From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kiszka Subject: Re: [PATCH v2 4/4] KVM: Allow host IRQ sharing for passed-through PCI 2.3 devices Date: Tue, 02 Nov 2010 20:30:25 +0100 Message-ID: <4CD066D1.4050803@siemens.com> References: <70406157f1f29ade425369f82310a3963f0d0e97.1288712958.git.jan.kiszka@siemens.com> <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> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Avi Kivity , Marcelo Tosatti , kvm , Alex Williamson To: "Michael S. Tsirkin" Return-path: Received: from goliath.siemens.de ([192.35.17.28]:20316 "EHLO goliath.siemens.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753073Ab0KBTao (ORCPT ); Tue, 2 Nov 2010 15:30:44 -0400 In-Reply-To: <20101102185428.GD2341@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: 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 -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux