> -----Original Message----- > From: Alexander Graf [mailto:ag...@suse.de] > Sent: Tuesday, July 29, 2014 7:35 PM > To: Wood Scott-B07421; Bhushan Bharat-R65777 > Cc: kvm-ppc@vger.kernel.org; k...@vger.kernel.org; Yoder Stuart-B08248 > Subject: Re: [PATCH 5/6] KVM: PPC: BOOKE: Allow guest to change MSR_DE > > > On 29.07.14 00:01, Scott Wood wrote: > > On Fri, 2014-07-11 at 14:09 +0530, Bharat Bhushan wrote: > >> When userspace is debugging guest then MSR_DE is always set and > >> MSRP_DEP is set so that guest cannot change MSR_DE. > >> Guest debug resources are not yet emulated, So there seems no reason > >> we should stop guest controlling MSR_DE. > >> Also a followup patch will enable debug emulation and that requires > >> guest to control MSR_DE. > > Why does it matter whether we emulate debug resources? We still don't > > want the guest to be able to clear MSR[DE] and thus break host debug. > > The patch description is misleading. This patch changes the default of DEP to > "guest controlled" when it boots up. Once QEMU wants control over the debug > registers, it gets switched to "QEMU controlled" (that code is already there).
Yes, now default MSR_DE is controlled by guest and when QEMU wants to use debug resources then MSR_DEP is set, so guest cannot change MSR_DE. Thanks -Bharat > > > Alex
