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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2520EC433FE for ; Tue, 8 Nov 2022 08:56:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233425AbiKHI4u (ORCPT ); Tue, 8 Nov 2022 03:56:50 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55416 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229843AbiKHI4t (ORCPT ); Tue, 8 Nov 2022 03:56:49 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1CFD52F390 for ; Tue, 8 Nov 2022 00:55:56 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1667897756; 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=4yipTWvAKK59+UDaW0mZvnxyflOnwLDwk1GJZlatPJg=; b=CuZR7opWThqtdRZIOQ7ABJ9I837OHqlJUjwEEnGY/U6703VbTypXmJCcVCvkkbNNqA6LQd wca/zo0HAtS+BNKMobAdYr6ywp/dT0dpmORPzBskKQ+l9Y7Qjz+iSnFUPEVqjkfEZCw9eX wlBTCEEjcI2shXeO0XfTkWAcx9DcXos= Received: from mail-qv1-f69.google.com (mail-qv1-f69.google.com [209.85.219.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-350-CsznFY_VN2O16L-ijpsQpQ-1; Tue, 08 Nov 2022 03:55:55 -0500 X-MC-Unique: CsznFY_VN2O16L-ijpsQpQ-1 Received: by mail-qv1-f69.google.com with SMTP id x2-20020a0cff22000000b004bb07bf7557so9220706qvt.11 for ; Tue, 08 Nov 2022 00:55:54 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to: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=4yipTWvAKK59+UDaW0mZvnxyflOnwLDwk1GJZlatPJg=; b=N+CkNv+D63sN1cCGBZ5bujshftI0EGNng2tcGTdErXkMspWF3m9guyNNTrNtYMhAeJ aIyFvonbC1N8wcbg9Mihi603dDfqCPFnJckkbqDqeaOnz1o1KbgE01FuMq8jPPpXKlNl CfUpaUEvFAyV/FY1k9hBPSZJyYGdLIHpxeRnr3HJsSbs8XE4AoB+sgV58vVmzpZksCRh JodEdUDZf/fTRZE8TH8NU9cHyW6gHf4Vp4G/Gu0k6TY6hNw7EUBsvamG7PN6/OZFsC8R IXs+iy40U33SUzM+PbvcKkhmkXvuyFduh1zK66Nb92Rp1qOH3sGGtCXYSNhC7zawbo6n U6tg== X-Gm-Message-State: ACrzQf08bFFt5Nb1ppK5hZ2Mx/Bw2yt14lZz7X24fD5bPSCu1ZWpCB7Q lkTW3fjKmm3Kom8yiw+qo2P6aQnphQcGsscg/ARuXM+CLNQwVM7leRKV/Nz5mFmlWhic5gpcCKR Uw9p9bg4AYqszInYC X-Received: by 2002:a37:603:0:b0:6fa:6fa6:1019 with SMTP id 3-20020a370603000000b006fa6fa61019mr20362210qkg.27.1667897754408; Tue, 08 Nov 2022 00:55:54 -0800 (PST) X-Google-Smtp-Source: AMsMyM4sAQ/1DJwa8nDgW33KcEepaQdX8eNEfpVaNQCy6RzDEu4X9alIhMotTbpwFmqZnXU/fXpW6A== X-Received: by 2002:a37:603:0:b0:6fa:6fa6:1019 with SMTP id 3-20020a370603000000b006fa6fa61019mr20362199qkg.27.1667897754116; Tue, 08 Nov 2022 00:55:54 -0800 (PST) Received: from redhat.com ([138.199.52.3]) by smtp.gmail.com with ESMTPSA id r16-20020ac87ef0000000b003996aa171b9sm7624944qtc.97.2022.11.08.00.55.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 08 Nov 2022 00:55:53 -0800 (PST) Date: Tue, 8 Nov 2022 03:55:48 -0500 From: "Michael S. Tsirkin" To: Jason Wang Cc: Eric Auger , eric.auger.pro@gmail.com, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, peterx@redhat.com Subject: Re: [RFC] vhost: Clear the pending messages on vhost_init_device_iotlb() Message-ID: <20221108035142-mutt-send-email-mst@kernel.org> References: <20221107203431.368306-1-eric.auger@redhat.com> <20221107153924-mutt-send-email-mst@kernel.org> <20221107180022-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Tue, Nov 08, 2022 at 11:09:36AM +0800, Jason Wang wrote: > On Tue, Nov 8, 2022 at 7:06 AM Michael S. Tsirkin wrote: > > > > On Mon, Nov 07, 2022 at 10:10:06PM +0100, Eric Auger wrote: > > > Hi Michael, > > > On 11/7/22 21:42, Michael S. Tsirkin wrote: > > > > On Mon, Nov 07, 2022 at 09:34:31PM +0100, Eric Auger wrote: > > > >> When the vhost iotlb is used along with a guest virtual iommu > > > >> and the guest gets rebooted, some MISS messages may have been > > > >> recorded just before the reboot and spuriously executed by > > > >> the virtual iommu after the reboot. Despite the device iotlb gets > > > >> re-initialized, the messages are not cleared. Fix that by calling > > > >> vhost_clear_msg() at the end of vhost_init_device_iotlb(). > > > >> > > > >> Signed-off-by: Eric Auger > > > >> --- > > > >> drivers/vhost/vhost.c | 1 + > > > >> 1 file changed, 1 insertion(+) > > > >> > > > >> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c > > > >> index 40097826cff0..422a1fdee0ca 100644 > > > >> --- a/drivers/vhost/vhost.c > > > >> +++ b/drivers/vhost/vhost.c > > > >> @@ -1751,6 +1751,7 @@ int vhost_init_device_iotlb(struct vhost_dev *d, bool enabled) > > > >> } > > > >> > > > >> vhost_iotlb_free(oiotlb); > > > >> + vhost_clear_msg(d); > > > >> > > > >> return 0; > > > >> } > > > > Hmm. Can't messages meanwhile get processes and affect the > > > > new iotlb? > > > Isn't the msg processing stopped at the moment this function is called > > > (VHOST_SET_FEATURES)? > > > > > > Thanks > > > > > > Eric > > > > It's pretty late here I'm not sure. You tell me what prevents it. > > So the proposed code assumes that Qemu doesn't process device IOTLB > before VHOST_SET_FEAETURES. Consider there's no reset in the general > vhost uAPI, I wonder if it's better to move the clear to device code > like VHOST_NET_SET_BACKEND. So we can clear it per vq? Hmm this makes no sense to me. iommu sits between backend and frontend. Tying one to another is going to backfire. I'm thinking more along the lines of doing everything under iotlb_lock. > > > > BTW vhost_init_device_iotlb gets enabled parameter but ignores > > it, we really should drop that. > > Yes. > > > > > Also, it looks like if features are set with VIRTIO_F_ACCESS_PLATFORM > > and then cleared, iotlb is not properly cleared - bug? > > Not sure, old IOTLB may still work. But for safety, we need to disable > device IOTLB in this case. > > Thanks > > > > > > > > > > > > > > > > >> -- > > > >> 2.37.3 > >