From: Scott Wood <scottwood@freescale.com>
To: Bhushan Bharat-R65777 <R65777@freescale.com>
Cc: Alexander Graf <agraf@suse.de>,
"kvm-ppc@vger.kernel.org" <kvm-ppc@vger.kernel.org>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
Wood Scott-B07421 <B07421@freescale.com>
Subject: Re: [PATCH 7/7] KVM: PPC: Add userspace debug stub support
Date: Thu, 14 Mar 2013 11:05:30 -0500 [thread overview]
Message-ID: <1363277130.28440.3@snotra> (raw)
In-Reply-To: <6A3DF150A5B70D4F9B66A25E3F7C888D065EC808@039-SN2MPN1-023.039d.mgd.msft.net> (from R65777@freescale.com on Thu Mar 14 08:57:53 2013)
On 03/14/2013 08:57:53 AM, Bhushan Bharat-R65777 wrote:
> > >>> diff --git a/arch/powerpc/kvm/e500mc.c
> b/arch/powerpc/kvm/e500mc.c
> > >>> index 1f89d26..f5fc6f5 100644
> > >>> --- a/arch/powerpc/kvm/e500mc.c
> > >>> +++ b/arch/powerpc/kvm/e500mc.c
> > >>> @@ -182,8 +182,7 @@ int kvmppc_core_vcpu_setup(struct kvm_vcpu
> > >>> *vcpu) {
> > >>> struct kvmppc_vcpu_e500 *vcpu_e500 = to_e500(vcpu);
> > >>>
> > >>> - vcpu->arch.shadow_epcr = SPRN_EPCR_DSIGS |
> SPRN_EPCR_DGTMI | \
> > >>> - SPRN_EPCR_DUVD;
> > >>> + vcpu->arch.shadow_epcr = SPRN_EPCR_DSIGS |
> SPRN_EPCR_DGTMI;
> > >>
> > >> Doesn't this route all debug events through the host?
> > >
> > > No; This means that debug events can occur in hypervisor state or
> not.
> > >
> > > EPCR.DUVD = 0 ; Debug events can occur in the hypervisor state.
> > >
> > > EPCR.DUVD = 1 ; Debug events cannot occur in the hypervisor state.
> > >
> > > So we allow debug events to occur in hypervisor state.
> >
> > Why do we care about debug events in our entry/exit code and didn't
> care about
> > them before?
>
> We care for single stepping in guest to not step in KVM code.
>
> > If anything, this is a completely separate patch, orthogonal to
> > this patch series, and requires a good bit of explanation.
>
> Not sure why you think separate patch; this patch add support for
> single stepping and also takes care that debug event does not comes
> in host when doing single stepping.
How does *removing* DUVD ensure that?
-Scott
next prev parent reply other threads:[~2013-03-14 16:05 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-28 4:13 [PATCH 0/7] KVM :PPC: Userspace Debug support Bharat Bhushan
2013-02-28 4:13 ` [PATCH 1/7] KVM: PPC: booke: Added debug handler Bharat Bhushan
2013-03-07 14:02 ` Alexander Graf
2013-02-28 4:13 ` [PATCH 2/7] Added ONE_REG interface for debug instruction Bharat Bhushan
2013-02-28 16:23 ` Scott Wood
2013-02-28 16:52 ` Alexander Graf
2013-03-01 5:28 ` Bhushan Bharat-R65777
2013-03-07 13:07 ` Alexander Graf
2013-03-14 4:30 ` Bhushan Bharat-R65777
2013-03-14 11:56 ` Alexander Graf
2013-02-28 4:13 ` [PATCH 3/7] KVM: PPC: debug stub interface parameter defined Bharat Bhushan
2013-03-07 13:20 ` Alexander Graf
2013-03-14 4:42 ` Bhushan Bharat-R65777
2013-03-14 11:54 ` Alexander Graf
2013-03-14 11:57 ` Jan Kiszka
2013-03-14 12:09 ` Alexander Graf
2013-03-14 12:13 ` Jan Kiszka
2013-03-14 12:19 ` Alexander Graf
2013-03-14 12:22 ` Jan Kiszka
2013-03-14 12:28 ` Alexander Graf
2013-02-28 4:13 ` [PATCH 4/7] booke: Save and restore debug registers on guest entry and exit Bharat Bhushan
2013-03-07 13:25 ` Alexander Graf
2013-03-14 4:50 ` Bhushan Bharat-R65777
2013-03-14 11:52 ` Alexander Graf
2013-03-14 14:44 ` Bhushan Bharat-R65777
2013-02-28 4:13 ` [PATCH 5/7] bookehv: " Bharat Bhushan
2013-02-28 4:13 ` [PATCH 6/7] Rename EMULATE_DO_PAPR to EMULATE_EXIT_USER Bharat Bhushan
2013-02-28 16:31 ` Scott Wood
2013-02-28 16:51 ` Alexander Graf
2013-02-28 16:53 ` Scott Wood
2013-03-07 10:47 ` Alexander Graf
2013-03-14 5:59 ` Bhushan Bharat-R65777
2013-02-28 4:13 ` [PATCH 7/7] KVM: PPC: Add userspace debug stub support Bharat Bhushan
2013-03-07 13:39 ` Alexander Graf
2013-03-14 5:18 ` Bhushan Bharat-R65777
2013-03-14 11:50 ` Alexander Graf
2013-03-14 13:57 ` Bhushan Bharat-R65777
2013-03-14 16:05 ` Scott Wood [this message]
2013-03-14 16:11 ` Bhushan Bharat-R65777
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