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

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Date:   Fri, 15 Oct 2021 04:51:48 -0400
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     nathan@...nel.org, seanjc@...gle.com, torvic9@...lbox.org,
        Jim Mattson <jmattson@...gle.com>
Subject: [PATCH] KVM: x86: avoid warning with -Wbitwise-instead-of-logical

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

Reported-by: torvic9@...lbox.org
Suggested-by: Jim Mattson <jmattson@...gle.com>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
 arch/x86/kvm/mmu/spte.h | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/mmu/spte.h b/arch/x86/kvm/mmu/spte.h
index eb7b227fc6cf..32bc7268c9ea 100644
--- a/arch/x86/kvm/mmu/spte.h
+++ b/arch/x86/kvm/mmu/spte.h
@@ -314,9 +314,12 @@ static __always_inline bool is_rsvd_spte(struct rsvd_bits_validate *rsvd_check,
 	 * 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).
+	 *
+	 * (int) avoids clang's "use of bitwise '|' with boolean operands"
+	 * warning.
 	 */
-	return __is_bad_mt_xwr(rsvd_check, spte) |
-	       __is_rsvd_bits_set(rsvd_check, spte, level);
+	return (int)__is_bad_mt_xwr(rsvd_check, spte) |
+	       (int)__is_rsvd_bits_set(rsvd_check, spte, level);
 }
 
 static inline bool spte_can_locklessly_be_made_writable(u64 spte)
-- 
2.27.0