KVM: PPC: Book3e: Add AltiVec support

Add AltiVec support in KVM for Book3e. FPU support gracefully reuse host
infrastructure so follow the same approach for AltiVec.

Book3e specification defines shared interrupt numbers for SPE and AltiVec
units. Still SPE is present in e200/e500v2 cores while AltiVec is present in
e6500 core. So we can currently decide at compile-time which of the SPE or
AltiVec units to support exclusively by using CONFIG_SPE_POSSIBLE and
CONFIG_PPC_E500MC defines. As Alexander Graf suggested, keep SPE and AltiVec
exception handlers distinct to improve code readability.

Guests have the privilege to enable AltiVec, so we always need to support
AltiVec in KVM and implicitly in host to reflect interrupts and to save/restore
the unit context. KVM will be loaded on cores with AltiVec unit only if
CONFIG_ALTIVEC is defined. Use this define to guard KVM AltiVec logic.

Signed-off-by: Mihai Caraman <mihai.caraman@freescale.com>
Signed-off-by: Alexander Graf <agraf@suse.de>

1 files changed, 73 insertions, 1 deletions

diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
index 91e7217db9d9..8ace6120ef9b 100644
--- a/arch/powerpc/kvm/booke.c
+++ b/arch/powerpc/kvm/booke.c
@@ -168,6 +168,40 @@ static void kvmppc_vcpu_sync_fpu(struct kvm_vcpu *vcpu)
 #endif
 }
 
+/*
+ * Simulate AltiVec unavailable fault to load guest state
+ * from thread to AltiVec unit.
+ * It requires to be called with preemption disabled.
+ */
+static inline void kvmppc_load_guest_altivec(struct kvm_vcpu *vcpu)
+{
+#ifdef CONFIG_ALTIVEC
+	if (cpu_has_feature(CPU_FTR_ALTIVEC)) {
+		if (!(current->thread.regs->msr & MSR_VEC)) {
+			enable_kernel_altivec();
+			load_vr_state(&vcpu->arch.vr);
+			current->thread.vr_save_area = &vcpu->arch.vr;
+			current->thread.regs->msr |= MSR_VEC;
+		}
+	}
+#endif
+}
+
+/*
+ * Save guest vcpu AltiVec state into thread.
+ * It requires to be called with preemption disabled.
+ */
+static inline void kvmppc_save_guest_altivec(struct kvm_vcpu *vcpu)
+{
+#ifdef CONFIG_ALTIVEC
+	if (cpu_has_feature(CPU_FTR_ALTIVEC)) {
+		if (current->thread.regs->msr & MSR_VEC)
+			giveup_altivec(current);
+		current->thread.vr_save_area = NULL;
+	}
+#endif
+}
+
 static void kvmppc_vcpu_sync_debug(struct kvm_vcpu *vcpu)
 {
 	/* Synchronize guest's desire to get debug interrupts into shadow MSR */
@@ -375,9 +409,15 @@ static int kvmppc_booke_irqprio_deliver(struct kvm_vcpu *vcpu,
 	case BOOKE_IRQPRIO_ITLB_MISS:
 	case BOOKE_IRQPRIO_SYSCALL:
 	case BOOKE_IRQPRIO_FP_UNAVAIL:
+#ifdef CONFIG_SPE_POSSIBLE
 	case BOOKE_IRQPRIO_SPE_UNAVAIL:
 	case BOOKE_IRQPRIO_SPE_FP_DATA:
 	case BOOKE_IRQPRIO_SPE_FP_ROUND:
+#endif
+#ifdef CONFIG_ALTIVEC
+	case BOOKE_IRQPRIO_ALTIVEC_UNAVAIL:
+	case BOOKE_IRQPRIO_ALTIVEC_ASSIST:
+#endif
 	case BOOKE_IRQPRIO_AP_UNAVAIL:
 		allowed = 1;
 		msr_mask = MSR_CE | MSR_ME | MSR_DE;
@@ -697,6 +737,17 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
 	kvmppc_load_guest_fp(vcpu);
 #endif
 
+#ifdef CONFIG_ALTIVEC
+	/* Save userspace AltiVec state in stack */
+	if (cpu_has_feature(CPU_FTR_ALTIVEC))
+		enable_kernel_altivec();
+	/*
+	 * Since we can't trap on MSR_VEC in GS-mode, we consider the guest
+	 * as always using the AltiVec.
+	 */
+	kvmppc_load_guest_altivec(vcpu);
+#endif
+
 	/* Switch to guest debug context */
 	debug = vcpu->arch.dbg_reg;
 	switch_booke_debug_regs(&debug);
@@ -719,6 +770,10 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
 	kvmppc_save_guest_fp(vcpu);
 #endif
 
+#ifdef CONFIG_ALTIVEC
+	kvmppc_save_guest_altivec(vcpu);
+#endif
+
 out:
 	vcpu->mode = OUTSIDE_GUEST_MODE;
 	return ret;
@@ -1025,7 +1080,7 @@ int kvmppc_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu,
 		kvmppc_booke_queue_irqprio(vcpu, BOOKE_IRQPRIO_SPE_FP_ROUND);
 		r = RESUME_GUEST;
 		break;
-#else
+#elif defined(CONFIG_SPE_POSSIBLE)
 	case BOOKE_INTERRUPT_SPE_UNAVAIL:
 		/*
 		 * Guest wants SPE, but host kernel doesn't support it.  Send
@@ -1046,6 +1101,22 @@ int kvmppc_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu,
 		run->hw.hardware_exit_reason = exit_nr;
 		r = RESUME_HOST;
 		break;
+#endif /* CONFIG_SPE_POSSIBLE */
+
+/*
+ * On cores with Vector category, KVM is loaded only if CONFIG_ALTIVEC,
+ * see kvmppc_core_check_processor_compat().
+ */
+#ifdef CONFIG_ALTIVEC
+	case BOOKE_INTERRUPT_ALTIVEC_UNAVAIL:
+		kvmppc_booke_queue_irqprio(vcpu, BOOKE_IRQPRIO_ALTIVEC_UNAVAIL);
+		r = RESUME_GUEST;
+		break;
+
+	case BOOKE_INTERRUPT_ALTIVEC_ASSIST:
+		kvmppc_booke_queue_irqprio(vcpu, BOOKE_IRQPRIO_ALTIVEC_ASSIST);
+		r = RESUME_GUEST;
+		break;
 #endif
 
 	case BOOKE_INTERRUPT_DATA_STORAGE:
@@ -1223,6 +1294,7 @@ out:
 			/* interrupts now hard-disabled */
 			kvmppc_fix_ee_before_entry();
 			kvmppc_load_guest_fp(vcpu);
+			kvmppc_load_guest_altivec(vcpu);
 		}
 	}