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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 61FCCE8783F for ; Tue, 3 Feb 2026 15:34:29 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 1156710E335; Tue, 3 Feb 2026 15:34:29 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="ZQED0SBM"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.19]) by gabe.freedesktop.org (Postfix) with ESMTPS id 8555810E335 for ; Tue, 3 Feb 2026 15:34:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1770132868; x=1801668868; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=2u1q6jJQWQ7hZxirif+ECTYroq2n7zrquLrjw45k0jU=; b=ZQED0SBMbeElGYA20vvt4z98Pi5po8bMCipVj4o0+vfAg3s3SjTAZ06x 2FDrvJQRY/ylbvA1gQ0AU3aJpzGbiL0YPIz85SsKw1ejfZmHLeynuInX/ fBj+OlzUBS40QIuRi9F9lExYdgIwRmJt6uNX/eVQyzOW+Q5PCABjpqxDv 33SxjW/B+JXUfdjgbypdx5fCv0FEH5P+XJ6aI/r04Wd8Eyq98qb2Gm8Qk qpKP0GQFjp9hQq9itw1Jv+HgAKmeMSro50mGq1X3VrrmaOvXTL8vAlPeQ wC9Nbz9BbIUMckz19J/VvCJyZ6N3W38gyPMNt+kmLu4psOCC7b8BdgNXX A==; X-CSE-ConnectionGUID: bCmOefuUSyaH6sp8CRBiNA== X-CSE-MsgGUID: AoDuQYnkTXmAc1lgLfJS8g== X-IronPort-AV: E=McAfee;i="6800,10657,11690"; a="71204305" X-IronPort-AV: E=Sophos;i="6.21,270,1763452800"; d="scan'208";a="71204305" Received: from orviesa001.jf.intel.com ([10.64.159.141]) by orvoesa111.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Feb 2026 07:34:28 -0800 X-CSE-ConnectionGUID: SYleyK8BSmqKlttCE7rskw== X-CSE-MsgGUID: FiNkmjVhSQGVV1h2XYt6jA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.21,270,1763452800"; d="scan'208";a="247479443" Received: from soc-5cg43972f8.clients.intel.com (HELO localhost) ([172.28.182.93]) by smtpauth.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Feb 2026 07:34:27 -0800 From: Marcin Bernatowicz To: igt-dev@lists.freedesktop.org Cc: jakub1.kolakowski@intel.com, lukasz.laguna@intel.com, michal.winiarski@intel.com, Marcin Bernatowicz , Adam Miszczak , Kamil Konieczny Subject: [PATCH v2 i-g-t 2/4] lib/igt_pci: Add generic PCI driver override and bind/unbind helpers Date: Tue, 3 Feb 2026 16:33:43 +0100 Message-ID: <20260203153349.128551-3-marcin.bernatowicz@linux.intel.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260203153349.128551-1-marcin.bernatowicz@linux.intel.com> References: <20260203153349.128551-1-marcin.bernatowicz@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=y Content-Transfer-Encoding: 8bit X-BeenThere: igt-dev@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Development mailing list for IGT GPU Tools List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: igt-dev-bounces@lists.freedesktop.org Sender: "igt-dev" Add generic helpers for controlling PCI driver binding via sysfs. The new APIs provide driver- and device-centric primitives for: - setting and clearing driver_override - triggering PCI driver reprobe - binding and unbinding devices to a specific PCI driver - query the currently bound PCI driver Signed-off-by: Marcin Bernatowicz Cc: Adam Miszczak Cc: Jakub Kolakowski Cc: Kamil Konieczny Cc: Lukasz Laguna --- v2: - Add igt_pci_get_bound_driver_name() to query the currently bound PCI driver via the /sys/bus/pci/devices//driver symlink. - Extend igt_pci_bind_driver_override() and igt_pci_unbind_driver_override() with a timeout_ms parameter so callers can wait for bind/unbind to actually complete, instead of relying on drivers_probe write success. Signed-off-by: Marcin Bernatowicz --- lib/igt_pci.c | 351 ++++++++++++++++++++++++++++++++++++++++++++++++++ lib/igt_pci.h | 13 +- 2 files changed, 363 insertions(+), 1 deletion(-) diff --git a/lib/igt_pci.c b/lib/igt_pci.c index 61aaf939d..80aaf07c5 100644 --- a/lib/igt_pci.c +++ b/lib/igt_pci.c @@ -3,9 +3,18 @@ * Copyright © 2022 Intel Corporation */ +#include +#include +#include +#include +#include +#include +#include #include +#include "igt_aux.h" #include "igt_core.h" #include "igt_pci.h" +#include "igt_sysfs.h" static int find_pci_cap_offset_at(struct pci_device *dev, enum pci_cap_id cap_id, int start_offset) @@ -51,3 +60,345 @@ int find_pci_cap_offset(struct pci_device *dev, enum pci_cap_id cap_id) { return find_pci_cap_offset_at(dev, cap_id, PCI_CAPS_START); } + +static int open_pci_driver_dir(const char *driver) +{ + char path[PATH_MAX]; + + snprintf(path, sizeof(path), "/sys/bus/pci/drivers/%s", driver); + return open(path, O_RDONLY | O_CLOEXEC); +} + +/** + * igt_pci_device_unbind: + * @pci_slot: BDF like "0000:01:00.0" + * + * Unbind @pci_slot from its currently bound driver, if any. + * Returns 0 on success, or a negative errno-like value. + */ +int igt_pci_device_unbind(const char *pci_slot) +{ + char path[PATH_MAX]; + int dirfd; + int ret; + + snprintf(path, sizeof(path), "/sys/bus/pci/devices/%s/driver", pci_slot); + dirfd = open(path, O_RDONLY | O_CLOEXEC); + if (dirfd < 0) + return 0; /* already unbound */ + + ret = igt_sysfs_set(dirfd, "unbind", pci_slot) ? 0 : -errno; + close(dirfd); + + return ret; +} + +/** + * igt_pci_driver_bind: + * @driver: PCI driver name under /sys/bus/pci/drivers/ + * @pci_slot: device to bind + * + * Bind @pci_slot to @driver. Driver must be present/loaded. + * Returns 0 on success, or a negative errno-like value. + */ +int igt_pci_driver_bind(const char *driver, const char *pci_slot) +{ + int dirfd, ret; + + dirfd = open_pci_driver_dir(driver); + if (dirfd < 0) + return -errno; + + ret = igt_sysfs_set(dirfd, "bind", pci_slot) ? 0 : -errno; + close(dirfd); + + return ret; +} + +/** + * igt_pci_driver_unbind: + * @driver: PCI driver name + * @pci_slot: device to unbind + * + * Unbind @pci_slot from @driver. + * Returns 0 on success, or a negative errno-like value. + */ +int igt_pci_driver_unbind(const char *driver, const char *pci_slot) +{ + int dirfd, ret; + + dirfd = open_pci_driver_dir(driver); + if (dirfd < 0) + return -errno; + + ret = igt_sysfs_set(dirfd, "unbind", pci_slot) ? 0 : -errno; + close(dirfd); + + return ret; +} + +/** + * igt_pci_driver_unbind_all: + * @driver: PCI driver name + * + * Unbind all devices currently bound to @driver. + * Returns 0 on success, or a negative errno-like value. + */ +int igt_pci_driver_unbind_all(const char *driver) +{ + char path[PATH_MAX]; + DIR *dir; + struct dirent *de; + int driver_fd; + + snprintf(path, sizeof(path), "/sys/bus/pci/drivers/%s", driver); + dir = opendir(path); + if (!dir) + return -errno; + + driver_fd = dirfd(dir); + + while ((de = readdir(dir))) { + bool ok; + + /* BDF symlinks are like "0000:01:00.0" and start with digit */ + if (de->d_type != DT_LNK || !isdigit(de->d_name[0])) + continue; + + ok = igt_sysfs_set(driver_fd, "unbind", de->d_name); + if (!ok) { + int err = -errno; + + closedir(dir); + return err; + } + } + + closedir(dir); + return 0; +} + +/** + * igt_pci_set_driver_override: + * @pci_slot: PCI device BDF (e.g. "0000:01:00.0") + * @driver: PCI driver name to force-bind (e.g. "xe-vfio-pci"), or + * NULL / empty string to clear an existing override + * + * Set or clear the PCI driver_override for @pci_slot via sysfs. + * + * This does not trigger driver reprobe by itself. Call + * igt_pci_probe_drivers() afterwards to apply the override. + * + * Returns: 0 on success, negative errno on failure. + */ +int igt_pci_set_driver_override(const char *pci_slot, const char *driver) +{ + char devpath[PATH_MAX]; + int dev; + bool ok; + + snprintf(devpath, sizeof(devpath), "/sys/bus/pci/devices/%s", pci_slot); + dev = open(devpath, O_DIRECTORY | O_RDONLY); + if (dev < 0) + return -errno; + + ok = igt_sysfs_set(dev, "driver_override", driver ? driver : ""); + close(dev); + + return ok ? 0 : -errno; +} + +/** + * igt_pci_probe_drivers: + * @pci_slot: PCI device BDF (e.g. "0000:01:00.0") + * + * Trigger PCI driver reprobe for @pci_slot by writing to + * /sys/bus/pci/drivers_probe. + * + * This causes the kernel to attempt binding the device, honoring any + * driver_override previously set. + * + * Note: a successful write only means the reprobe request was accepted. + * It does not guarantee that a driver actually bound to the device. + * + * Returns: 0 on success, negative errno on failure. + */ +int igt_pci_probe_drivers(const char *pci_slot) +{ + int pci; + bool ok; + + pci = open("/sys/bus/pci", O_DIRECTORY | O_RDONLY); + if (pci < 0) + return -errno; + + ok = igt_sysfs_set(pci, "drivers_probe", pci_slot); + close(pci); + + return ok ? 0 : -errno; +} + +/** + * igt_pci_get_bound_driver_name: + * @pci_slot: PCI device BDF (e.g. "0000:01:00.0") + * @driver: destination buffer for the bound driver name + * @driver_len: size of @driver in bytes + * + * Read the currently bound PCI driver name for @pci_slot by inspecting the + * /sys/bus/pci/devices//driver symlink. + * + * Return values: + * 1: device is bound and @driver contains the driver name + * 0: device is unbound (no driver symlink) + * <0: negative errno-like value on error + */ +int igt_pci_get_bound_driver_name(const char *pci_slot, char *driver, size_t driver_len) +{ + char path[PATH_MAX]; + char link[PATH_MAX]; + const char *base; + ssize_t len; + + if (driver && driver_len) + driver[0] = '\0'; + + snprintf(path, sizeof(path), "/sys/bus/pci/devices/%s/driver", pci_slot); + len = readlink(path, link, sizeof(link) - 1); + if (len < 0) { + if (errno == ENOENT) + return 0; /* unbound */ + + return -errno; + } + + link[len] = '\0'; + base = strrchr(link, '/'); + base = base ? base + 1 : link; + + if (driver && driver_len) + snprintf(driver, driver_len, "%s", base); + + return 1; +} + +/** + * igt_pci_bind_driver_override: + * @pci_slot: PCI device BDF (e.g. "0000:01:00.0") + * @driver: PCI driver name to bind (must not be NULL or empty) + * @timeout_ms: how long to wait for the device to become bound. + * If 0, don't wait (best-effort immediate check only). + * + * Bind @pci_slot to @driver using the driver_override mechanism. + * + * This helper sets driver_override and immediately triggers driver + * reprobe so that the device is bound to the requested driver. + * + * Returns: 0 on success, negative errno-like value on failure. + * A reprobe request can be accepted by sysfs while the driver probe + * fails later; this helper verifies the device ended up bound. + * + * On bind failure, returns a negative error and the failure reason may + * also be logged to dmesg by the kernel driver. + */ +int igt_pci_bind_driver_override(const char *pci_slot, const char *driver, + unsigned int timeout_ms) +{ + int ret; + char bound[64]; + int bound_ret; + bool bound_ok; + + if (!driver || !driver[0]) + return -EINVAL; + + ret = igt_pci_set_driver_override(pci_slot, driver); + if (ret) + return ret; + + ret = igt_pci_probe_drivers(pci_slot); + if (ret) + return ret; + + /* + * Writing to drivers_probe only tells us the kernel accepted the request. + * The actual driver probe may still fail (and only be reported via dmesg). + * Verify that the device ended up bound to the requested driver. + */ + bound_ret = igt_pci_get_bound_driver_name(pci_slot, bound, sizeof(bound)); + if (bound_ret < 0) + return bound_ret; + + if (timeout_ms == 0) { + /* + * No waiting requested. If the device is already bound, validate + * it is bound to the expected driver; otherwise treat as + * best-effort request-only success. + */ + if (bound_ret > 0 && strcmp(bound, driver)) + return -EBUSY; + + return 0; + } + + bound_ok = igt_wait((bound_ret = + igt_pci_get_bound_driver_name(pci_slot, bound, sizeof(bound))) != 0, + timeout_ms, 1); + if (!bound_ok) + return -EIO; + + if (bound_ret < 0) + return bound_ret; + + if (strcmp(bound, driver)) + return -EBUSY; + + return 0; +} + +/** + * igt_pci_unbind_driver_override: + * @pci_slot: PCI device BDF (e.g. "0000:01:00.0") + * @timeout_ms: how long to wait for the device to become unbound. + * If 0, don't wait (best-effort immediate check only). + * + * Unbind @pci_slot from its currently bound driver (if any) and clear + * any driver_override setting. + * + * This is the inverse operation of igt_pci_bind_driver_override(). + * + * Returns: 0 on success, negative errno on failure. + */ +int igt_pci_unbind_driver_override(const char *pci_slot, unsigned int timeout_ms) +{ + int ret; + int bound_ret; + char bound[64]; + bool unbound_ok; + + ret = igt_pci_device_unbind(pci_slot); + if (ret) + return ret; + + ret = igt_pci_set_driver_override(pci_slot, ""); + if (ret) + return ret; + + bound_ret = igt_pci_get_bound_driver_name(pci_slot, bound, sizeof(bound)); + if (bound_ret < 0) + return bound_ret; + + if (timeout_ms == 0) + return 0; + + /* Verify the device actually ends up unbound (driver symlink removed). */ + unbound_ok = igt_wait((bound_ret = + igt_pci_get_bound_driver_name(pci_slot, bound, sizeof(bound))) == 0, + timeout_ms, 1); + if (!unbound_ok) + return -EBUSY; + + if (bound_ret < 0) + return bound_ret; + + return 0; +} diff --git a/lib/igt_pci.h b/lib/igt_pci.h index 92b9cc392..a66eeebf2 100644 --- a/lib/igt_pci.h +++ b/lib/igt_pci.h @@ -6,8 +6,9 @@ #ifndef __IGT_PCI_H__ #define __IGT_PCI_H__ -#include #include +#include +#include /* forward declaration */ struct pci_device; @@ -24,5 +25,15 @@ enum pci_cap_id { #define PCI_SLOT_PWR_CTRL_PRESENT (1 << 1) int find_pci_cap_offset(struct pci_device *dev, enum pci_cap_id cap_id); +int igt_pci_device_unbind(const char *pci_slot); +int igt_pci_driver_bind(const char *driver, const char *pci_slot); +int igt_pci_driver_unbind(const char *driver, const char *pci_slot); +int igt_pci_driver_unbind_all(const char *driver); +int igt_pci_set_driver_override(const char *pci_slot, const char *driver); +int igt_pci_probe_drivers(const char *pci_slot); +int igt_pci_get_bound_driver_name(const char *pci_slot, char *driver, size_t driver_len); +int igt_pci_bind_driver_override(const char *pci_slot, const char *driver, + unsigned int timeout_ms); +int igt_pci_unbind_driver_override(const char *pci_slot, unsigned int timeout_ms); #endif -- 2.43.0