From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: virtio-dev-return-7550-cohuck=redhat.com@lists.oasis-open.org Sender: List-Post: List-Help: List-Unsubscribe: List-Subscribe: Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id 74866985E55 for ; Wed, 15 Jul 2020 11:49:01 +0000 (UTC) Date: Wed, 15 Jul 2020 12:48:55 +0100 From: Stefan Hajnoczi Message-ID: <20200715114855.GF18817@stefanha-x1.localdomain> References: <87r1tdydpz.fsf@linaro.org> MIME-Version: 1.0 In-Reply-To: <87r1tdydpz.fsf@linaro.org> Subject: Re: [virtio-dev] On doorbells (queue notifications) Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="vA66WO2vHvL/CRSR" Content-Disposition: inline To: Alex =?iso-8859-1?Q?Benn=E9e?= Cc: virtio-dev@lists.oasis-open.org, Zha Bin , Jing Liu , Chao Peng List-ID: --vA66WO2vHvL/CRSR Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Jul 14, 2020 at 10:43:36PM +0100, Alex Benn=E9e wrote: > I'm slightly confused by the MSI terminology because this only seems to > be relevant for the PCI legacy interface and AFAICT only touch the > outgoing path in setup and del_vq. Do incoming MSI interrupts just get > mapped directly to the appropriate handler function to process the > queues or the config? When MSI is used the VIRTIO ISR register does not need to be read by the guest interrupt handler. > Finally I'm curious if this is just a problem avoided by the s390 > channel approach? Does the use of messages over a channel just avoid the > sort of bouncing back and forth that other hypervisors have to do when > emulating a device? What does "bouncing back and forth" mean exactly? Stefan --vA66WO2vHvL/CRSR Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEhpWov9P5fNqsNXdanKSrs4Grc8gFAl8O7ScACgkQnKSrs4Gr c8hEuQgAop36NaS2lIRkw3zhoKUKgopt6f8t35TnhvO6Abehb4mBHVWFyo1Rg/ga K3vmsF/y4nuUVojAUjkpZXjmKQbCHmZYD9OBpCbl0cd/InUK0nQd7ArLpx2yVFdo VBvtEwA6ClCAIByRVZRZvTL0Igy74+2xhJdvrPighO2T39D6uGTwJs0fnY6NPN9x pxwn4YmS2frfLl4b2hNjk8GgcznUxEXQL7UY36GQ2djlA0HSVycRJBgcaoobU8N+ sTl1BHPjktaeSghrUXAyymgSzV81ZpdsQVkpy0OpnCrPUU51haJzj0JvBLr0dJAi v5gO6KdVNQFGFgT9BHahJ+ek5dsCZQ== =PEWc -----END PGP SIGNATURE----- --vA66WO2vHvL/CRSR--