SPURR Fix

arch/powerpc/include/asm/kvm_book3s.h

@@ -104,6 +104,7 @@ struct kvmppc_vcore {
 	ulong vtb;		/* virtual timebase */
 	ulong conferring_threads;
 	unsigned int halt_poll_ns;
+	atomic_t online_count;
 };
 
 struct kvmppc_vcpu_book3s {

arch/powerpc/include/asm/kvm_host.h

@@ -676,6 +676,8 @@ struct kvm_vcpu_arch {
 	u64 busy_preempt;
 
 	u32 emul_inst;
+
+	u32 online;
 #endif
 
 #ifdef CONFIG_KVM_BOOK3S_HV_EXIT_TIMING

arch/powerpc/include/asm/reg.h

@@ -302,6 +302,7 @@
 #define SPRN_PMMAR	0x356	/* Power Management Memory Activity Register */
 #define SPRN_PSSCR	0x357	/* Processor Stop Status and Control Register (ISA 3.0) */
 #define SPRN_PMCR	0x374	/* Power Management Control Register */
+#define SPRN_RWMR	0x375	/* Region-Weighting Mode Register */
 
 /* HFSCR and FSCR bit numbers are the same */
 #define FSCR_LM_LG	11	/* Enable Load Monitor Registers */

arch/powerpc/include/uapi/asm/kvm.h

@@ -597,6 +597,7 @@ struct kvm_ppc_cpu_char {
 #define KVM_REG_PPC_WORT	(KVM_REG_PPC | KVM_REG_SIZE_U64 | 0xb9)
 #define KVM_REG_PPC_SPRG9	(KVM_REG_PPC | KVM_REG_SIZE_U64 | 0xba)
 #define KVM_REG_PPC_DBSR	(KVM_REG_PPC | KVM_REG_SIZE_U32 | 0xbb)
+#define KVM_REG_PPC_ONLINE	(KVM_REG_PPC | KVM_REG_SIZE_U32 | 0xbf)
 
 /* Transactional Memory checkpointed state:
  * This is all GPRs, all VSX regs and a subset of SPRs

arch/powerpc/kvm/book3s_hv.c

@@ -124,6 +124,32 @@ MODULE_PARM_DESC(halt_poll_ns_shrink, "Factor halt poll time is shrunk by");
 static void kvmppc_end_cede(struct kvm_vcpu *vcpu);
 static int kvmppc_hv_setup_htab_rma(struct kvm_vcpu *vcpu);
 
+/*
+ * RWMR values for POWER8.  These control the rate at which PURR
+ * and SPURR count and should be set according to the number of
+ * online threads in the vcore being run.
+ */
+#define RWMR_RPA_P8_1THREAD	0x164520C62609AECA
+#define RWMR_RPA_P8_2THREAD	0x7FFF2908450D8DA9
+#define RWMR_RPA_P8_3THREAD	0x164520C62609AECA
+#define RWMR_RPA_P8_4THREAD	0x199A421245058DA9
+#define RWMR_RPA_P8_5THREAD	0x164520C62609AECA
+#define RWMR_RPA_P8_6THREAD	0x164520C62609AECA
+#define RWMR_RPA_P8_7THREAD	0x164520C62609AECA
+#define RWMR_RPA_P8_8THREAD	0x164520C62609AECA
+
+static unsigned long p8_rwmr_values[MAX_SMT_THREADS + 1] = {
+	RWMR_RPA_P8_1THREAD,
+	RWMR_RPA_P8_1THREAD,
+	RWMR_RPA_P8_2THREAD,
+	RWMR_RPA_P8_3THREAD,
+	RWMR_RPA_P8_4THREAD,
+	RWMR_RPA_P8_5THREAD,
+	RWMR_RPA_P8_6THREAD,
+	RWMR_RPA_P8_7THREAD,
+	RWMR_RPA_P8_8THREAD,
+};
+
 static inline struct kvm_vcpu *next_runnable_thread(struct kvmppc_vcore *vc,
 		int *ip)
 {
@@ -1321,6 +1347,9 @@ static int kvmppc_get_one_reg_hv(struct kvm_vcpu *vcpu, u64 id,
 	case KVM_REG_PPC_ARCH_COMPAT:
 		*val = get_reg_val(id, vcpu->arch.vcore->arch_compat);
 		break;
+	case KVM_REG_PPC_ONLINE:
+		*val = get_reg_val(id, vcpu->arch.online);
+		break;
 	default:
 		r = -EINVAL;
 		break;
@@ -1534,6 +1563,14 @@ static int kvmppc_set_one_reg_hv(struct kvm_vcpu *vcpu, u64 id,
 	case KVM_REG_PPC_ARCH_COMPAT:
 		r = kvmppc_set_arch_compat(vcpu, set_reg_val(id, *val));
 		break;
+	case KVM_REG_PPC_ONLINE:
+		i = set_reg_val(id, *val);
+		if (i && !vcpu->arch.online)
+			atomic_inc(&vcpu->arch.vcore->online_count);
+		else if (!i && vcpu->arch.online)
+			atomic_dec(&vcpu->arch.vcore->online_count);
+		vcpu->arch.online = i;
+		break;
 	default:
 		r = -EINVAL;
 		break;
@@ -2309,6 +2346,7 @@ static noinline void kvmppc_run_core(struct kvmppc_vcore *vc)
 	unsigned long cmd_bit, stat_bit;
 	int pcpu, thr;
 	int target_threads;
+	bool is_power8;
 
 	/*
 	 * Remove from the list any threads that have a signal pending
@@ -2358,6 +2396,9 @@ static noinline void kvmppc_run_core(struct kvmppc_vcore *vc)
 	cmd_bit = stat_bit = 0;
 	split = core_info.n_subcores;
 	sip = NULL;
+	is_power8 = cpu_has_feature(CPU_FTR_ARCH_207S)
+		&& !cpu_has_feature(CPU_FTR_ARCH_300);
+
 	if (split > 1) {
 		/* threads_per_subcore must be MAX_SMT_THREADS (8) here */
 		if (split == 2 && (dynamic_mt_modes & 2)) {
@@ -2404,6 +2445,25 @@ static noinline void kvmppc_run_core(struct kvmppc_vcore *vc)
 
 	kvmppc_clear_host_core(pcpu);
 
+	/*
+	 * On POWER8, set RWMR register.
+	 * Since it only affects PURR and SPURR, it doesn't affect
+	 * the host, so we don't save/restore the host value.
+	 */
+	if (is_power8) {
+		unsigned long rwmr_val = RWMR_RPA_P8_8THREAD;
+		int n_online = atomic_read(&vc->online_count);
+
+		/*
+		 * Use the 8-thread value if we're doing split-core
+		 * or if the vcore's online count looks bogus.
+		 */
+		if (split == 1 && threads_per_subcore == MAX_SMT_THREADS &&
+		    n_online >= 1 && n_online <= MAX_SMT_THREADS)
+			rwmr_val = p8_rwmr_values[n_online];
+		mtspr(SPRN_RWMR, rwmr_val);
+	}
+
 	/* Start all the threads */
 	active = 0;
 	for (sub = 0; sub < core_info.n_subcores; ++sub) {
@@ -2836,6 +2896,15 @@ static int kvmppc_vcpu_run_hv(struct kvm_run *run, struct kvm_vcpu *vcpu)
 	}
 #endif
 
+	/*
+	 * Force online to 1 for the sake of old userspace which doesn't
+	 * set it.
+	 */
+	if (!vcpu->arch.online) {
+		atomic_inc(&vcpu->arch.vcore->online_count);
+		vcpu->arch.online = 1;
+	}
+
 	kvmppc_core_prepare_to_enter(vcpu);
 
 	/* No need to go into the guest when all we'll do is come back out */