From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexander Graf Subject: Re: [PATCH 27/27] KVM: PPC: Add Documentation about PV interface Date: Sun, 4 Jul 2010 11:02:16 +0200 Message-ID: <02965CC4-D0E5-4689-8F39-0F9636B88B07@suse.de> References: <1277980982-12433-1-git-send-email-agraf@suse.de> <1277980982-12433-28-git-send-email-agraf@suse.de> <3085B58A-01A1-4B5C-A0E7-024DCFDFD4B2@suse.de> <20100702141003.75302a9a@schlenkerla.am.freescale.net> Mime-Version: 1.0 (Apple Message framework v1078) Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8BIT Cc: Hollis Blanchard , kvm-ppc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, KVM list , linuxppc-dev , Stuart Yoder , Dan Hettena , Jimi Xenidis To: Scott Wood Return-path: In-Reply-To: <20100702141003.75302a9a-1MYqz8GpK7RekFaExTCHk1jVikpgYyvb5NbjCUgZEJk@public.gmane.org> Sender: kvm-ppc-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: kvm.vger.kernel.org On 02.07.2010, at 21:10, Scott Wood wrote: > On Fri, 2 Jul 2010 20:47:44 +0200 > Alexander Graf wrote: > >> >> On 02.07.2010, at 19:59, Hollis Blanchard wrote: >> >>> [Resending...] >>> >>> Please reconcile this with >>> http://www.linux-kvm.org/page/PowerPC_Hypercall_ABI, which has been >>> discussed in the (admittedly closed) Power.org embedded hypervisor >>> working group. Bear in mind that other hypervisors are already >>> implementing the documented ABI, so if you have concerns, you should >>> probably raise them with that audience... >> >> We can not use sc with LV=1 because that would break the KVM in >> something else case which is KVM's strong point on PPC. > > The current proposal involves the hypervisor specifying the hcall opcode > sequence in the device tree -- to allow either "sc 1" or "sc 0 plus > magic GPR" depending on whether you've got the hardware hypervisor > feature (hereafter HHV). Ah right, so you can still trap a hypercall with HHV. Makes sense. > > With HHV, "sc 0 plus magic GPR" just doesn't work, since it won't trap > to the hypervisor. "sc 1 plus magic GPR" might be problematic on some > non-HHV implementations, especially if you *do* have HHV but the > non-HHV hypervisor is running as an HHV guest. Yes, that's why I need sc 0 plus magic GPR in r0 and r3 - to accomodate for all the non-HHV cases. And it would be clever to have a way to expose the same functionality when we do use the HHV features. So, is that draft available anywhere? The wiki page Hollis pointed to is very vague. Alex From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx2.suse.de (cantor2.suse.de [195.135.220.15]) by ozlabs.org (Postfix) with ESMTP id C8872B6F10 for ; Sun, 4 Jul 2010 19:02:23 +1000 (EST) Subject: Re: [PATCH 27/27] KVM: PPC: Add Documentation about PV interface Mime-Version: 1.0 (Apple Message framework v1078) Content-Type: text/plain; charset=us-ascii From: Alexander Graf In-Reply-To: <20100702141003.75302a9a@schlenkerla.am.freescale.net> Date: Sun, 4 Jul 2010 11:02:16 +0200 Message-Id: <02965CC4-D0E5-4689-8F39-0F9636B88B07@suse.de> References: <1277980982-12433-1-git-send-email-agraf@suse.de> <1277980982-12433-28-git-send-email-agraf@suse.de> <3085B58A-01A1-4B5C-A0E7-024DCFDFD4B2@suse.de> <20100702141003.75302a9a@schlenkerla.am.freescale.net> To: Scott Wood Cc: KVM list , kvm-ppc@vger.kernel.org, Dan Hettena , linuxppc-dev , Hollis Blanchard List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 02.07.2010, at 21:10, Scott Wood wrote: > On Fri, 2 Jul 2010 20:47:44 +0200 > Alexander Graf wrote: >=20 >>=20 >> On 02.07.2010, at 19:59, Hollis Blanchard wrote: >>=20 >>> [Resending...] >>>=20 >>> Please reconcile this with >>> http://www.linux-kvm.org/page/PowerPC_Hypercall_ABI, which has been >>> discussed in the (admittedly closed) Power.org embedded hypervisor >>> working group. Bear in mind that other hypervisors are already >>> implementing the documented ABI, so if you have concerns, you should >>> probably raise them with that audience... >>=20 >> We can not use sc with LV=3D1 because that would break the KVM in >> something else case which is KVM's strong point on PPC. >=20 > The current proposal involves the hypervisor specifying the hcall = opcode > sequence in the device tree -- to allow either "sc 1" or "sc 0 plus > magic GPR" depending on whether you've got the hardware hypervisor > feature (hereafter HHV). Ah right, so you can still trap a hypercall with HHV. Makes sense. >=20 > With HHV, "sc 0 plus magic GPR" just doesn't work, since it won't trap > to the hypervisor. "sc 1 plus magic GPR" might be problematic on some > non-HHV implementations, especially if you *do* have HHV but the > non-HHV hypervisor is running as an HHV guest. Yes, that's why I need sc 0 plus magic GPR in r0 and r3 - to accomodate = for all the non-HHV cases. And it would be clever to have a way to = expose the same functionality when we do use the HHV features. So, is that draft available anywhere? The wiki page Hollis pointed to is = very vague. Alex From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexander Graf Date: Sun, 04 Jul 2010 09:02:16 +0000 Subject: Re: [PATCH 27/27] KVM: PPC: Add Documentation about PV interface Message-Id: <02965CC4-D0E5-4689-8F39-0F9636B88B07@suse.de> List-Id: References: <1277980982-12433-1-git-send-email-agraf@suse.de> <1277980982-12433-28-git-send-email-agraf@suse.de> <3085B58A-01A1-4B5C-A0E7-024DCFDFD4B2@suse.de> <20100702141003.75302a9a@schlenkerla.am.freescale.net> In-Reply-To: <20100702141003.75302a9a-1MYqz8GpK7RekFaExTCHk1jVikpgYyvb5NbjCUgZEJk@public.gmane.org> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Scott Wood Cc: Hollis Blanchard , kvm-ppc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, KVM list , linuxppc-dev , Stuart Yoder , Dan Hettena , Jimi Xenidis On 02.07.2010, at 21:10, Scott Wood wrote: > On Fri, 2 Jul 2010 20:47:44 +0200 > Alexander Graf wrote: > >> >> On 02.07.2010, at 19:59, Hollis Blanchard wrote: >> >>> [Resending...] >>> >>> Please reconcile this with >>> http://www.linux-kvm.org/page/PowerPC_Hypercall_ABI, which has been >>> discussed in the (admittedly closed) Power.org embedded hypervisor >>> working group. Bear in mind that other hypervisors are already >>> implementing the documented ABI, so if you have concerns, you should >>> probably raise them with that audience... >> >> We can not use sc with LV=1 because that would break the KVM in >> something else case which is KVM's strong point on PPC. > > The current proposal involves the hypervisor specifying the hcall opcode > sequence in the device tree -- to allow either "sc 1" or "sc 0 plus > magic GPR" depending on whether you've got the hardware hypervisor > feature (hereafter HHV). Ah right, so you can still trap a hypercall with HHV. Makes sense. > > With HHV, "sc 0 plus magic GPR" just doesn't work, since it won't trap > to the hypervisor. "sc 1 plus magic GPR" might be problematic on some > non-HHV implementations, especially if you *do* have HHV but the > non-HHV hypervisor is running as an HHV guest. Yes, that's why I need sc 0 plus magic GPR in r0 and r3 - to accomodate for all the non-HHV cases. And it would be clever to have a way to expose the same functionality when we do use the HHV features. So, is that draft available anywhere? The wiki page Hollis pointed to is very vague. Alex