* [PATCH] KVM: x86: avoid warning with -Wbitwise-instead-of-logical
@ 2021-10-15 8:51 Paolo Bonzini
2021-10-15 16:37 ` Nathan Chancellor
0 siblings, 1 reply; 3+ messages in thread
From: Paolo Bonzini @ 2021-10-15 8:51 UTC (permalink / raw)
To: linux-kernel, kvm; +Cc: nathan, seanjc, torvic9, Jim Mattson
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>
---
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
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] KVM: x86: avoid warning with -Wbitwise-instead-of-logical
2021-10-15 8:51 [PATCH] KVM: x86: avoid warning with -Wbitwise-instead-of-logical Paolo Bonzini
@ 2021-10-15 16:37 ` Nathan Chancellor
2021-10-15 17:46 ` Nick Desaulniers
0 siblings, 1 reply; 3+ messages in thread
From: Nathan Chancellor @ 2021-10-15 16:37 UTC (permalink / raw)
To: Paolo Bonzini; +Cc: linux-kernel, kvm, seanjc, torvic9, Jim Mattson, llvm
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
>
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] KVM: x86: avoid warning with -Wbitwise-instead-of-logical
2021-10-15 16:37 ` Nathan Chancellor
@ 2021-10-15 17:46 ` Nick Desaulniers
0 siblings, 0 replies; 3+ messages in thread
From: Nick Desaulniers @ 2021-10-15 17:46 UTC (permalink / raw)
To: Nathan Chancellor
Cc: Paolo Bonzini, linux-kernel, kvm, seanjc, torvic9, Jim Mattson, llvm
On Fri, Oct 15, 2021 at 9:37 AM Nathan Chancellor <nathan@kernel.org> wrote:
>
> 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>
Link: https://github.com/ClangBuiltLinux/linux/issues/1474
Acked-by: Nick Desaulniers <ndesaulniers@google.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
> >
> >
>
--
Thanks,
~Nick Desaulniers
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2021-10-15 8:51 [PATCH] KVM: x86: avoid warning with -Wbitwise-instead-of-logical Paolo Bonzini
2021-10-15 16:37 ` Nathan Chancellor
2021-10-15 17:46 ` Nick Desaulniers
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