From mboxrd@z Thu Jan 1 00:00:00 1970 From: Scott Wood Subject: Re: [PATCH 2/2] kvm: powerpc: set cache coherency only for kernel managed pages Date: Thu, 18 Jul 2013 11:11:49 -0500 Message-ID: <1374163909.5357.3@snotra> References: <1374127456-9614-1-git-send-email-Bharat.Bhushan@freescale.com> <1374127456-9614-2-git-send-email-Bharat.Bhushan@freescale.com> <51E78A88.4000904@windriver.com> <6A3DF150A5B70D4F9B66A25E3F7C888D070D6AFF@039-SN2MPN1-013.039d.mgd.msft.net> <51E799D0.1030406@windriver.com> <6A3DF150A5B70D4F9B66A25E3F7C888D070D6DAB@039-SN2MPN1-013.039d.mgd.msft.net> <51E7A5A2.5040107@windriver.com> <6A3DF150A5B70D4F9B66A25E3F7C888D070D6E79@039-SN2MPN1-013.039d.mgd.msft.net> <51E7AD7F.5080004@windriver.com> <42B0AAD2-F16A-4931-9B84-284260E4B436@suse.de> <51E7BBCA.6020908@windriver.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; delsp=Yes; format=Flowed Content-Transfer-Encoding: 8BIT Cc: =?UTF-8?b?4oCcdGllanVuLmNoZW7igJ0=?= , Bhushan Bharat-R65777 , "kvm-ppc@vger.kernel.org" , "kvm@vger.kernel.org" , Wood Scott-B07421 To: Alexander Graf Return-path: Received: from mail-db9lp0252.outbound.messaging.microsoft.com ([213.199.154.252]:34688 "EHLO db9outboundpool.messaging.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932590Ab3GRQL5 convert rfc822-to-8bit (ORCPT ); Thu, 18 Jul 2013 12:11:57 -0400 In-Reply-To: (from agraf@suse.de on Thu Jul 18 05:00:42 2013) Content-Disposition: inline Sender: kvm-owner@vger.kernel.org List-ID: On 07/18/2013 05:00:42 AM, Alexander Graf wrote: > Now why is setting invalid flags a problem? If I understand Scott > correctly, it can break the host if you access certain host devices > with caching enabled. But to be sure I'd say we ask him directly :). The architecture makes it illegal to mix cacheable and cache-inhibited mappings to the same physical page. Mixing W or M bits is generally bad as well. I've seen it cause machine checks, error interrupts, etc. -- not just corrupting the page in question. -Scott From mboxrd@z Thu Jan 1 00:00:00 1970 From: Scott Wood Date: Thu, 18 Jul 2013 16:11:49 +0000 Subject: Re: [PATCH 2/2] kvm: powerpc: set cache coherency only for kernel managed pages Message-Id: <1374163909.5357.3@snotra> List-Id: References: <1374127456-9614-1-git-send-email-Bharat.Bhushan@freescale.com> <1374127456-9614-2-git-send-email-Bharat.Bhushan@freescale.com> <51E78A88.4000904@windriver.com> <6A3DF150A5B70D4F9B66A25E3F7C888D070D6AFF@039-SN2MPN1-013.039d.mgd.msft.net> <51E799D0.1030406@windriver.com> <6A3DF150A5B70D4F9B66A25E3F7C888D070D6DAB@039-SN2MPN1-013.039d.mgd.msft.net> <51E7A5A2.5040107@windriver.com> <6A3DF150A5B70D4F9B66A25E3F7C888D070D6E79@039-SN2MPN1-013.039d.mgd.msft.net> <51E7AD7F.5080004@windriver.com> <42B0AAD2-F16A-4931-9B84-284260E4B436@suse.de> <51E7BBCA.6020908@windriver.com> In-Reply-To: (from agraf@suse.de on Thu Jul 18 05:00:42 2013) MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Alexander Graf Cc: =?UTF-8?b?4oCcdGllanVuLmNoZW7igJ0=?= , Bhushan Bharat-R65777 , "kvm-ppc@vger.kernel.org" , "kvm@vger.kernel.org" , Wood Scott-B07421 On 07/18/2013 05:00:42 AM, Alexander Graf wrote: > Now why is setting invalid flags a problem? If I understand Scott > correctly, it can break the host if you access certain host devices > with caching enabled. But to be sure I'd say we ask him directly :). The architecture makes it illegal to mix cacheable and cache-inhibited mappings to the same physical page. Mixing W or M bits is generally bad as well. I've seen it cause machine checks, error interrupts, etc. -- not just corrupting the page in question. -Scott