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 04D7DC433F5 for ; Tue, 10 May 2022 11:32:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241027AbiEJLgr (ORCPT ); Tue, 10 May 2022 07:36:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35906 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233899AbiEJLgl (ORCPT ); Tue, 10 May 2022 07:36:41 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id AE4AE41F8E for ; Tue, 10 May 2022 04:32:43 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1652182362; 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=/6JGU3yCeXbwd8q2TiB3We0T+2lr2Ip1+nsoAPs6S2s=; b=YOifvgOohhYD3h49AFuojryzEohmk0Fu58c6erBapOPMwpSnGn3uysWyHELu3aK+RNKBN4 ZEPuphFdTNlJcKKPFGImkpmQcO/tov3uOxtoGPyjdo2MucBCBcRoQ4IfRVTxWkwNV/8Ze9 huH8V1+YHqQVzFYMR/nNeLvr+1g/Dig= Received: from mail-wm1-f69.google.com (mail-wm1-f69.google.com [209.85.128.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-612-jGV8qUgyP3muJtob3e284A-1; Tue, 10 May 2022 07:32:41 -0400 X-MC-Unique: jGV8qUgyP3muJtob3e284A-1 Received: by mail-wm1-f69.google.com with SMTP id z23-20020a05600c221700b003942fd37764so1141276wml.8 for ; Tue, 10 May 2022 04:32:41 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=/6JGU3yCeXbwd8q2TiB3We0T+2lr2Ip1+nsoAPs6S2s=; b=zVEeCHaoPQAC/flNJPDZDCj4lWNOtfTaSzQOttTI32zPXS9TLpkjpVk9vRcLeR7SXR FS8JirdTpXOyBzyRAyXbZ0hfansBL9boF2T2zUClcsWHvV1jnVXJ89/MgAuZ+NvKcG4t le32ooHutIK/aDgoWAMT9uzD664KCKOJysSUHzwOnjsOXD3urOyeemRg1rHIn2xNVuQF ARRn/7IU4CCozd0lRqTQccH5QpzwFCKoWaGq5Bff2RB+TRYiunXFdb8XyKBN9Cs6klH3 qTmqBtCyTZxIPYw5kVsUh8g/iAsYjKxonZRKqxKjicZKcq/VJElMrGoCzxaWsE6yWTlK hL2w== X-Gm-Message-State: AOAM533Ka+4b/7eR/pj2PXD4ysQgAR4lRie7CEkraOa2G72ZBPO5ld+D VDAl1Oli9Dlv3Oewlg8frwL9Q4FwKg8uG6UdO6F+FEv+Y0lqwjkghHOcCobkyYLbdTty+WMeQbz +LV45UYVdXJI6ZszzY09BX0fu X-Received: by 2002:a05:6000:144f:b0:20c:6090:3040 with SMTP id v15-20020a056000144f00b0020c60903040mr17724136wrx.479.1652182360186; Tue, 10 May 2022 04:32:40 -0700 (PDT) X-Google-Smtp-Source: ABdhPJzsEleGX5w1OSWKo2o5f2WSyJKHdkzs/SrI4J/pz4kEhj9uYYK5k7bkfywVoL/OsCq+T9m4og== X-Received: by 2002:a05:6000:144f:b0:20c:6090:3040 with SMTP id v15-20020a056000144f00b0020c60903040mr17724121wrx.479.1652182359954; Tue, 10 May 2022 04:32:39 -0700 (PDT) Received: from redhat.com ([2.55.130.230]) by smtp.gmail.com with ESMTPSA id c17-20020a056000105100b0020c5253d8ccsm13457840wrx.24.2022.05.10.04.32.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 May 2022 04:32:39 -0700 (PDT) Date: Tue, 10 May 2022 07:32:35 -0400 From: "Michael S. Tsirkin" To: Jason Wang Cc: virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, peterz@infradead.org, paulmck@kernel.org, maz@kernel.org, pasic@linux.ibm.com, cohuck@redhat.com, eperezma@redhat.com, lulu@redhat.com, sgarzare@redhat.com, xuanzhuo@linux.alibaba.com Subject: Re: [PATCH V4 8/9] virtio: harden vring IRQ Message-ID: <20220510072833-mutt-send-email-mst@kernel.org> References: <20220507071954.14455-1-jasowang@redhat.com> <20220507071954.14455-9-jasowang@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220507071954.14455-9-jasowang@redhat.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, May 07, 2022 at 03:19:53PM +0800, Jason Wang wrote: > This is a rework on the previous IRQ hardening that is done for > virtio-pci where several drawbacks were found and were reverted: > > 1) try to use IRQF_NO_AUTOEN which is not friendly to affinity managed IRQ > that is used by some device such as virtio-blk > 2) done only for PCI transport > > The vq->broken is re-used in this patch for implementing the IRQ > hardening. The vq->broken is set to true during both initialization > and reset. And the vq->broken is set to false in > virtio_device_ready(). Then vring_interrupt can check and return when > vq->broken is true. And in this case, switch to return IRQ_NONE to let > the interrupt core aware of such invalid interrupt to prevent IRQ > storm. > > The reason of using a per queue variable instead of a per device one > is that we may need it for per queue reset hardening in the future. > > Note that the hardening is only done for vring interrupt since the > config interrupt hardening is already done in commit 22b7050a024d7 > ("virtio: defer config changed notifications"). But the method that is > used by config interrupt can't be reused by the vring interrupt > handler because it uses spinlock to do the synchronization which is > expensive. > > Cc: Thomas Gleixner > Cc: Peter Zijlstra > Cc: "Paul E. McKenney" > Cc: Marc Zyngier > Cc: Halil Pasic > Cc: Cornelia Huck > Signed-off-by: Jason Wang > --- > drivers/virtio/virtio.c | 15 ++++++++++++--- > drivers/virtio/virtio_ring.c | 11 +++++++---- > include/linux/virtio_config.h | 12 ++++++++++++ > 3 files changed, 31 insertions(+), 7 deletions(-) > > diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c > index 8dde44ea044a..696f5ba4f38e 100644 > --- a/drivers/virtio/virtio.c > +++ b/drivers/virtio/virtio.c > @@ -220,6 +220,15 @@ static int virtio_features_ok(struct virtio_device *dev) > * */ > void virtio_reset_device(struct virtio_device *dev) > { > + /* > + * The below virtio_synchronize_cbs() guarantees that any > + * interrupt for this line arriving after > + * virtio_synchronize_vqs() has completed is guaranteed to see > + * driver_ready == false. > + */ > + virtio_break_device(dev); > + virtio_synchronize_cbs(dev); > + > dev->config->reset(dev); > } > EXPORT_SYMBOL_GPL(virtio_reset_device); > @@ -428,6 +437,9 @@ int register_virtio_device(struct virtio_device *dev) > dev->config_enabled = false; > dev->config_change_pending = false; > > + INIT_LIST_HEAD(&dev->vqs); > + spin_lock_init(&dev->vqs_list_lock); > + > /* We always start by resetting the device, in case a previous > * driver messed it up. This also tests that code path a little. */ > virtio_reset_device(dev); > @@ -435,9 +447,6 @@ int register_virtio_device(struct virtio_device *dev) > /* Acknowledge that we've seen the device. */ > virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE); > > - INIT_LIST_HEAD(&dev->vqs); > - spin_lock_init(&dev->vqs_list_lock); > - > /* > * device_add() causes the bus infrastructure to look for a matching > * driver. > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > index 5b7df7c455f0..9dfad2890d7a 100644 > --- a/drivers/virtio/virtio_ring.c > +++ b/drivers/virtio/virtio_ring.c > @@ -1690,7 +1690,7 @@ static struct virtqueue *vring_create_virtqueue_packed( > vq->we_own_ring = true; > vq->notify = notify; > vq->weak_barriers = weak_barriers; > - vq->broken = false; > + vq->broken = true; > vq->last_used_idx = 0; > vq->event_triggered = false; > vq->num_added = 0; > @@ -2136,8 +2136,11 @@ irqreturn_t vring_interrupt(int irq, void *_vq) > return IRQ_NONE; > } > > - if (unlikely(vq->broken)) > - return IRQ_HANDLED; > + if (unlikely(vq->broken)) { > + dev_warn_once(&vq->vq.vdev->dev, > + "virtio vring IRQ raised before DRIVER_OK"); > + return IRQ_NONE; > + } > > /* Just a hint for performance: so it's ok that this can be racy! */ > if (vq->event) > @@ -2179,7 +2182,7 @@ struct virtqueue *__vring_new_virtqueue(unsigned int index, > vq->we_own_ring = false; > vq->notify = notify; > vq->weak_barriers = weak_barriers; > - vq->broken = false; > + vq->broken = true; > vq->last_used_idx = 0; > vq->event_triggered = false; > vq->num_added = 0; > diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h > index d8a2340f928e..23f1694cdbd5 100644 > --- a/include/linux/virtio_config.h > +++ b/include/linux/virtio_config.h > @@ -256,6 +256,18 @@ void virtio_device_ready(struct virtio_device *dev) > unsigned status = dev->config->get_status(dev); > > BUG_ON(status & VIRTIO_CONFIG_S_DRIVER_OK); > + > + /* > + * The virtio_synchronize_cbs() makes sure vring_interrupt() > + * will see the driver specific setup if it sees vq->broken > + * as false. > + */ > + virtio_synchronize_cbs(dev); since you mention vq->broken above, maybe add "set vq->broken to false" > + __virtio_unbreak_device(dev); > + /* > + * The transport is expected ensure the visibility of to ensure > + * vq->broken let's add: "visibility by vq callbacks" > before setting VIRTIO_CONFIG_S_DRIVER_OK. > + */ Can I see some analysis of existing transports showing this is actually the case for them? And maybe add a comment near set_status to document the requirement. > dev->config->set_status(dev, status | VIRTIO_CONFIG_S_DRIVER_OK); > } > > -- > 2.25.1