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SubjectRe: [PATCH] KVM: x86: avoid warning with -Wbitwise-instead-of-logical
On Fri, Oct 15, 2021 at 04:51:48AM -0400, Paolo Bonzini wrote:
> 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@mailbox.org
> Suggested-by: Jim Mattson <jmattson@google.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Reviewed-by: Nathan Chancellor <nathan@kernel.org>

> ---
> 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
>
>

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