From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A1D2B14A63D for ; Tue, 18 Jun 2024 10:33:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718706810; cv=none; b=pW7F0sxL3u3tl99JtKdR0eVT3br0qY75ACFM/KWWa1yN6rXHvMFzcWZVWz5LWpA+2NGEtxC+RQxc5GoHDIaBCxbhqEdyPTtkfBjwTnDJH8AYbbFrdpjLheB19Oo90M3f98t3MemuZnzvP8rUHyco3DkZuuaWgQzJ1Ud4KuIvdYw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718706810; c=relaxed/simple; bh=3R4ZmGYRCOnDC4CMT6od2Me4vHZyyR45godSVXHsnik=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=bvllU5KFBvwFu4aFIuwYSrAF/6FFwyu7oPVBrUpYA86vM0xyRCJRblbhRubbkuxgIxok0kQLJAgAm2+AVCXJtXFxOQxrUhPWAK6eD9KThnUYPG/e2BcqRdlk8ZDwSIEBbVqFIl+bVJY9jwAgfkkF39con7akJMi15CtMC6Sx9Ic= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=K+1a7fWW; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="K+1a7fWW" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1718706807; 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=f2CpynTXKAlpaIQ4wYDBqhxXchA8ClbLULqxJerRJ5E=; b=K+1a7fWW8rKsfAt9FGFAZwklyWb7FNYy4LPHvOrvSKZhZctQOXl1HLJ+ysH7fUDmeWq8Sm EWO1sVAv3ndBiKaBioW4VXlybi8QDkcM1gIFYhr7y5S0InDSl/vxQxXdq6+GZmn+Rqwsn3 l68I/ZfVwzS/dH+xZbz6snZTQxp7fRk= Received: from mail-wm1-f70.google.com (mail-wm1-f70.google.com [209.85.128.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-547-xKkb6fm_MICKDe9FlsMjhA-1; Tue, 18 Jun 2024 06:33:26 -0400 X-MC-Unique: xKkb6fm_MICKDe9FlsMjhA-1 Received: by mail-wm1-f70.google.com with SMTP id 5b1f17b1804b1-4215b0b1c11so40314775e9.3 for ; Tue, 18 Jun 2024 03:33:26 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1718706805; x=1719311605; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=f2CpynTXKAlpaIQ4wYDBqhxXchA8ClbLULqxJerRJ5E=; b=RYZ224quixzt2WS2w3yqCv9iPw8iggwFT128fZVVHDN9yLMmSvAYiDTQGQEnBsvLi/ 2x3fMAJLFq/1uJbybeRDUD5Aqssfk0+3NnBb5dIEcqhEZdJskeT5zk17Rvb4CHUQn6OA CT3ixfhzdLZyWppmyVB/IW4O88bogKTWpbRCvWxl8JtX39G92LQTWz8eoJ5+itM7efgY 00u/qKgfUpMXtHDA5azE+gvjVJ4xxpQWcHw/8oB51HaOCIR1Ed7QXFxVW9+eIxjvomuj pxmTl0ONxj8mifZH7mOVV0HQidbd5X+/aRPn8wrFVk9LHnwl/NwxHZgGWH00RtTILMxh 97xA== X-Forwarded-Encrypted: i=1; AJvYcCVWR0MIp1AGDNsmy+1V9jLKVcODvfvB12m6levty0Xm/dfPfgvoajXjjP4UmtiK0ZRTy+pu+TXoQlB3lS5gM2VTGG2qegHB+wXh X-Gm-Message-State: AOJu0YyxDB0JDvoaU0RQ49dGvxd+8lM6+MahjHO9eRMFU6Y53+c8W2KD KYqp5QErbBjs+S6dWnx9bLuiRrMdbJ5bBXrDiJHHEU8klKgya5MTRhq1NRGo+1Ie16W744g+Hmu 2Qeg2T7ZsSY3sB6n09FOqGtrqNj/UkLlJlYCHsjg2naLM/ae4DEzHiYaeBw== X-Received: by 2002:a05:600c:1d29:b0:421:79dc:56e4 with SMTP id 5b1f17b1804b1-42304862690mr89911125e9.41.1718706804950; Tue, 18 Jun 2024 03:33:24 -0700 (PDT) X-Google-Smtp-Source: AGHT+IGLRfy7oQumt6boNaSCbATqsBOpWpSCLkxQ2tSrk9aiZf1c10yHgUWugziswJPSySUZAewIvA== X-Received: by 2002:a05:600c:1d29:b0:421:79dc:56e4 with SMTP id 5b1f17b1804b1-42304862690mr89910975e9.41.1718706804436; Tue, 18 Jun 2024 03:33:24 -0700 (PDT) Received: from redhat.com ([2a0d:6fc7:441:67bf:ebbb:9f62:dc29:2bdc]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-42286eef70csm224360215e9.3.2024.06.18.03.33.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 18 Jun 2024 03:33:23 -0700 (PDT) Date: Tue, 18 Jun 2024 06:33:19 -0400 From: "Michael S. Tsirkin" To: Shunsuke Mie Cc: Manivannan Sadhasivam , linux-pci@vger.kernel.org, virtualization@lists.linux.dev, jasowang@redhat.com, xuanzhuo@linux.alibaba.com Subject: Re: [RFC] Legacy Virtio Driver with Device Has Limited Memory Access Message-ID: <20240618061705-mutt-send-email-mst@kernel.org> References: <20240516125913.GC11261@thinkpad> <20240520090809-mutt-send-email-mst@kernel.org> <20240614095033.GA59574@thinkpad> <20240618054115-mutt-send-email-mst@kernel.org> Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Tue, Jun 18, 2024 at 07:15:47PM +0900, Shunsuke Mie wrote: > Thank you for your response. > > 2024年6月18日(火) 18:47 Michael S. Tsirkin : > > > > On Tue, Jun 18, 2024 at 08:41:09AM +0900, Shunsuke Mie wrote: > > > Let's clarify the situation. > > > > > > The Virtio device and driver are not working properly due to a > > > combination of the following reasons: > > > > > > 1. Regarding VIRTIO_F_ACCESS_PLATFORM: > > > - The modern spec includes VIRTIO_F_ACCESS_PLATFORM, which allows > > > Physical DMAC to be used. > > > - This feature is not available in the legacy spec. > > > > ... because legacy drivers don't set it > > > > > 2. Regarding Virtio PCIe Capability: > > > - The modern spec requires Virtio PCIe Capability. > > > > It's a PCI capability actually. People have been asking > > about option to make it a pcie extended capability, > > but no one did the spec, qemu and driver work, yet. > > > > > - In some environments, Virtio PCIe Capability cannot be provided. > > > > why not? > PCIe Endpoint Controller chips are available from several vendors and allow > software to describe the behavior of PCIe Endpoint functions. However, they > offer only limited functionality. Specifically, while PCIe bus communication is > programmable, PCIe Capabilities are fixed and cannot be made to show as > virtio's. Okay. So where could these structures live, if not in pci config? -- MST