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Subject[PATCH v7 1/3] virt: vmgenid: change implementation to use a platform driver
Date
From: Sudan Landge <sudanl@amazon.com>

Re-implement vmgenid as a platform driver in preparation for adding
devicetree bindings support in next commits.

Signed-off-by: Sudan Landge <sudanl@amazon.com>
Reviewed-by: Alexander Graf <graf@amazon.com>
[Jason: - Small style cleanups and refactoring.]
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
drivers/virt/vmgenid.c | 99 +++++++++++++++++++++++++++---------------
1 file changed, 65 insertions(+), 34 deletions(-)

diff --git a/drivers/virt/vmgenid.c b/drivers/virt/vmgenid.c
index a1c467a0e9f7..aebbd24512c9 100644
--- a/drivers/virt/vmgenid.c
+++ b/drivers/virt/vmgenid.c
@@ -7,9 +7,10 @@
* information to random.c.
*/

+#include <linux/acpi.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 +22,41 @@ 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));
+}
+
+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"));
@@ -49,53 +72,61 @@ 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;
}

-static void vmgenid_notify(struct acpi_device *device, u32 event)
+static int vmgenid_add(struct platform_device *pdev)
{
- struct vmgenid_state *state = acpi_driver_data(device);
- u8 old_id[VMGENID_SIZE];
+ struct vmgenid_state *state;
+ struct device *dev = &pdev->dev;
+ int ret = 0;

- 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));
+ state = devm_kmalloc(dev, sizeof(*state), GFP_KERNEL);
+ if (!state)
+ return -ENOMEM;
+
+ ret = vmgenid_add_acpi(dev, state);
+
+ if (ret)
+ devm_kfree(dev, state);
+ return ret;
}

-static const struct acpi_device_id vmgenid_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,
- .owner = THIS_MODULE,
- .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,
+ },
};

-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>");
--
2.44.0

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