KVM: PPC: Book3S HV P9: Move host OS save/restore functions to built-in

Move the P9 guest/host register switching functions to the built-in
P9 entry code, and export it for nested to use as well.

This allows more flexibility in scheduling these supervisor privileged
SPR accesses with the HV privileged and PR SPR accesses in the low level
entry code.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211123095231.1036501-30-npiggin@gmail.com

arch/powerpc/kvm/book3s_hv.h

+// SPDX-License-Identifier: GPL-2.0-only
+
+/*
+ * Privileged (non-hypervisor) host registers to save.
+ */
+struct p9_host_os_sprs {
+	unsigned long dscr;
+	unsigned long tidr;
+	unsigned long iamr;
+	unsigned long amr;
+	unsigned long fscr;
+
+	unsigned int pmc1;
+	unsigned int pmc2;
+	unsigned int pmc3;
+	unsigned int pmc4;
+	unsigned int pmc5;
+	unsigned int pmc6;
+	unsigned long mmcr0;
+	unsigned long mmcr1;
+	unsigned long mmcr2;
+	unsigned long mmcr3;
+	unsigned long mmcra;
+	unsigned long siar;
+	unsigned long sier1;
+	unsigned long sier2;
+	unsigned long sier3;
+	unsigned long sdar;
+};
+
+static inline bool nesting_enabled(struct kvm *kvm)
+{
+	return kvm->arch.nested_enable && kvm_is_radix(kvm);
+}
+
+bool load_vcpu_state(struct kvm_vcpu *vcpu,
+			   struct p9_host_os_sprs *host_os_sprs);
+void store_vcpu_state(struct kvm_vcpu *vcpu);
+void save_p9_host_os_sprs(struct p9_host_os_sprs *host_os_sprs);
+void restore_p9_host_os_sprs(struct kvm_vcpu *vcpu,
+				    struct p9_host_os_sprs *host_os_sprs);
+void switch_pmu_to_guest(struct kvm_vcpu *vcpu,
+			    struct p9_host_os_sprs *host_os_sprs);
+void switch_pmu_to_host(struct kvm_vcpu *vcpu,
+			    struct p9_host_os_sprs *host_os_sprs);