From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751415Ab2GSQ7P (ORCPT ); Thu, 19 Jul 2012 12:59:15 -0400 Received: from mx1.redhat.com ([209.132.183.28]:32000 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750804Ab2GSQ7M (ORCPT ); Thu, 19 Jul 2012 12:59:12 -0400 Date: Thu, 19 Jul 2012 19:59:45 +0300 From: "Michael S. Tsirkin" To: Alex Williamson Cc: avi@redhat.com, gleb@redhat.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, jan.kiszka@siemens.com Subject: Re: [PATCH v5 0/4] kvm: level irqfd and new eoifd Message-ID: <20120719165944.GB17213@redhat.com> References: <20120716202711.1752.71007.stgit@bling.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120716202711.1752.71007.stgit@bling.home> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 16, 2012 at 02:33:38PM -0600, Alex Williamson wrote: > v5: > - irqfds now have a one-to-one mapping with eoifds to prevent users > from consuming all of kernel memory by repeatedly creating eoifds > from a single irqfd. > - implement a kvm_clear_irq() which does a test_and_clear_bit of > the irq_state, only updating the pic/ioapic if changes and allowing > the caller to know if anything was done. I added this onto the end > as it's essentially an optimization on the previous design. It's > hard to tell if there's an actual performance benefit to this. > - dropped eoifd gsi support patch as it was only an FYI. > > Thanks, > > Alex So 3/4, 4/4 are racy and I think you convinced me it's best to drop it for now. I hope that fact that we already scan all vcpus under spinlock for level interrupts is enough to justify adding a lock here. To summarize issues still outstanding with 1/2, 2/2: - source id lingering after irqfd was destroyed/deassigned prevents assigning a new irqfd - if same irqfd is deassigned and re-assigned, this seems to succeed but does not give any more EOIs - document that user needs to re-inject interrupts injected by level IRQFD after migration as they are cleared Hope this helps! > --- > > Alex Williamson (4): > kvm: Convert eoifd to use kvm_clear_irq > kvm: Create kvm_clear_irq() > kvm: KVM_EOIFD, an eventfd for EOIs > kvm: Extend irqfd to support level interrupts > > > Documentation/virtual/kvm/api.txt | 28 +++ > arch/x86/kvm/x86.c | 3 > include/linux/kvm.h | 18 ++ > include/linux/kvm_host.h | 16 ++ > virt/kvm/eventfd.c | 333 +++++++++++++++++++++++++++++++++++++ > virt/kvm/irq_comm.c | 78 +++++++++ > virt/kvm/kvm_main.c | 11 + > 7 files changed, 483 insertions(+), 4 deletions(-)