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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 32124C433F5 for ; Wed, 3 Nov 2021 07:45:10 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (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 97CB460240 for ; Wed, 3 Nov 2021 07:45:09 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 97CB460240 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=nongnu.org Received: from localhost ([::1]:55128 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1miAxI-0003BJ-KN for qemu-devel@archiver.kernel.org; Wed, 03 Nov 2021 03:45:08 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:39634) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1miAwQ-0001s2-6H for qemu-devel@nongnu.org; Wed, 03 Nov 2021 03:44:14 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:41928) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1miAwM-0002Pi-4R for qemu-devel@nongnu.org; Wed, 03 Nov 2021 03:44:12 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1635925449; 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=XtJFq5rlIfDVjmLQuVwNJxeWZKl+1LKmrDZWYseC+4Q=; b=XEQNJ4c+E+0i8SJcwA0a6yLZ8//6ZrM9aSi4WZlxCLjiAqJgygzE8M6BTzpQF1fPvqfOO/ hkpk2vOGA6UkUFXg66MyAjZ9IxAtCvAglslZQx8uXNkvr63DoHYuIZmwGyP42pONGTEJc8 IvUGau0RAbXwETQWBWqZwimeXycI9Mg= Received: from mail-qk1-f200.google.com (mail-qk1-f200.google.com [209.85.222.200]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-6-DMArSBxwPxqVp_oROtC6qw-1; Wed, 03 Nov 2021 03:44:06 -0400 X-MC-Unique: DMArSBxwPxqVp_oROtC6qw-1 Received: by mail-qk1-f200.google.com with SMTP id bk21-20020a05620a1a1500b004631b196a46so1629238qkb.4 for ; Wed, 03 Nov 2021 00:44:06 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=XtJFq5rlIfDVjmLQuVwNJxeWZKl+1LKmrDZWYseC+4Q=; b=x05aMEqR1IJ6hiCoQpTrvvAUne8tbxlheCHvoVfK4caftDLZz73QZ7LS4bBQ19rq1F VNd/xq0umL90B33XJ56eEFXIeh5rTvTI6Bv3SyCMhwrhz3SaDc9sQ377nk5MK22fO1Ch ihnILEVUQsnMAEtjbTNwN1vKmxyaE1qi6gb8S85HZHbFTuDRDkS2wZ3uNjuKtxhCHSBA Uim/oE+f16wLRPNBUkso6YahwxoaxHxRp6v3RAUtYM3HGGsN2qiURAgigXnS8wM+dsMi PmLUiYbpRP2lXahdZIKbFOVAcnBtm09WjhWYvKvuwZJFkzRHtbKrFbBKYPrjrqQzjEBW Qq2w== X-Gm-Message-State: AOAM533PU8Rw7dqsSlBJC4rZawNy6sOrKS1sNC2yXPznNb8RpDGFLBYf HM7ExvrbnKraE+9nJtXk5AdP3AqCc+kpgR+4iWy2oBk1WCshDhllca3EQyBG+FlvvQBdzu1hfdW RkHNl62n+XT8ssPwXrj4MkbPSfCCqTbA= X-Received: by 2002:a37:9acd:: with SMTP id c196mr8843427qke.495.1635925445757; Wed, 03 Nov 2021 00:44:05 -0700 (PDT) X-Google-Smtp-Source: ABdhPJzuVMFbr0D3lIQvlww2XHGNSYhxcIYgiqZz/JSwTzoTwKEwAIOjHmiVyWrhSk7OmUtJmXywTcdfM7eVaP/rb2k= X-Received: by 2002:a37:9acd:: with SMTP id c196mr8843417qke.495.1635925445566; Wed, 03 Nov 2021 00:44:05 -0700 (PDT) MIME-Version: 1.0 References: <20211029183525.1776416-1-eperezma@redhat.com> <20211029183525.1776416-22-eperezma@redhat.com> In-Reply-To: From: Eugenio Perez Martin Date: Wed, 3 Nov 2021 08:43:29 +0100 Message-ID: Subject: Re: [RFC PATCH v5 21/26] vhost: Add vhost_svq_valid_guest_features to shadow vq To: Jason Wang Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=eperezma@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=170.10.133.124; envelope-from=eperezma@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.702, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Laurent Vivier , Eduardo Habkost , "Michael S. Tsirkin" , Juan Quintela , Richard Henderson , qemu-devel , Peter Xu , Markus Armbruster , Stefan Hajnoczi , Xiao W Wang , Harpreet Singh Anand , Eli Cohen , Paolo Bonzini , Stefano Garzarella , Eric Blake , virtualization , Parav Pandit Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, Nov 3, 2021 at 4:18 AM Jason Wang wrote: > > On Tue, Nov 2, 2021 at 4:10 PM Eugenio Perez Martin = wrote: > > > > On Tue, Nov 2, 2021 at 6:26 AM Jason Wang wrote: > > > > > > On Sat, Oct 30, 2021 at 2:44 AM Eugenio P=C3=A9rez wrote: > > > > > > > > This allows it to test if the guest has aknowledge an invalid trans= port > > > > feature for SVQ. This will include packed vq layout or event_idx, > > > > where VirtIO device needs help from SVQ. > > > > > > > > There is not needed at this moment, but since SVQ will not re-negot= iate > > > > features again with the guest, a failure in acknowledge them is fat= al > > > > for SVQ. > > > > > > > > > > It's not clear to me why we need this. Maybe you can give me an > > > example. E.g isn't it sufficient to filter out the device with > > > event_idx? > > > > > > > If the guest did negotiate _F_EVENT_IDX, it expects to be notified > > only when device marks as used a specific number of descriptors. > > > > If we use VirtQueue notification, the VirtQueue code handles it > > transparently. But if we want to be able to change the guest VQ's > > call_fd, we cannot use VirtQueue's, so this needs to be handled by SVQ > > code. And that is still not implemented. > > > > Of course in the event_idx case we could just ignore it and notify in > > all used descriptors, but it seems not polite to me :). I will develop > > event_idx on top of this, either exposing the needed pieces in > > VirtQueue (I prefer this) or rolling our own in SVQ. > > Yes, but what I meant is, we can fail the SVQ enabling if the device > supports event_idx. Then we're sure guests won't negotiate event_idx. > We can go that way for sure, but then we leave out the scenario where the device supports event_idx but the guest has not acked it. This is a valid scenario for SVQ to work in. Thanks! > Thanks > > > > > Same reasoning can be applied to unknown transport features. > > > > Thanks! > > > > > Thanks > > > > > > > Signed-off-by: Eugenio P=C3=A9rez > > > > --- > > > > hw/virtio/vhost-shadow-virtqueue.h | 1 + > > > > hw/virtio/vhost-shadow-virtqueue.c | 6 ++++++ > > > > 2 files changed, 7 insertions(+) > > > > > > > > diff --git a/hw/virtio/vhost-shadow-virtqueue.h b/hw/virtio/vhost-s= hadow-virtqueue.h > > > > index 946b2c6295..ac55588009 100644 > > > > --- a/hw/virtio/vhost-shadow-virtqueue.h > > > > +++ b/hw/virtio/vhost-shadow-virtqueue.h > > > > @@ -16,6 +16,7 @@ > > > > typedef struct VhostShadowVirtqueue VhostShadowVirtqueue; > > > > > > > > bool vhost_svq_valid_device_features(uint64_t *features); > > > > +bool vhost_svq_valid_guest_features(uint64_t *features); > > > > > > > > void vhost_svq_set_svq_kick_fd(VhostShadowVirtqueue *svq, int svq_= kick_fd); > > > > void vhost_svq_set_guest_call_notifier(VhostShadowVirtqueue *svq, = int call_fd); > > > > diff --git a/hw/virtio/vhost-shadow-virtqueue.c b/hw/virtio/vhost-s= hadow-virtqueue.c > > > > index 6e0508a231..cb9ffcb015 100644 > > > > --- a/hw/virtio/vhost-shadow-virtqueue.c > > > > +++ b/hw/virtio/vhost-shadow-virtqueue.c > > > > @@ -62,6 +62,12 @@ bool vhost_svq_valid_device_features(uint64_t *d= ev_features) > > > > return true; > > > > } > > > > > > > > +/* If the guest is using some of these, SVQ cannot communicate */ > > > > +bool vhost_svq_valid_guest_features(uint64_t *guest_features) > > > > +{ > > > > + return true; > > > > +} > > > > + > > > > /* Forward guest notifications */ > > > > static void vhost_handle_guest_kick(EventNotifier *n) > > > > { > > > > -- > > > > 2.27.0 > > > > > > > > > >