[PATCH 1/1] vmgenid: emit uevent when VMGENID updates

Babis Chalios
2023-05-31T09:52:01Z

We receive an ACPI notification every time the VM Generation ID changes
and use the new ID as fresh randomness added to the entropy pool. This
commits emits a uevent every time we receive the ACPI notification, as a
means to notify the user space that it now is in a new VM.

Signed-off-by: Babis Chalios <bchalios@amazon.es>
---
drivers/virt/vmgenid.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/virt/vmgenid.c b/drivers/virt/vmgenid.c
index a1c467a0e9f7..b67a28da4702 100644
--- a/drivers/virt/vmgenid.c
+++ b/drivers/virt/vmgenid.c
@@ -68,6 +68,7 @@ static int vmgenid_add(struct acpi_device *device)
static void vmgenid_notify(struct acpi_device *device, u32 event)
{
struct vmgenid_state *state = acpi_driver_data(device);
+ char *envp[] = { "NEW_VMGENID=1", NULL };
u8 old_id[VMGENID_SIZE];

memcpy(old_id, state->this_id, sizeof(old_id));
@@ -75,6 +76,7 @@ static void vmgenid_notify(struct acpi_device *device, u32 event)
if (!memcmp(old_id, state->this_id, sizeof(old_id)))
return;
add_vmfork_randomness(state->this_id, sizeof(state->this_id));
+ kobject_uevent_env(&device->dev.kobj, KOBJ_CHANGE, envp);
}

static const struct acpi_device_id vmgenid_ids[] = {
--
2.39.2