KVM: VMX: Allow the guest to own some cr0 bits

We will use this later to give the guest ownership of cr0.ts.
Signed-off-by: Avi Kivity <avi@redhat.com>

arch/x86/include/asm/kvm_host.h

@@ -269,6 +269,7 @@ struct kvm_vcpu_arch {
 	u32 regs_dirty;
 
 	unsigned long cr0;
+	unsigned long cr0_guest_owned_bits;
 	unsigned long cr2;
 	unsigned long cr3;
 	unsigned long cr4;
@@ -489,6 +490,7 @@ struct kvm_x86_ops {
 	void (*set_segment)(struct kvm_vcpu *vcpu,
 			    struct kvm_segment *var, int seg);
 	void (*get_cs_db_l_bits)(struct kvm_vcpu *vcpu, int *db, int *l);
+	void (*decache_cr0_guest_bits)(struct kvm_vcpu *vcpu);
 	void (*decache_cr4_guest_bits)(struct kvm_vcpu *vcpu);
 	void (*set_cr0)(struct kvm_vcpu *vcpu, unsigned long cr0);
 	void (*set_cr3)(struct kvm_vcpu *vcpu, unsigned long cr3);

arch/x86/kvm/kvm_cache_regs.h

@@ -40,6 +40,8 @@ static inline u64 kvm_pdptr_read(struct kvm_vcpu *vcpu, int index)
 
 static inline ulong kvm_read_cr0_bits(struct kvm_vcpu *vcpu, ulong mask)
 {
+	if (mask & vcpu->arch.cr0_guest_owned_bits)
+		kvm_x86_ops->decache_cr0_guest_bits(vcpu);
 	return vcpu->arch.cr0 & mask;
 }
 

arch/x86/kvm/svm.c

@@ -956,6 +956,10 @@ static void svm_set_gdt(struct kvm_vcpu *vcpu, struct descriptor_table *dt)
 	svm->vmcb->save.gdtr.base = dt->base ;
 }
 
+static void svm_decache_cr0_guest_bits(struct kvm_vcpu *vcpu)
+{
+}
+
 static void svm_decache_cr4_guest_bits(struct kvm_vcpu *vcpu)
 {
 }
@@ -2948,6 +2952,7 @@ static struct kvm_x86_ops svm_x86_ops = {
 	.set_segment = svm_set_segment,
 	.get_cpl = svm_get_cpl,
 	.get_cs_db_l_bits = kvm_get_cs_db_l_bits,
+	.decache_cr0_guest_bits = svm_decache_cr0_guest_bits,
 	.decache_cr4_guest_bits = svm_decache_cr4_guest_bits,
 	.set_cr0 = svm_set_cr0,
 	.set_cr3 = svm_set_cr3,

arch/x86/kvm/vmx.c

@@ -1653,6 +1653,14 @@ static void vmx_flush_tlb(struct kvm_vcpu *vcpu)
 		ept_sync_context(construct_eptp(vcpu->arch.mmu.root_hpa));
 }
 
+static void vmx_decache_cr0_guest_bits(struct kvm_vcpu *vcpu)
+{
+	ulong cr0_guest_owned_bits = vcpu->arch.cr0_guest_owned_bits;
+
+	vcpu->arch.cr0 &= ~cr0_guest_owned_bits;
+	vcpu->arch.cr0 |= vmcs_readl(GUEST_CR0) & cr0_guest_owned_bits;
+}
+
 static void vmx_decache_cr4_guest_bits(struct kvm_vcpu *vcpu)
 {
 	ulong cr4_guest_owned_bits = vcpu->arch.cr4_guest_owned_bits;
@@ -4106,6 +4114,7 @@ static struct kvm_x86_ops vmx_x86_ops = {
 	.set_segment = vmx_set_segment,
 	.get_cpl = vmx_get_cpl,
 	.get_cs_db_l_bits = vmx_get_cs_db_l_bits,
+	.decache_cr0_guest_bits = vmx_decache_cr0_guest_bits,
 	.decache_cr4_guest_bits = vmx_decache_cr4_guest_bits,
 	.set_cr0 = vmx_set_cr0,
 	.set_cr3 = vmx_set_cr3,