linux-kernel - [tip: x86/cpu] x86/cpufeatures: Add enumeration for SERIALIZE instruction

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Date:   Mon, 27 Jul 2020 12:46:17 -0000
From:   "tip-bot2 for Ricardo Neri" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>,
        Ingo Molnar <mingo@...nel.org>,
        Tony Luck <tony.luck@...el.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        x86 <x86@...nel.org>, LKML <linux-kernel@...r.kernel.org>
Subject: [tip: x86/cpu] x86/cpufeatures: Add enumeration for SERIALIZE instruction

The following commit has been merged into the x86/cpu branch of tip:

Commit-ID:     85b23fbc7d88f8c6e3951721802d7845bc39663d
Gitweb:        https://git.kernel.org/tip/85b23fbc7d88f8c6e3951721802d7845bc39663d
Author:        Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
AuthorDate:    Sun, 26 Jul 2020 21:31:29 -07:00
Committer:     Ingo Molnar <mingo@...nel.org>
CommitterDate: Mon, 27 Jul 2020 12:42:06 +02:00

x86/cpufeatures: Add enumeration for SERIALIZE instruction

The Intel architecture defines a set of Serializing Instructions (a
detailed definition can be found in Vol.3 Section 8.3 of the Intel "main"
manual, SDM). However, these instructions do more than what is required,
have side effects and/or may be rather invasive. Furthermore, some of
these instructions are only available in kernel mode or may cause VMExits.
Thus, software using these instructions only to serialize execution (as
defined in the manual) must handle the undesired side effects.

As indicated in the name, SERIALIZE is a new Intel architecture
Serializing Instruction. Crucially, it does not have any of the mentioned
side effects. Also, it does not cause VMExit and can be used in user mode.

This new instruction is currently documented in the latest "extensions"
manual (ISE). It will appear in the "main" manual in the future.

Signed-off-by: Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Reviewed-by: Tony Luck <tony.luck@...el.com>
Acked-by: Dave Hansen <dave.hansen@...ux.intel.com>
Link: https://lore.kernel.org/r/20200727043132.15082-2-ricardo.neri-calderon@linux.intel.com
---
 arch/x86/include/asm/cpufeatures.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index 02dabc9..adf45cf 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -365,6 +365,7 @@
 #define X86_FEATURE_SRBDS_CTRL		(18*32+ 9) /* "" SRBDS mitigation MSR available */
 #define X86_FEATURE_MD_CLEAR		(18*32+10) /* VERW clears CPU buffers */
 #define X86_FEATURE_TSX_FORCE_ABORT	(18*32+13) /* "" TSX_FORCE_ABORT */
+#define X86_FEATURE_SERIALIZE		(18*32+14) /* SERIALIZE instruction */
 #define X86_FEATURE_PCONFIG		(18*32+18) /* Intel PCONFIG */
 #define X86_FEATURE_SPEC_CTRL		(18*32+26) /* "" Speculation Control (IBRS + IBPB) */
 #define X86_FEATURE_INTEL_STIBP		(18*32+27) /* "" Single Thread Indirect Branch Predictors */