From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=38902 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1OY1Iw-0001jJ-UT for qemu-devel@nongnu.org; Sun, 11 Jul 2010 14:31:08 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1OY1Iv-0000Fp-L2 for qemu-devel@nongnu.org; Sun, 11 Jul 2010 14:31:06 -0400 Received: from mx1.redhat.com ([209.132.183.28]:45021) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1OY1Iv-0000Fe-B7 for qemu-devel@nongnu.org; Sun, 11 Jul 2010 14:31:05 -0400 Message-ID: <4C3A0DE3.8010806@redhat.com> Date: Sun, 11 Jul 2010 21:30:59 +0300 From: Avi Kivity MIME-Version: 1.0 References: <20100711180910.20121.93313.stgit@localhost6.localdomain6> <20100711180936.20121.35376.stgit@localhost6.localdomain6> <4C3A09F3.8010304@redhat.com> <1278872784.20397.18.camel@x201> In-Reply-To: <1278872784.20397.18.camel@x201> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Subject: [Qemu-devel] Re: [RFC PATCH 4/5] APIC/IOAPIC EOI callback List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alex Williamson Cc: chrisw@redhat.com, mst@redhat.com, qemu-devel@nongnu.org, kvm@vger.kernel.org, pugs@cisco.com On 07/11/2010 09:26 PM, Alex Williamson wrote: > On Sun, 2010-07-11 at 21:14 +0300, Avi Kivity wrote: > >> On 07/11/2010 09:09 PM, Alex Williamson wrote: >> >>> For device assignment, we need to know when the VM writes an end >>> of interrupt to the APIC, which allows us to de-assert the interrupt >>> line and clear the DisINTx bit. Add a new wrapper for ioapic >>> generated interrupts with a callback on eoi and create an interface >>> for drivers to be notified on eoi. >>> >>> >> You aren't going to get this with kvm's in-kernel irqchip, so we need a >> new interface there. >> > Registering an eventfd for the eoi seems like a reasonable alternative. > I'm worried about that racing (with what?) > I also need to figure out how to avoid bouncing the vfio interrupt > events through qemu, but it's a functional start. Thanks, > I thought the scheduler has/wants to have something that moves the irq to whatever thread it wakes up. With irqfd, it would flow naturally. -- I have a truly marvellous patch that fixes the bug which this signature is too narrow to contain.