linux-kernel - Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in update_permission

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Message-ID: <ffe4b263-8a8d-c8ed-7ba1-ca55600ab273@redhat.com>
Date:   Tue, 19 Jun 2018 17:19:18 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Nick Desaulniers <ndesaulniers@...gle.com>, joe@...ches.com
Cc:     Matthias Kaehlcke <mka@...omium.org>, rkrcmar@...hat.com,
        Thomas Gleixner <tglx@...utronix.de>, hpa@...or.com,
        x86@...nel.org, kvm@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] kvm: x86: mmu: Add cast to negated bitmasks in
 update_permission_bitmask()

On 15/06/2018 20:45, Nick Desaulniers wrote:
>>
>>> In any case I think it it preferable to fix the code over disabling
>>> the warning, unless the warning is bogus or there are just too many
>>> occurrences.
>> Maybe.
> Spurious warning today, actual bug tomorrow?  I prefer to not to
> disable warnings wholesale.  They don't need to find actual bugs to be
> useful.  Flagging code that can be further specified does not hurt.
> Part of the effort to compile the kernel with different compilers is
> to add warning coverage, not remove it.  That said, there may be
> warnings that are never useful (or at least due to some invariant that
> only affects the kernel).  I cant think of any off the top of my head,
> but I'm also not sure this is one.

This one really makes the code uglier though, so I'm not really inclined
to applying the patch.

Paolo