KVM: arm64: Unify identifiers used to distinguish host and hypervisor

The 'pkvm_component_id' enum type provides constants to refer to the
host and the hypervisor, yet this information is duplicated by the
'pkvm_hyp_id' constant.

Remove the definition of 'pkvm_hyp_id' and move the 'pkvm_component_id'
type definition to 'mem_protect.h' so that it can be used outside of
the memory protection code, for example when initialising the owner for
hypervisor-owned pages.

Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Tested-by: Vincent Donnefort <vdonnefort@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221110190259.26861-6-will@kernel.org

arch/arm64/kvm/hyp/include/nvhe/mem_protect.h

@@ -51,7 +51,11 @@ struct host_kvm {
 };
 extern struct host_kvm host_kvm;
 
-extern const u8 pkvm_hyp_id;
+/* This corresponds to page-table locking order */
+enum pkvm_component_id {
+	PKVM_ID_HOST,
+	PKVM_ID_HYP,
+};
 
 int __pkvm_prot_finalize(void);
 int __pkvm_host_share_hyp(u64 pfn);

arch/arm64/kvm/hyp/nvhe/mem_protect.c

@@ -26,8 +26,6 @@ struct host_kvm host_kvm;
 
 static struct hyp_pool host_s2_pool;
 
-const u8 pkvm_hyp_id = 1;
-
 static void host_lock_component(void)
 {
 	hyp_spin_lock(&host_kvm.lock);
@@ -380,12 +378,6 @@ void handle_host_mem_abort(struct kvm_cpu_context *host_ctxt)
 	BUG_ON(ret && ret != -EAGAIN);
 }
 
-/* This corresponds to locking order */
-enum pkvm_component_id {
-	PKVM_ID_HOST,
-	PKVM_ID_HYP,
-};
-
 struct pkvm_mem_transition {
 	u64				nr_pages;
 

arch/arm64/kvm/hyp/nvhe/setup.c

@@ -212,7 +212,7 @@ static int fix_host_ownership_walker(u64 addr, u64 end, u32 level,
 	state = pkvm_getstate(kvm_pgtable_hyp_pte_prot(pte));
 	switch (state) {
 	case PKVM_PAGE_OWNED:
-		return host_stage2_set_owner_locked(phys, PAGE_SIZE, pkvm_hyp_id);
+		return host_stage2_set_owner_locked(phys, PAGE_SIZE, PKVM_ID_HYP);
 	case PKVM_PAGE_SHARED_OWNED:
 		prot = pkvm_mkstate(PKVM_HOST_MEM_PROT, PKVM_PAGE_SHARED_BORROWED);
 		break;