Merge tag 'random-6.10-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...

Pull random number generator updates from Jason Donenfeld:

 - The vmgenid driver can now be bound using device tree, rather than
   just ACPI.

   The improvement, from Sudan Landge, lets Amazon's Firecracker VMM
   make use of the virtual device without having to expose an otherwise
   unused ACPI stack in their "micro VM".

* tag 'random-6.10-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random:
  virt: vmgenid: add support for devicetree bindings
  dt-bindings: rng: Add vmgenid support
  virt: vmgenid: change implementation to use a platform driver

diff --git a/Documentation/devicetree/bindings/rng/microsoft,vmgenid.yaml b/Documentation/devicetree/bindings/rng/microsoft,vmgenid.yaml
new file mode 100644 (file)
index 0000000..8f20dee
--- /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 7bb9b84c3b7835b5e7ff98a8e7fb7424bbefc519..ca389fd49d743c239c27222b78f0c4bbe6b7a4fe 100644 (file)
--- 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 40129b6f0eca41ced6c6213776571a5ae8374ebe..d8c848cf09a6afad65b28be20f5fd7e90a0c5307 100644 (file)
--- 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 eba4250ab3cfed80323945a8967796341df92246..66135eac3abffa3b65e39efc97c217a3da13c287 100644 (file)
--- 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>");