From mboxrd@z Thu Jan 1 00:00:00 1970 From: Scott Wood Date: Tue, 25 Oct 2011 20:38:58 +0000 Subject: Re: Mapping of Shared Page in e500 Powerpc kvm Message-Id: <4EA71E62.2090302@freescale.com> List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: kvm-ppc@vger.kernel.org On 10/23/2011 08:45 AM, Aashish Mittal wrote: > Hi > > I'm working on powerpc e500 machine (Freescale P2020RDB machine) and > using the paravirtualization guest support available inside kvm and wanted > to some bookkeeping of my own on the shared page and from what i > understood is that a single tlb entry is reserved for the shared page > (magic page) when running the guest which is never preempted or flushed > but when i tried printing out the dtlb misses on this shared page it show > me a large number of dtlb misses on this shared page which means that > this page is being preempted or flushed out in some way . Can someone pleas > e clarify this situation if i'm understanding something wrong or is it a bug ? What kernel are you running, and how many is "a large number"? The magic page TLB entry will need to be reloaded if the shadow PID gets invalidated, another guest gets scheduled on that CPU, or if something like hugetlbfs steps on that TLB entry. If you're running a kernel that predates shadow PID support, it will be invalidated (along with everything else in the TLB) whenever you schedule out or change guest execution mode . -Scott