[RFC PATCH 02/10] KVM: PPC: BOOK3S: PR: Emulate virtual timebase register

["Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>]

virtual time base register is a per vm register and need to saved
and restored on vm exit and entry. Writing to VTB is not allowed
in the privileged mode.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 arch/powerpc/include/asm/kvm_host.h |  1 +
 arch/powerpc/include/asm/reg.h      |  7 +++++++
 arch/powerpc/include/asm/time.h     | 12 ++++++++++++
 arch/powerpc/kvm/book3s_emulate.c   |  3 +++
 arch/powerpc/kvm/book3s_pr.c        |  3 +++
 5 files changed, 26 insertions(+)

diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index 0a3785271f34..9ebdd12e50a9 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -508,6 +508,7 @@ struct kvm_vcpu_arch {
 #endif
 	/* Time base value when we entered the guest */
 	u64 entry_tb;
+	u64 entry_vtb;
 	u32 tcr;
 	ulong tsr; /* we need to perform set/clr_bits() which requires ulong */
 	u32 ivor[64];
diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index e789f76c9bc2..6c649355b1e9 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -1161,6 +1161,13 @@
 #define mtspr(rn, v)	asm volatile("mtspr " __stringify(rn) ",%0" : \
 				     : "r" ((unsigned long)(v)) \
 				     : "memory")
+#ifdef CONFIG_PPC_BOOK3S_64
+#define mfvtb()		({unsigned long rval;				\
+			asm volatile("mfspr %0, %1" :			\
+				     "=r" (rval) : "i" (SPRN_VTB)); rval;})
+#else
+#define mfvtb() BUG()
+#endif
 
 #ifdef __powerpc64__
 #if defined(CONFIG_PPC_CELL) || defined(CONFIG_PPC_FSL_BOOK3E)
diff --git a/arch/powerpc/include/asm/time.h b/arch/powerpc/include/asm/time.h
index c1f267694acb..1e89dbc665d9 100644
--- a/arch/powerpc/include/asm/time.h
+++ b/arch/powerpc/include/asm/time.h
@@ -101,6 +101,18 @@ static inline u64 get_rtc(void)
 	return (u64)hi * 1000000000 + lo;
 }
 
+#ifdef CONFIG_PPC_BOOK3S_64
+static inline u64 get_vtb(void)
+{
+	return mfvtb();
+}
+#else
+static inline u64 get_vtb(void)
+{
+	return 0;
+}
+#endif
+
 #ifdef CONFIG_PPC64
 static inline u64 get_tb(void)
 {
diff --git a/arch/powerpc/kvm/book3s_emulate.c b/arch/powerpc/kvm/book3s_emulate.c
index e1f1e5e16449..4b58d8a90cb5 100644
--- a/arch/powerpc/kvm/book3s_emulate.c
+++ b/arch/powerpc/kvm/book3s_emulate.c
@@ -528,6 +528,9 @@ int kvmppc_core_emulate_mfspr_pr(struct kvm_vcpu *vcpu, int sprn, ulong *spr_val
 		 */
 		*spr_val = vcpu->arch.spurr;
 		break;
+	case SPRN_VTB:
+		*spr_val = vcpu->arch.vtb;
+		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 02231f5193c2..b5598e9cdd09 100644
--- a/arch/powerpc/kvm/book3s_pr.c
+++ b/arch/powerpc/kvm/book3s_pr.c
@@ -120,6 +120,8 @@ void kvmppc_copy_to_svcpu(struct kvmppc_book3s_shadow_vcpu *svcpu,
 	 * to find the guest purr and spurr value.
 	 */
 	vcpu->arch.entry_tb = get_tb();
+	vcpu->arch.entry_vtb = get_vtb();
+
 }
 
 /* Copy data touched by real-mode code from shadow vcpu back to vcpu */
@@ -171,6 +173,7 @@ 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;
 }
 
 static int kvmppc_core_check_requests_pr(struct kvm_vcpu *vcpu)
-- 
1.8.5.3