From mboxrd@z Thu Jan 1 00:00:00 1970 From: Will Deacon Subject: Re: [PATCH 15/15] KVM: ARM: Guest wait-for-interrupts (WFI) support Date: Tue, 25 Sep 2012 18:04:23 +0100 Message-ID: <20120925170423.GG28728@mudshark.cambridge.arm.com> References: <20120915153359.21241.86002.stgit@ubuntu> <20120915153605.21241.75455.stgit@ubuntu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "kvm@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "kvmarm@lists.cs.columbia.edu" To: Christoffer Dall Return-path: Received: from cam-admin0.cambridge.arm.com ([217.140.96.50]:44951 "EHLO cam-admin0.cambridge.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756654Ab2IYREf (ORCPT ); Tue, 25 Sep 2012 13:04:35 -0400 Content-Disposition: inline In-Reply-To: <20120915153605.21241.75455.stgit@ubuntu> Sender: kvm-owner@vger.kernel.org List-ID: On Sat, Sep 15, 2012 at 04:36:05PM +0100, Christoffer Dall wrote: > From: Christoffer Dall > > When the guest executes a WFI instruction the operation is trapped to > KVM, which emulates the instruction in software. There is no correlation > between a guest executing a WFI instruction and actually putting the > hardware into a low-power mode, since a KVM guest is essentially a > process and the WFI instruction can be seen as 'sleep' call from this > process. Therefore, we block the vcpu when the guest excecutes a wfi > instruction and the IRQ or FIQ lines are not raised. > > When an interrupt comes in through KVM_IRQ_LINE (see previous patch) we > signal the VCPU thread and unflag the VCPU to no longer wait for > interrupts. Seems a bit strange tagging this small addition on the end of this series. Can you merge it in with the rest? Will