vmgenid: emit uevent when VMGENID updates

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>
Reviewed-by: Alexander Graf <graf@amazon.com>
Reviewed-by: Lennart Poettering <mzxreary@0pointer.de>
Link: https://lore.kernel.org/r/20230531095119.11202-2-bchalios@amazon.es
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/virt/vmgenid.c b/drivers/virt/vmgenid.c
index a1c467a0e9f719665fc02fa559d5c94545e5725f..b67a28da47026d0299b8a1f8c22a40fc36b1c4a2 100644 (file)
--- a/drivers/virt/vmgenid.c
+++ b/drivers/virt/vmgenid.c
@@ -68,6 +68,7 @@ out:
 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[] = {