2 files changed, 46 insertions, 3 deletions

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index a5d14b5e2ea4..c86a7b0d3e6b 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1927,6 +1927,12 @@ static void perform_access(struct kvm_vcpu *vcpu,
 {
 	trace_kvm_sys_access(*vcpu_pc(vcpu), params, r);
 
+	/* Check for regs disabled by runtime config */
+	if (sysreg_hidden_from_guest(vcpu, r)) {
+		kvm_inject_undefined(vcpu);
+		return;
+	}
+
 	/*
 	 * Not having an accessor means that we have configured a trap
 	 * that we don't know how to handle. This certainly qualifies
@@ -2438,6 +2444,10 @@ int kvm_arm_sys_reg_get_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg
 	if (!r)
 		return get_invariant_sys_reg(reg->id, uaddr);
 
+	/* Check for regs disabled by runtime config */
+	if (sysreg_hidden_from_user(vcpu, r))
+		return -ENOENT;
+
 	if (r->get_user)
 		return (r->get_user)(vcpu, r, reg, uaddr);
 
@@ -2459,6 +2469,10 @@ int kvm_arm_sys_reg_set_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg
 	if (!r)
 		return set_invariant_sys_reg(reg->id, uaddr);
 
+	/* Check for regs disabled by runtime config */
+	if (sysreg_hidden_from_user(vcpu, r))
+		return -ENOENT;
+
 	if (r->set_user)
 		return (r->set_user)(vcpu, r, reg, uaddr);
 
@@ -2515,7 +2529,8 @@ static bool copy_reg_to_user(const struct sys_reg_desc *reg, u64 __user **uind)
 	return true;
 }
 
-static int walk_one_sys_reg(const struct sys_reg_desc *rd,
+static int walk_one_sys_reg(const struct kvm_vcpu *vcpu,
+			    const struct sys_reg_desc *rd,
 			    u64 __user **uind,
 			    unsigned int *total)
 {
@@ -2526,6 +2541,9 @@ static int walk_one_sys_reg(const struct sys_reg_desc *rd,
 	if (!(rd->reg || rd->get_user))
 		return 0;
 
+	if (sysreg_hidden_from_user(vcpu, rd))
+		return 0;
+
 	if (!copy_reg_to_user(rd, uind))
 		return -EFAULT;
 
@@ -2554,9 +2572,9 @@ static int walk_sys_regs(struct kvm_vcpu *vcpu, u64 __user *uind)
 		int cmp = cmp_sys_reg(i1, i2);
 		/* target-specific overrides generic entry. */
 		if (cmp <= 0)
-			err = walk_one_sys_reg(i1, &uind, &total);
+			err = walk_one_sys_reg(vcpu, i1, &uind, &total);
 		else
-			err = walk_one_sys_reg(i2, &uind, &total);
+			err = walk_one_sys_reg(vcpu, i2, &uind, &total);
 
 		if (err)
 			return err;
diff --git a/arch/arm64/kvm/sys_regs.h b/arch/arm64/kvm/sys_regs.h
index 3b1bc7f01d0b..2be99508dcb9 100644
--- a/arch/arm64/kvm/sys_regs.h
+++ b/arch/arm64/kvm/sys_regs.h
@@ -64,8 +64,15 @@ struct sys_reg_desc {
 			const struct kvm_one_reg *reg, void __user *uaddr);
 	int (*set_user)(struct kvm_vcpu *vcpu, const struct sys_reg_desc *rd,
 			const struct kvm_one_reg *reg, void __user *uaddr);
+
+	/* Return mask of REG_* runtime visibility overrides */
+	unsigned int (*visibility)(const struct kvm_vcpu *vcpu,
+				   const struct sys_reg_desc *rd);
 };
 
+#define REG_HIDDEN_USER		(1 << 0) /* hidden from userspace ioctls */
+#define REG_HIDDEN_GUEST	(1 << 1) /* hidden from guest */
+
 static inline void print_sys_reg_instr(const struct sys_reg_params *p)
 {
 	/* Look, we even formatted it for you to paste into the table! */
@@ -102,6 +109,24 @@ static inline void reset_val(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r
 	__vcpu_sys_reg(vcpu, r->reg) = r->val;
 }
 
+static inline bool sysreg_hidden_from_guest(const struct kvm_vcpu *vcpu,
+					    const struct sys_reg_desc *r)
+{
+	if (likely(!r->visibility))
+		return false;
+
+	return r->visibility(vcpu, r) & REG_HIDDEN_GUEST;
+}
+
+static inline bool sysreg_hidden_from_user(const struct kvm_vcpu *vcpu,
+					   const struct sys_reg_desc *r)
+{
+	if (likely(!r->visibility))
+		return false;
+
+	return r->visibility(vcpu, r) & REG_HIDDEN_USER;
+}
+
 static inline int cmp_sys_reg(const struct sys_reg_desc *i1,
 			      const struct sys_reg_desc *i2)
 {