KVM: x86/mmu: Remove redundant root_hpa checks

The root_hpa checks below the top-level check in kvm_mmu_page_fault are
theoretically redundant since there is no longer a way for the root_hpa
to be reset during a page fault. The details of why are described in
commit ddce6208 ("KVM: x86/mmu: Move root_hpa validity checks to top
of page fault handler")

__direct_map, kvm_tdp_mmu_map, and get_mmio_spte are all only reachable
through kvm_mmu_page_fault, therefore their root_hpa checks are
redundant.
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20210617231948.2591431-5-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/mmu/mmu.c

@@ -2859,9 +2859,6 @@ static int __direct_map(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,
 	gfn_t gfn = gpa >> PAGE_SHIFT;
 	gfn_t base_gfn = gfn;
 
-	if (WARN_ON(!VALID_PAGE(vcpu->arch.mmu->root_hpa)))
-		return RET_PF_RETRY;
-
 	level = kvm_mmu_hugepage_adjust(vcpu, gfn, max_level, &pfn,
 					huge_page_disallowed, &req_level);
 
@@ -3603,11 +3600,6 @@ static bool get_mmio_spte(struct kvm_vcpu *vcpu, u64 addr, u64 *sptep)
 	int root, leaf, level;
 	bool reserved = false;
 
-	if (!VALID_PAGE(vcpu->arch.mmu->root_hpa)) {
-		*sptep = 0ull;
-		return reserved;
-	}
-
 	if (is_tdp_mmu(vcpu->arch.mmu))
 		leaf = kvm_tdp_mmu_get_walk(vcpu, addr, sptes, &root);
 	else

arch/x86/kvm/mmu/tdp_mmu.c

@@ -983,9 +983,6 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,
 	int level;
 	int req_level;
 
-	if (WARN_ON(!VALID_PAGE(vcpu->arch.mmu->root_hpa)))
-		return RET_PF_RETRY;
-
 	level = kvm_mmu_hugepage_adjust(vcpu, gfn, max_level, &pfn,
 					huge_page_disallowed, &req_level);