Alexander Graf [off-list ref] writes:

On 01/28/2014 05:44 PM, Aneesh Kumar K.V wrote:

quoted

Writing to IC is not allowed in the privileged mode.

This is not a patch description.

quoted

Signed-off-by: Aneesh Kumar K.V <redacted>
---
  arch/powerpc/include/asm/kvm_host.h | 1 +
  arch/powerpc/kvm/book3s_emulate.c   | 3 +++
  arch/powerpc/kvm/book3s_pr.c        | 2 ++
  3 files changed, 6 insertions(+)

diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index 9ebdd12e50a9..e0b13aca98e6 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h

@@ -509,6 +509,7 @@ struct kvm_vcpu_arch {
  	/* Time base value when we entered the guest */
  	u64 entry_tb;
  	u64 entry_vtb;
+	u64 entry_ic;
  	u32 tcr;
  	ulong tsr; /* we need to perform set/clr_bits() which requires ulong */
  	u32 ivor[64];

diff --git a/arch/powerpc/kvm/book3s_emulate.c b/arch/powerpc/kvm/book3s_emulate.c
index 4b58d8a90cb5..abe6f3057e5b 100644
--- a/arch/powerpc/kvm/book3s_emulate.c
+++ b/arch/powerpc/kvm/book3s_emulate.c

@@ -531,6 +531,9 @@ int kvmppc_core_emulate_mfspr_pr(struct kvm_vcpu *vcpu, int sprn, ulong *spr_val
  	case SPRN_VTB:
  		*spr_val = vcpu->arch.vtb;
  		break;
+	case SPRN_IC:
+		*spr_val = vcpu->arch.ic;
+		break;
  	case SPRN_GQR0:
  	case SPRN_GQR1:
  	case SPRN_GQR2:

diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c
index b5598e9cdd09..51d469f8c9fd 100644
--- a/arch/powerpc/kvm/book3s_pr.c
+++ b/arch/powerpc/kvm/book3s_pr.c

@@ -121,6 +121,7 @@ void kvmppc_copy_to_svcpu(struct kvmppc_book3s_shadow_vcpu *svcpu,
  	 */
  	vcpu->arch.entry_tb = get_tb();
  	vcpu->arch.entry_vtb = get_vtb();
+	vcpu->arch.entry_ic = mfspr(SPRN_IC);

Is this implemented on all systems?

quoted

  
  }
  

@@ -174,6 +175,7 @@ out:
  	vcpu->arch.purr += get_tb() - vcpu->arch.entry_tb;
  	vcpu->arch.spurr += get_tb() - vcpu->arch.entry_tb;
  	vcpu->arch.vtb += get_vtb() - vcpu->arch.entry_vtb;
+	vcpu->arch.ic += mfspr(SPRN_IC) - vcpu->arch.entry_ic;

This is getting quite convoluted. How about we act slightly more fuzzy 
and put all of this into vcpu_load/put?

I am not sure whether vcpu_load/put is too early/late to save these
context ?

-aneesh