From mboxrd@z Thu Jan 1 00:00:00 1970 From: Will Deacon Subject: Re: [kvmarm] [PATCH v2 08/10] ARM: KVM: VGIC initialisation code Date: Wed, 3 Oct 2012 11:02:05 +0100 Message-ID: <20121003100205.GL22445@mudshark.cambridge.arm.com> References: <20121001091244.49503.96318.stgit@ubuntu> <20121001091426.49503.94722.stgit@ubuntu> <20121002092412.GB8847@mudshark.cambridge.arm.com> <20121002192806.GC20411@mudshark.cambridge.arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Christoffer Dall , Marc Zyngier , "" , "" , "" To: Peter Maydell Return-path: Received: from cam-admin0.cambridge.arm.com ([217.140.96.50]:44510 "EHLO cam-admin0.cambridge.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753562Ab2JCKDK (ORCPT ); Wed, 3 Oct 2012 06:03:10 -0400 Content-Disposition: inline In-Reply-To: Sender: kvm-owner@vger.kernel.org List-ID: On Tue, Oct 02, 2012 at 08:45:54PM +0100, Peter Maydell wrote: > On 2 October 2012 20:28, Will Deacon wrote: > > On Tue, Oct 02, 2012 at 07:31:43PM +0100, Peter Maydell wrote: > >> We probably want to be passing in the "base of the cpu-internal > >> peripherals", rather than "base of the GIC" specifically. For the > >> A15 these are the same thing, but that's not inherent [compare the > >> A9 which has more devices at fixed offsets from a configurable > >> base address]. > > > > If you do that, userspace will need a way to probe the emulated CPU so > > that is knows exactly which set of peripherals there are and which ones it > > needs to emulate. This feels pretty nasty, given that the vgic is handled > > more or less completely by the kernel-side of things. > > Userspace knows what the emulated CPU is because it tells the > kernel which CPU to provide -- the kernel can say "yes" or "no" but > it can't provide a different CPU to the one we ask for, or > one with bits mising... Aha, ok, I didn't realise that's how it works. Does userspace just pass the CPUID or is there an identifier provided by kvm? /me jumps back into the code. Thanks, Will