linux-kernel - [PATCH 1/1] x86: deduplicate the spectre_v2

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Date:   Wed,  4 Nov 2020 19:14:06 -0500
From:   Andrea Arcangeli <aarcange@...hat.com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     YiFei Zhu <zhuyifei1999@...il.com>,
        Linux Containers <containers@...ts.linux-foundation.org>,
        YiFei Zhu <yifeifz2@...inois.edu>, bpf <bpf@...r.kernel.org>,
        kernel list <linux-kernel@...r.kernel.org>,
        Aleksa Sarai <cyphar@...har.com>,
        Andy Lutomirski <luto@...capital.net>,
        David Laight <David.Laight@...lab.com>,
        Dimitrios Skarlatos <dskarlat@...cmu.edu>,
        Giuseppe Scrivano <gscrivan@...hat.com>,
        Hubertus Franke <frankeh@...ibm.com>,
        Jack Chen <jianyan2@...inois.edu>,
        Jann Horn <jannh@...gle.com>,
        Josep Torrellas <torrella@...inois.edu>,
        Tianyin Xu <tyxu@...inois.edu>,
        Tobin Feldman-Fitzthum <tobin@....com>,
        Tycho Andersen <tycho@...ho.pizza>,
        Valentin Rothberg <vrothber@...hat.com>,
        Will Drewry <wad@...omium.org>, Jiri Kosina <jikos@...nel.org>,
        Waiman Long <longman@...hat.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Andi Kleen <ak@...ux.intel.com>
Subject: [PATCH 1/1] x86: deduplicate the spectre_v2_user documentation

This would need updating to make prctl be the new default, but it's
simpler to delete it and refer to the dup.

Signed-off-by: Andrea Arcangeli <aarcange@...hat.com>
---
 Documentation/admin-guide/hw-vuln/spectre.rst | 51 +------------------
 1 file changed, 2 insertions(+), 49 deletions(-)

diff --git a/Documentation/admin-guide/hw-vuln/spectre.rst b/Documentation/admin-guide/hw-vuln/spectre.rst
index 19b897cb1d45..ab7d402c1677 100644
--- a/Documentation/admin-guide/hw-vuln/spectre.rst
+++ b/Documentation/admin-guide/hw-vuln/spectre.rst
@@ -593,61 +593,14 @@ kernel command line.
 		Not specifying this option is equivalent to
 		spectre_v2=auto.
 
-For user space mitigation:
-
-        spectre_v2_user=
-
-		[X86] Control mitigation of Spectre variant 2
-		(indirect branch speculation) vulnerability between
-		user space tasks
-
-		on
-			Unconditionally enable mitigations. Is
-			enforced by spectre_v2=on
-
-		off
-			Unconditionally disable mitigations. Is
-			enforced by spectre_v2=off
-
-		prctl
-			Indirect branch speculation is enabled,
-			but mitigation can be enabled via prctl
-			per thread. The mitigation control state
-			is inherited on fork.
-
-		prctl,ibpb
-			Like "prctl" above, but only STIBP is
-			controlled per thread. IBPB is issued
-			always when switching between different user
-			space processes.
-
-		seccomp
-			Same as "prctl" above, but all seccomp
-			threads will enable the mitigation unless
-			they explicitly opt out.
-
-		seccomp,ibpb
-			Like "seccomp" above, but only STIBP is
-			controlled per thread. IBPB is issued
-			always when switching between different
-			user space processes.
-
-		auto
-			Kernel selects the mitigation depending on
-			the available CPU features and vulnerability.
-
-		Default mitigation:
-		If CONFIG_SECCOMP=y then "seccomp", otherwise "prctl"
-
-		Not specifying this option is equivalent to
-		spectre_v2_user=auto.
-
 		In general the kernel by default selects
 		reasonable mitigations for the current CPU. To
 		disable Spectre variant 2 mitigations, boot with
 		spectre_v2=off. Spectre variant 1 mitigations
 		cannot be disabled.
 
+For spectre_v2_user see :doc:`/admin-guide/kernel-parameters`.
+
 Mitigation selection guide
 --------------------------