From mboxrd@z Thu Jan 1 00:00:00 1970 From: Scott Wood Subject: Re: [PATCH 8/8] KVM:PPC:booke: Allow debug interrupt injection to guest Date: Thu, 31 Jan 2013 12:54:33 -0600 Message-ID: <1359658473.31540.8@snotra> References: <1359657795.31540.5@snotra> <1A30DCCA-FCBA-4D0A-918E-12B529028DA4@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; delsp=Yes; format=Flowed Content-Transfer-Encoding: 8BIT Cc: Bhushan Bharat-R65777 , "kvm-ppc@vger.kernel.org" , "kvm@vger.kernel.org" To: Alexander Graf Return-path: In-Reply-To: <1A30DCCA-FCBA-4D0A-918E-12B529028DA4@suse.de> (from agraf@suse.de on Thu Jan 31 12:52:41 2013) Content-Disposition: inline Sender: kvm-ppc-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On 01/31/2013 12:52:41 PM, Alexander Graf wrote: > > On 31.01.2013, at 19:43, Scott Wood wrote: > > > On 01/31/2013 12:21:07 PM, Alexander Graf wrote: > >> How about something like this? Then both targets at least suck as > much :). > > > > I'm not sure that should be the goal... > > > >> Thanks to e500mc's awful hardware design, we don't know who sets > the MSR_DE bit. Once we forced it onto the guest, we have no change > to know whether the guest also set it or not. We could only guess. > > > > MSRP[DEP] can prevent the guest from modifying MSR[DE] -- but we > still need to set it in the first place. > > > > According to ISA V2.06B, the hypervisor should set DBCR0[EDM] to > let the guest know that the debug resources are not available, and > that "the value of MSR[DE] is not specified and not modifiable". > > So what would the guest do then to tell the hypervisor that it > actually wants to know about debug events? The guest is out of luck, just as if a JTAG were in use. -Scott