From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gregory Haskins Subject: Re: [RFC PATCH 0/3] generic hypercall support Date: Thu, 07 May 2009 14:16:59 -0400 Message-ID: <4A03259B.3050500@gmail.com> References: <20090505132005.19891.78436.stgit@dev.haskins.net> <4A0040C0.1080102@redhat.com> <4A0041BA.6060106@novell.com> <4A004676.4050604@redhat.com> <4A0049CD.3080003@gmail.com> <20090505231718.GT3036@sequoia.sous-sol.org> <4A010927.6020207@novell.com> <20090506072212.GV3036@sequoia.sous-sol.org> <4A018DF2.6010301@novell.com> <20090506160712.GW3036@sequoia.sous-sol.org> <4A031471.7000406@novell.com> <4A0322F1.2000905@redhat.com> <4A032390.6030100@gmail.com> <4A032472.4030106@redhat.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enigEF03B0BB0D1BADDCD9123E37" Cc: Gregory Haskins , Chris Wright , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Anthony Liguori To: Avi Kivity Return-path: Received: from yw-out-2324.google.com ([74.125.46.29]:16118 "EHLO yw-out-2324.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751123AbZEGSRI (ORCPT ); Thu, 7 May 2009 14:17:08 -0400 In-Reply-To: <4A032472.4030106@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enigEF03B0BB0D1BADDCD9123E37 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Avi Kivity wrote: > Gregory Haskins wrote: >>> What do you think of my mmio hypercall? That will speed up all mmio >>> to be as fast as a hypercall, and then we can use ordinary mmio/pio >>> writes to trigger things. >>> >>> =20 >> I like it! >> >> Bigger question is what kind of work goes into making mmio a pv_op (or= >> is this already done)? >> >> =20 > > Looks like it isn't there. But it isn't any different than set_pte - > convert a write into a hypercall. > > I guess technically mmio can just be a simple access of the page which would be problematic to trap locally without a PF. However it seems that most mmio always passes through a ioread()/iowrite() call so this is perhaps the hook point. If we set the stake in the ground that mmios that go through some other mechanism like PFs can just hit the "slow path" are an acceptable casualty, I think we can make that work. Thoughts? -Greg --------------enigEF03B0BB0D1BADDCD9123E37 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG/MacGPG2 v2.0.11 (Darwin) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iEYEARECAAYFAkoDJZsACgkQP5K2CMvXmqEhvgCdH6VbUWBm2NoOdFRHfBSZyNKD HhoAn0aykkwtIc0RDqzqUWXqGi7MvIIV =bT5l -----END PGP SIGNATURE----- --------------enigEF03B0BB0D1BADDCD9123E37--