From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Roedel, Joerg" Subject: Re: kvm PCI assignment & VFIO ramblings Date: Wed, 24 Aug 2011 10:53:21 +0200 Message-ID: <20110824085321.GC2079@amd.com> References: <1312310121.2653.470.camel@bling.home> <20110803020422.GF29719@yookeroo.fritz.box> <4E3F9E33.5000706@redhat.com> <1312932258.4524.55.camel@bling.home> <1312944513.29273.28.camel@pasglop> <1313859105.6866.192.camel@x201.home> <20110822172508.GJ2079@amd.com> <1314047033.7662.39.camel@pasglop> <20110823131819.GO2079@amd.com> <1314142537.30478.59.camel@pasglop> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Cc: Alex Williamson , chrisw , Alexey Kardashevskiy , "kvm@vger.kernel.org" , Paul Mackerras , "linux-pci@vger.kernel.org" , qemu-devel , iommu , Avi Kivity , Anthony Liguori , linuxppc-dev , "benve@cisco.com" To: Benjamin Herrenschmidt Return-path: Content-Disposition: inline In-Reply-To: <1314142537.30478.59.camel@pasglop> Sender: linux-pci-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On Tue, Aug 23, 2011 at 07:35:37PM -0400, Benjamin Herrenschmidt wrote: > On Tue, 2011-08-23 at 15:18 +0200, Roedel, Joerg wrote: > > Hmm, good idea. But as far as I know the hotplug-event needs to be in > > the guest _before_ the device is actually unplugged (so that the guest > > can unbind its driver first). That somehow brings back the sleep-idea > > and the timeout in the .release function. > > That's for normal assisted hotplug, but don't we support hard hotplug ? > I mean, things like cardbus, thunderbolt (if we ever support that) > etc... will need it and some platforms do support hard hotplug of PCIe > devices. > > (That's why drivers should never spin on MMIO waiting for a 1 bit to > clear without a timeout :-) Right, thats probably the best semantic for this issue then. The worst thing that happens is that the admin crashed the guest. Joerg -- AMD Operating System Research Center Advanced Micro Devices GmbH Einsteinring 24 85609 Dornach General Managers: Alberto Bozzo, Andrew Bowd Registration: Dornach, Landkr. Muenchen; Registerger. Muenchen, HRB Nr. 43632 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from TX2EHSOBE001.bigfish.com (tx2ehsobe001.messaging.microsoft.com [65.55.88.11]) (using TLSv1 with cipher AES128-SHA (128/128 bits)) (Client CN "mail.global.frontbridge.com", Issuer "Microsoft Secure Server Authority" (verified OK)) by ozlabs.org (Postfix) with ESMTPS id D995BB6F70 for ; Wed, 24 Aug 2011 18:55:42 +1000 (EST) Date: Wed, 24 Aug 2011 10:53:21 +0200 From: "Roedel, Joerg" To: Benjamin Herrenschmidt Subject: Re: kvm PCI assignment & VFIO ramblings Message-ID: <20110824085321.GC2079@amd.com> References: <1312310121.2653.470.camel@bling.home> <20110803020422.GF29719@yookeroo.fritz.box> <4E3F9E33.5000706@redhat.com> <1312932258.4524.55.camel@bling.home> <1312944513.29273.28.camel@pasglop> <1313859105.6866.192.camel@x201.home> <20110822172508.GJ2079@amd.com> <1314047033.7662.39.camel@pasglop> <20110823131819.GO2079@amd.com> <1314142537.30478.59.camel@pasglop> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" In-Reply-To: <1314142537.30478.59.camel@pasglop> Cc: Alexey Kardashevskiy , "kvm@vger.kernel.org" , Paul Mackerras , "linux-pci@vger.kernel.org" , qemu-devel , iommu , chrisw , Alex Williamson , Avi Kivity , Anthony Liguori , linuxppc-dev , "benve@cisco.com" List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Tue, Aug 23, 2011 at 07:35:37PM -0400, Benjamin Herrenschmidt wrote: > On Tue, 2011-08-23 at 15:18 +0200, Roedel, Joerg wrote: > > Hmm, good idea. But as far as I know the hotplug-event needs to be in > > the guest _before_ the device is actually unplugged (so that the guest > > can unbind its driver first). That somehow brings back the sleep-idea > > and the timeout in the .release function. > > That's for normal assisted hotplug, but don't we support hard hotplug ? > I mean, things like cardbus, thunderbolt (if we ever support that) > etc... will need it and some platforms do support hard hotplug of PCIe > devices. > > (That's why drivers should never spin on MMIO waiting for a 1 bit to > clear without a timeout :-) Right, thats probably the best semantic for this issue then. The worst thing that happens is that the admin crashed the guest. Joerg -- AMD Operating System Research Center Advanced Micro Devices GmbH Einsteinring 24 85609 Dornach General Managers: Alberto Bozzo, Andrew Bowd Registration: Dornach, Landkr. Muenchen; Registerger. Muenchen, HRB Nr. 43632 From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:36179) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Qw9QB-0003bI-Q6 for qemu-devel@nongnu.org; Wed, 24 Aug 2011 05:06:53 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Qw9FM-0003di-LZ for qemu-devel@nongnu.org; Wed, 24 Aug 2011 04:55:56 -0400 Received: from tx2ehsobe001.messaging.microsoft.com ([65.55.88.11]:19614 helo=TX2EHSOBE001.bigfish.com) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Qw9FL-0003bu-Sc for qemu-devel@nongnu.org; Wed, 24 Aug 2011 04:55:40 -0400 Date: Wed, 24 Aug 2011 10:53:21 +0200 From: "Roedel, Joerg" Message-ID: <20110824085321.GC2079@amd.com> References: <1312310121.2653.470.camel@bling.home> <20110803020422.GF29719@yookeroo.fritz.box> <4E3F9E33.5000706@redhat.com> <1312932258.4524.55.camel@bling.home> <1312944513.29273.28.camel@pasglop> <1313859105.6866.192.camel@x201.home> <20110822172508.GJ2079@amd.com> <1314047033.7662.39.camel@pasglop> <20110823131819.GO2079@amd.com> <1314142537.30478.59.camel@pasglop> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <1314142537.30478.59.camel@pasglop> Subject: Re: [Qemu-devel] kvm PCI assignment & VFIO ramblings List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Benjamin Herrenschmidt Cc: Alexey Kardashevskiy , "kvm@vger.kernel.org" , Paul Mackerras , "linux-pci@vger.kernel.org" , qemu-devel , iommu , chrisw , Alex Williamson , Avi Kivity , linuxppc-dev , "benve@cisco.com" On Tue, Aug 23, 2011 at 07:35:37PM -0400, Benjamin Herrenschmidt wrote: > On Tue, 2011-08-23 at 15:18 +0200, Roedel, Joerg wrote: > > Hmm, good idea. But as far as I know the hotplug-event needs to be in > > the guest _before_ the device is actually unplugged (so that the guest > > can unbind its driver first). That somehow brings back the sleep-idea > > and the timeout in the .release function. > > That's for normal assisted hotplug, but don't we support hard hotplug ? > I mean, things like cardbus, thunderbolt (if we ever support that) > etc... will need it and some platforms do support hard hotplug of PCIe > devices. > > (That's why drivers should never spin on MMIO waiting for a 1 bit to > clear without a timeout :-) Right, thats probably the best semantic for this issue then. The worst thing that happens is that the admin crashed the guest. Joerg -- AMD Operating System Research Center Advanced Micro Devices GmbH Einsteinring 24 85609 Dornach General Managers: Alberto Bozzo, Andrew Bowd Registration: Dornach, Landkr. Muenchen; Registerger. Muenchen, HRB Nr. 43632