From owner-freebsd-virtualization@FreeBSD.ORG Mon Aug 26 11:38:14 2013 Return-Path: Delivered-To: freebsd-virtualization@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTP id 38344171 for ; Mon, 26 Aug 2013 11:38:14 +0000 (UTC) (envelope-from gofd-freebsd-virtualization@m.gmane.org) Received: from plane.gmane.org (plane.gmane.org [80.91.229.3]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id E4F9F2BD6 for ; Mon, 26 Aug 2013 11:38:13 +0000 (UTC) Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1VDv7Z-0006TP-96 for freebsd-virtualization@freebsd.org; Mon, 26 Aug 2013 13:38:09 +0200 Received: from lara.cc.fer.hr ([161.53.72.113]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Mon, 26 Aug 2013 13:38:09 +0200 Received: from ivoras by lara.cc.fer.hr with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Mon, 26 Aug 2013 13:38:09 +0200 X-Injected-Via-Gmane: http://gmane.org/ To: freebsd-virtualization@freebsd.org From: Ivan Voras Subject: Re: CFT: nested page table integration with amd64/pmap Date: Mon, 26 Aug 2013 13:37:57 +0200 Lines: 56 Message-ID: References: <5217DAB2.3020204@freebsd.org> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="----enig2NLPFFCTIKSWKSOWPVILW" X-Complaints-To: usenet@ger.gmane.org X-Gmane-NNTP-Posting-Host: lara.cc.fer.hr User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:17.0) Gecko/20130322 Thunderbird/17.0.4 In-Reply-To: <5217DAB2.3020204@freebsd.org> X-Enigmail-Version: 1.5.1 X-BeenThere: freebsd-virtualization@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: "Discussion of various virtualization techniques FreeBSD supports." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 26 Aug 2013 11:38:14 -0000 This is an OpenPGP/MIME signed message (RFC 4880 and 3156) ------enig2NLPFFCTIKSWKSOWPVILW Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 23/08/2013 23:57, Peter Grehan wrote: >> I always wondered about virtualization environments which have pageabl= e >> guest memory - how does the guest kernel handle situations where it >> really needs non-pageable memory? Does is simply "not care" because fo= r >> it the memory access looks just like it isn't paged but is simply very= , >> very slow? >=20 > Yes - from the guest's point of view, what it thinks is physical memor= y > appears wired. >=20 >> What about time-sensitive situations (like the originally >> mentioned PCI-passthrough)? >=20 > PCI passthru is a special case since the h/w requires that the target > of a DMA transfer is present - there is currently no way for the IOMMU > to generate the equivalent of page faults. So, for PCI passthru, all of= > guest memory has to be wired host memory. >=20 > For time-sensitive situations, there's not a lot of options other than= > forcing guest memory to be wired, since there isn't visibility into the= > host without having o/s-specific "tools" that could communicate this > information to the hypervisor. Ok, that is how I understood it also, but I thought that maybe there was some way of telling which guest memory belongs to the kernel and only wire those pages. ------enig2NLPFFCTIKSWKSOWPVILW Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.19 (FreeBSD) Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iEYEARECAAYFAlIbPhUACgkQ/QjVBj3/HSzWjwCfcnzArU4Z2B5YSuliqK9/H4Ji GucAoJyfhU5Izyns6FiJDZWuRG66Ki0h =MtW9 -----END PGP SIGNATURE----- ------enig2NLPFFCTIKSWKSOWPVILW--