From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Vrabel Subject: Re: [Xen-devel] [PATCH v2 34/34] xen/io: use virt_xxx barriers Date: Mon, 4 Jan 2016 11:32:28 +0000 Message-ID: <568A584C.2070501@citrix.com> References: <1451572003-2440-1-git-send-email-mst@redhat.com> <1451572003-2440-35-git-send-email-mst@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1451572003-2440-35-git-send-email-mst@redhat.com> Sender: linux-sh-owner@vger.kernel.org List-Archive: List-Post: To: "Michael S. Tsirkin" , linux-kernel@vger.kernel.org Cc: linux-mips@linux-mips.org, linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org, Peter Zijlstra , virtualization@lists.linux-foundation.org, "H. Peter Anvin" , sparclinux@vger.kernel.org, Boris Ostrovsky , linux-arch@vger.kernel.org, linux-s390@vger.kernel.org, Arnd Bergmann , x86@kernel.org, xen-devel@lists.xenproject.org, Ingo Molnar , linux-xtensa@linux-xtensa.org, user-mode-linux-devel@lists.sourceforge.net, Stefano Stabellini , adi-buildroot-devel@lists.sourceforge.net, Thomas Gleixner , linux-metag@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Andrew Cooper , David Vrabel , linuxppc-dev@lists.ozlabs.org, David Miller List-ID: On 31/12/15 19:10, Michael S. Tsirkin wrote: > include/xen/interface/io/ring.h uses > full memory barriers to communicate with the other side. > > For guests compiled with CONFIG_SMP, smp_wmb and smp_mb > would be sufficient, so mb() and wmb() here are only needed if > a non-SMP guest runs on an SMP host. > > Switch to virt_xxx barriers which serve this exact purpose. Acked-by: David Vrabel David