0012-x86-pass-through-documents-as-security-unsupported-w.patch


1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42

From 3e8a2217f211d49dd771f7918d72df057121109f Mon Sep 17 00:00:00 2001
From: Jan Beulich <jbeulich@suse.com>
Date: Tue, 13 Aug 2024 16:48:13 +0200
Subject: [PATCH 12/35] x86/pass-through: documents as security-unsupported
 when sharing resources

When multiple devices share resources and one of them is to be passed
through to a guest, security of the entire system and of respective
guests individually cannot really be guaranteed without knowing
internals of any of the involved guests.  Therefore such a configuration
cannot really be security-supported, yet making that explicit was so far
missing.

This is XSA-461 / CVE-2024-31146.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
master commit: 9c94eda1e3790820699a6de3f6a7c959ecf30600
master date: 2024-08-13 16:37:25 +0200
---
 SUPPORT.md | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/SUPPORT.md b/SUPPORT.md
index 8b998d9bc7..1d8b38cbd0 100644
--- a/SUPPORT.md
+++ b/SUPPORT.md
@@ -841,6 +841,11 @@ This feature is not security supported: see https://xenbits.xen.org/xsa/advisory
 
 Only systems using IOMMUs are supported.
 
+Passing through of devices sharing resources with another device is not
+security supported.  Such sharing could e.g. be the same line interrupt being
+used by multiple devices, one of which is to be passed through, or two such
+devices having memory BARs within the same 4k page.
+
 Not compatible with migration, populate-on-demand, altp2m,
 introspection, memory sharing, or memory paging.
 
-- 
2.46.1