From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ingo Molnar Subject: Re: [PATCH] Enhance perf to collect KVM guest os statistics from host side Date: Mon, 22 Mar 2010 11:37:51 +0100 Message-ID: <20100322103751.GA3483@elte.hu> References: <1268717232.2813.36.camel@localhost> <1268969929.2813.184.camel@localhost> <20100319082122.GE12576@elte.hu> <20100319172903.GI13108@8bytes.org> <20100321184300.GB25922@elte.hu> <20100322101451.GK13108@8bytes.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "Zhang, Yanmin" , Peter Zijlstra , Avi Kivity , Sheng Yang , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Marcelo Tosatti , Jes Sorensen , Gleb Natapov , Zachary Amsden , zhiteng.huang@intel.com, Fr??d??ric Weisbecker , Arnaldo Carvalho de Melo To: oerg Roedel Return-path: Content-Disposition: inline In-Reply-To: <20100322101451.GK13108@8bytes.org> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org * oerg Roedel wrote: > > It can decide whether it exposes the files. Nor are there any "security > > issues" to begin with. > > I am not talking about security. [...] You were talking about security, in the portion of your mail that you snipped out, and which i replied to: > > 2. The guest can decide for its own if it want to pass this > > inforamtion to the host-perf. No security issues at all. I understood that portion to mean what it says: that your claim that your proposal 'has no security issues at all', in contrast to my suggestion. > [...] Security was sufficiently flamed about already. All i saw was my suggestion to allow a guest to securely (and scalably and conveniently) integrate/mount its filesystems to the host if both sides (both the host and the guest) permit it, to make it easier for instrumentation to pick up symbol details. I.e. if a guest runs then its filesystem may be present on the host side as: /guests/Fedora-G1/ /guests/Fedora-G1/proc/ /guests/Fedora-G1/usr/ /guests/Fedora-G1/.../ ( This feature would be configurable and would be default-off, to maintain the current status quo. ) i.e. it's a bit like sshfs or NFS or loopback block mounts, just in an integrated and working fashion (sshfs doesnt work well with /proc for example) and more guest transparent (obviously sshfs or NFS exports need per guest configuration), and lower overhead than sshfs/NFS - i.e. without the (unnecessary) networking overhead. That suggestion was 'countered' by an unsubstantiated claim by Anthony that this kind of usability feature would somehow be a 'security nighmare'. In reality it is just an incremental, more usable, faster and more guest-transparent form of what is already possible today via: - loopback mounts on host - NFS exports - SMB exports - sshfs - (and other mechanisms) I wish there was at least flaming about it - as flames tend to have at least some specifics in them. What i saw instead was a claim about a 'security nightmare', which was, when i asked for specifics, was followed by deafening silence. And you appear to have repeated that claim here, unwilling to back it up with specifics. Thanks, Ingo