From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BF8F548F83A for ; Mon, 7 Sep 2026 13:13:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788786827; cv=none; b=BvXun5tw6EXVtxE2rJbKa3LM1RlE+nr91tl9XxTOWofjZN9qBbSfdiqWjdTFSXEitajv1G26AeIcUboHG7QVzO3ekQYgZV97jWduoRHXl58hIqgIXE61eDO9+bLGJTtTdYvfidrc+cWMoPjnJ9GnnnCs+JyZh3xBbFh6n1V/LYo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788786827; c=relaxed/simple; bh=bbyM8+xnMNKO6fyiNZM2V/dxEjYjP4AdG79mC8RAzeM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Ks6/hupL2CJJ9vW72YOv6fxuybDuc/aXCpobh+L6/iCNSTONqFD7kqpClW3hCDG9Z9Tunry4sLbRcc8FBQ8xJvkX82MJ6atmbDk1+Cz+TRbn2sHbkBEH2aW+VbY5ZF4STnsig0rQK3cauDVsCmV2svXewwCGt+O4hCi0C8l3hQE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=BHNlFA48; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b=gy0OdkN6; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="BHNlFA48"; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b="gy0OdkN6" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1788786816; 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=5punYBPTQYCYDbZdD+Tip6UD659TFwSyiVivgWnd/bQ=; b=BHNlFA48L6Asxjk6Ul+pWL3mabZqd5KTjnSteMGdxnnZyajaCr5ADj0iKLTlFUGCEO5+WY YAMEizLB05z4sEZqsrsQPDfWoUgbFoV+jn7DI2SyMJWuZOgl9rx2C6l4WjjfohV8Mx7FQP 6MDH0UD/97lsDKfJ6/Lk9lzKva4/Idg= Received: from mail-wm1-f70.google.com (mail-wm1-f70.google.com [209.85.128.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-543-MO_tU5wUOFO-NkQL9VfPAg-1; Mon, 07 Sep 2026 09:13:34 -0400 X-MC-Unique: MO_tU5wUOFO-NkQL9VfPAg-1 X-Mimecast-MFC-AGG-ID: MO_tU5wUOFO-NkQL9VfPAg_1788786814 Received: by mail-wm1-f70.google.com with SMTP id 5b1f17b1804b1-49545071724so27732365e9.0 for ; Mon, 07 Sep 2026 06:13:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=google; t=1788786813; x=1789391613; darn=vger.kernel.org; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:from:to:cc:subject :date:message-id:reply-to:content-type; bh=5punYBPTQYCYDbZdD+Tip6UD659TFwSyiVivgWnd/bQ=; b=gy0OdkN6w26QFaOXv6fYnw8KuIo1/jlD0unXb1oGGSeoNrDrS7mYYQLaJiR6oDbzMF teCyJbW66P7C3M/aCB9FZfW+5GRRyDB/Rq23ykl1KB6k6eksjLwb7l90ZQy4ALCGjylK 6ZOXfRnWwOfMy6iTBarbpaBKWoubHxdVWsuBaQu9mHs5IfpFxxQCrLk46MSzhThSPjri hJsPXQCudWjdBKNId+zsEFwKwQ+gw1HAGxC4t2g7VTaF85nzmkRhKfrBlJyDA26flBYq Qxwzw6UqsPJ8Xu/wgOVuhnlDkwpo6is8QNCtDEqp6tzuI+6LnV0tahMLVEy12wjsjcMr fvtw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1788786813; x=1789391613; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=5punYBPTQYCYDbZdD+Tip6UD659TFwSyiVivgWnd/bQ=; b=GK4HKt54jTr2a+yJQBVVJ9E1EP+E3ZpC3ccyP3jOtrloECOQDNK5kedvgtMb7V8GSt FOso/C1FmcFcc4LXnR72w6xodiNlNvWy4e+tYdR8X7e6s0b052hngEkvn4F1FkgUmQ6Z XW7eBk+X+a1KIpgcx3IKf/RtsGu5Dh47p2nVsiWJNyGBx9R5LHV8vN09KtdE4/gR6ih1 Z3T1Zw0OP9D/Oauy0muk6DAj/0F2bn7abkXd0i2uMy8/5MRyQxSioDtnUWMk6M4AGZ8d JMNP7IlCPgWtERL9NX+rMrwpmPhqzr3gcwjCyPZ3mCqJrmlg9oe0moCXXHL0qRrcQXlk JUQw== X-Forwarded-Encrypted: i=1; AKwUvBzVsxxllwNYRJxjagXg2bha+DlCimVC+1SeX4j2cHVweWQl/HiPL6w89HJ4igHAjXRayFw=@vger.kernel.org X-Gm-Message-State: AFuF++mbzSodCcaVAPkCiTNMOcSdVoUsBcOs4Y6hR46eADHm+7lKdDiH 3FyOTSnrRivt4sPNxT3gMQq/pl0OSYA/ZKjxHuOXSGy/D/VhXfBFgeaWowu7mr0GqqSStO73VQT gDVGc02XXdQExlwGttrifAQwrOqsuqbb01xIQj542YxNGOzKzA2yZFQ== X-Gm-Gg: AYBFou3JLRHyon1gRO4Cgv386eflgf15bhJVxIc34hXcVqqtyQilNAODu9xU4YJQxBN HUZn+VL7peJYNnsMAxAkRecvo8NYmcVdi5q3NAKifiYqrQ5HYIBTD/BFXMSKkk7xlmRaqUaUogo bKq9/1QThOlgFb2wYQkiZVUYxRRHkl5ESS6Fmj1tzzvkhMN1n99qe0WrXw68nr8LZZFhjOCEEMo 34u1mA//S9rmJ4eeexzcK+zGBAO1TU+uTXMoRENNa2RE7Cl68rjCv9ZQ0cDPJgI6hMPB7AwjiTN Ap42eWndzHQZsUpCdX9AeqSVN6ZcSynZtNT9wq9MMaAIzhLCxGjPbo6CAZEttXHGhGULLdbVsuf bpugxQ7FMcDLdi6vCJCeoQJM= X-Received: by 2002:a05:600c:4684:b0:49c:fc6c:be14 with SMTP id 5b1f17b1804b1-49cfc6cc10bmr197561185e9.26.1788786813428; Mon, 07 Sep 2026 06:13:33 -0700 (PDT) X-Received: by 2002:a05:600c:4684:b0:49c:fc6c:be14 with SMTP id 5b1f17b1804b1-49cfc6cc10bmr197560545e9.26.1788786812906; Mon, 07 Sep 2026 06:13:32 -0700 (PDT) Received: from redhat.com (IGLD-80-230-79-236.inter.net.il. [80.230.79.236]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-49cfd3f8192sm270920615e9.3.2026.09.07.06.13.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 07 Sep 2026 06:13:32 -0700 (PDT) Date: Mon, 7 Sep 2026 09:13:28 -0400 From: "Michael S. Tsirkin" To: Karl Mehltretter Cc: Jason Wang , Gerd Hoffmann , Xuan Zhuo , Eugenio =?iso-8859-1?Q?P=E9rez?= , Dmitry Torokhov , Rusty Russell , Pawel Moll , Cornelia Huck , Halil Pasic , Eric Farman , Richard Weinberger , Anton Ivanov , Johannes Berg , Hans de Goede , Ilpo =?iso-8859-1?Q?J=E4rvinen?= , Vadim Pasternak , Bjorn Andersson , Mathieu Poirier , virtualization@lists.linux.dev, linux-input@vger.kernel.org, linux-s390@vger.kernel.org, kvm@vger.kernel.org, linux-um@lists.infradead.org, platform-driver-x86@vger.kernel.org, linux-remoteproc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 0/3] virtio: synchronize callbacks during device reset Message-ID: <20260907091033-mutt-send-email-mst@kernel.org> References: <20260905152059.89560-1-kmehltretter@gmail.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260905152059.89560-1-kmehltretter@gmail.com> On Sat, Sep 05, 2026 at 05:20:56PM +0200, Karl Mehltretter wrote: > A virtqueue callback can outlive virtio_reset_device() and race with a > driver freeing the state it uses. The reset helper documents that no > callbacks remain in progress, but that depends on the transport: > virtio-pci waits in vp_reset(), while virtio-mmio does not. > > virtio_input has a related ordering problem: it unregisters the input > device before resetting the virtio device, while an event callback may > still be using the input device. > > Patch 1 moves the callback wait into the core, using the existing > virtio_synchronize_cbs() operation. Patch 2 fixes the virtio_input teardown > order. Patch 3 adds the missing synchronize_cbs hooks for UML, TmFIFO, > remoteproc and virtio-vdpa. Remoteproc uses one SRCU domain per processor. > > The new hooks wait for callbacks already running. UML, TmFIFO and > remoteproc still allow new callbacks after reset; fixing that is separate > work. The event-virtqueue DMA mapping issue is also separate. > > Changes in v2: > - Patch 1: move the wait into the core instead of fixing only MMIO, as > Michael suggested. Remove the duplicate PCI wait, preserve its shutdown > wait, and fix CCW callback locking. Drop the MMIO polling: reset polling > for v3 and newer is already in fa8833c085b6 ("virtio-mmio: add support > for transport version 3"). > - Patch 2: keep draining completed events when ready becomes false, > instead of breaking out, so teardown does not truncate an input packet. > - Patch 3 is new, at Michael's request. got all 3 patches now. it's a good start, thanks, but they need a bit more work, in particular addressing sashiko comments. I'd also prefer patch 1 to be split: moving code from pci to core is separate from ccw fixes. Pls write or at least edit commit log messages yourself, after reviewing Documentation/process/coding-assistants.rst Thanks a lot! > I reran the 120-cycle unbind/rebind test in an arm64 KASAN guest with four > vCPUs and a 5 ms busy delay per event. With patch 2 alone over virtio-mmio, > reset returned with the callback still running in all 84 overlapping > cycles. With the series, it waited in all 103. Over PCI with per-queue > MSI-X, it waited in all 66, including runs with threadirqs. No KASAN or > lockdep reports. These runs predate the per-rproc change, which leaves > the tested MMIO and PCI paths unchanged. They confirmed the missing wait, > but did not reproduce a use-after-free: with evdev attached, > input_unregister_device() waits for an RCU grace period that the IRQ > callback blocks. > > That version also passed QEMU input, rebind and shutdown checks on arm64 > MMIO and x86-64 PCI, including arm64 RT, KASAN and KCSAN builds, and x86 > UP/Tiny SRCU. A legacy INTx NIC was present for an additional x86 > shutdown check. The changed objects built with W=1 without warnings on > arm64, x86-64, s390 and SMP UML. The per-rproc version built with W=1 > on arm64 KASAN and x86 Tiny SRCU, and passed six remoteproc callback and > lifetime KUnit tests on each, using mock remoteproc devices. > > Link: https://lore.kernel.org/r/20260818040433.66986-1-kmehltretter@gmail.com > > Karl Mehltretter (3): > virtio: synchronize callbacks during device reset > virtio_input: stop callbacks before unregistering input device > virtio: implement synchronize_cbs for remaining transports > > arch/um/drivers/virtio_uml.c | 10 ++++++++++ > drivers/platform/mellanox/mlxbf-tmfifo.c | 14 ++++++++++++++ > drivers/remoteproc/remoteproc_core.c | 10 ++++++++++ > drivers/remoteproc/remoteproc_virtio.c | 20 +++++++++++++++++--- > drivers/s390/virtio/virtio_ccw.c | 6 +----- > drivers/virtio/virtio.c | 2 ++ > drivers/virtio/virtio_input.c | 8 ++++++-- > drivers/virtio/virtio_pci_legacy.c | 2 -- > drivers/virtio/virtio_pci_modern.c | 3 --- > drivers/virtio/virtio_vdpa.c | 21 ++++++++++++++++++++- > include/linux/remoteproc.h | 3 +++ > include/linux/virtio_config.h | 6 +++--- > 12 files changed, 86 insertions(+), 19 deletions(-) > > base-commit: a500db7819c50db59e55f1b4fa1c3baa5a2616f3 > -- > 2.39.5 (Apple Git-154)