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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 279D9109E528 for ; Wed, 25 Mar 2026 23:13:50 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 798576B0089; Wed, 25 Mar 2026 19:13:49 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 748556B008C; Wed, 25 Mar 2026 19:13:49 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 637CB6B0092; Wed, 25 Mar 2026 19:13:49 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 512CD6B0089 for ; Wed, 25 Mar 2026 19:13:49 -0400 (EDT) Received: from smtpin19.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 204921A0A8F for ; Wed, 25 Mar 2026 23:13:49 +0000 (UTC) X-FDA: 84586139778.19.30D0382 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf27.hostedemail.com (Postfix) with ESMTP id 69CE640013 for ; Wed, 25 Mar 2026 23:13:47 +0000 (UTC) Authentication-Results: imf27.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=i7j6QyFf; spf=pass (imf27.hostedemail.com: domain of helgaas@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=helgaas@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1774480427; h=from:from:sender: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: in-reply-to:in-reply-to:references:dkim-signature; bh=8k/92Vl0S2lizBewoJmB2ydadzdk7wy8S0qCfjQ/afs=; b=qseANPvDQhdirpF/5dK8B/J/jseNWoqLx6LoLbrAugQ+QB3aNan24pxG2zm4mHtKxGB0jU gsXJPJDURdhEBbj1FSlINqsr3scfHNoJDPoUiq50ubYWZrbbXW5Zvp+1qR5GaevPW397HM ON/iclEAHXDxmkAc3PsKNgGLILRPdAo= ARC-Authentication-Results: i=1; imf27.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=i7j6QyFf; spf=pass (imf27.hostedemail.com: domain of helgaas@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=helgaas@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1774480427; a=rsa-sha256; cv=none; b=uLa5eh11wfG6PudQ7Km3RFfY7Tq8GvU9qnez7tjwMM+7dryMHKOZKT1I4hm4WaLH4a7b73 7n64dMIdLMe4DpwrZD7LHI+8cvL+CyxPKhaU1Wr8Tih39QwsU4Aaz8U5nz/cFOzO7U0x5y MDPrYjQcXMazorb4lEeS1SidOeW0ZrM= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 08A2E443C1; Wed, 25 Mar 2026 23:13:46 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AD25EC4CEF7; Wed, 25 Mar 2026 23:13:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774480425; bh=6HOi28c0aIsZQhT8sVNi8T1x2rw2HK7r7jexGLskZ5Q=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=i7j6QyFfV4EDmQQsY0gJwgpsIW7ADhhYgGnyo8je+pZf/Yd1/B6CSVyfqsiGz5whw ffi5t6lwmD73ikTBg4EWjDEh8WdW0XprkdwnHJsz0VO6ETGA7mmy0gNFFDKvQlzplP mVeoq1VreB4lz1/RKR4DFbZJ8FyS3vZ1boOSmPiVM/bPleVXHxEEpInuJg5mP/MyFB F5htIIPnERsMGLVuolqa8UZcItUTh0ekV4PoSoKgsr96fDtqm2RVYvDPbDGGvEu42B tdjEKu5BUx7ahAJDO+rjjuyxNWMVkkWYRXpVaUgrelTRl7IvIJ6sVYrlkuTtugFytx 5zvSEuGK+u7MQ== Date: Wed, 25 Mar 2026 18:13:44 -0500 From: Bjorn Helgaas To: David Matlack Cc: Alex Williamson , Bjorn Helgaas , Adithya Jayachandran , Alexander Graf , Alex Mastro , Andrew Morton , Ankit Agrawal , Arnd Bergmann , Askar Safin , "Borislav Petkov (AMD)" , Chris Li , Dapeng Mi , David Rientjes , Feng Tang , Jacob Pan , Jason Gunthorpe , Jason Gunthorpe , Jonathan Corbet , Josh Hilke , Kees Cook , Kevin Tian , kexec@lists.infradead.org, kvm@vger.kernel.org, Leon Romanovsky , Leon Romanovsky , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, linux-pci@vger.kernel.org, Li RongQing , Lukas Wunner , Marco Elver , =?utf-8?Q?Micha=C5=82?= Winiarski , Mike Rapoport , Parav Pandit , Pasha Tatashin , "Paul E. McKenney" , Pawan Gupta , "Peter Zijlstra (Intel)" , Pranjal Shrivastava , Pratyush Yadav , Raghavendra Rao Ananta , Randy Dunlap , Rodrigo Vivi , Saeed Mahameed , Samiullah Khawaja , Shuah Khan , Vipin Sharma , Vivek Kasireddy , William Tu , Yi Liu , Zhu Yanjun Subject: Re: [PATCH v3 03/24] PCI: Require Live Update preserved devices are in singleton iommu_groups Message-ID: <20260325231344.GA1293155@bhelgaas> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260323235817.1960573-4-dmatlack@google.com> X-Rspamd-Queue-Id: 69CE640013 X-Stat-Signature: tazigbdkn173wm94dgbnip5zfrdbfuy1 X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1774480427-828779 X-HE-Meta: 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 lNQaLYPl MWlE8LypgBgvzwFOHSOociKJ80satawrout2F+l1JaaS69tmENX2GXy1ELIsA8sPtm9Y27ImyX0txAQs4g731TrUh89PA5ThU7NZZ0Q0P2JvtfcjVW3BLCNGGUN0JxRU0Jf+BP93UblHdFZxeY/hBcE7zHkUa49R6ufMyD4b42OK7hgb2k8ex3lsvg53pC8e6gXBJx0Z68UqmUX/M6nsU6f8m0KSAUNnq/mR2y6DI7gC4wBFpTyMGuNgeRrKIIQPImPbta6UdtJezqK0P0BkQkT9jE0CNQdXnEgG73V4q545L+ZfXXwiW8j7dFbi25hcJ+uMsti55pg6Q6oFc8x41rH3r3WQV3wB3OtoekT/C0gKI4Dx1tRMeNrmXrg== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Mar 23, 2026 at 11:57:55PM +0000, David Matlack wrote: > Require that Live Update preserved devices are in singleton iommu_groups > during preservation (outgoing kernel) and retrieval (incoming kernel). > > PCI devices preserved across Live Update will be allowed to perform > memory transactions throughout the Live Update. Thus IOMMU groups for > preserved devices must remain fixed. Since all current use cases for > Live Update are for PCI devices in singleton iommu_groups, require that > as a starting point. This avoids the complexity of needing to enforce > arbitrary iommu_group topologies while still allowing all current use > cases. > > Suggested-by: Jason Gunthorpe > Signed-off-by: David Matlack > --- > drivers/pci/liveupdate.c | 34 +++++++++++++++++++++++++++++++++- > 1 file changed, 33 insertions(+), 1 deletion(-) > > diff --git a/drivers/pci/liveupdate.c b/drivers/pci/liveupdate.c > index bec7b3500057..a3dbe06650ff 100644 > --- a/drivers/pci/liveupdate.c > +++ b/drivers/pci/liveupdate.c > @@ -75,6 +75,8 @@ > * > * * The device must not be a Physical Function (PF). > * > + * * The device must be the only device in its IOMMU group. > + * > * Preservation Behavior > * ===================== > * > @@ -105,6 +107,7 @@ > > #include > #include > +#include > #include > #include > #include > @@ -222,6 +225,31 @@ static void pci_ser_delete(struct pci_ser *ser, struct pci_dev *dev) > ser->nr_devices--; > } > > +static int count_devices(struct device *dev, void *__nr_devices) > +{ > + (*(int *)__nr_devices)++; > + return 0; > +} > + > +static int pci_liveupdate_validate_iommu_group(struct pci_dev *dev) > +{ > + struct iommu_group *group; > + int nr_devices = 0; > + > + group = iommu_group_get(&dev->dev); > + if (group) { > + iommu_group_for_each_dev(group, &nr_devices, count_devices); > + iommu_group_put(group); > + } > + > + if (nr_devices != 1) { > + pci_warn(dev, "Live Update preserved devices must be in singleton iommu groups!"); > + return -EINVAL; > + } > + > + return 0; I assume the requirement is that there *is* an iommu_group and also that dev is the only member. If so, I think the intent would be a little clearer as: group = iommu_group_get(&dev->dev); if (!group) goto no_group; iommu_group_for_each_dev(group, &nr_devices, count_devices); iommu_group_put(group); if (nr_devices == 1) { return 0; no_group: pci_warn(...); return -EINVAL; > +} > + > int pci_liveupdate_preserve(struct pci_dev *dev) > { > struct pci_dev_ser new = INIT_PCI_DEV_SER(dev); > @@ -232,6 +260,10 @@ int pci_liveupdate_preserve(struct pci_dev *dev) > if (dev->is_virtfn || dev->is_physfn) > return -EINVAL; > > + ret = pci_liveupdate_validate_iommu_group(dev); > + if (ret) > + return ret; > + > guard(mutex)(&pci_flb_outgoing_lock); > > if (dev->liveupdate_outgoing) > @@ -357,7 +389,7 @@ int pci_liveupdate_retrieve(struct pci_dev *dev) > if (!dev->liveupdate_incoming) > return -EINVAL; > > - return 0; > + return pci_liveupdate_validate_iommu_group(dev); > } > EXPORT_SYMBOL_GPL(pci_liveupdate_retrieve); > > -- > 2.53.0.983.g0bb29b3bc5-goog >