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

From: Paolo Bonzini
Date: Fri Oct 15 2021 - 04:51:59 EST


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@xxxxxxxxxxx
Suggested-by: Jim Mattson <jmattson@xxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
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