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 1DAA5C433EF for ; Wed, 22 Jun 2022 07:09:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1352099AbiFVHJv (ORCPT ); Wed, 22 Jun 2022 03:09:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46838 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232097AbiFVHJs (ORCPT ); Wed, 22 Jun 2022 03:09:48 -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 8D44236B61 for ; Wed, 22 Jun 2022 00:09:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1655881786; 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=1j0naFDRK4ezIvjusKXtbA3Bm71U034ui+b38Iv9ly0=; b=DQ5IXs2nPdc0hmDod4LQh6BAex0YyEFsLrSdXJKD+3t0d9aQsH4m8SDFRrtL7UDAUwjswI 1tYGTbglEtWcyAdnvolEghPFujSJ/7HOhQghsp0gczb9gEQ6NO7M3zyqpswXTpnIAaK6XN YWjbIDo7kuJuWFV7q3RTtmiiVLN3wGo= Received: from mail-lj1-f198.google.com (mail-lj1-f198.google.com [209.85.208.198]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-400-vNjChodUONixtVXITlqQow-1; Wed, 22 Jun 2022 03:09:44 -0400 X-MC-Unique: vNjChodUONixtVXITlqQow-1 Received: by mail-lj1-f198.google.com with SMTP id z10-20020a05651c022a00b00255a0bf5ccfso2162126ljn.13 for ; Wed, 22 Jun 2022 00:09:44 -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; bh=1j0naFDRK4ezIvjusKXtbA3Bm71U034ui+b38Iv9ly0=; b=F9Udh0oyuOaqYIMBEbwPflpNPe3o1/jl6XwBn8ACV6Eto8baZCSFe9QkGbHOMoQeJw YMxC/zyLOwILsgqOIkykhw0Hatvm88zg+UPDHNZVFhOxKAXw2EzEA/Ia/1RFNjYY9byk Yh43YduYqgXjHdqVKcBURcLsQEXKkM8FrwekU2nE8nHEZu+fIF0X+Ts3YwPcGrjmGwIa e31lNxpYgrw5nD92p2I1WtzbjGOsL7bLch4t6xCk2qD9d0mtXt4UlzPaUBzUTP3/fwUM ZbGy1eJe0GAevi359s1UqOZ4hG9XVsG8yl5WWpWdBCF8n/tY4b/SNG6i8NmbnHvbpNax s8Xg== X-Gm-Message-State: AJIora8fjzTOwtwr8+WiUQGEvno0dZPm/yE2HClTZMhELB2cjX6MMSyP MbzqRpS63/n06iZsP5p65CZmYCS4xUyKsiYjxMfkQXky2lTO5I+Ca5OuXC6YtrpyPGXPOGiYGnL 3jKRacrDyCvzyfg3OSEBiv2qlBh/BO2Ex8nEPKQqN X-Received: by 2002:ac2:51a5:0:b0:47f:79a1:5c02 with SMTP id f5-20020ac251a5000000b0047f79a15c02mr1252860lfk.575.1655881783024; Wed, 22 Jun 2022 00:09:43 -0700 (PDT) X-Google-Smtp-Source: AGRyM1tq42OMcdXjoSnnpCbSjESrNsMW03LT2BQ9mcgGzfwle50vtAU5p80ztyv3WPK0HK2yNJdCKqUoZQoVQawiuxo= X-Received: by 2002:ac2:51a5:0:b0:47f:79a1:5c02 with SMTP id f5-20020ac251a5000000b0047f79a15c02mr1252846lfk.575.1655881782745; Wed, 22 Jun 2022 00:09:42 -0700 (PDT) MIME-Version: 1.0 References: <20220622012940.21441-1-jasowang@redhat.com> <20220622025047-mutt-send-email-mst@kernel.org> In-Reply-To: <20220622025047-mutt-send-email-mst@kernel.org> From: Jason Wang Date: Wed, 22 Jun 2022 15:09:31 +0800 Message-ID: Subject: Re: [PATCH V3] virtio: disable notification hardening by default To: "Michael S. Tsirkin" Cc: Cornelia Huck , Halil Pasic , Heiko Carstens , Vasily Gorbik , Christian Borntraeger , Alexander Gordeev , linux-s390@vger.kernel.org, virtualization , kvm , linux-kernel , Ben Hutchings , David Hildenbrand Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 22, 2022 at 3:03 PM Michael S. Tsirkin wrote: > > On Wed, Jun 22, 2022 at 09:29:40AM +0800, Jason Wang wrote: > > We try to harden virtio device notifications in 8b4ec69d7e09 ("virtio: > > harden vring IRQ"). It works with the assumption that the driver or > > core can properly call virtio_device_ready() at the right > > place. Unfortunately, this seems to be not true and uncover various > > bugs of the existing drivers, mainly the issue of using > > virtio_device_ready() incorrectly. > > > > So let's having a Kconfig option and disable it by default. It gives > > us a breath to fix the drivers and then we can consider to enable it > > by default. > > > > Signed-off-by: Jason Wang > > > OK I will queue, but I think the problem is fundamental. If I understand correctly, you want some core IRQ work? As discussed before, it doesn't solve all the problems, we still need to do per driver audit. Thanks > > > > --- > > Changes since V2: > > - Tweak the Kconfig help > > - Add comment for the read_lock() pairing in virtio_ccw > > --- > > drivers/s390/virtio/virtio_ccw.c | 9 ++++++++- > > drivers/virtio/Kconfig | 13 +++++++++++++ > > drivers/virtio/virtio.c | 2 ++ > > drivers/virtio/virtio_ring.c | 12 ++++++++++++ > > include/linux/virtio_config.h | 2 ++ > > 5 files changed, 37 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/s390/virtio/virtio_ccw.c b/drivers/s390/virtio/virtio_ccw.c > > index 97e51c34e6cf..1f6a358f65f0 100644 > > --- a/drivers/s390/virtio/virtio_ccw.c > > +++ b/drivers/s390/virtio/virtio_ccw.c > > @@ -1136,8 +1136,13 @@ static void virtio_ccw_int_handler(struct ccw_device *cdev, > > vcdev->err = -EIO; > > } > > virtio_ccw_check_activity(vcdev, activity); > > - /* Interrupts are disabled here */ > > +#ifdef CONFIG_VIRTIO_HARDEN_NOTIFICATION > > + /* > > + * Paried with virtio_ccw_synchronize_cbs() and interrupts are > > + * disabled here. > > + */ > > read_lock(&vcdev->irq_lock); > > +#endif > > for_each_set_bit(i, indicators(vcdev), > > sizeof(*indicators(vcdev)) * BITS_PER_BYTE) { > > /* The bit clear must happen before the vring kick. */ > > @@ -1146,7 +1151,9 @@ static void virtio_ccw_int_handler(struct ccw_device *cdev, > > vq = virtio_ccw_vq_by_ind(vcdev, i); > > vring_interrupt(0, vq); > > } > > +#ifdef CONFIG_VIRTIO_HARDEN_NOTIFICATION > > read_unlock(&vcdev->irq_lock); > > +#endif > > if (test_bit(0, indicators2(vcdev))) { > > virtio_config_changed(&vcdev->vdev); > > clear_bit(0, indicators2(vcdev)); > > diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig > > index b5adf6abd241..c04f370a1e5c 100644 > > --- a/drivers/virtio/Kconfig > > +++ b/drivers/virtio/Kconfig > > @@ -35,6 +35,19 @@ menuconfig VIRTIO_MENU > > > > if VIRTIO_MENU > > > > +config VIRTIO_HARDEN_NOTIFICATION > > + bool "Harden virtio notification" > > + help > > + Enable this to harden the device notifications and suppress > > + those that happen at a time where notifications are illegal. > > + > > + Experimental: Note that several drivers still have bugs that > > + may cause crashes or hangs when correct handling of > > + notifications is enforced; depending on the subset of > > + drivers and devices you use, this may or may not work. > > + > > + If unsure, say N. > > + > > config VIRTIO_PCI > > tristate "PCI driver for virtio devices" > > depends on PCI > > diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c > > index ef04a96942bf..21dc08d2f32d 100644 > > --- a/drivers/virtio/virtio.c > > +++ b/drivers/virtio/virtio.c > > @@ -220,6 +220,7 @@ static int virtio_features_ok(struct virtio_device *dev) > > * */ > > void virtio_reset_device(struct virtio_device *dev) > > { > > +#ifdef CONFIG_VIRTIO_HARDEN_NOTIFICATION > > /* > > * The below virtio_synchronize_cbs() guarantees that any > > * interrupt for this line arriving after > > @@ -228,6 +229,7 @@ void virtio_reset_device(struct virtio_device *dev) > > */ > > virtio_break_device(dev); > > virtio_synchronize_cbs(dev); > > +#endif > > > > dev->config->reset(dev); > > } > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > > index 13a7348cedff..d9d3b6e201fb 100644 > > --- a/drivers/virtio/virtio_ring.c > > +++ b/drivers/virtio/virtio_ring.c > > @@ -1688,7 +1688,11 @@ static struct virtqueue *vring_create_virtqueue_packed( > > vq->we_own_ring = true; > > vq->notify = notify; > > vq->weak_barriers = weak_barriers; > > +#ifdef CONFIG_VIRTIO_HARDEN_NOTIFICATION > > vq->broken = true; > > +#else > > + vq->broken = false; > > +#endif > > vq->last_used_idx = 0; > > vq->event_triggered = false; > > vq->num_added = 0; > > @@ -2135,9 +2139,13 @@ irqreturn_t vring_interrupt(int irq, void *_vq) > > } > > > > if (unlikely(vq->broken)) { > > +#ifdef CONFIG_VIRTIO_HARDEN_NOTIFICATION > > dev_warn_once(&vq->vq.vdev->dev, > > "virtio vring IRQ raised before DRIVER_OK"); > > return IRQ_NONE; > > +#else > > + return IRQ_HANDLED; > > +#endif > > } > > > > /* Just a hint for performance: so it's ok that this can be racy! */ > > @@ -2180,7 +2188,11 @@ struct virtqueue *__vring_new_virtqueue(unsigned int index, > > vq->we_own_ring = false; > > vq->notify = notify; > > vq->weak_barriers = weak_barriers; > > +#ifdef CONFIG_VIRTIO_HARDEN_NOTIFICATION > > vq->broken = true; > > +#else > > + vq->broken = false; > > +#endif > > 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 9a36051ceb76..d15c3cdda2d2 100644 > > --- a/include/linux/virtio_config.h > > +++ b/include/linux/virtio_config.h > > @@ -257,6 +257,7 @@ void virtio_device_ready(struct virtio_device *dev) > > > > WARN_ON(status & VIRTIO_CONFIG_S_DRIVER_OK); > > > > +#ifdef CONFIG_VIRTIO_HARDEN_NOTIFICATION > > /* > > * The virtio_synchronize_cbs() makes sure vring_interrupt() > > * will see the driver specific setup if it sees vq->broken > > @@ -264,6 +265,7 @@ void virtio_device_ready(struct virtio_device *dev) > > */ > > virtio_synchronize_cbs(dev); > > __virtio_unbreak_device(dev); > > +#endif > > /* > > * The transport should ensure the visibility of vq->broken > > * before setting DRIVER_OK. See the comments for the transport > > -- > > 2.25.1 >