From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dario Faggioli Subject: Re: [PATCH v3 1/6] VMX: Statically assign two PI hooks Date: Tue, 6 Sep 2016 10:42:31 +0200 Message-ID: <1473151351.19612.84.camel@citrix.com> References: <1472615791-8664-1-git-send-email-feng.wu@intel.com> <1472615791-8664-2-git-send-email-feng.wu@intel.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============8430173103863237810==" Return-path: In-Reply-To: <1472615791-8664-2-git-send-email-feng.wu@intel.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xen.org Sender: "Xen-devel" To: Feng Wu , xen-devel@lists.xen.org Cc: george.dunlap@eu.citrix.com, andrew.cooper3@citrix.com, kevin.tian@intel.com, jbeulich@suse.com List-Id: xen-devel@lists.xenproject.org --===============8430173103863237810== Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="=-85St4e4eQp/FoPQo0ZaA" --=-85St4e4eQp/FoPQo0ZaA Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Wed, 2016-08-31 at 11:56 +0800, Feng Wu wrote: > PI hooks: vmx_pi_switch_from() and vmx_pi_switch_to() are > needed even all the assigned devices were dettached from > the domain.=20 > maybe "are needed even when any previously passed through device is detached from the domain" (or something like that)? > We change the state of SN bit in these two > functions, and evaluate this bit in vmx_deliver_posted_intr() > when trying to deliver the interrupt in posted way via software. > The problem is if we deassign the hooks while the vCPU is runnable > in the runqueue with 'SN' set, all the furture notificaton event > will be suppressed. This patch makes these two hooks statically > assigned. >=20 Which, if SN is used only for controlling VT-d PI from passed thru devices does not sound like an issue to me. What I sort of get from the discussion you had with Jan, however, is that this is an issue, because SN is also used for other things, i.e., it is indeed useful even when there are no passed thru device, is that the case? If yes, I think this deserves at least a quick mention in the sentence above. Regards, Dario --=20 <> (Raistlin Majere) ----------------------------------------------------------------- Dario Faggioli, Ph.D, http://about.me/dario.faggioli Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK) --=-85St4e4eQp/FoPQo0ZaA Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAABCAAGBQJXzoF3AAoJEBZCeImluHPu5KkP/0wVhPT1V2QovRCVd8ZWZSeY e9D4WKBgQeLPYHT66D+4wL9w6o5TQkY73//ZlpKB4/jcw0oTATg4ti2xgUcwcJDb AmgqYbgDR5YtAydjZj0iga2hIAfQhnLssdva6PjWrWvJkE49wpyN1VWADmSjFQQ2 OudJaDZ+mxiwNEeMdburN5cf9tHUxakUYtSC3yJX2iI1Ut3x3lkDP8rZZjh+vE++ tfw2NUsjP5A9GJ7WSrEKuQLS7crImtOjD8lCQC3N/0OCvXzmtiZAwDx4lTke4Rh6 uYP454iPnhHHbNHKyri5xuqaVMV6WaBKGOm4ZzDgLh3QNN2iK7/oOe3BulzYmV0a ip5cSYCZt4mvtgIivytEQQ6QP18h9QXYYCxZo6HgOGFR1L7NABtjRFZB+KJd8iEk CeTtReaabMPPnJsV8lWF9088cn1RaQzL8Pn1QoluuGpnOsPqub3zDCuVPkBshn8D 8OtTkbwkmFatKj88oJ1Fw21VFBSWfLF7uZr2vncwX8IOP9l0k+Uq0mblSYFRdEcK HzBTEK7JbdmEOy4N+ulFz3N0xBAGJqcFiV8Ien6wejtHKLon1/cYgGzPRqrw+mWx mtClUR/PWQ3Nnb/klBCqxU+Wfst/Ps+WsGaI0kiVyt/Ok0ZiV7QzcXxvoMfsFTNa HD8QJWYavivrpgp8Kir5 =yhTa -----END PGP SIGNATURE----- --=-85St4e4eQp/FoPQo0ZaA-- --===============8430173103863237810== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: base64 Content-Disposition: inline X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18KWGVuLWRldmVs IG1haWxpbmcgbGlzdApYZW4tZGV2ZWxAbGlzdHMueGVuLm9yZwpodHRwczovL2xpc3RzLnhlbi5v cmcveGVuLWRldmVsCg== --===============8430173103863237810==--