KVM: x86/mmu: constify uses of struct kvm_mmu_role_regs

struct kvm_mmu_role_regs is computed just once and then accessed.  Use
const to make this clearer, even though the const fields of struct
kvm_mmu_role_regs already prevent (or make it harder...) to modify
the contents of the struct.
Reviewed-by: David Matlack <dmatlack@google.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/mmu/mmu.c

@@ -197,7 +197,8 @@ struct kvm_mmu_role_regs {
  * the single source of truth for the MMU's state.
  */
 #define BUILD_MMU_ROLE_REGS_ACCESSOR(reg, name, flag)			\
-static inline bool __maybe_unused ____is_##reg##_##name(struct kvm_mmu_role_regs *regs)\
+static inline bool __maybe_unused					\
+____is_##reg##_##name(const struct kvm_mmu_role_regs *regs)		\
 {									\
 	return !!(regs->reg & flag);					\
 }
@@ -244,7 +245,7 @@ static struct kvm_mmu_role_regs vcpu_to_role_regs(struct kvm_vcpu *vcpu)
 	return regs;
 }
 
-static int role_regs_to_root_level(struct kvm_mmu_role_regs *regs)
+static int role_regs_to_root_level(const struct kvm_mmu_role_regs *regs)
 {
 	if (!____is_cr0_pg(regs))
 		return 0;
@@ -4748,7 +4749,7 @@ static void paging32_init_context(struct kvm_mmu *context)
 }
 
 static union kvm_mmu_extended_role kvm_calc_mmu_role_ext(struct kvm_vcpu *vcpu,
-							 struct kvm_mmu_role_regs *regs)
+							 const struct kvm_mmu_role_regs *regs)
 {
 	union kvm_mmu_extended_role ext = {0};
 
@@ -4771,7 +4772,7 @@ static union kvm_mmu_extended_role kvm_calc_mmu_role_ext(struct kvm_vcpu *vcpu,
 }
 
 static union kvm_mmu_role kvm_calc_mmu_role_common(struct kvm_vcpu *vcpu,
-						   struct kvm_mmu_role_regs *regs,
+						   const struct kvm_mmu_role_regs *regs,
 						   bool base_only)
 {
 	union kvm_mmu_role role = {0};
@@ -4807,7 +4808,8 @@ static inline int kvm_mmu_get_tdp_level(struct kvm_vcpu *vcpu)
 
 static union kvm_mmu_role
 kvm_calc_tdp_mmu_root_page_role(struct kvm_vcpu *vcpu,
-				struct kvm_mmu_role_regs *regs, bool base_only)
+				const struct kvm_mmu_role_regs *regs,
+				bool base_only)
 {
 	union kvm_mmu_role role = kvm_calc_mmu_role_common(vcpu, regs, base_only);
 
@@ -4853,7 +4855,8 @@ static void init_kvm_tdp_mmu(struct kvm_vcpu *vcpu)
 
 static union kvm_mmu_role
 kvm_calc_shadow_root_page_role_common(struct kvm_vcpu *vcpu,
-				      struct kvm_mmu_role_regs *regs, bool base_only)
+				      const struct kvm_mmu_role_regs *regs,
+				      bool base_only)
 {
 	union kvm_mmu_role role = kvm_calc_mmu_role_common(vcpu, regs, base_only);
 
@@ -4866,7 +4869,8 @@ kvm_calc_shadow_root_page_role_common(struct kvm_vcpu *vcpu,
 
 static union kvm_mmu_role
 kvm_calc_shadow_mmu_root_page_role(struct kvm_vcpu *vcpu,
-				   struct kvm_mmu_role_regs *regs, bool base_only)
+				   const struct kvm_mmu_role_regs *regs,
+				   bool base_only)
 {
 	union kvm_mmu_role role =
 		kvm_calc_shadow_root_page_role_common(vcpu, regs, base_only);
@@ -4884,7 +4888,7 @@ kvm_calc_shadow_mmu_root_page_role(struct kvm_vcpu *vcpu,
 }
 
 static void shadow_mmu_init_context(struct kvm_vcpu *vcpu, struct kvm_mmu *context,
-				    struct kvm_mmu_role_regs *regs,
+				    const struct kvm_mmu_role_regs *regs,
 				    union kvm_mmu_role new_role)
 {
 	if (new_role.as_u64 == context->mmu_role.as_u64)
@@ -4907,7 +4911,7 @@ static void shadow_mmu_init_context(struct kvm_vcpu *vcpu, struct kvm_mmu *conte
 }
 
 static void kvm_init_shadow_mmu(struct kvm_vcpu *vcpu,
-				struct kvm_mmu_role_regs *regs)
+				const struct kvm_mmu_role_regs *regs)
 {
 	struct kvm_mmu *context = &vcpu->arch.root_mmu;
 	union kvm_mmu_role new_role =
@@ -4918,7 +4922,7 @@ static void kvm_init_shadow_mmu(struct kvm_vcpu *vcpu,
 
 static union kvm_mmu_role
 kvm_calc_shadow_npt_root_page_role(struct kvm_vcpu *vcpu,
-				   struct kvm_mmu_role_regs *regs)
+				   const struct kvm_mmu_role_regs *regs)
 {
 	union kvm_mmu_role role =
 		kvm_calc_shadow_root_page_role_common(vcpu, regs, false);
@@ -5018,7 +5022,7 @@ static void init_kvm_softmmu(struct kvm_vcpu *vcpu)
 }
 
 static union kvm_mmu_role
-kvm_calc_nested_mmu_role(struct kvm_vcpu *vcpu, struct kvm_mmu_role_regs *regs)
+kvm_calc_nested_mmu_role(struct kvm_vcpu *vcpu, const struct kvm_mmu_role_regs *regs)
 {
 	union kvm_mmu_role role;