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-rw-r--r--Documentation/devicetree/bindings/rng/microsoft,vmgenid.yaml49
-rw-r--r--MAINTAINERS1
-rw-r--r--drivers/virt/Kconfig1
-rw-r--r--drivers/virt/vmgenid.c149
4 files changed, 165 insertions, 35 deletions
diff --git a/Documentation/devicetree/bindings/rng/microsoft,vmgenid.yaml b/Documentation/devicetree/bindings/rng/microsoft,vmgenid.yaml
new file mode 100644
index 000000000000..8f20dee93e7e
--- /dev/null
+++ b/Documentation/devicetree/bindings/rng/microsoft,vmgenid.yaml
@@ -0,0 +1,49 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/rng/microsoft,vmgenid.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Virtual Machine Generation ID
+
+maintainers:
+ - Jason A. Donenfeld <Jason@zx2c4.com>
+
+description:
+ Firmwares or hypervisors can use this devicetree to describe an
+ interrupt and a shared resource to inject a Virtual Machine Generation ID.
+ Virtual Machine Generation ID is a globally unique identifier (GUID) and
+ the devicetree binding follows VMGenID specification defined in
+ http://go.microsoft.com/fwlink/?LinkId=260709.
+
+properties:
+ compatible:
+ const: microsoft,vmgenid
+
+ reg:
+ description:
+ Specifies a 16-byte VMGenID in endianness-agnostic hexadecimal format.
+ maxItems: 1
+
+ interrupts:
+ description:
+ Interrupt used to notify that a new VMGenID is available.
+ maxItems: 1
+
+required:
+ - compatible
+ - reg
+ - interrupts
+
+additionalProperties: false
+
+examples:
+ - |
+ #include <dt-bindings/interrupt-controller/arm-gic.h>
+ rng@80000000 {
+ compatible = "microsoft,vmgenid";
+ reg = <0x80000000 0x1000>;
+ interrupts = <GIC_SPI 35 IRQ_TYPE_EDGE_RISING>;
+ };
+
+...
diff --git a/MAINTAINERS b/MAINTAINERS
index 7bb9b84c3b78..ca389fd49d74 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -18669,6 +18669,7 @@ M: "Theodore Ts'o" <tytso@mit.edu>
M: Jason A. Donenfeld <Jason@zx2c4.com>
S: Maintained
T: git https://git.kernel.org/pub/scm/linux/kernel/git/crng/random.git
+F: Documentation/devicetree/bindings/rng/microsoft,vmgenid.yaml
F: drivers/char/random.c
F: drivers/virt/vmgenid.c
diff --git a/drivers/virt/Kconfig b/drivers/virt/Kconfig
index 40129b6f0eca..d8c848cf09a6 100644
--- a/drivers/virt/Kconfig
+++ b/drivers/virt/Kconfig
@@ -16,7 +16,6 @@ if VIRT_DRIVERS
config VMGENID
tristate "Virtual Machine Generation ID driver"
default y
- depends on ACPI
help
Say Y here to use the hypervisor-provided Virtual Machine Generation ID
to reseed the RNG when the VM is cloned. This is highly recommended if
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>");