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From:   Babis Chalios <bchalios@amazon.es>
To:     Theodore Ts'o <tytso@mit.edu>,
        "Jason A. Donenfeld" <Jason@zx2c4.com>,
        <linux-kernel@vger.kernel.org>
CC:     <bchalios@amazon.es>, <graf@amazon.de>, <mzxreary@0pointer.de>,
        <xmarcalx@amazon.co.uk>
Subject: [PATCH 1/1] vmgenid: emit uevent when VMGENID updates
Date:   Wed, 31 May 2023 11:51:19 +0200
Message-ID: <20230531095119.11202-2-bchalios@amazon.es>
In-Reply-To: <20230531095119.11202-1-bchalios@amazon.es>
References: <20230531095119.11202-1-bchalios@amazon.es>
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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