KVM: PPC: Add giveup_ext() hook to PPC KVM ops

Currently HV will save math regs(FP/VEC/VSX) when trap into host. But
PR KVM will only save math regs when qemu task switch out of CPU, or
when returning from qemu code.

To emulate FP/VEC/VSX mmio load, PR KVM need to make sure that math
regs were flushed firstly and then be able to update saved VCPU
FPR/VEC/VSX area reasonably.

This patch adds giveup_ext() field to KVM ops. Only PR KVM has non-NULL
giveup_ext() ops. kvmppc_complete_mmio_load() can invoke that hook
(when not NULL) to flush math regs accordingly, before updating saved
register vals.

Math regs flush is also necessary for STORE, which will be covered
in later patch within this patch series.
Signed-off-by: Simon Guo <wei.guo.simon@gmail.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>

arch/powerpc/include/asm/kvm_ppc.h

@@ -324,6 +324,7 @@ struct kvmppc_ops {
 	int (*get_rmmu_info)(struct kvm *kvm, struct kvm_ppc_rmmu_info *info);
 	int (*set_smt_mode)(struct kvm *kvm, unsigned long mode,
 			    unsigned long flags);
+	void (*giveup_ext)(struct kvm_vcpu *vcpu, ulong msr);
 };
 
 extern struct kvmppc_ops *kvmppc_hv_ops;

arch/powerpc/kvm/book3s_pr.c

@@ -1789,6 +1789,7 @@ static struct kvmppc_ops kvm_ops_pr = {
 #ifdef CONFIG_PPC_BOOK3S_64
 	.hcall_implemented = kvmppc_hcall_impl_pr,
 #endif
+	.giveup_ext = kvmppc_giveup_ext,
 };
 
 

arch/powerpc/kvm/powerpc.c

@@ -1061,6 +1061,9 @@ static void kvmppc_complete_mmio_load(struct kvm_vcpu *vcpu,
 		kvmppc_set_gpr(vcpu, vcpu->arch.io_gpr, gpr);
 		break;
 	case KVM_MMIO_REG_FPR:
+		if (vcpu->kvm->arch.kvm_ops->giveup_ext)
+			vcpu->kvm->arch.kvm_ops->giveup_ext(vcpu, MSR_FP);
+
 		VCPU_FPR(vcpu, vcpu->arch.io_gpr & KVM_MMIO_REG_MASK) = gpr;
 		break;
 #ifdef CONFIG_PPC_BOOK3S
@@ -1074,6 +1077,9 @@ static void kvmppc_complete_mmio_load(struct kvm_vcpu *vcpu,
 #endif
 #ifdef CONFIG_VSX
 	case KVM_MMIO_REG_VSX:
+		if (vcpu->kvm->arch.kvm_ops->giveup_ext)
+			vcpu->kvm->arch.kvm_ops->giveup_ext(vcpu, MSR_VSX);
+
 		if (vcpu->arch.mmio_vsx_copy_type == KVMPPC_VSX_COPY_DWORD)
 			kvmppc_set_vsr_dword(vcpu, gpr);
 		else if (vcpu->arch.mmio_vsx_copy_type == KVMPPC_VSX_COPY_WORD)
@@ -1088,6 +1094,9 @@ static void kvmppc_complete_mmio_load(struct kvm_vcpu *vcpu,
 #endif
 #ifdef CONFIG_ALTIVEC
 	case KVM_MMIO_REG_VMX:
+		if (vcpu->kvm->arch.kvm_ops->giveup_ext)
+			vcpu->kvm->arch.kvm_ops->giveup_ext(vcpu, MSR_VEC);
+
 		kvmppc_set_vmx_dword(vcpu, gpr);
 		break;
 #endif