KVM: SVM: Remove references to VCPU_EXREG_CR3

VCPU_EXREG_CR3 is never cleared from vcpu->arch.regs_avail or
vcpu->arch.regs_dirty in SVM; therefore, marking CR3 as available is
merely a NOP, and testing it will likewise always succeed.
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Message-Id: <20211108124407.12187-9-jiangshanlai@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/svm/nested.c

@@ -468,7 +468,6 @@ static int nested_svm_load_cr3(struct kvm_vcpu *vcpu, unsigned long cr3,
 		kvm_mmu_new_pgd(vcpu, cr3);
 
 	vcpu->arch.cr3 = cr3;
-	kvm_register_mark_available(vcpu, VCPU_EXREG_CR3);
 
 	/* Re-initialize the MMU, e.g. to pick up CR4 MMU role changes. */
 	kvm_init_mmu(vcpu);

arch/x86/kvm/svm/svm.c

@@ -4010,8 +4010,6 @@ static void svm_load_mmu_pgd(struct kvm_vcpu *vcpu, hpa_t root_hpa,
 
 		hv_track_root_tdp(vcpu, root_hpa);
 
-		if (!test_bit(VCPU_EXREG_CR3, (ulong *)&vcpu->arch.regs_avail))
-			return;
 		cr3 = vcpu->arch.cr3;
 	} else if (vcpu->arch.mmu->shadow_root_level >= PT64_ROOT_4LEVEL) {
 		cr3 = __sme_set(root_hpa) | kvm_get_active_pcid(vcpu);