From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kiszka Subject: Re: KVM handling external interrupts Date: Thu, 07 Jun 2012 13:40:57 +0200 Message-ID: <4FD09349.6090305@web.de> References: <4FD062BC.5090703@web.de> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enigE44E54ADA1799F0005A4780E" Cc: Alex Landau , Dan Tsafrir , sheng qiu , kvm , Muli Ben-Yehuda , Nadav Har'El , Nadav Amit To: Abel Gordon Return-path: Received: from mout.web.de ([212.227.17.12]:57966 "EHLO mout.web.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752665Ab2FGLlD (ORCPT ); Thu, 7 Jun 2012 07:41:03 -0400 In-Reply-To: Sender: kvm-owner@vger.kernel.org List-ID: This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enigE44E54ADA1799F0005A4780E Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable On 2012-06-07 11:55, Abel Gordon wrote: > Security holes: not if you are OK with the threat model we describe in = the > paper Back to this: I don't get your threat model completely. How should the guest be able to manipulate the shadow IDT if we a) mark it read-only in the host's page table that maps the guest physical memory and b) prevent via the IOMMU that any assigned devices can address this page via DMA? But even if we consider the IDT unsafe, what does that IDT limiting buy us? The guest can still mask interrupts above that limit via cli, no? Also, unless I misunderstood your suggestions, I wouldn't try to run normal interrupt handlers in NMI context. That's asking for lots of troubles or lots of code changes. So the only measures that save us from CPU hogging guests are the preemption timer and kicking via NMI. Or what am I missing? Jan --------------enigE44E54ADA1799F0005A4780E Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.16 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAk/Qk0kACgkQitSsb3rl5xSLXgCfYNq8fqc7tSIcKrsuFCYbTtUn 900AmwQkD734JrRZf5GNBpT0fIgiYnK2 =H5DN -----END PGP SIGNATURE----- --------------enigE44E54ADA1799F0005A4780E--