-send-email-mst@kernel.org> References: <1588240976-10213-1-git-send-email-vatsa@codeaurora.org> <1588240976-10213-2-git-send-email-vatsa@codeaurora.org> <20200430101431.GD19932@willie-the-truck> <20200430103446.GH5097@quicinc.com> <20200430104149.GG19932@willie-the-truck> <20200430111156.GI5097@quicinc.com> <7bf8bffe-267b-6c66-86c9-40017d3ca4c2@siemens.com> <20200430133321.GC3204@quicinc.com> MIME-Version: 1.0 In-Reply-To: <20200430133321.GC3204@quicinc.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Disposition: inline Cc: tsoni@codeaurora.org, virtio-dev@lists.oasis-open.org, konrad.wilk@oracle.com, Jan Kiszka , jasowang@redhat.com, christoffer.dall@arm.com, virtualization@lists.linux-foundation.org, alex.bennee@linaro.org, iommu@lists.linux-foundation.org, stefano.stabellini@xilinx.com, Will Deacon , linux-kernel@vger.kernel.org, pratikp@codeaurora.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 Thu, Apr 30, 2020 at 07:03:21PM +0530, Srivatsa Vaddagiri wrote: > * Jan Kiszka [2020-04-30 14:59:50]: > > > >I believe ivshmem2_virtio requires hypervisor to support PCI device emulation > > >(for life-cycle management of VMs), which our hypervisor may not support. PCI is mostly just 2 registers. One sets the affected device, one the data to read/write. > A > > >simple shared memory and doorbell or message-queue based transport will work for > > >us. > > > > As written in our private conversation, a mapping of the ivshmem2 device > > discovery to platform mechanism (device tree etc.) and maybe even the > > register access for doorbell and life-cycle management to something > > hypercall-like would be imaginable. What would count more from virtio > > perspective is a common mapping on a shared memory transport. > > Yes that sounds simpler for us. > > > That said, I also warned about all the features that PCI already defined > > (such as message-based interrupts) which you may have to add when going a > > different way for the shared memory device. > > Is it really required to present this shared memory as belonging to a PCI > device? But then you will go on and add MSI, and NUMA, and security, and and and ... > I would expect the device-tree to indicate the presence of this shared > memory region, which we should be able to present to ivshmem2 as shared memory > region to use (along with some handles for doorbell or message queue use). > > I understand the usefulness of modeling the shared memory as part of device so > that hypervisor can send events related to peers going down or coming up. In our > case, there will be other means to discover those events and avoiding this > requirement on hypervisor (to emulate PCI) will simplify the solution for us. > > Any idea when we can expect virtio over ivshmem2 to become available?! Check out the virtio spec. Right at the beginning it states: These devices are found in virtual environments, yet by design they look like physical devices to the guest within the virtual machine - and this document treats them as such. This similarity allows the guest to use standard drivers and discovery mechanisms > -- > QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member > of Code Aurora Forum, hosted by The Linux Foundation _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu