From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
stable@vger.kernel.org, Kim Phillips <kim.phillips@amd.com>,
Borislav Petkov <bp@suse.de>, Ben Hutchings <ben@decadent.org.uk>
Subject: [PATCH 4.9 13/24] x86/speculation: Use generic retpoline by default on AMD
Date: Wed, 9 Mar 2022 16:59:26 +0100 [thread overview]
Message-ID: <20220309155856.690698640@linuxfoundation.org> (raw)
In-Reply-To: <20220309155856.295480966@linuxfoundation.org>
From: Kim Phillips <kim.phillips@amd.com>
commit 244d00b5dd4755f8df892c86cab35fb2cfd4f14b upstream.
AMD retpoline may be susceptible to speculation. The speculation
execution window for an incorrect indirect branch prediction using
LFENCE/JMP sequence may potentially be large enough to allow
exploitation using Spectre V2.
By default, don't use retpoline,lfence on AMD. Instead, use the
generic retpoline.
Signed-off-by: Kim Phillips <kim.phillips@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/kernel/cpu/bugs.c | 8 --------
1 file changed, 8 deletions(-)
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -897,14 +897,6 @@ static enum spectre_v2_mitigation __init
return SPECTRE_V2_NONE;
}
- if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) {
- if (!boot_cpu_has(X86_FEATURE_LFENCE_RDTSC)) {
- pr_err("LFENCE not serializing, switching to generic retpoline\n");
- return SPECTRE_V2_RETPOLINE;
- }
- return SPECTRE_V2_LFENCE;
- }
-
return SPECTRE_V2_RETPOLINE;
}
next prev parent reply other threads:[~2022-03-09 16:02 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-09 15:59 [PATCH 4.9 00/24] 4.9.306-rc1 review Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 01/24] x86/speculation: Add RETPOLINE_AMD support to the inline asm CALL_NOSPEC variant Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 02/24] x86/retpoline: Make CONFIG_RETPOLINE depend on compiler support Greg Kroah-Hartman
2022-03-09 19:58 ` Ben Hutchings
2022-03-09 22:39 ` Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 03/24] x86/retpoline: Remove minimal retpoline support Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 04/24] Documentation: Add section about CPU vulnerabilities for Spectre Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 05/24] Documentation: Add swapgs description to the Spectre v1 documentation Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 06/24] Documentation: refer to config RANDOMIZE_BASE for kernel address-space randomization Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 07/24] x86/speculation: Merge one test in spectre_v2_user_select_mitigation() Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 08/24] x86,bugs: Unconditionally allow spectre_v2=retpoline,amd Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 09/24] x86/speculation: Rename RETPOLINE_AMD to RETPOLINE_LFENCE Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 10/24] x86/speculation: Add eIBRS + Retpoline options Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 11/24] Documentation/hw-vuln: Update spectre doc Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 12/24] x86/speculation: Include unprivileged eBPF status in Spectre v2 mitigation reporting Greg Kroah-Hartman
2022-03-09 15:59 ` Greg Kroah-Hartman [this message]
2022-03-09 15:59 ` [PATCH 4.9 14/24] x86/speculation: Update link to AMD speculation whitepaper Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 15/24] x86/speculation: Warn about Spectre v2 LFENCE mitigation Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 16/24] x86/speculation: Warn about eIBRS + LFENCE + Unprivileged eBPF + SMT Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 17/24] arm/arm64: Provide a wrapper for SMCCC 1.1 calls Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 18/24] arm/arm64: smccc/psci: add arm_smccc_1_1_get_conduit() Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 19/24] ARM: report Spectre v2 status through sysfs Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 20/24] ARM: early traps initialisation Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 21/24] ARM: use LOADADDR() to get load address of sections Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 22/24] ARM: Spectre-BHB workaround Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 23/24] ARM: include unprivileged BPF status in Spectre V2 reporting Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 24/24] ARM: fix build error when BPF_SYSCALL is disabled Greg Kroah-Hartman
2022-03-09 18:40 ` [PATCH 4.9 00/24] 4.9.306-rc1 review Daniel Díaz
2022-03-09 19:18 ` Daniel Díaz
2022-03-10 3:32 ` Florian Fainelli
2022-03-10 11:41 ` Pavel Machek
2022-03-10 11:48 ` Greg Kroah-Hartman
2022-03-09 20:26 ` Shuah Khan
2022-03-10 3:45 ` Florian Fainelli
2022-03-10 11:39 ` Pavel Machek
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=20220309155856.690698640@linuxfoundation.org \
--to=gregkh@linuxfoundation.org \
--cc=ben@decadent.org.uk \
--cc=bp@suse.de \
--cc=kim.phillips@amd.com \
--cc=linux-kernel@vger.kernel.org \
--cc=stable@vger.kernel.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).