The kvm_tdp_mmu_alloc_root() function currently always returns 0. This
allows for the caller, mmu_alloc_direct_roots(), to call
kvm_tdp_mmu_alloc_root() and also return 0 in one line:
   return kvm_tdp_mmu_alloc_root(vcpu);

So it is useful even though the return value of kvm_tdp_mmu_alloc_root()
is always the same. However, in future changes, kvm_tdp_mmu_alloc_root()
will be called twice in mmu_alloc_direct_roots(). This will force the
first call to either awkwardly handle the return value that will always
be zero or ignore it. So change kvm_tdp_mmu_alloc_root() to return void.
Do it in a separate change so the future change will be cleaner.

Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
---
v3:
 - Add Paolo's reviewed-by

v1:
 - New patch
---
 arch/x86/kvm/mmu/mmu.c     | 6 ++++--
 arch/x86/kvm/mmu/tdp_mmu.c | 3 +--
 arch/x86/kvm/mmu/tdp_mmu.h | 2 +-
 3 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 50ba7f63a067..2f7f372a4bfe 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -3703,8 +3703,10 @@ static int mmu_alloc_direct_roots(struct kvm_vcpu *vcpu)
 	unsigned i;
 	int r;
 
-	if (tdp_mmu_enabled)
-		return kvm_tdp_mmu_alloc_root(vcpu);
+	if (tdp_mmu_enabled) {
+		kvm_tdp_mmu_alloc_root(vcpu);
+		return 0;
+	}
 
 	write_lock(&vcpu->kvm->mmu_lock);
 	r = make_mmu_pages_available(vcpu);
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 2d09c353e4bc..f4df20b91817 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -224,7 +224,7 @@ static void tdp_mmu_init_child_sp(struct kvm_mmu_page *child_sp,
 	tdp_mmu_init_sp(child_sp, iter->sptep, iter->gfn, role);
 }
 
-int kvm_tdp_mmu_alloc_root(struct kvm_vcpu *vcpu)
+void kvm_tdp_mmu_alloc_root(struct kvm_vcpu *vcpu)
 {
 	struct kvm_mmu *mmu = vcpu->arch.mmu;
 	union kvm_mmu_page_role role = mmu->root_role;
@@ -285,7 +285,6 @@ int kvm_tdp_mmu_alloc_root(struct kvm_vcpu *vcpu)
 	 */
 	mmu->root.hpa = __pa(root->spt);
 	mmu->root.pgd = 0;
-	return 0;
 }
 
 static void handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn,
diff --git a/arch/x86/kvm/mmu/tdp_mmu.h b/arch/x86/kvm/mmu/tdp_mmu.h
index 14421d080fe6..a0e00284b75d 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.h
+++ b/arch/x86/kvm/mmu/tdp_mmu.h
@@ -10,7 +10,7 @@
 void kvm_mmu_init_tdp_mmu(struct kvm *kvm);
 void kvm_mmu_uninit_tdp_mmu(struct kvm *kvm);
 
-int kvm_tdp_mmu_alloc_root(struct kvm_vcpu *vcpu);
+void kvm_tdp_mmu_alloc_root(struct kvm_vcpu *vcpu);
 
 __must_check static inline bool kvm_tdp_mmu_get_root(struct kvm_mmu_page *root)
 {
-- 
2.34.1