From 119e9db233ad0f4cbd4cfb9f9385a7bca378b37d Mon Sep 17 00:00:00 2001 From: Zeng Chi Date: Mon, 21 Sep 2026 18:24:42 +0800 Subject: KVM: Don't pre-reserve xarray entries when storing empty/NULL attributes Skip the xarray reservation loop when clearing all memory attributes, as storing NULL only erases the entry and never needs to allocate, so no reservation (and no cleanup of a failed one) is required in that case. Suggested-by: Sean Christopherson Cc: David Ballesteros Signed-off-by: Zeng Chi Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com [sean: split to separate patch] Signed-off-by: Sean Christopherson --- drivers/dma/idxd/compat.c | 121 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 121 insertions(+) create mode 100644 drivers/dma/idxd/compat.c (limited to 'drivers/dma/idxd/compat.c') diff --git a/drivers/dma/idxd/compat.c b/drivers/dma/idxd/compat.c new file mode 100644 index 000000000..95b8ef958 --- /dev/null +++ b/drivers/dma/idxd/compat.c @@ -0,0 +1,121 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright(c) 2021 Intel Corporation. All rights rsvd. */ +#include +#include +#include +#include +#include +#include "idxd.h" + +extern void device_driver_detach(struct device *dev); + +#define DRIVER_ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store) \ + struct driver_attribute driver_attr_##_name = \ + __ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store) + +static ssize_t unbind_store(struct device_driver *drv, const char *buf, size_t count) +{ + const struct bus_type *bus = drv->bus; + struct device *dev; + int rc = -ENODEV; + + dev = bus_find_device_by_name(bus, NULL, buf); + if (!dev) + return -ENODEV; + + if (dev->driver) { + device_driver_detach(dev); + rc = count; + } + + put_device(dev); + + return rc; +} +static DRIVER_ATTR_IGNORE_LOCKDEP(unbind, 0200, NULL, unbind_store); + +static ssize_t bind_store(struct device_driver *drv, const char *buf, size_t count) +{ + const struct bus_type *bus = drv->bus; + struct device *dev; + struct device_driver *alt_drv = NULL; + int rc = -ENODEV; + struct idxd_dev *idxd_dev; + + dev = bus_find_device_by_name(bus, NULL, buf); + if (!dev) + return -ENODEV; + + if (dev->driver || drv != &dsa_drv.drv) + goto err_put_dev; + + idxd_dev = confdev_to_idxd_dev(dev); + if (is_idxd_dev(idxd_dev)) { + alt_drv = driver_find("idxd", bus); + } else if (is_idxd_wq_dev(idxd_dev)) { + struct idxd_wq *wq = confdev_to_wq(dev); + + if (is_idxd_wq_kernel(wq)) + alt_drv = driver_find("dmaengine", bus); + else if (is_idxd_wq_user(wq)) + alt_drv = driver_find("user", bus); + } + if (!alt_drv) + goto err_put_dev; + + rc = device_driver_attach(alt_drv, dev); + if (rc < 0) + goto err_put_dev; + + put_device(dev); + + return count; + +err_put_dev: + put_device(dev); + + return rc; +} +static DRIVER_ATTR_IGNORE_LOCKDEP(bind, 0200, NULL, bind_store); + +static struct attribute *dsa_drv_compat_attrs[] = { + &driver_attr_bind.attr, + &driver_attr_unbind.attr, + NULL, +}; + +static const struct attribute_group dsa_drv_compat_attr_group = { + .attrs = dsa_drv_compat_attrs, +}; + +static const struct attribute_group *dsa_drv_compat_groups[] = { + &dsa_drv_compat_attr_group, + NULL, +}; + +static int idxd_dsa_drv_probe(struct idxd_dev *idxd_dev) +{ + return -ENODEV; +} + +static void idxd_dsa_drv_remove(struct idxd_dev *idxd_dev) +{ +} + +static enum idxd_dev_type dev_types[] = { + IDXD_DEV_NONE, +}; + +struct idxd_device_driver dsa_drv = { + .name = "dsa", + .probe = idxd_dsa_drv_probe, + .remove = idxd_dsa_drv_remove, + .type = dev_types, + .drv = { + .suppress_bind_attrs = true, + .groups = dsa_drv_compat_groups, + }, +}; + +module_idxd_driver(dsa_drv); +MODULE_IMPORT_NS("IDXD"); -- cgit v1.3.1