Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754850AbaLVLvy (ORCPT ); Mon, 22 Dec 2014 06:51:54 -0500 Received: from foss-mx-na.foss.arm.com ([217.140.108.86]:52840 "EHLO foss-mx-na.foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754265AbaLVLvw (ORCPT ); Mon, 22 Dec 2014 06:51:52 -0500 Message-ID: <549805BF.4080400@arm.com> Date: Mon, 22 Dec 2014 11:51:27 +0000 From: Marc Zyngier User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Icedove/31.2.0 MIME-Version: 1.0 To: Peng Fan , "christoffer.dall@linaro.org" CC: "gleb@kernel.org" , "pbonzini@redhat.com" , "linux@arm.linux.org.uk" , "linux-arm-kernel@lists.infradead.org" , "kvmarm@lists.cs.columbia.edu" , "kvm@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH 2/2] arm:kvm remove len 8 for mmio read write buf References: <1419247399-26113-1-git-send-email-van.freenix@gmail.com> <1419247399-26113-2-git-send-email-van.freenix@gmail.com> In-Reply-To: <1419247399-26113-2-git-send-email-van.freenix@gmail.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 22/12/14 11:23, Peng Fan wrote: > For arm 32 bit architecture, 8 bytes load/store operation in one instruction > will not be generated by compiler. Ever heard of lrdr/strd? > And before invoke mmio_read_buf, there is a piece of code: > " > len = run->mmio.len; > if (len > sizeof(unsigned long)) > return -EINVAL; > > data = mmio_read_buf(run->mmio.data, len); > " > > This piece code also tells that len variable does not exceeds 4 bytes. > So, remove 8 bytes assign in mmio_read_buf and mmio_write_buf. NAK. This code is shared between arm and arm64. See commit f42798c. M. > > Signed-off-by: Peng Fan > CC: Gleb Natapov > CC: Paolo Bonzini > CC: Christoffer Dall > CC: Marc Zyngier > CC: Russell King > --- > arch/arm/kvm/mmio.c | 10 ---------- > 1 file changed, 10 deletions(-) > > diff --git a/arch/arm/kvm/mmio.c b/arch/arm/kvm/mmio.c > index 4cb5a93..953a819 100644 > --- a/arch/arm/kvm/mmio.c > +++ b/arch/arm/kvm/mmio.c > @@ -30,7 +30,6 @@ static void mmio_write_buf(char *buf, unsigned int len, unsigned long data) > u8 byte; > u16 hword; > u32 word; > - u64 dword; > } tmp; > > switch (len) { > @@ -46,10 +45,6 @@ static void mmio_write_buf(char *buf, unsigned int len, unsigned long data) > tmp.word = data; > datap = &tmp.word; > break; > - case 8: > - tmp.dword = data; > - datap = &tmp.dword; > - break; > } > > memcpy(buf, datap, len); > @@ -61,7 +56,6 @@ static unsigned long mmio_read_buf(char *buf, unsigned int len) > union { > u16 hword; > u32 word; > - u64 dword; > } tmp; > > switch (len) { > @@ -76,10 +70,6 @@ static unsigned long mmio_read_buf(char *buf, unsigned int len) > memcpy(&tmp.word, buf, len); > data = tmp.word; > break; > - case 8: > - memcpy(&tmp.dword, buf, len); > - data = tmp.dword; > - break; > } > > return data; > -- Jazz is not dead. It just smells funny... -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/