linux-kernel - [tip: x86/core] x86/cpufeatures: Move X86_FEATURE_CALL_DEPTH from bit 18 to bit 19 of word 11, to leave space for WIP X86_FEATURE_SGX

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Date:   Sun, 06 Nov 2022 09:05:06 -0000
From:   "tip-bot2 for Ingo Molnar" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...nel.org>
Subject: [tip: x86/core] x86/cpufeatures: Move X86_FEATURE_CALL_DEPTH from bit
 18 to bit 19 of word 11, to leave space for WIP X86_FEATURE_SGX_EDECCSSA bit

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

Commit-ID:     b1599915f09157e98f59556e1b2eafe473603347
Gitweb:        https://git.kernel.org/tip/b1599915f09157e98f59556e1b2eafe473603347
Author:        Ingo Molnar <mingo@...nel.org>
AuthorDate:    Sun, 06 Nov 2022 09:55:56 +01:00
Committer:     Ingo Molnar <mingo@...nel.org>
CommitterDate: Sun, 06 Nov 2022 09:58:36 +01:00

x86/cpufeatures: Move X86_FEATURE_CALL_DEPTH from bit 18 to bit 19 of word 11, to leave space for WIP X86_FEATURE_SGX_EDECCSSA bit

Reallocate a soft-cpufeatures bit allocated for call-depth tracking
code, which clashes with this recent KVM/SGX patch being worked on:

        KVM/VMX: Allow exposing EDECCSSA user leaf function to KVM guest

Instead of reallocating cpufeatures bits in evil merges, make the
allocation explicit.

Acked-by: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: x86@...nel.org
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: linux-kernel@...r.kernel.org
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/include/asm/cpufeatures.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index aefd081..864c9b0 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -304,7 +304,8 @@
 #define X86_FEATURE_UNRET		(11*32+15) /* "" AMD BTB untrain return */
 #define X86_FEATURE_USE_IBPB_FW		(11*32+16) /* "" Use IBPB during runtime firmware calls */
 #define X86_FEATURE_RSB_VMEXIT_LITE	(11*32+17) /* "" Fill RSB on VM exit when EIBRS is enabled */
-#define X86_FEATURE_CALL_DEPTH		(11*32+18) /* "" Call depth tracking for RSB stuffing */
+						   /* Hole left for X86_FEATURE_SGX_EDECCSSA */
+#define X86_FEATURE_CALL_DEPTH		(11*32+19) /* "" Call depth tracking for RSB stuffing */
 
 /* Intel-defined CPU features, CPUID level 0x00000007:1 (EAX), word 12 */
 #define X86_FEATURE_AVX_VNNI		(12*32+ 4) /* AVX VNNI instructions */