From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:46960) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1X9rOt-0004T4-6x for qemu-devel@nongnu.org; Wed, 23 Jul 2014 03:55:54 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1X9rOl-0005NW-Tf for qemu-devel@nongnu.org; Wed, 23 Jul 2014 03:55:47 -0400 Received: from mout.web.de ([212.227.17.11]:57456) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1X9rOl-0005NH-IS for qemu-devel@nongnu.org; Wed, 23 Jul 2014 03:55:39 -0400 Message-ID: <53CF6A69.8030402@web.de> Date: Wed, 23 Jul 2014 09:55:21 +0200 From: Jan Kiszka MIME-Version: 1.0 References: <53CAA314.10005@web.de> <20140720194842.GA2536@redhat.com> <53CC3866.3010605@web.de> <20140720210301.GA3997@redhat.com> <53CC3CE6.7020004@web.de> <20140722190612.GC9881@redhat.com> In-Reply-To: <20140722190612.GC9881@redhat.com> Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="x8GsK7LI57wvB2xA9hIPc3fcCT4sicBrL" Subject: Re: [Qemu-devel] [PATCH] pci: Don't deliver MSI/MSI-X messages if bus master support is off List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Michael S. Tsirkin" Cc: qemu-devel This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --x8GsK7LI57wvB2xA9hIPc3fcCT4sicBrL Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable On 2014-07-22 21:06, Michael S. Tsirkin wrote: > On Mon, Jul 21, 2014 at 12:04:22AM +0200, Jan Kiszka wrote: >> On 2014-07-20 23:03, Michael S. Tsirkin wrote: >>> On Sun, Jul 20, 2014 at 11:45:10PM +0200, Jan Kiszka wrote: >>>> On 2014-07-20 21:48, Michael S. Tsirkin wrote: >>>>> On Sat, Jul 19, 2014 at 06:55:48PM +0200, Jan Kiszka wrote: >>>>>> From: Jan Kiszka >>>>>> >>>>>> The spec says (and real HW confirms this) that, if the bus master = bit >>>>>> is 0, the device will not generate any PCI accesses. MSI and MSI-X= >>>>>> messages fall among these. >>>>>> >>>>>> Signed-off-by: Jan Kiszka >>>>> >>>>> I guess an alternative is for callers to check before >>>>> invoking msi_notify. Please note is this is only option >>>>> when using e.g. irqfd, so this has some advantages. >>>>> Is there a specific device that is affected by this? >>>>> I would expect drivers to disable msi before clearing >>>>> bus master bit ... >>>> >>>> This is about emulating conforming behaviour without touching each a= nd >>>> every device. I stumbled over this while playing with emulated vs. r= eal >>>> Intel HDA. >>> >>> Right so that's my question. >>> How did you hit it? With a custom driver? >> >> So to say: with a hand full lines of code to tickle some MSI event out= >> of that device for testing purposes. >> >>> Doesn't regulat driver disable MSI? >> >> Sure. This is not fixing a regular's driver problem. It's a behavioral= >> correction for faulty corner cases. >> >> Jan >=20 > OK based on this I think this is not 2.1 material. Agree? Agree. I'll look into Paolo's suggestion how to model this asap. Jan --x8GsK7LI57wvB2xA9hIPc3fcCT4sicBrL Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.19 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iEYEARECAAYFAlPPamwACgkQitSsb3rl5xQzpwCg546QNcR8nAtB7PPTduzJ83tG NMYAnRx8KCiT/26LEveaLYjuL8rk/VME =17od -----END PGP SIGNATURE----- --x8GsK7LI57wvB2xA9hIPc3fcCT4sicBrL--