KVM: MMU: inline set_spte in mmu_set_spte

Since the two callers of set_spte do different things with the results,
inlining it actually makes the code simpler to reason about.  For example,
mmu_set_spte looks quite like tdp_mmu_map_handle_target_level, but the
similarity is hidden by set_spte.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/mmu/mmu.c

@@ -2700,10 +2700,12 @@ static int mmu_set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
 			gfn_t gfn, kvm_pfn_t pfn, bool speculative,
 			bool host_writable)
 {
+	struct kvm_mmu_page *sp = sptep_to_sp(sptep);
 	int was_rmapped = 0;
-	int set_spte_ret;
 	int ret = RET_PF_FIXED;
 	bool flush = false;
+	int make_spte_ret;
+	u64 spte;
 
 	pgprintk("%s: spte %llx write_fault %d gfn %llx\n", __func__,
 		 *sptep, write_fault, gfn);
@@ -2734,30 +2736,29 @@ static int mmu_set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
 			was_rmapped = 1;
 	}
 
-	set_spte_ret = set_spte(vcpu, sptep, pte_access, level, gfn, pfn,
-				speculative, true, host_writable);
-	if (set_spte_ret & SET_SPTE_WRITE_PROTECTED_PT) {
+	make_spte_ret = make_spte(vcpu, pte_access, level, gfn, pfn, *sptep, speculative,
+				 true, host_writable, sp_ad_disabled(sp), &spte);
+
+	if (*sptep == spte) {
+		ret = RET_PF_SPURIOUS;
+	} else {
+		trace_kvm_mmu_set_spte(level, gfn, sptep);
+		flush |= mmu_spte_update(sptep, spte);
+	}
+
+	if (make_spte_ret & SET_SPTE_WRITE_PROTECTED_PT) {
 		if (write_fault)
 			ret = RET_PF_EMULATE;
 	}
 
-	if (set_spte_ret & SET_SPTE_NEED_REMOTE_TLB_FLUSH || flush)
+	if (flush)
 		kvm_flush_remote_tlbs_with_address(vcpu->kvm, gfn,
 				KVM_PAGES_PER_HPAGE(level));
 
-	/*
-	 * The fault is fully spurious if and only if the new SPTE and old SPTE
-	 * are identical, and emulation is not required.
-	 */
-	if ((set_spte_ret & SET_SPTE_SPURIOUS) && ret == RET_PF_FIXED) {
-		WARN_ON_ONCE(!was_rmapped);
-		return RET_PF_SPURIOUS;
-	}
-
 	pgprintk("%s: setting spte %llx\n", __func__, *sptep);
-	trace_kvm_mmu_set_spte(level, gfn, sptep);
 
 	if (!was_rmapped) {
+		WARN_ON_ONCE(ret == RET_PF_SPURIOUS);
 		kvm_update_page_stats(vcpu->kvm, level, 1);
 		rmap_add(vcpu, sptep, gfn);
 	}