linux-kernel - [PATCH 5.14 03/24] KVM: x86: avoid warning with -Wbitwise-instead-of-logical

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Date:   Wed, 10 Nov 2021 19:43:55 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, torvic9@...lbox.org,
        Paolo Bonzini <pbonzini@...hat.com>,
        Nathan Chancellor <nathan@...nel.org>
Subject: [PATCH 5.14 03/24] KVM: x86: avoid warning with -Wbitwise-instead-of-logical

From: Paolo Bonzini <pbonzini@...hat.com>

commit 3d5e7a28b1ea2d603dea478e58e37ce75b9597ab upstream.

This is a new warning in clang top-of-tree (will be clang 14):

In file included from arch/x86/kvm/mmu/mmu.c:27:
arch/x86/kvm/mmu/spte.h:318:9: error: use of bitwise '|' with boolean operands [-Werror,-Wbitwise-instead-of-logical]
        return __is_bad_mt_xwr(rsvd_check, spte) |
               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                                                 ||
arch/x86/kvm/mmu/spte.h:318:9: note: cast one or both operands to int to silence this warning

The code is fine, but change it anyway to shut up this clever clogs
of a compiler.

Reported-by: torvic9@...lbox.org
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
Cc: Nathan Chancellor <nathan@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/x86/kvm/mmu/spte.h |    7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

--- a/arch/x86/kvm/mmu/spte.h
+++ b/arch/x86/kvm/mmu/spte.h
@@ -310,12 +310,7 @@ static inline bool __is_bad_mt_xwr(struc
 static __always_inline bool is_rsvd_spte(struct rsvd_bits_validate *rsvd_check,
 					 u64 spte, int level)
 {
-	/*
-	 * Use a bitwise-OR instead of a logical-OR to aggregate the reserved
-	 * bits and EPT's invalid memtype/XWR checks to avoid an extra Jcc
-	 * (this is extremely unlikely to be short-circuited as true).
-	 */
-	return __is_bad_mt_xwr(rsvd_check, spte) |
+	return __is_bad_mt_xwr(rsvd_check, spte) ||
 	       __is_rsvd_bits_set(rsvd_check, spte, level);
 }