KVM: arm64: Add get_reg_by_id() as a sys_reg_desc retrieving helper

find_reg_by_id() requires a sys_reg_param as input, which most
users provide as a on-stack variable, but don't make any use of
the result.

Provide a helper that doesn't have this requirement and simplify
the callers (all but one).

Reviewed-by: Reiji Watanabe <reijiw@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>

1 files changed, 17 insertions, 11 deletions

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index c06c0477fab5..1f410283c592 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -2650,21 +2650,29 @@ const struct sys_reg_desc *find_reg_by_id(u64 id,
 	return find_reg(params, table, num);
 }
 
+const struct sys_reg_desc *get_reg_by_id(u64 id,
+					 const struct sys_reg_desc table[],
+					 unsigned int num)
+{
+	struct sys_reg_params params;
+
+	if (!index_to_params(id, &params))
+		return NULL;
+
+	return find_reg(&params, table, num);
+}
+
 /* Decode an index value, and find the sys_reg_desc entry. */
 static const struct sys_reg_desc *index_to_sys_reg_desc(struct kvm_vcpu *vcpu,
 						    u64 id)
 {
 	const struct sys_reg_desc *r;
-	struct sys_reg_params params;
 
 	/* We only do sys_reg for now. */
 	if ((id & KVM_REG_ARM_COPROC_MASK) != KVM_REG_ARM64_SYSREG)
 		return NULL;
 
-	if (!index_to_params(id, &params))
-		return NULL;
-
-	r = find_reg(&params, sys_reg_descs, ARRAY_SIZE(sys_reg_descs));
+	r = get_reg_by_id(id, sys_reg_descs, ARRAY_SIZE(sys_reg_descs));
 
 	/* Not saved in the sys_reg array and not otherwise accessible? */
 	if (r && !(r->reg || r->get_user))
@@ -2723,11 +2731,10 @@ static int reg_to_user(void __user *uaddr, const u64 *val, u64 id)
 
 static int get_invariant_sys_reg(u64 id, void __user *uaddr)
 {
-	struct sys_reg_params params;
 	const struct sys_reg_desc *r;
 
-	r = find_reg_by_id(id, &params, invariant_sys_regs,
-			   ARRAY_SIZE(invariant_sys_regs));
+	r = get_reg_by_id(id, invariant_sys_regs,
+			  ARRAY_SIZE(invariant_sys_regs));
 	if (!r)
 		return -ENOENT;
 
@@ -2736,13 +2743,12 @@ static int get_invariant_sys_reg(u64 id, void __user *uaddr)
 
 static int set_invariant_sys_reg(u64 id, void __user *uaddr)
 {
-	struct sys_reg_params params;
 	const struct sys_reg_desc *r;
 	int err;
 	u64 val = 0; /* Make sure high bits are 0 for 32-bit regs */
 
-	r = find_reg_by_id(id, &params, invariant_sys_regs,
-			   ARRAY_SIZE(invariant_sys_regs));
+	r = get_reg_by_id(id, invariant_sys_regs,
+			  ARRAY_SIZE(invariant_sys_regs));
 	if (!r)
 		return -ENOENT;