From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dario Faggioli Subject: Re: Possible bug on ARM with irq passthrough Date: Wed, 5 Jul 2017 15:42:02 +0200 Message-ID: <1499262122.7486.14.camel@citrix.com> References: <067da1b2-66fa-d57d-f278-c020401d1533@arm.com> <4a6da40c-84f9-6be1-1ecd-2b231352aa83@fer.hr> <78bd7ab8-23bf-637b-6ec8-ea777e3623ee@arm.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============6332097670197790775==" Return-path: In-Reply-To: <78bd7ab8-23bf-637b-6ec8-ea777e3623ee@arm.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xen.org Sender: "Xen-devel" To: Julien Grall , Ivan Pavic , "xen-devel@lists.xen.org" , Stefano Stabellini List-Id: xen-devel@lists.xenproject.org --===============6332097670197790775== Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="=-O7rK6vDE8cyhAw8ndaAc" --=-O7rK6vDE8cyhAw8ndaAc Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Wed, 2017-07-05 at 13:55 +0100, Julien Grall wrote: >=20 > If you got a message in the former, but not the latter. Then you hit > the=C2=A0 > bug described in my previous e-mail. >=20 > This would happen if some of the pCPUs are idle states (using wfi).r. > The main difference between credit1 and credit2 (I am not sure for > RTDS)=C2=A0 > is there are IPI traffic with credit1 on idle pCPU because of the > ticker. >=20 Exactly, It's a bug in RCU, which happens to be exposed (or, at least, it turns out to be this severe) only by certain schedulers, and only on ARM. I think it makes sense that this is visible with RTDS as well, because it also does not have a periodic timer. Dario --=20 <> (Raistlin Majere) ----------------------------------------------------------------- Dario Faggioli, Ph.D, http://about.me/dario.faggioli Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK) --=-O7rK6vDE8cyhAw8ndaAc 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 iQIcBAABCAAGBQJZXOyrAAoJEBZCeImluHPuHpoP/0MRlmjMNAWPwc22dZRO7B+f 1FRiL1Z39eBWhYzFqCF780svNCBVzAwjXfMElHm0Q/S6646sMJqvWfNauev1R3qE g3gQIwm/dtGHpyiG+4hiS0Fd2CuoC8RXp/HaleYpbXZYwjTd4OlDAKSaYfS0GigZ uENlexyzqGeEJPXXd5qZsX4Ryq8EvLghxEmI7sW9tEH8HfG/elRAiHmeAi93vAuu aqECAmqWiEHc2govYDLUbqYiOHm9IqqZEu4Kra3PfPz1qTQPskIMeX1jOuhCtUD1 b+77LJsgKsa2CLBiB6aQ1iULCDqk7zBWdTnyyFEVwvbL/dXOTC9QLtSQh2r2wmyC 2SR+dYGtMp+yfLC229QIcQ3MIvBASjh36ct6P7E9nk8zbQQiiaqOK0klxT5uRamI OUOOhMggdasOYCv29Zws18CtrgA3WzrPnNYqupzZezIkSY3Uj3JONb9Fsb7lgUs5 0qaI1MQ8L0DW/FutDG0s6YeNeHiv607gVF2VXPR9s1wEB5PpUWZU33QBgddbuxVK QylxYMhMhucawyLGyNWJQChDQFfn785+J49k3EcA+94pNtF4oMWB6a2iuLdTiHpQ hHnZyR/Q7HcrNoZ9+lHDZDEa/huVbUjtIIHdH6jUmgVqVJeRZnzI917PPcLpeI3H OalDd75PTMgjlVGA1KVL =6Ez8 -----END PGP SIGNATURE----- --=-O7rK6vDE8cyhAw8ndaAc-- --===============6332097670197790775== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: base64 Content-Disposition: inline X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18KWGVuLWRldmVs IG1haWxpbmcgbGlzdApYZW4tZGV2ZWxAbGlzdHMueGVuLm9yZwpodHRwczovL2xpc3RzLnhlbi5v cmcveGVuLWRldmVsCg== --===============6332097670197790775==--