diff options
Diffstat (limited to 'drivers/virt/vmgenid.c')
-rw-r--r-- | drivers/virt/vmgenid.c | 149 |
1 files changed, 115 insertions, 34 deletions
diff --git a/drivers/virt/vmgenid.c b/drivers/virt/vmgenid.c index eba4250ab3cf..66135eac3abf 100644 --- a/drivers/virt/vmgenid.c +++ b/drivers/virt/vmgenid.c @@ -2,14 +2,16 @@ /* * Copyright (C) 2022 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved. * - * The "Virtual Machine Generation ID" is exposed via ACPI and changes when a + * The "Virtual Machine Generation ID" is exposed via ACPI or DT and changes when a * virtual machine forks or is cloned. This driver exists for shepherding that * information to random.c. */ +#include <linux/acpi.h> +#include <linux/interrupt.h> #include <linux/kernel.h> #include <linux/module.h> -#include <linux/acpi.h> +#include <linux/platform_device.h> #include <linux/random.h> ACPI_MODULE_NAME("vmgenid"); @@ -21,19 +23,42 @@ struct vmgenid_state { u8 this_id[VMGENID_SIZE]; }; -static int vmgenid_add(struct acpi_device *device) +static void vmgenid_notify(struct device *device) +{ + struct vmgenid_state *state = device->driver_data; + u8 old_id[VMGENID_SIZE]; + + memcpy(old_id, state->this_id, sizeof(old_id)); + memcpy(state->this_id, state->next_id, sizeof(state->this_id)); + if (!memcmp(old_id, state->this_id, sizeof(old_id))) + return; + add_vmfork_randomness(state->this_id, sizeof(state->this_id)); +} + +static void setup_vmgenid_state(struct vmgenid_state *state, void *virt_addr) +{ + state->next_id = virt_addr; + memcpy(state->this_id, state->next_id, sizeof(state->this_id)); + add_device_randomness(state->this_id, sizeof(state->this_id)); +} + +#ifdef CONFIG_ACPI +static void vmgenid_acpi_handler(acpi_handle __always_unused handle, + u32 __always_unused event, void *dev) +{ + vmgenid_notify(dev); +} + +static int vmgenid_add_acpi(struct device *dev, struct vmgenid_state *state) { + struct acpi_device *device = ACPI_COMPANION(dev); struct acpi_buffer parsed = { ACPI_ALLOCATE_BUFFER }; - struct vmgenid_state *state; union acpi_object *obj; phys_addr_t phys_addr; acpi_status status; + void *virt_addr; int ret = 0; - state = devm_kmalloc(&device->dev, sizeof(*state), GFP_KERNEL); - if (!state) - return -ENOMEM; - status = acpi_evaluate_object(device->handle, "ADDR", NULL, &parsed); if (ACPI_FAILURE(status)) { ACPI_EXCEPTION((AE_INFO, status, "Evaluating ADDR")); @@ -49,52 +74,108 @@ static int vmgenid_add(struct acpi_device *device) phys_addr = (obj->package.elements[0].integer.value << 0) | (obj->package.elements[1].integer.value << 32); - state->next_id = devm_memremap(&device->dev, phys_addr, VMGENID_SIZE, MEMREMAP_WB); - if (IS_ERR(state->next_id)) { - ret = PTR_ERR(state->next_id); + + virt_addr = devm_memremap(&device->dev, phys_addr, VMGENID_SIZE, MEMREMAP_WB); + if (IS_ERR(virt_addr)) { + ret = PTR_ERR(virt_addr); goto out; } + setup_vmgenid_state(state, virt_addr); - memcpy(state->this_id, state->next_id, sizeof(state->this_id)); - add_device_randomness(state->this_id, sizeof(state->this_id)); - - device->driver_data = state; + status = acpi_install_notify_handler(device->handle, ACPI_DEVICE_NOTIFY, + vmgenid_acpi_handler, dev); + if (ACPI_FAILURE(status)) { + ret = -ENODEV; + goto out; + } + dev->driver_data = state; out: ACPI_FREE(parsed.pointer); return ret; } +#else +static int vmgenid_add_acpi(struct device *dev, struct vmgenid_state *state) +{ + return -EINVAL; +} +#endif -static void vmgenid_notify(struct acpi_device *device, u32 event) +static irqreturn_t vmgenid_of_irq_handler(int __always_unused irq, void *dev) { - struct vmgenid_state *state = acpi_driver_data(device); - u8 old_id[VMGENID_SIZE]; + vmgenid_notify(dev); + return IRQ_HANDLED; +} - memcpy(old_id, state->this_id, sizeof(old_id)); - memcpy(state->this_id, state->next_id, sizeof(state->this_id)); - if (!memcmp(old_id, state->this_id, sizeof(old_id))) - return; - add_vmfork_randomness(state->this_id, sizeof(state->this_id)); +static int vmgenid_add_of(struct platform_device *pdev, + struct vmgenid_state *state) +{ + void *virt_addr; + int ret; + + virt_addr = devm_platform_get_and_ioremap_resource(pdev, 0, NULL); + if (IS_ERR(virt_addr)) + return PTR_ERR(virt_addr); + + setup_vmgenid_state(state, virt_addr); + + ret = platform_get_irq(pdev, 0); + if (ret < 0) + return ret; + + ret = devm_request_irq(&pdev->dev, ret, vmgenid_of_irq_handler, + IRQF_SHARED, "vmgenid", &pdev->dev); + if (ret < 0) + return ret; + + pdev->dev.driver_data = state; + return 0; } -static const struct acpi_device_id vmgenid_ids[] = { +static int vmgenid_add(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct vmgenid_state *state; + int ret; + + state = devm_kmalloc(dev, sizeof(*state), GFP_KERNEL); + if (!state) + return -ENOMEM; + + if (dev->of_node) + ret = vmgenid_add_of(pdev, state); + else + ret = vmgenid_add_acpi(dev, state); + + if (ret < 0) + devm_kfree(dev, state); + return ret; +} + +static const struct of_device_id vmgenid_of_ids[] = { + { .compatible = "microsoft,vmgenid", }, + { }, +}; +MODULE_DEVICE_TABLE(of, vmgenid_of_ids); + +static const struct acpi_device_id vmgenid_acpi_ids[] = { { "VMGENCTR", 0 }, { "VM_GEN_COUNTER", 0 }, { } }; - -static struct acpi_driver vmgenid_driver = { - .name = "vmgenid", - .ids = vmgenid_ids, - .ops = { - .add = vmgenid_add, - .notify = vmgenid_notify - } +MODULE_DEVICE_TABLE(acpi, vmgenid_acpi_ids); + +static struct platform_driver vmgenid_plaform_driver = { + .probe = vmgenid_add, + .driver = { + .name = "vmgenid", + .acpi_match_table = vmgenid_acpi_ids, + .of_match_table = vmgenid_of_ids, + }, }; -module_acpi_driver(vmgenid_driver); +module_platform_driver(vmgenid_plaform_driver) -MODULE_DEVICE_TABLE(acpi, vmgenid_ids); MODULE_DESCRIPTION("Virtual Machine Generation ID"); MODULE_LICENSE("GPL v2"); MODULE_AUTHOR("Jason A. Donenfeld <Jason@zx2c4.com>"); |