From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kiszka Subject: Re: [PATCH 0/4 v9] MSI-X MMIO support for KVM Date: Tue, 06 Sep 2011 10:49:40 +0200 Message-ID: <4E65DEA4.8070203@siemens.com> References: <1298019193-12742-1-git-send-email-sheng@linux.intel.com> <20110222180858.GA5784@amt.cnet> <4E5F6C20.7020701@siemens.com> <4E65D149.1070807@redhat.com> <20110906081247.GE13286@redhat.com> <4E65DB89.6020909@siemens.com> <1315298760.2615.2.camel@sasha> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: "Michael S. Tsirkin" , Avi Kivity , Marcelo Tosatti , "kvm@vger.kernel.org" , Alex Williamson To: Sasha Levin Return-path: Received: from goliath.siemens.de ([192.35.17.28]:17391 "EHLO goliath.siemens.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753791Ab1IFIts (ORCPT ); Tue, 6 Sep 2011 04:49:48 -0400 In-Reply-To: <1315298760.2615.2.camel@sasha> Sender: kvm-owner@vger.kernel.org List-ID: On 2011-09-06 10:46, Sasha Levin wrote: > On Tue, 2011-09-06 at 10:36 +0200, Jan Kiszka wrote: >> On 2011-09-06 10:12, Michael S. Tsirkin wrote: >>> On Tue, Sep 06, 2011 at 10:52:41AM +0300, Avi Kivity wrote: >>>>> >>>>> BTW, the same is also true for that optional per-vector masking of >>>>> legacy MSI. Are there devices in the field that actually support this? I >>>>> haven't found one so far and tend to consider this feature not worth >>>>> implementing. >>>> >>>> Don't know. I don't like implementing features on the basis of bug >>>> reports, though. On the other hand we can't really test it without >>>> a real device. >>> >>> Linux will use this capability if present. So >>> we could add support for an emulated device (e.g. e1000), >>> then test with nested virt once iommu emulation lands :) >> >> Yeah, would be kind of cool. Still, I would feel better having it tested >> against a real silicon as well. Also to prove that there is a real need. >> >> So, in case someone stumbles for such a device (bit 8 set in MSI control >> word), please let us know! > > Doesn't any device that supports MSI-X supports per-vector masking? > >>>From the spec: > > "MSI and MSI-X each support per-vector masking. Per-vector masking is an > optional extension to MSI, and a standard feature with MSI-X" Right, but the cap flag still has to be set. Do you have any MSI-X device in reach? Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux