From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PATCH v2 4/4] KVM: Allow host IRQ sharing for passed-through PCI 2.3 devices Date: Tue, 2 Nov 2010 22:05:52 +0200 Message-ID: <20101102200552.GA3692@redhat.com> References: <20101102174149.GC1304@redhat.com> <4CD050BE.5010703@siemens.com> <20101102182401.GB1939@redhat.com> <4CD05B2E.1050005@siemens.com> <4CD05CF5.1040203@siemens.com> <4CD05DBB.5010005@siemens.com> <20101102185428.GD2341@redhat.com> <4CD066D1.4050803@siemens.com> <20101102195307.GB3228@redhat.com> <4CD06D6C.3030009@web.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Avi Kivity , Marcelo Tosatti , kvm , Alex Williamson To: Jan Kiszka Return-path: Received: from mx1.redhat.com ([209.132.183.28]:15489 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751591Ab0KBUFy (ORCPT ); Tue, 2 Nov 2010 16:05:54 -0400 Content-Disposition: inline In-Reply-To: <4CD06D6C.3030009@web.de> Sender: kvm-owner@vger.kernel.org List-ID: On Tue, Nov 02, 2010 at 08:58:36PM +0100, Jan Kiszka wrote: > Am 02.11.2010 20:53, Michael S. Tsirkin wrote: > > On Tue, Nov 02, 2010 at 08:30:25PM +0100, Jan Kiszka wrote: > >> Am 02.11.2010 19:54, Michael S. Tsirkin wrote: > >>> On Tue, Nov 02, 2010 at 07:51:39PM +0100, Jan Kiszka wrote: > >>>> Am 02.11.2010 19:48, Jan Kiszka wrote: > >>>>> Am 02.11.2010 19:40, Jan Kiszka wrote: > >>>>>>>>>> @@ -199,6 +343,13 @@ static void kvm_free_assigned_device(struct kvm *kvm, > >>>>>>>>>> > >>>>>>>>>> pci_reset_function(assigned_dev->dev); > >>>>>>>>>> > >>>>>>>>>> + /* > >>>>>>>>>> + * Unmask the IRQ at PCI level once the reset is done - the next user > >>>>>>>>>> + * may not expect the IRQ being masked. > >>>>>>>>>> + */ > >>>>>>>>>> + if (assigned_dev->pci_2_3) > >>>>>>>>>> + pci_2_3_irq_unmask(assigned_dev->dev); > >>>>>>>>>> + > >>>>>>>>> > >>>>>>>>> Doesn't pci_reset_function clear mask bit? It seems to ... > >>>>>>>> > >>>>>>>> I was left with non-functional devices for the host here if I was not > >>>>>>>> doing this. Need to recheck, but I think it was required. > >>>>>>> > >>>>>>> Interesting. Could you check why please? > >>>>>>> > >>>>>> > >>>>>> Can't reproduce anymore. This was early code, maybe affected by some > >>>>>> bits or buts that no longer exist. > >>>>>> > >>>>>> Spec says it's cleared on reset, so I removed those lines now. > >>>>>> > >>>>> > >>>>> Hmpf, it just happened again: Guest was using my ath9k, I killed the > >>>>> guest, lspci says DisINTx+. Strange. Is anyone (qemu) restoring the > >>>>> config space after the reset, bringing the disable bit back? > >>>> > >>>> Or does the kernel cache the control word? > >>>> > >>>> Jan > >>> > >>> Maybe it does, need to dig in drivers/pci. If it does this > >>> might have other implications. > >> > >> OK, that mystery is resolved now: pci_reset_function saves & restores > >> the device state. > >> > >> Jan > > > > Aha. I wonder what other state we need to clear. > > > > Maybe just save/restore before/after assigning the device? > > Jan > Yea. Sounds good. -- MST