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 Received: from ws5-mx01.kavi.com (ws5-mx01.kavi.com [34.193.7.191]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 06564C072A2 for ; Fri, 17 Nov 2023 11:11:12 +0000 (UTC) Received: from lists.oasis-open.org (oasis.ws5.connectedcommunity.org [10.110.1.242]) by ws5-mx01.kavi.com (Postfix) with ESMTP id 36DB2C6239 for ; Fri, 17 Nov 2023 11:11:12 +0000 (UTC) Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id 1460F986E26 for ; Fri, 17 Nov 2023 11:11:12 +0000 (UTC) Received: from host09.ws5.connectedcommunity.org (host09.ws5.connectedcommunity.org [10.110.1.97]) by lists.oasis-open.org (Postfix) with QMQP id EDCD3986E1C; Fri, 17 Nov 2023 11:11:11 +0000 (UTC) Mailing-List: contact virtio-comment-help@lists.oasis-open.org; run by ezmlm List-ID: Sender: Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id DF14D986E1D for ; Fri, 17 Nov 2023 11:11:11 +0000 (UTC) X-Virus-Scanned: amavisd-new at kavi.com X-MC-Unique: IqalJk8uMxG9uZoR25VMYQ-1 X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1700219466; x=1700824266; 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=wAR8URUZ7qQIHbBO0DEWqA+iEOPsJrPIcQZXOmluWPM=; b=CSbSGHDFLkwFrOpAc6EItCKF2a1BdsbDU0Ca1EKkZbnEOURYhmUX9ZpaYRnU15U1NE ESAjkjLV8Il0oC72556yTDrdCiV+cHDROQb3ofUD8gD3h+s6J9IV1tn5/1yy7p4zJpKx Xg6axJqu0QDtWdWAIvk/g8aNk28kL6r5IrSwpmT/HCnqlX23alu0kndEdAQID5aUSmB7 cELmFkGNKOPccQeRnHR8HHQYWaoYlHtcEcL41ZTdEnm8k1FMP5mrLVzE+jNsk1wq0UXp t/j7+zhA8GbDsEdbt7oqaLMqODNmLTGOj6596Cd5xCgqcrntQ0SwrL639cf4Wmi2b65+ n2hA== X-Gm-Message-State: AOJu0YzpTeVF3u3jc7LIqOJcZiTGw7xZdDZUFPOmrqUO09TWYumpgZsy TC8jK0eHHu0GV0TzZUMFdUWzVUJ4NajtDTLJBk+Zq/f3VXEJpe+6dCwXIuF+EfwnBAIZu5e7odC 3/6VkEsw2pc734kGcDfUHQRmzTLBxegAQ/Q== X-Received: by 2002:ac2:5dc2:0:b0:509:dd0:9414 with SMTP id x2-20020ac25dc2000000b005090dd09414mr13302449lfq.24.1700219466487; Fri, 17 Nov 2023 03:11:06 -0800 (PST) X-Google-Smtp-Source: AGHT+IF6itobiTIJ9hEWPQojs4auqK3EE36uiPyqAy2FWad3zXhvTgtpSP06Ils/Z/lCvDUoeqnV7g== X-Received: by 2002:ac2:5dc2:0:b0:509:dd0:9414 with SMTP id x2-20020ac25dc2000000b005090dd09414mr13302438lfq.24.1700219466149; Fri, 17 Nov 2023 03:11:06 -0800 (PST) Date: Fri, 17 Nov 2023 06:11:00 -0500 From: "Michael S. Tsirkin" To: Parav Pandit Cc: Jason Wang , "Zhu, Lingshan" , "virtio-comment@lists.oasis-open.org" , "cohuck@redhat.com" , "sburla@marvell.com" , Shahaf Shuler , Maor Gottlieb , Yishai Hadas Message-ID: <20231117060456-mutt-send-email-mst@kernel.org> References: <20231117050357-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit Subject: Re: [virtio-comment] [PATCH v1 1/8] admin: Add theory of operation for device migration On Fri, Nov 17, 2023 at 10:20:45AM +0000, Parav Pandit wrote: > > > > From: Michael S. Tsirkin > > Sent: Friday, November 17, 2023 3:38 PM > > > > On Wed, Nov 15, 2023 at 05:39:43PM +0000, Parav Pandit wrote: > > > > > > > > > > Additionally, if hypervisor has put the trap on virtio config, and > > > > > because the memory device already has the interface for virtio > > > > > config, > > > > > > > > > > Hypervisor can directly write/read from the virtual config to the > > > > > member's > > > > config space, without going through the device context, right? > > > > > > > > If it can do it or it can choose to not. I don't see how it is > > > > related to the discussion here. > > > > > > > It is. I don’t see a point of hypervisor not using the native interface provided > > by the member device. > > > > So for example, it seems reasonable to a member supporting both existing pci > > register interface for compatibility and the future DMA based one for scale. In > > such a case, it seems possible that DMA will expose more features than pci. And > > then a hypervisor might decide to use that in preference to pci registers. > > We don’t find it right to involve owner device for mediating at > current scale In this model, device will be its own owner. Should not be a problem. > and to not break TDISP efforts in upcoming time by such > design. Look you either stop mentioning TDISP as motivation or actually try to address it. Safe migration with TDISP is really hard. For example, your current patches are clearly broken for TDISP: owner can control queue state at any time making device modify memory in any way it wants. > And for future scale, having new SIOV interface makes more sense which has its own direct interface to device. > > I finally captured all past discussions in form of a FAQ at [1]. > > [1] https://docs.google.com/document/d/1Iyn-l3Nm0yls3pZaul4lZiVj8x1s73Ed6rOsmn6LfXc/edit?usp=sharing Yea skimmed that, "Cons: None". Are you 100% sure? Anyway, discussion will take place on the mailing list please. -- MST This publicly archived list offers a means to provide input to the OASIS Virtual I/O Device (VIRTIO) TC. In order to verify user consent to the Feedback License terms and to minimize spam in the list archive, subscription is required before posting. Subscribe: virtio-comment-subscribe@lists.oasis-open.org Unsubscribe: virtio-comment-unsubscribe@lists.oasis-open.org List help: virtio-comment-help@lists.oasis-open.org List archive: https://lists.oasis-open.org/archives/virtio-comment/ Feedback License: https://www.oasis-open.org/who/ipr/feedback_license.pdf List Guidelines: https://www.oasis-open.org/policies-guidelines/mailing-lists Committee: https://www.oasis-open.org/committees/virtio/ Join OASIS: https://www.oasis-open.org/join/