From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH] prepopulate guest pages after write-protecting Date: Sat, 05 Apr 2008 00:06:15 +0300 Message-ID: <47F69847.7090609@qumranet.com> References: <20080404175644.GA444@dmt> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel , Zdenek Kabelac To: Marcelo Tosatti Return-path: In-Reply-To: <20080404175644.GA444@dmt> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces@lists.sourceforge.net Errors-To: kvm-devel-bounces@lists.sourceforge.net List-Id: kvm.vger.kernel.org Marcelo Tosatti wrote: > Zdenek reported a bug where a looping "dmsetup status" eventually hangs > on SMP guests. > > The problem is that kvm_mmu_get_page() prepopulates the shadow MMU > before write protecting the guest page tables. By doing so, it leaves a > window open where the guest can mark a pte as present while the host has > shadow cached such pte as "notrap". Accesses to such address will fault > in the guest without the host having a chance to fix the situation. > Applied, thanks. Impressive catch. -- Any sufficiently difficult bug is indistinguishable from a feature. ------------------------------------------------------------------------- Check out the new SourceForge.net Marketplace. It's the best place to buy or sell services for just about anything Open Source. http://ad.doubleclick.net/clk;164216239;13503038;w?http://sf.net/marketplace