Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: [PATCH] kvm/x86 : avoid shifting signed 32-bit value by 31 bits
To:     Paolo Bonzini <pbonzini@redhat.com>, peng.hao2@zte.com.cn,
        richard.weiyang@gmail.com
Cc:     penghao122@sina.com.cn, rkrcmar@redhat.com, tglx@linutronix.de,
        mingo@redhat.com, joro@8bytes.org, linux-kernel@vger.kernel.org,
        kvm@vger.kernel.org, x86@kernel.org
References: <201810080904344038939@zte.com.cn>
 <717c02f3-bb36-33c4-a463-f5759fde30fd@zytor.com>
 <08fd066f-e6c5-f82c-544f-536e9f29e6f3@redhat.com>
From:   "H. Peter Anvin" <hpa@zytor.com>
Message-ID: <32ae2c96-51da-304f-9fc0-d531979eff97@zytor.com>
Date:   Mon, 15 Oct 2018 10:30:43 -0700
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101
 Thunderbird/60.2.1
MIME-Version: 1.0
In-Reply-To: <08fd066f-e6c5-f82c-544f-536e9f29e6f3@redhat.com>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On 10/15/18 10:23 AM, Paolo Bonzini wrote:
> 
> Even for a value from a 32-bit register?  That would be _BIT, which
> doesn't exist.
> 

Just use _BITUL(). gcc is smart enough to know that that the resulting value
is representable in 32 bits.

Or if you really care, submit a patch to create _BITU(), but I don't
personally see much of a point.

	-hpa