KVM: PPC: Resolve real-mode handlers through function exports

Up until now, Book3S KVM had variables stored in the kernel that a kernel module
or the kvm code in the kernel could read from to figure out where some real mode
helper functions are located.

This is all unnecessary. The high bits of the EA get ignore in real mode, so we
can just use the pointer as is. Also, it's a lot easier on relocations when we
use the normal way of resolving the address to a function, instead of jumping
through hoops.

This patch fixes compilation with CONFIG_RELOCATABLE=y.

Signed-off-by: Alexander Graf <agraf@suse.de>

arch/powerpc/include/asm/kvm_book3s.h

@@ -133,8 +133,8 @@ extern void kvmppc_giveup_ext(struct kvm_vcpu *vcpu, ulong msr);
 extern int kvmppc_emulate_paired_single(struct kvm_run *run, struct kvm_vcpu *vcpu);
 extern pfn_t kvmppc_gfn_to_pfn(struct kvm_vcpu *vcpu, gfn_t gfn);
 
-extern ulong kvmppc_trampoline_lowmem;
-extern ulong kvmppc_trampoline_enter;
+extern void kvmppc_handler_lowmem_trampoline(void);
+extern void kvmppc_handler_trampoline_enter(void);
 extern void kvmppc_rmcall(ulong srr0, ulong srr1);
 extern void kvmppc_load_up_fpu(void);
 extern void kvmppc_load_up_altivec(void);

arch/powerpc/kvm/book3s.c

@@ -1342,8 +1342,8 @@ struct kvm_vcpu *kvmppc_core_vcpu_create(struct kvm *kvm, unsigned int id)
 	vcpu_book3s->slb_nr = 64;
 
 	/* remember where some real-mode handlers are */
-	vcpu->arch.trampoline_lowmem = kvmppc_trampoline_lowmem;
-	vcpu->arch.trampoline_enter = kvmppc_trampoline_enter;
+	vcpu->arch.trampoline_lowmem = (ulong)kvmppc_handler_lowmem_trampoline;
+	vcpu->arch.trampoline_enter = (ulong)kvmppc_handler_trampoline_enter;
 	vcpu->arch.highmem_handler = (ulong)kvmppc_handler_highmem;
 #ifdef CONFIG_PPC_BOOK3S_64
 	vcpu->arch.rmcall = *(ulong*)kvmppc_rmcall;

arch/powerpc/kvm/book3s_exports.c

@@ -20,8 +20,8 @@
 #include <linux/module.h>
 #include <asm/kvm_book3s.h>
 
-EXPORT_SYMBOL_GPL(kvmppc_trampoline_enter);
-EXPORT_SYMBOL_GPL(kvmppc_trampoline_lowmem);
+EXPORT_SYMBOL_GPL(kvmppc_handler_trampoline_enter);
+EXPORT_SYMBOL_GPL(kvmppc_handler_lowmem_trampoline);
 EXPORT_SYMBOL_GPL(kvmppc_rmcall);
 EXPORT_SYMBOL_GPL(kvmppc_load_up_fpu);
 #ifdef CONFIG_ALTIVEC

arch/powerpc/kvm/book3s_rmhandlers.S

@@ -251,12 +251,4 @@ define_load_up(altivec)
 define_load_up(vsx)
 #endif
 
-.global kvmppc_trampoline_lowmem
-kvmppc_trampoline_lowmem:
-	PPC_LONG kvmppc_handler_lowmem_trampoline - CONFIG_KERNEL_START
-
-.global kvmppc_trampoline_enter
-kvmppc_trampoline_enter:
-	PPC_LONG kvmppc_handler_trampoline_enter - CONFIG_KERNEL_START
-
 #include "book3s_segment.S"