From nobody Thu Apr 2 21:58:32 2026 Received: from mail-pj1-f73.google.com (mail-pj1-f73.google.com [209.85.216.73]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 87B9E38838C for ; Mon, 23 Mar 2026 23:58:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.73 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774310330; cv=none; b=eUDCdPag1L9EmkAtldE+qCLFKqlaVkCAPlxITD2Xoj8dCBf+rTHvy6mHc7PUqv0qp8Su+2MfNoru+/uTXTD/hdT11I6HYf6USwgm6hy9ysnPWiF1pT983lzYAYQecfJHjEklzt5gGz2iOx5pH2YmUhhriWefd40SUYLiovvSSNE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774310330; c=relaxed/simple; bh=l00LIHmX2FmWkYpSjP6Q+peOSbjX0cWvYczRtB6/PPc=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=p/XAz6qAIHX72Gm7dcraZSsozKKk7wJe4mmXEsbVAiT4OzqnG/xAy8xXL0WVK5ODHFm8JYsh+cg1+k+gCUZKojGDa6oSVLnDyMjOfP9yhH9DPXK7wKfBPg1VQ87vaG77tLp7RzzdpYy9rjyaIubdNegsJA1I5ZxjfI10Vkbnt/U= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--dmatlack.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=hIg1nEzq; arc=none smtp.client-ip=209.85.216.73 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--dmatlack.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="hIg1nEzq" Received: by mail-pj1-f73.google.com with SMTP id 98e67ed59e1d1-35a032cdd78so2910332a91.1 for ; Mon, 23 Mar 2026 16:58:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1774310328; x=1774915128; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=YCGcH5x5HW+NRzEKEkZIp2gqKlZo/LGIoKmQ3sM/JLo=; b=hIg1nEzq82bKlCD8cGLW1/bMAov6oOdwDux59+GdjIx8RqTysB6T+jrl0B95VUknVV 4lYrJ2YnYqK+txBL8gaIXpBZ+GN1C0LMFd54OJiE36GQn8znAQrOmAkaAM8Jj4lir0Gs NG7BfovrRadhImYowOKg6Sfi2D8SmIDBXG7EPP7dCJZnc004J4AUvN2HlwEqADgGOIwd 3BuXaIAuVhRb8/8MWWQp9m827fs9UCVweyAyErS616OsWAJ5niWsSWnJM5cNhSHh8Kup DS6oSwNEhxNV+X/9swNSqWqJ+Dm+VjRDnjKUj7BZ/7o3VpR+hfDzpAgin6edngvqGz32 lX/Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1774310328; x=1774915128; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=YCGcH5x5HW+NRzEKEkZIp2gqKlZo/LGIoKmQ3sM/JLo=; b=Q+eS/bzv3o3DVeqyZApE9r/9aCBvLsqxxyy82+PUxQECQWJSWJ/qN4ZPNhN9UaLW7O DycoXBZm33rrOn+UfLE1VeIrzBOuUaakxwfUA2XnufYgomFZHco8CnPdVfzvSviK8D9W IkVNE3YnXUonTaEBzXKJGKuy5xUXcT6spJTNqvgznMudlNuCvBEG7+/2LQuvQ5cedngn NzZaVNcN7dr/djWz3jIv//DvNYwMwy2rAzk+Ry384bdFPoaOYs7KUgLPoBx1oto3TKde qux52JoyOEiozmBJhzPcudQXT4NgxiVtQiwaEMoiNUX+xG5mEc2XlyI/jY0ll7ATzzTt eJwg== X-Forwarded-Encrypted: i=1; AJvYcCXCTz+Zg18LQ5TNO2Nn3qlcqLljQ/9gw3vO036cXyiLRGwH3Gy4cW8qKooKuUS1QaL/KzAHfydj4qbh1UM=@vger.kernel.org X-Gm-Message-State: AOJu0YxywIySw6KIutjZDTuNNYVGKvAWQpjpPIaENDaHJFttHAc3JZwV oNRlvaUlY3bt9eFsZbxVCrpZ6QwfwYmis9IkCgBwpr1aiTc/OTLtff79rJ4wsS6fmfRwkot8Dux EaJQm1jckcDaYng== X-Received: from pjvp18.prod.google.com ([2002:a17:90a:df92:b0:35b:9822:9f79]) (user=dmatlack job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:1a8a:b0:359:f43d:4a6e with SMTP id 98e67ed59e1d1-35bd2996301mr12903584a91.0.1774310327594; Mon, 23 Mar 2026 16:58:47 -0700 (PDT) Date: Mon, 23 Mar 2026 23:57:58 +0000 In-Reply-To: <20260323235817.1960573-1-dmatlack@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260323235817.1960573-1-dmatlack@google.com> X-Mailer: git-send-email 2.53.0.983.g0bb29b3bc5-goog Message-ID: <20260323235817.1960573-7-dmatlack@google.com> Subject: [PATCH v3 06/24] vfio/pci: Register a file handler with Live Update Orchestrator From: David Matlack To: Alex Williamson , Bjorn Helgaas Cc: Adithya Jayachandran , Alexander Graf , Alex Mastro , Andrew Morton , Ankit Agrawal , Arnd Bergmann , Askar Safin , "Borislav Petkov (AMD)" , Chris Li , Dapeng Mi , David Matlack , 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=20Winiarski?=" , 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 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Vipin Sharma Register a live update file handler for vfio-pci device files. Add stub implementations of all required callbacks so that registration does not fail (i.e. to avoid breaking git-bisect). This file handler will be extended in subsequent commits to enable a device bound to vfio-pci to run without interruption while the host is going through a kexec Live Update. Put this support behind a new Kconfig VFIO_PCI_LIVEUPDATE that is marked experimental and default-disabled until more of the device preservation support has landed in the kernel. Signed-off-by: Vipin Sharma Co-developed-by: David Matlack Signed-off-by: David Matlack --- MAINTAINERS | 1 + drivers/vfio/pci/Kconfig | 11 ++++ drivers/vfio/pci/Makefile | 1 + drivers/vfio/pci/vfio_pci.c | 12 ++++- drivers/vfio/pci/vfio_pci_liveupdate.c | 69 ++++++++++++++++++++++++++ drivers/vfio/pci/vfio_pci_priv.h | 14 ++++++ include/linux/kho/abi/vfio_pci.h | 28 +++++++++++ 7 files changed, 135 insertions(+), 1 deletion(-) create mode 100644 drivers/vfio/pci/vfio_pci_liveupdate.c create mode 100644 include/linux/kho/abi/vfio_pci.h diff --git a/MAINTAINERS b/MAINTAINERS index 96ea84948d76..a16a7ecc67a4 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -27685,6 +27685,7 @@ F: Documentation/ABI/testing/debugfs-vfio F: Documentation/ABI/testing/sysfs-devices-vfio-dev F: Documentation/driver-api/vfio.rst F: drivers/vfio/ +F: include/linux/kho/abi/vfio_pci.h F: include/linux/vfio.h F: include/linux/vfio_pci_core.h F: include/uapi/linux/vfio.h diff --git a/drivers/vfio/pci/Kconfig b/drivers/vfio/pci/Kconfig index 1e82b44bda1a..8f087f7b58c3 100644 --- a/drivers/vfio/pci/Kconfig +++ b/drivers/vfio/pci/Kconfig @@ -58,6 +58,17 @@ config VFIO_PCI_ZDEV_KVM config VFIO_PCI_DMABUF def_bool y if VFIO_PCI_CORE && PCI_P2PDMA && DMA_SHARED_BUFFER =20 +config VFIO_PCI_LIVEUPDATE + bool "VFIO PCI support for Live Update (EXPERIMENTAL)" + depends on VFIO_PCI && PCI_LIVEUPDATE + help + Support for preserving devices bound to vfio-pci across a Live + Update. This option should only be enabled by developers working on + implementing this support. Once enough support has landed in the + kernel, this option will no longer be marked EXPERIMENTAL. + + If you don't know what to do here, say N. + source "drivers/vfio/pci/mlx5/Kconfig" =20 source "drivers/vfio/pci/hisilicon/Kconfig" diff --git a/drivers/vfio/pci/Makefile b/drivers/vfio/pci/Makefile index e0a0757dd1d2..f462df61edb9 100644 --- a/drivers/vfio/pci/Makefile +++ b/drivers/vfio/pci/Makefile @@ -7,6 +7,7 @@ obj-$(CONFIG_VFIO_PCI_CORE) +=3D vfio-pci-core.o =20 vfio-pci-y :=3D vfio_pci.o vfio-pci-$(CONFIG_VFIO_PCI_IGD) +=3D vfio_pci_igd.o +vfio-pci-$(CONFIG_VFIO_PCI_LIVEUPDATE) +=3D vfio_pci_liveupdate.o obj-$(CONFIG_VFIO_PCI) +=3D vfio-pci.o =20 obj-$(CONFIG_MLX5_VFIO_PCI) +=3D mlx5/ diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c index 0c771064c0b8..41dcbe4ace67 100644 --- a/drivers/vfio/pci/vfio_pci.c +++ b/drivers/vfio/pci/vfio_pci.c @@ -170,6 +170,7 @@ static int vfio_pci_probe(struct pci_dev *pdev, const s= truct pci_device_id *id) ret =3D vfio_pci_core_register_device(vdev); if (ret) goto out_put_vdev; + return 0; =20 out_put_vdev: @@ -264,10 +265,14 @@ static int __init vfio_pci_init(void) =20 vfio_pci_core_set_params(nointxmask, is_disable_vga, disable_idle_d3); =20 + ret =3D vfio_pci_liveupdate_init(); + if (ret) + return ret; + /* Register and scan for devices */ ret =3D pci_register_driver(&vfio_pci_driver); if (ret) - return ret; + goto err_liveupdate_cleanup; =20 vfio_pci_fill_ids(); =20 @@ -275,12 +280,17 @@ static int __init vfio_pci_init(void) pr_warn("device denylist disabled.\n"); =20 return 0; + +err_liveupdate_cleanup: + vfio_pci_liveupdate_cleanup(); + return ret; } module_init(vfio_pci_init); =20 static void __exit vfio_pci_cleanup(void) { pci_unregister_driver(&vfio_pci_driver); + vfio_pci_liveupdate_cleanup(); } module_exit(vfio_pci_cleanup); =20 diff --git a/drivers/vfio/pci/vfio_pci_liveupdate.c b/drivers/vfio/pci/vfio= _pci_liveupdate.c new file mode 100644 index 000000000000..5ea5af46b159 --- /dev/null +++ b/drivers/vfio/pci/vfio_pci_liveupdate.c @@ -0,0 +1,69 @@ +// SPDX-License-Identifier: GPL-2.0 + +/* + * Copyright (c) 2026, Google LLC. + * Vipin Sharma + * David Matlack + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include +#include +#include + +#include "vfio_pci_priv.h" + +static bool vfio_pci_liveupdate_can_preserve(struct liveupdate_file_handle= r *handler, + struct file *file) +{ + return false; +} + +static int vfio_pci_liveupdate_preserve(struct liveupdate_file_op_args *ar= gs) +{ + return -EOPNOTSUPP; +} + +static void vfio_pci_liveupdate_unpreserve(struct liveupdate_file_op_args = *args) +{ +} + +static int vfio_pci_liveupdate_retrieve(struct liveupdate_file_op_args *ar= gs) +{ + return -EOPNOTSUPP; +} + +static void vfio_pci_liveupdate_finish(struct liveupdate_file_op_args *arg= s) +{ +} + +static const struct liveupdate_file_ops vfio_pci_liveupdate_file_ops =3D { + .can_preserve =3D vfio_pci_liveupdate_can_preserve, + .preserve =3D vfio_pci_liveupdate_preserve, + .unpreserve =3D vfio_pci_liveupdate_unpreserve, + .retrieve =3D vfio_pci_liveupdate_retrieve, + .finish =3D vfio_pci_liveupdate_finish, + .owner =3D THIS_MODULE, +}; + +static struct liveupdate_file_handler vfio_pci_liveupdate_fh =3D { + .ops =3D &vfio_pci_liveupdate_file_ops, + .compatible =3D VFIO_PCI_LUO_FH_COMPATIBLE, +}; + +int __init vfio_pci_liveupdate_init(void) +{ + int ret; + + ret =3D liveupdate_register_file_handler(&vfio_pci_liveupdate_fh); + if (ret && ret !=3D -EOPNOTSUPP) + return ret; + + return 0; +} + +void vfio_pci_liveupdate_cleanup(void) +{ + liveupdate_unregister_file_handler(&vfio_pci_liveupdate_fh); +} diff --git a/drivers/vfio/pci/vfio_pci_priv.h b/drivers/vfio/pci/vfio_pci_p= riv.h index 27ac280f00b9..cbf46e09da30 100644 --- a/drivers/vfio/pci/vfio_pci_priv.h +++ b/drivers/vfio/pci/vfio_pci_priv.h @@ -133,4 +133,18 @@ static inline void vfio_pci_dma_buf_move(struct vfio_p= ci_core_device *vdev, } #endif =20 +#ifdef CONFIG_VFIO_PCI_LIVEUPDATE +int __init vfio_pci_liveupdate_init(void); +void vfio_pci_liveupdate_cleanup(void); +#else +static inline int vfio_pci_liveupdate_init(void) +{ + return 0; +} + +static inline void vfio_pci_liveupdate_cleanup(void) +{ +} +#endif /* CONFIG_VFIO_PCI_LIVEUPDATE */ + #endif diff --git a/include/linux/kho/abi/vfio_pci.h b/include/linux/kho/abi/vfio_= pci.h new file mode 100644 index 000000000000..e2412b455e61 --- /dev/null +++ b/include/linux/kho/abi/vfio_pci.h @@ -0,0 +1,28 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +/* + * Copyright (c) 2025, Google LLC. + * Vipin Sharma + * David Matlack + */ + +#ifndef _LINUX_LIVEUPDATE_ABI_VFIO_PCI_H +#define _LINUX_LIVEUPDATE_ABI_VFIO_PCI_H + +/** + * DOC: VFIO PCI Live Update ABI + * + * VFIO uses the ABI defined below for preserving device files across a ke= xec + * reboot using LUO. + * + * Device metadata is serialized into memory which is then handed to the n= ext + * kernel via KHO. + * + * This interface is a contract. Any modification to any of the serializat= ion + * structs defined here constitutes a breaking change. Such changes require + * incrementing the version number in the VFIO_PCI_LUO_FH_COMPATIBLE strin= g. + */ + +#define VFIO_PCI_LUO_FH_COMPATIBLE "vfio-pci-v1" + +#endif /* _LINUX_LIVEUPDATE_ABI_VFIO_PCI_H */ --=20 2.53.0.983.g0bb29b3bc5-goog