Re: [PATCH 1/6] KVM: PPC: BOOKE: No need to set DBCR0_EDM in guest visible register
On Fri, 2014-07-11 at 14:08 +0530, Bharat Bhushan wrote: > This is not used and even I do not remember why this was added > in first place. > > Signed-off-by: Bharat Bhushan > --- > arch/powerpc/kvm/booke.c | 2 -- > 1 file changed, 2 deletions(-) > > diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c > index ab62109..a5ee42c 100644 > --- a/arch/powerpc/kvm/booke.c > +++ b/arch/powerpc/kvm/booke.c > @@ -1804,8 +1804,6 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu > *vcpu, > kvm_guest_protect_msr(vcpu, MSR_DE, true); > vcpu->guest_debug = dbg->control; > vcpu->arch.shadow_dbg_reg.dbcr0 = 0; > - /* Set DBCR0_EDM in guest visible DBCR0 register. */ > - vcpu->arch.dbg_reg.dbcr0 = DBCR0_EDM; > > if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) > vcpu->arch.shadow_dbg_reg.dbcr0 |= DBCR0_IDM | DBCR0_IC; This was intended to let the guest know that the host owns the debug resources, by analogy to what a JTAG debugger would do. The Power ISA has this "Virtualized Implementation Note": It is the responsibility of the hypervisor to ensure that DBCR0[EDM] is consistent with usage of DEP. -Scott -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
RE: [PATCH 1/6] KVM: PPC: BOOKE: No need to set DBCR0_EDM in guest visible register
> -Original Message-
> From: Wood Scott-B07421
> Sent: Tuesday, July 29, 2014 3:22 AM
> To: Bhushan Bharat-R65777
> Cc: ag...@suse.de; kvm-...@vger.kernel.org; kvm@vger.kernel.org; Yoder Stuart-
> B08248
> Subject: Re: [PATCH 1/6] KVM: PPC: BOOKE: No need to set DBCR0_EDM in guest
> visible register
>
> On Fri, 2014-07-11 at 14:08 +0530, Bharat Bhushan wrote:
> > This is not used and even I do not remember why this was added in
> > first place.
> >
> > Signed-off-by: Bharat Bhushan
> > ---
> > arch/powerpc/kvm/booke.c | 2 --
> > 1 file changed, 2 deletions(-)
> >
> > diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c index
> > ab62109..a5ee42c 100644
> > --- a/arch/powerpc/kvm/booke.c
> > +++ b/arch/powerpc/kvm/booke.c
> > @@ -1804,8 +1804,6 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct
> > kvm_vcpu
> *vcpu,
> > kvm_guest_protect_msr(vcpu, MSR_DE, true);
> > vcpu->guest_debug = dbg->control;
> > vcpu->arch.shadow_dbg_reg.dbcr0 = 0;
> > - /* Set DBCR0_EDM in guest visible DBCR0 register. */
> > - vcpu->arch.dbg_reg.dbcr0 = DBCR0_EDM;
> >
> > if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP)
> > vcpu->arch.shadow_dbg_reg.dbcr0 |= DBCR0_IDM | DBCR0_IC;
>
> This was intended to let the guest know that the host owns the debug
> resources,
> by analogy to what a JTAG debugger would do.
>
> The Power ISA has this "Virtualized Implementation Note":
>
> It is the responsibility of the hypervisor to ensure that
> DBCR0[EDM] is consistent with usage of DEP.
Ok, That means that if MSRP_DEP is set then set DBCR0_EDM and if MSRP_DEP is
clear then clear DBCR0_EDM, right?
We need to implement above mentioned this.
Thanks
-Bharat
>
> -Scott
>
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Re: [PATCH 1/6] KVM: PPC: BOOKE: No need to set DBCR0_EDM in guest visible register
On Wed, 2014-07-30 at 00:21 -0500, Bhushan Bharat-R65777 wrote: > > > -Original Message- > > From: Wood Scott-B07421 > > Sent: Tuesday, July 29, 2014 3:22 AM > > To: Bhushan Bharat-R65777 > > Cc: ag...@suse.de; kvm-...@vger.kernel.org; kvm@vger.kernel.org; Yoder > > Stuart- > > B08248 > > Subject: Re: [PATCH 1/6] KVM: PPC: BOOKE: No need to set DBCR0_EDM in guest > > visible register > > > > On Fri, 2014-07-11 at 14:08 +0530, Bharat Bhushan wrote: > > > This is not used and even I do not remember why this was added in > > > first place. > > > > > > Signed-off-by: Bharat Bhushan > > > --- > > > arch/powerpc/kvm/booke.c | 2 -- > > > 1 file changed, 2 deletions(-) > > > > > > diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c index > > > ab62109..a5ee42c 100644 > > > --- a/arch/powerpc/kvm/booke.c > > > +++ b/arch/powerpc/kvm/booke.c > > > @@ -1804,8 +1804,6 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct > > > kvm_vcpu > > *vcpu, > > > kvm_guest_protect_msr(vcpu, MSR_DE, true); > > > vcpu->guest_debug = dbg->control; > > > vcpu->arch.shadow_dbg_reg.dbcr0 = 0; > > > - /* Set DBCR0_EDM in guest visible DBCR0 register. */ > > > - vcpu->arch.dbg_reg.dbcr0 = DBCR0_EDM; > > > > > > if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) > > > vcpu->arch.shadow_dbg_reg.dbcr0 |= DBCR0_IDM | DBCR0_IC; > > > > This was intended to let the guest know that the host owns the debug > > resources, > > by analogy to what a JTAG debugger would do. > > > > The Power ISA has this "Virtualized Implementation Note": > > > > It is the responsibility of the hypervisor to ensure that > > DBCR0[EDM] is consistent with usage of DEP. > > Ok, That means that if MSRP_DEP is set then set DBCR0_EDM and if MSRP_DEP is > clear then clear DBCR0_EDM, right? > We need to implement above mentioned this. We should probably clear EDM only when guest debug emulation is working and enabled (i.e. not until at least patch 6/6). -Scott -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
RE: [PATCH 1/6] KVM: PPC: BOOKE: No need to set DBCR0_EDM in guest visible register
> -Original Message- > From: Wood Scott-B07421 > Sent: Wednesday, July 30, 2014 11:18 PM > To: Bhushan Bharat-R65777 > Cc: ag...@suse.de; kvm-...@vger.kernel.org; kvm@vger.kernel.org; Yoder Stuart- > B08248 > Subject: Re: [PATCH 1/6] KVM: PPC: BOOKE: No need to set DBCR0_EDM in guest > visible register > > On Wed, 2014-07-30 at 00:21 -0500, Bhushan Bharat-R65777 wrote: > > > > > -Original Message- > > > From: Wood Scott-B07421 > > > Sent: Tuesday, July 29, 2014 3:22 AM > > > To: Bhushan Bharat-R65777 > > > Cc: ag...@suse.de; kvm-...@vger.kernel.org; kvm@vger.kernel.org; > > > Yoder Stuart- > > > B08248 > > > Subject: Re: [PATCH 1/6] KVM: PPC: BOOKE: No need to set DBCR0_EDM > > > in guest visible register > > > > > > On Fri, 2014-07-11 at 14:08 +0530, Bharat Bhushan wrote: > > > > This is not used and even I do not remember why this was added in > > > > first place. > > > > > > > > Signed-off-by: Bharat Bhushan > > > > --- > > > > arch/powerpc/kvm/booke.c | 2 -- > > > > 1 file changed, 2 deletions(-) > > > > > > > > diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c > > > > index ab62109..a5ee42c 100644 > > > > --- a/arch/powerpc/kvm/booke.c > > > > +++ b/arch/powerpc/kvm/booke.c > > > > @@ -1804,8 +1804,6 @@ int > > > > kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu > > > *vcpu, > > > > kvm_guest_protect_msr(vcpu, MSR_DE, true); > > > > vcpu->guest_debug = dbg->control; > > > > vcpu->arch.shadow_dbg_reg.dbcr0 = 0; > > > > - /* Set DBCR0_EDM in guest visible DBCR0 register. */ > > > > - vcpu->arch.dbg_reg.dbcr0 = DBCR0_EDM; > > > > > > > > if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) > > > > vcpu->arch.shadow_dbg_reg.dbcr0 |= DBCR0_IDM | DBCR0_IC; > > > > > > This was intended to let the guest know that the host owns the debug > > > resources, by analogy to what a JTAG debugger would do. > > > > > > The Power ISA has this "Virtualized Implementation Note": > > > > > > It is the responsibility of the hypervisor to ensure that > > > DBCR0[EDM] is consistent with usage of DEP. > > > > Ok, That means that if MSRP_DEP is set then set DBCR0_EDM and if MSRP_DEP > > is > clear then clear DBCR0_EDM, right? > > We need to implement above mentioned this. > > We should probably clear EDM only when guest debug emulation is working and > enabled (i.e. not until at least patch 6/6). But if EDM is set then guest debug emulation will not start/allowed. Thanks -Bharat > > -Scott >
Re: [PATCH 1/6] KVM: PPC: BOOKE: No need to set DBCR0_EDM in guest visible register
On Wed, 2014-07-30 at 12:57 -0500, Bhushan Bharat-R65777 wrote: > > > -Original Message- > > From: Wood Scott-B07421 > > Sent: Wednesday, July 30, 2014 11:18 PM > > To: Bhushan Bharat-R65777 > > Cc: ag...@suse.de; kvm-...@vger.kernel.org; kvm@vger.kernel.org; Yoder > > Stuart- > > B08248 > > Subject: Re: [PATCH 1/6] KVM: PPC: BOOKE: No need to set DBCR0_EDM in guest > > visible register > > > > On Wed, 2014-07-30 at 00:21 -0500, Bhushan Bharat-R65777 wrote: > > > > > > > -Original Message- > > > > From: Wood Scott-B07421 > > > > Sent: Tuesday, July 29, 2014 3:22 AM > > > > To: Bhushan Bharat-R65777 > > > > Cc: ag...@suse.de; kvm-...@vger.kernel.org; kvm@vger.kernel.org; > > > > Yoder Stuart- > > > > B08248 > > > > Subject: Re: [PATCH 1/6] KVM: PPC: BOOKE: No need to set DBCR0_EDM > > > > in guest visible register > > > > > > > > On Fri, 2014-07-11 at 14:08 +0530, Bharat Bhushan wrote: > > > > > This is not used and even I do not remember why this was added in > > > > > first place. > > > > > > > > > > Signed-off-by: Bharat Bhushan > > > > > --- > > > > > arch/powerpc/kvm/booke.c | 2 -- > > > > > 1 file changed, 2 deletions(-) > > > > > > > > > > diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c > > > > > index ab62109..a5ee42c 100644 > > > > > --- a/arch/powerpc/kvm/booke.c > > > > > +++ b/arch/powerpc/kvm/booke.c > > > > > @@ -1804,8 +1804,6 @@ int > > > > > kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu > > > > *vcpu, > > > > > kvm_guest_protect_msr(vcpu, MSR_DE, true); > > > > > vcpu->guest_debug = dbg->control; > > > > > vcpu->arch.shadow_dbg_reg.dbcr0 = 0; > > > > > - /* Set DBCR0_EDM in guest visible DBCR0 register. */ > > > > > - vcpu->arch.dbg_reg.dbcr0 = DBCR0_EDM; > > > > > > > > > > if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) > > > > > vcpu->arch.shadow_dbg_reg.dbcr0 |= DBCR0_IDM | DBCR0_IC; > > > > > > > > This was intended to let the guest know that the host owns the debug > > > > resources, by analogy to what a JTAG debugger would do. > > > > > > > > The Power ISA has this "Virtualized Implementation Note": > > > > > > > > It is the responsibility of the hypervisor to ensure that > > > > DBCR0[EDM] is consistent with usage of DEP. > > > > > > Ok, That means that if MSRP_DEP is set then set DBCR0_EDM and if > > > MSRP_DEP is > > clear then clear DBCR0_EDM, right? > > > We need to implement above mentioned this. > > > > We should probably clear EDM only when guest debug emulation is working and > > enabled (i.e. not until at least patch 6/6). > > But if EDM is set then guest debug emulation will not start/allowed. I don't mean after the guest tries to write to the registers -- I mean after the code has been added to KVM to allow it to work. -Scott -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
