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The current VFIO implementation allows pci-stub driver to be bound to a PCI device with other devices in the same IOMMU group being assigned to userspace. The pci-stub driver has no dependencies on DMA or the IOVA mapping of the device, but it does prevent the user from having direct access to the device, which is useful in some circumstances. The pci_dma_configure() marks the iommu_group as containing only devices with kernel drivers that manage DMA. For compatibility with the VFIO usage, avoid this default behavior for the pci_stub. This allows the pci_stub still able to be used by the admin to block driver binding after applying the DMA ownership to VFIO. Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Acked-by: Bjorn Helgaas <bhelgaas@google.com> Link: https://lore.kernel.org/r/20220418005000.897664-6-baolu.lu@linux.intel.com Signed-off-by: Joerg Roedel <jroedel@suse.de>
97 lines
2.3 KiB
C
97 lines
2.3 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Simple stub driver to reserve a PCI device
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*
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* Copyright (C) 2008 Red Hat, Inc.
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* Author:
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* Chris Wright
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*
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* Usage is simple, allocate a new id to the stub driver and bind the
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* device to it. For example:
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*
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* # echo "8086 10f5" > /sys/bus/pci/drivers/pci-stub/new_id
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* # echo -n 0000:00:19.0 > /sys/bus/pci/drivers/e1000e/unbind
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* # echo -n 0000:00:19.0 > /sys/bus/pci/drivers/pci-stub/bind
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* # ls -l /sys/bus/pci/devices/0000:00:19.0/driver
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* .../0000:00:19.0/driver -> ../../../bus/pci/drivers/pci-stub
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*/
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#include <linux/module.h>
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#include <linux/pci.h>
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static char ids[1024] __initdata;
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module_param_string(ids, ids, sizeof(ids), 0);
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MODULE_PARM_DESC(ids, "Initial PCI IDs to add to the stub driver, format is "
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"\"vendor:device[:subvendor[:subdevice[:class[:class_mask]]]]\""
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" and multiple comma separated entries can be specified");
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static int pci_stub_probe(struct pci_dev *dev, const struct pci_device_id *id)
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{
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pci_info(dev, "claimed by stub\n");
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return 0;
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}
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static struct pci_driver stub_driver = {
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.name = "pci-stub",
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.id_table = NULL, /* only dynamic id's */
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.probe = pci_stub_probe,
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.driver_managed_dma = true,
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};
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static int __init pci_stub_init(void)
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{
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char *p, *id;
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int rc;
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rc = pci_register_driver(&stub_driver);
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if (rc)
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return rc;
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/* no ids passed actually */
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if (ids[0] == '\0')
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return 0;
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/* add ids specified in the module parameter */
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p = ids;
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while ((id = strsep(&p, ","))) {
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unsigned int vendor, device, subvendor = PCI_ANY_ID,
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subdevice = PCI_ANY_ID, class = 0, class_mask = 0;
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int fields;
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if (!strlen(id))
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continue;
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fields = sscanf(id, "%x:%x:%x:%x:%x:%x",
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&vendor, &device, &subvendor, &subdevice,
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&class, &class_mask);
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if (fields < 2) {
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pr_warn("pci-stub: invalid ID string \"%s\"\n", id);
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continue;
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}
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pr_info("pci-stub: add %04X:%04X sub=%04X:%04X cls=%08X/%08X\n",
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vendor, device, subvendor, subdevice, class, class_mask);
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rc = pci_add_dynid(&stub_driver, vendor, device,
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subvendor, subdevice, class, class_mask, 0);
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if (rc)
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pr_warn("pci-stub: failed to add dynamic ID (%d)\n",
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rc);
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}
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return 0;
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}
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static void __exit pci_stub_exit(void)
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{
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pci_unregister_driver(&stub_driver);
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}
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module_init(pci_stub_init);
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module_exit(pci_stub_exit);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Chris Wright <chrisw@sous-sol.org>");
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