From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Subject: Re: [RFC PATCH 0/3] generic hypercall support Date: Fri, 8 May 2009 00:11:52 +0200 Message-ID: <200905080011.52958.arnd@arndb.de> References: <4A031471.7000406@novell.com> <4A034F0E.6010603@gmail.com> <20090507215712.GI3036@sequoia.sous-sol.org> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Gregory Haskins , Gregory Haskins , Avi Kivity , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Anthony Liguori , Benjamin Herrenschmidt To: Chris Wright Return-path: Received: from moutng.kundenserver.de ([212.227.126.187]:56644 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751731AbZEGWNI convert rfc822-to-8bit (ORCPT ); Thu, 7 May 2009 18:13:08 -0400 In-Reply-To: <20090507215712.GI3036@sequoia.sous-sol.org> Content-Disposition: inline Sender: kvm-owner@vger.kernel.org List-ID: On Thursday 07 May 2009, Chris Wright wrote: >=20 > > Chris, is that issue with the non ioread/iowrite access of a mangle= d > > pointer still an issue here? =A0I would think so, but I am a bit fu= zzy on > > whether there is still an issue of non-wrapped MMIO ever occuring. >=20 > Arnd was saying it's a bug for other reasons, so perhaps it would wor= k > out fine. Well, maybe. I only said that __raw_writel and pointer dereference is bad, but not writel. IIRC when we had that discussion about io-workarounds on powerpc, the outcome was that passing an IORESOURCE_MEM resource into pci_iomap must still result in something that can be passed into writel in additi= on to iowrite32, while an IORESOURCE_IO resource may or may not be valid f= or writel and/or outl. Unfortunately, this means that either readl/writel needs to be adapted in some way (e.g. the address also ioremapped to the mangled pointer) or the mechanism will be limited to I/O space accesses. Maybe BenH remembers the details better than me. Arnd <><