From: George Dunlap <george.dunlap@citrix.com>
To: <security@xenproject.org>
Cc: <xen-devel@lists.xenproject.org>,
George Dunlap <george.dunlap@citrix.com>,
Jann Horn <jannh@google.com>, Jan Beulich <jbeulich@suse.com>
Subject: [PATCH v2] SUPPORT.md: Un-shimmed 32-bit PV guests are no longer supported
Date: Thu, 6 May 2021 13:47:52 +0100 [thread overview]
Message-ID: <20210506124752.65844-1-george.dunlap@citrix.com> (raw)
The support status of 32-bit guests doesn't seem particularly useful.
With it changed to fully unsupported outside of PV-shim, adjust the PV32
Kconfig default accordingly.
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: George Dunlap <george.dunlap@citrix.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
---
v2:
- add in Kconfig from advisory, ported over c/s d23d792478d
---
SUPPORT.md | 9 +--------
xen/arch/x86/Kconfig | 7 +++++--
2 files changed, 6 insertions(+), 10 deletions(-)
diff --git a/SUPPORT.md b/SUPPORT.md
index d0d4fc6f4f..a29680e04c 100644
--- a/SUPPORT.md
+++ b/SUPPORT.md
@@ -86,14 +86,7 @@ No hardware requirements
Status, x86_64: Supported
Status, x86_32, shim: Supported
- Status, x86_32, without shim: Supported, with caveats
-
-Due to architectural limitations,
-32-bit PV guests must be assumed to be able to read arbitrary host memory
-using speculative execution attacks.
-Advisories will continue to be issued
-for new vulnerabilities related to un-shimmed 32-bit PV guests
-enabling denial-of-service attacks or privilege escalation attacks.
+ Status, x86_32, without shim: Supported, not security supported
### x86/HVM
diff --git a/xen/arch/x86/Kconfig b/xen/arch/x86/Kconfig
index e55e029b79..9b164db641 100644
--- a/xen/arch/x86/Kconfig
+++ b/xen/arch/x86/Kconfig
@@ -55,7 +55,7 @@ config PV
config PV32
bool "Support for 32bit PV guests"
depends on PV
- default y
+ default PV_SHIM
select COMPAT
---help---
The 32bit PV ABI uses Ring1, an area of the x86 architecture which
@@ -67,7 +67,10 @@ config PV32
reduction, or performance reasons. Backwards compatibility can be
provided via the PV Shim mechanism.
- If unsure, say Y.
+ Note that outside of PV Shim, 32-bit PV guests are not security
+ supported anymore.
+
+ If unsure, use the default setting.
config PV_LINEAR_PT
bool "Support for PV linear pagetables"
--
2.30.2
next reply other threads:[~2021-05-06 12:48 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-06 12:47 George Dunlap [this message]
2021-05-06 13:09 ` [PATCH v2] SUPPORT.md: Un-shimmed 32-bit PV guests are no longer supported Jan Beulich
2021-05-06 14:32 ` Andrew Cooper
2021-05-07 10:26 ` Roger Pau Monné
2021-05-07 11:05 ` Jan Beulich
2021-06-04 13:14 ` George Dunlap
2021-06-07 9:18 ` Jan Beulich
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210506124752.65844-1-george.dunlap@citrix.com \
--to=george.dunlap@citrix.com \
--cc=jannh@google.com \
--cc=jbeulich@suse.com \
--cc=security@xenproject.org \
--cc=xen-devel@lists.xenproject.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).