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 A822BC77B7A for ; Wed, 7 Jun 2023 08:54:09 +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 EF91B42A6B for ; Wed, 7 Jun 2023 08:54:08 +0000 (UTC) Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id D1550986660 for ; Wed, 7 Jun 2023 08:54:08 +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 B6F4898664C; Wed, 7 Jun 2023 08:54:08 +0000 (UTC) Mailing-List: contact virtio-dev-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 A17D5986650 for ; Wed, 7 Jun 2023 08:54:08 +0000 (UTC) X-Virus-Scanned: amavisd-new at kavi.com X-MC-Unique: qcf8bC3zPoGQghEdyA3pIw-1 X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1686128045; x=1688720045; 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=mc5+jcBo5QHTAr/wig1xQu7FvVMd3URiYk8kDGkK1VY=; b=G+O5Psn/SDMs0YAoafCyqpLuZZruyuIysj4/eP6XgRpjM1pSLyvkk7EE8I0UIbRme/ 2mEdceSNgpzAuNBmNbvGwkMN5jGhlhAB3Oha4VrbuqUDFbgsz8eWyS6c2yBYZdy+qt9D wDVIQ9CqhSlgn1nRqQkX491ppGWKj/v8vMWVFUXIDAy3sMefZ43Q9Loxdk5mdliGY1TQ tgf/WWDkxAHrwgJuSAulCQDOPnRpazIC+oUJNw8cx7yCn8L55kz8GSQ4TFMLGhgSv3Ua A2QWEWZYl4azcg/4CF83tyggp5YRHHWsFdERLmS+IdrpcaE30xqbYStmi/CMBIz8eFDx UGrA== X-Gm-Message-State: AC+VfDwFf4/LhG9krs7KIKpNkOc5K30/a5Mm0O1XtlB504cZKRLTx/cg dGgLjcVmwBObXh7IdcQvghJ5fZI+032yu92zFhm84XuyoE5cCXLQKl9Y8/+O/opJvwhaFDs4Y9t 67NS3baw/H+UIbRq0+FX7I4+bDifz X-Received: by 2002:adf:df04:0:b0:30a:a715:66c8 with SMTP id y4-20020adfdf04000000b0030aa71566c8mr4018771wrl.8.1686128045499; Wed, 07 Jun 2023 01:54:05 -0700 (PDT) X-Google-Smtp-Source: ACHHUZ5sOlmVWEcM5SCoi1qlMfc6sNj2HHTIjxp6vEuCdY05ZCLUHBzfxoiCpHwsSwTch/zgJWH4EA== X-Received: by 2002:adf:df04:0:b0:30a:a715:66c8 with SMTP id y4-20020adfdf04000000b0030aa71566c8mr4018756wrl.8.1686128045145; Wed, 07 Jun 2023 01:54:05 -0700 (PDT) Date: Wed, 7 Jun 2023 04:54:00 -0400 From: "Michael S. Tsirkin" To: Jason Wang Cc: Parav Pandit , "virtio-dev@lists.oasis-open.org" , "cohuck@redhat.com" , "david.edmondson@oracle.com" , "sburla@marvell.com" , Yishai Hadas , Maor Gottlieb , "virtio-comment@lists.oasis-open.org" , Shahaf Shuler Message-ID: <20230607045225-mutt-send-email-mst@kernel.org> References: <20230605014539-mutt-send-email-mst@kernel.org> <20230605092859-mutt-send-email-mst@kernel.org> <20230605174755-mutt-send-email-mst@kernel.org> <20230606073544-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-dev] Re: [PATCH v3 0/3] transport-pci: Introduce legacy registers access using AQ On Wed, Jun 07, 2023 at 02:54:22PM +0800, Jason Wang wrote: > On Wed, Jun 7, 2023 at 11:06 AM Parav Pandit wrote: > > > > > > > > > From: Jason Wang > > > Sent: Tuesday, June 6, 2023 10:27 PM > > > > > > I can't say I like this. I prefer to do meditation on top of a modern device with > > > some lightweight features like _F_LEAGCY_HEADER. I don't see any advantages > > > of a new legacy ABI over _F_LEGACY_HEADER. I don't want to repeat but I don't > > > get any response here > > > > > It is net only and not generic. Not a big blocker. > > It doesnt stop at _F_LEAGCY_HEADER. > > > > > Anything that prevents you from adding things like VIRTIO_NET_F_LEGACY_HEADER? > > It requires hypervisor to mediate 1.x config region and intercept feature negotiation including q config and more. > > For config region, do you mean device configuration space or common > config space? > > I don't see why we need to do mediation on neiter of the above. > Hypervisor just need to prepare > > 1) legacy BAR with legacy config and device configuration space and > 2) modern BAR with modern capabilities (common cfg and device cfg) > > For 2) it could be mapped directly to the modern capabilities. For 1) > hypervisor needs to mediate > > > > > Additionally, 1.x device says the mac address is read only, while legacy is RW. > > And that requires yet another feature bit negotiation. > > Hypervisor can trap the legacy device configuration space write and > convert it to cvq commands. > > Thanks Hypervisor really can't access cvq if guest is doing it too - that requires emulating cvq in software. And *that* is going to be broken for workloads such as confidential computing. > > > > The main design goal is to not mediate 1.x specific region and not modify 1.x region definitions. > > Which is why we step forward with the AQ. > > > > > https://lore.kernel.org/virtio- > > > dev/CACGkMEuixsBibSq_pEQvcKOH0WBQWnta4Q2c28SV8qTS8gaVcA@mail.g > > > mail.com/#t --------------------------------------------------------------------- To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org For additional commands, e-mail: virtio-dev-help@lists.oasis-open.org