KVM: PPC: Book3S HV: Implement architecture compatibility modes for POWER8

This allows us to select architecture 2.05 (POWER6) or 2.06 (POWER7)
compatibility modes on a POWER8 processor.  (Note that transactional
memory is disabled for usermode if either or both of the PCR_TM_DIS
and PCR_ARCH_206 bits are set.)
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>

arch/powerpc/include/asm/reg.h

@@ -329,6 +329,8 @@
 #define SPRN_PCR	0x152	/* Processor compatibility register */
 #define   PCR_VEC_DIS	(1ul << (63-0))	/* Vec. disable (bit NA since POWER8) */
 #define   PCR_VSX_DIS	(1ul << (63-1))	/* VSX disable (bit NA since POWER8) */
+#define   PCR_TM_DIS	(1ul << (63-2))	/* Trans. memory disable (POWER8) */
+#define   PCR_ARCH_206	0x4		/* Architecture 2.06 */
 #define   PCR_ARCH_205	0x2		/* Architecture 2.05 */
 #define	SPRN_HEIR	0x153	/* Hypervisor Emulated Instruction Register */
 #define SPRN_TLBINDEXR	0x154	/* P7 TLB control register */

arch/powerpc/kvm/book3s_hv.c

@@ -184,14 +184,28 @@ int kvmppc_set_arch_compat(struct kvm_vcpu *vcpu, u32 arch_compat)
 
 		switch (arch_compat) {
 		case PVR_ARCH_205:
-			pcr = PCR_ARCH_205;
+			/*
+			 * If an arch bit is set in PCR, all the defined
+			 * higher-order arch bits also have to be set.
+			 */
+			pcr = PCR_ARCH_206 | PCR_ARCH_205;
 			break;
 		case PVR_ARCH_206:
 		case PVR_ARCH_206p:
+			pcr = PCR_ARCH_206;
+			break;
+		case PVR_ARCH_207:
 			break;
 		default:
 			return -EINVAL;
 		}
+
+		if (!cpu_has_feature(CPU_FTR_ARCH_207S)) {
+			/* POWER7 can't emulate POWER8 */
+			if (!(pcr & PCR_ARCH_206))
+				return -EINVAL;
+			pcr &= ~PCR_ARCH_206;
+		}
 	}
 
 	spin_lock(&vc->lock);