From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Gibson Subject: Re: [kvm-unit-tests PATCH 11/14] powerpc/ppc64: add rtas_power_off Date: Tue, 4 Aug 2015 14:09:52 +1000 Message-ID: <20150804040952.GE3080@voom.redhat.com> References: <1438612891-3718-1-git-send-email-drjones@redhat.com> <1438612891-3718-12-git-send-email-drjones@redhat.com> <55BFA001.6070900@redhat.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="+ts6NCQ4mrNQIV8p" Cc: Andrew Jones , kvm@vger.kernel.org, kvm-ppc@vger.kernel.org, dgibson@redhat.com, agraf@suse.de, thuth@redhat.com, lvivier@redhat.com To: Paolo Bonzini Return-path: Received: from ozlabs.org ([103.22.144.67]:42748 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752174AbbHDEUq (ORCPT ); Tue, 4 Aug 2015 00:20:46 -0400 Content-Disposition: inline In-Reply-To: <55BFA001.6070900@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: --+ts6NCQ4mrNQIV8p Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Aug 03, 2015 at 07:08:17PM +0200, Paolo Bonzini wrote: >=20 >=20 > On 03/08/2015 16:41, Andrew Jones wrote: > > Add enough RTAS support to support power-off, and apply it to > > exit(). > >=20 > > Signed-off-by: Andrew Jones >=20 > Why not use virtio-mmio + testdev on ppc as well? Similar to how we're > not using PSCI on ARM or ACPI on x86. Strange as it seems, MMIO is actually a PITA for a simple pseries guest like this. Basically, you have to enable the MMU - which requires a whole bunch of setup - in order to perform cache-inhibited loads and stores, which is what you need for IO. There are hypercalls to sidestep this (H_LOGICAL_CI_LOAD and H_LOGICAL_CI_STORE), but having a hypercall and KVM exit for every IO access may be hideously slow. In early development we did have a hypercall mediated virtio model, but it was abandoned once we got PCI working. --=20 David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson --+ts6NCQ4mrNQIV8p Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBAgAGBQJVwDsQAAoJEGw4ysog2bOS24gP/1rhU7ExP+r2cMHc2Mwq3IDI oztiVn7ihV+aLfR44ftNOooOz1U4tc2zGy6Hb24XPFACohDzqgKNm0LZjrQsiEUI T7FZ+0CCi9N2Rc4lD3qXbrVI5UCkk7pyRW4eZF+9AXf0yJsF9IcbbuvVdTkdKE7p xkJ5rDoamQapTEU21qA/Gq1204Agxnvk6Gau8W7Vevlpc4JLrbK/zY3Dy+Po3bdN 8Hfdxp/8q+wMbnBJPzZvuOL91qT4Jf8nAdq5yiRzfbADyd7Z0Lrlywl52leVHZRg ENgq4HK+pa/KmQL1Hk+5uSQjoHxaReoo7TUZsl8IQZ238IGlGxnrdjiUQgGJXDCI eY9FF73v33u1LzwdJ5xhjzS1zyAKSZHff9VJKglFySJmizPEQAP0DqWZO1IqDnP3 UwIwPBvfrYGpBoaNKg5YjgQSKvor5Q6IsNbk+3Cr6Ayrwd02T+MnZrhbwQWv+D2j gXLDRIkGIUP6TcARpLmMDsl3HUd0Ny5ga7Q9LNAgmzUtrjRgS0feZfJTxh/r/2DI 6FSizvm0xdmjiMpxtYaImPvaY45JfuCDdNWuZkf+zWWCNBACBMpTr0wTLwzDF4VN qHAOi3foSfa51LlPhjUQkx/uC0uUrr6Kh7DjzBiEcnvFBmnW3OyfKeqggnyYQdh5 +kpeJruIsFbBf6Ft7zxL =jZHY -----END PGP SIGNATURE----- --+ts6NCQ4mrNQIV8p--