powerpc/32s: move CTX_TO_VSID() into mmu-hash.h

In order to reuse it in switch_mmu_context(), this
patch moves CTX_TO_VSID() macro into asm/book3s/32/mmu-hash.h
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/26b36ef2939234a04b37baf6ffe50cba81f5d1b7.1622708530.git.christophe.leroy@csgroup.eu

arch/powerpc/include/asm/book3s/32/mmu-hash.h

@@ -66,6 +66,16 @@ struct ppc_bat {
 
 #ifndef __ASSEMBLY__
 
+/*
+ * This macro defines the mapping from contexts to VSIDs (virtual
+ * segment IDs).  We use a skew on both the context and the high 4 bits
+ * of the 32-bit virtual address (the "effective segment ID") in order
+ * to spread out the entries in the MMU hash table.  Note, if this
+ * function is changed then hash functions will have to be
+ * changed to correspond.
+ */
+#define CTX_TO_VSID(c, id)	((((c) * (897 * 16)) + (id * 0x111)) & 0xffffff)
+
 /*
  * Hardware Page Table Entry
  * Note that the xpn and x bitfields are used only by processors that

arch/powerpc/kvm/book3s_32_mmu_host.c

@@ -353,9 +353,6 @@ void kvmppc_mmu_destroy_pr(struct kvm_vcpu *vcpu)
 	preempt_enable();
 }
 
-/* From mm/mmu_context_hash32.c */
-#define CTX_TO_VSID(c, id)	((((c) * (897 * 16)) + (id * 0x111)) & 0xffffff)
-
 int kvmppc_mmu_init_pr(struct kvm_vcpu *vcpu)
 {
 	struct kvmppc_vcpu_book3s *vcpu3s = to_book3s(vcpu);

arch/powerpc/mm/book3s32/mmu_context.c

@@ -39,19 +39,6 @@
 #define LAST_CONTEXT    	32767
 #define FIRST_CONTEXT    	1
 
-/*
- * This function defines the mapping from contexts to VSIDs (virtual
- * segment IDs).  We use a skew on both the context and the high 4 bits
- * of the 32-bit virtual address (the "effective segment ID") in order
- * to spread out the entries in the MMU hash table.  Note, if this
- * function is changed then arch/ppc/mm/hashtable.S will have to be
- * changed to correspond.
- *
- *
- * CTX_TO_VSID(ctx, va)	(((ctx) * (897 * 16) + ((va) >> 28) * 0x111) \
- *				 & 0xffffff)
- */
-
 static unsigned long next_mmu_context;
 static unsigned long context_map[LAST_CONTEXT / BITS_PER_LONG + 1];