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3aadf100f9
This reverts commitad6bcdad2b. I had nak'd it, and Greg said on the thread that it links that he wasn't going to take it either, especially since it's not his code or his tree, but then, seemingly accidentally, it got pushed up some months later, in what looks like a mistake, with no further discussion in the linked thread. So revert it, since it's clearly not intended. Fixes:ad6bcdad2b("vmgenid: emit uevent when VMGENID updates") Cc: stable@vger.kernel.org Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Link: https://lore.kernel.org/r/20230531095119.11202-2-bchalios@amazon.es Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
102 lines
2.6 KiB
C
102 lines
2.6 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2022 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
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*
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* The "Virtual Machine Generation ID" is exposed via ACPI and changes when a
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* virtual machine forks or is cloned. This driver exists for shepherding that
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* information to random.c.
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/acpi.h>
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#include <linux/random.h>
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ACPI_MODULE_NAME("vmgenid");
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enum { VMGENID_SIZE = 16 };
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struct vmgenid_state {
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u8 *next_id;
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u8 this_id[VMGENID_SIZE];
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};
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static int vmgenid_add(struct acpi_device *device)
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{
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struct acpi_buffer parsed = { ACPI_ALLOCATE_BUFFER };
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struct vmgenid_state *state;
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union acpi_object *obj;
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phys_addr_t phys_addr;
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acpi_status status;
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int ret = 0;
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state = devm_kmalloc(&device->dev, sizeof(*state), GFP_KERNEL);
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if (!state)
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return -ENOMEM;
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status = acpi_evaluate_object(device->handle, "ADDR", NULL, &parsed);
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if (ACPI_FAILURE(status)) {
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ACPI_EXCEPTION((AE_INFO, status, "Evaluating ADDR"));
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return -ENODEV;
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}
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obj = parsed.pointer;
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if (!obj || obj->type != ACPI_TYPE_PACKAGE || obj->package.count != 2 ||
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obj->package.elements[0].type != ACPI_TYPE_INTEGER ||
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obj->package.elements[1].type != ACPI_TYPE_INTEGER) {
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ret = -EINVAL;
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goto out;
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}
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phys_addr = (obj->package.elements[0].integer.value << 0) |
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(obj->package.elements[1].integer.value << 32);
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state->next_id = devm_memremap(&device->dev, phys_addr, VMGENID_SIZE, MEMREMAP_WB);
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if (IS_ERR(state->next_id)) {
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ret = PTR_ERR(state->next_id);
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goto out;
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}
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memcpy(state->this_id, state->next_id, sizeof(state->this_id));
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add_device_randomness(state->this_id, sizeof(state->this_id));
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device->driver_data = state;
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out:
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ACPI_FREE(parsed.pointer);
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return ret;
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}
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static void vmgenid_notify(struct acpi_device *device, u32 event)
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{
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struct vmgenid_state *state = acpi_driver_data(device);
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u8 old_id[VMGENID_SIZE];
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memcpy(old_id, state->this_id, sizeof(old_id));
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memcpy(state->this_id, state->next_id, sizeof(state->this_id));
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if (!memcmp(old_id, state->this_id, sizeof(old_id)))
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return;
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add_vmfork_randomness(state->this_id, sizeof(state->this_id));
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}
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static const struct acpi_device_id vmgenid_ids[] = {
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{ "VMGENCTR", 0 },
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{ "VM_GEN_COUNTER", 0 },
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{ }
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};
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static struct acpi_driver vmgenid_driver = {
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.name = "vmgenid",
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.ids = vmgenid_ids,
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.owner = THIS_MODULE,
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.ops = {
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.add = vmgenid_add,
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.notify = vmgenid_notify
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}
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};
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module_acpi_driver(vmgenid_driver);
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MODULE_DEVICE_TABLE(acpi, vmgenid_ids);
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MODULE_DESCRIPTION("Virtual Machine Generation ID");
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MODULE_LICENSE("GPL v2");
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MODULE_AUTHOR("Jason A. Donenfeld <Jason@zx2c4.com>");
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