Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Mon, 4 Oct 2021 16:33:30 +0200 (CEST)
From:   torvic9@mailbox.org
To:     Paolo Bonzini <pbonzini@redhat.com>,
        "seanjc@google.com" <seanjc@google.com>,
        "vkuznets@redhat.com" <vkuznets@redhat.com>,
        "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
        "ndesaulniers@google.com" <ndesaulniers@google.com>,
        "nathan@kernel.org" <nathan@kernel.org>
Cc:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "tglx@linutronix.de" <tglx@linutronix.de>,
        "bp@alien8.de" <bp@alien8.de>
Message-ID: <1033024644.226.1633358010150@office.mailbox.org>
In-Reply-To: <1723492337.161319.1633342255263@office.mailbox.org>
References: <1446878298.170497.1633338512925@office.mailbox.org>
 <b6abc5a3-39ea-b463-9df5-f50bdcb16d08@redhat.com>
 <936688112.157288.1633339838738@office.mailbox.org>
 <c4773ecc-053f-9bc6-03af-5039397a4531@redhat.com>
 <1723492337.161319.1633342255263@office.mailbox.org>
Subject: Re: [BUG] [5.15] Compilation error in arch/x86/kvm/mmu/spte.h with
 clang-14
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit
Importance: Normal
Precedence: bulk


> torvic9@mailbox.org hat am 04.10.2021 12:10 geschrieben:
> 
>  
> > Paolo Bonzini <pbonzini@redhat.com> hat am 04.10.2021 11:49 geschrieben:
> > 
> >  
> > On 04/10/21 11:30, torvic9@mailbox.org wrote:
> > > 
> > >> Paolo Bonzini <pbonzini@redhat.com> hat am 04.10.2021 11:26 geschrieben:
> > >>
> > >>   
> > >> On 04/10/21 11:08, torvic9@mailbox.org wrote:
> > >>> I encounter the following issue when compiling 5.15-rc4 with 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 warning is wrong, as mentioned in the line right above:
> > > 
> > > So it's an issue with clang-14 then?
> > > (I add Nick and Nathan)
> > 
> > My clang here doesn't have the option, so I'm going to ask---are you 
> > using W=1?  I can see why clang is warning for KVM's code, but in my 
> > opinion such a check should only be in -Wextra.
> 
> I don't use any options (not that I'm aware of).
> Clang version 14.0.0 5f7a5353301b776ffb0e5fb048992898507bf7ee

Probably the cause for this bug is this recent llvm commit:
https://github.com/llvm/llvm-project/commit/f59cc9542bfb461d16ad12b2cc4be4abbfd9d96e

> 
> > 
> > Paolo
> > 
> > >>
> > >>           /*
> > >>            * 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).
> > >>            */
> > >>
> > >> Paolo
> > >