KVM: Add accessor for reading cr4 (or some bits of cr4)

Some bits of cr4 can be owned by the guest on vmx, so when we read them,
we copy them to the vcpu structure.  In preparation for making the set of
guest-owned bits dynamic, use helpers to access these bits so we don't need
to know where the bit resides.

No changes to svm since all bits are host-owned there.

Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 2793186..84dd33e 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -482,7 +482,7 @@
 
 void kvm_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)
 {
-	unsigned long old_cr4 = vcpu->arch.cr4;
+	unsigned long old_cr4 = kvm_read_cr4(vcpu);
 	unsigned long pdptr_bits = X86_CR4_PGE | X86_CR4_PSE | X86_CR4_PAE;
 
 	if (cr4 & CR4_RESERVED_BITS) {
@@ -1899,7 +1899,7 @@
 		return 0;
 	if (mce->status & MCI_STATUS_UC) {
 		if ((vcpu->arch.mcg_status & MCG_STATUS_MCIP) ||
-		    !(vcpu->arch.cr4 & X86_CR4_MCE)) {
+		    !kvm_read_cr4_bits(vcpu, X86_CR4_MCE)) {
 			printk(KERN_DEBUG "kvm: set_mce: "
 			       "injects mce exception while "
 			       "previous one is in progress!\n");
@@ -3616,7 +3616,6 @@
 {
 	unsigned long value;
 
-	kvm_x86_ops->decache_cr4_guest_bits(vcpu);
 	switch (cr) {
 	case 0:
 		value = vcpu->arch.cr0;
@@ -3628,7 +3627,7 @@
 		value = vcpu->arch.cr3;
 		break;
 	case 4:
-		value = vcpu->arch.cr4;
+		value = kvm_read_cr4(vcpu);
 		break;
 	case 8:
 		value = kvm_get_cr8(vcpu);
@@ -3656,7 +3655,7 @@
 		kvm_set_cr3(vcpu, val);
 		break;
 	case 4:
-		kvm_set_cr4(vcpu, mk_cr_64(vcpu->arch.cr4, val));
+		kvm_set_cr4(vcpu, mk_cr_64(kvm_read_cr4(vcpu), val));
 		break;
 	case 8:
 		kvm_set_cr8(vcpu, val & 0xfUL);
@@ -4237,11 +4236,10 @@
 	sregs->gdt.limit = dt.limit;
 	sregs->gdt.base = dt.base;
 
-	kvm_x86_ops->decache_cr4_guest_bits(vcpu);
 	sregs->cr0 = vcpu->arch.cr0;
 	sregs->cr2 = vcpu->arch.cr2;
 	sregs->cr3 = vcpu->arch.cr3;
-	sregs->cr4 = vcpu->arch.cr4;
+	sregs->cr4 = kvm_read_cr4(vcpu);
 	sregs->cr8 = kvm_get_cr8(vcpu);
 	sregs->efer = vcpu->arch.shadow_efer;
 	sregs->apic_base = kvm_get_apic_base(vcpu);
@@ -4737,13 +4735,11 @@
 	kvm_x86_ops->set_efer(vcpu, sregs->efer);
 	kvm_set_apic_base(vcpu, sregs->apic_base);
 
-	kvm_x86_ops->decache_cr4_guest_bits(vcpu);
-
 	mmu_reset_needed |= vcpu->arch.cr0 != sregs->cr0;
 	kvm_x86_ops->set_cr0(vcpu, sregs->cr0);
 	vcpu->arch.cr0 = sregs->cr0;
 
-	mmu_reset_needed |= vcpu->arch.cr4 != sregs->cr4;
+	mmu_reset_needed |= kvm_read_cr4(vcpu) != sregs->cr4;
 	kvm_x86_ops->set_cr4(vcpu, sregs->cr4);
 	if (!is_long_mode(vcpu) && is_pae(vcpu)) {
 		load_pdptrs(vcpu, vcpu->arch.cr3);