[PATCH 10/25] KVM: arm64: nv: Turn encoding ranges into discrete XArray stores

[Marc Zyngier]

In order to be able to store different values for member of an
encoding range, replace xa_store_range() calls with discrete
xa_store() calls and an encoding iterator.

We end-up using a bit more memory, but we gain some flexibility
that we will make use of shortly.

Signed-off-by: Marc Zyngier <maz at kernel.org>
---
 arch/arm64/kvm/emulate-nested.c | 31 ++++++++++++++++++++++++-------
 1 file changed, 24 insertions(+), 7 deletions(-)

diff --git a/arch/arm64/kvm/emulate-nested.c b/arch/arm64/kvm/emulate-nested.c
index ef46c2e45307..59622636b723 100644
--- a/arch/arm64/kvm/emulate-nested.c
+++ b/arch/arm64/kvm/emulate-nested.c
@@ -1757,6 +1757,28 @@ static __init void print_nv_trap_error(const struct encoding_to_trap_config *tc,
 		err);
 }
 
+static u32 encoding_next(u32 encoding)
+{
+	u8 op0, op1, crn, crm, op2;
+
+	op0 = sys_reg_Op0(encoding);
+	op1 = sys_reg_Op1(encoding);
+	crn = sys_reg_CRn(encoding);
+	crm = sys_reg_CRm(encoding);
+	op2 = sys_reg_Op2(encoding);
+
+	if (op2 < Op2_mask)
+		return sys_reg(op0, op1, crn, crm, op2 + 1);
+	if (crm < CRm_mask)
+		return sys_reg(op0, op1, crn, crm + 1, 0);
+	if (crn < CRn_mask)
+		return sys_reg(op0, op1, crn + 1, 0, 0);
+	if (op1 < Op1_mask)
+		return sys_reg(op0, op1 + 1, 0, 0, 0);
+
+	return sys_reg(op0 + 1, 0, 0, 0, 0);
+}
+
 int __init populate_nv_trap_config(void)
 {
 	int ret = 0;
@@ -1775,13 +1797,8 @@ int __init populate_nv_trap_config(void)
 			ret = -EINVAL;
 		}
 
-		if (cgt->encoding != cgt->end) {
-			prev = xa_store_range(&sr_forward_xa,
-					      cgt->encoding, cgt->end,
-					      xa_mk_value(cgt->tc.val),
-					      GFP_KERNEL);
-		} else {
-			prev = xa_store(&sr_forward_xa, cgt->encoding,
+		for (u32 enc = cgt->encoding; enc <= cgt->end; enc = encoding_next(enc)) {
+			prev = xa_store(&sr_forward_xa, enc,
 					xa_mk_value(cgt->tc.val), GFP_KERNEL);
 			if (prev && !xa_is_err(prev)) {
 				ret = -EINVAL;
-- 
2.39.2