[PATCH v2 3/7] LoongArch: KVM: Disable update property num_cpu and feature with eiointc

[Bibo Mao]

Property num_cpu and feature is read-only once eiointc is created, which
is set with KVM_DEV_LOONGARCH_EXTIOI_GRP_CTRL attr group before device
creation.

Attr group KVM_DEV_LOONGARCH_EXTIOI_GRP_SW_STATUS is to update register
and software state for migration and reset usage, property num_cpu and
feature can not be update again if it is created already.

Here discard write operation with property num_cpu and feature in attr
group KVM_DEV_LOONGARCH_EXTIOI_GRP_CTRL.

Cc: stable@xxxxxxxxxxxxxxx
Fixes: 1ad7efa552fd ("LoongArch: KVM: Add EIOINTC user mode read and write functions")
Signed-off-by: Bibo Mao <maobibo@xxxxxxxxxxx>
---
 arch/loongarch/kvm/intc/eiointc.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/arch/loongarch/kvm/intc/eiointc.c b/arch/loongarch/kvm/intc/eiointc.c
index 0b648c56b0c3..b48511f903b5 100644
--- a/arch/loongarch/kvm/intc/eiointc.c
+++ b/arch/loongarch/kvm/intc/eiointc.c
@@ -910,9 +910,22 @@ static int kvm_eiointc_sw_status_access(struct kvm_device *dev,
 	data = (void __user *)attr->addr;
 	switch (addr) {
 	case KVM_DEV_LOONGARCH_EXTIOI_SW_STATUS_NUM_CPU:
+		/*
+		 * Property num_cpu and feature is read-only once eiointc is
+		 * created with KVM_DEV_LOONGARCH_EXTIOI_GRP_CTRL group API
+		 *
+		 * Disable writing with KVM_DEV_LOONGARCH_EXTIOI_GRP_SW_STATUS
+		 * group API
+		 */
+		if (is_write)
+			return ret;
+
 		p = &s->num_cpu;
 		break;
 	case KVM_DEV_LOONGARCH_EXTIOI_SW_STATUS_FEATURE:
+		if (is_write)
+			return ret;
+
 		p = &s->features;
 		break;
 	case KVM_DEV_LOONGARCH_EXTIOI_SW_STATUS_STATE:
-- 
2.39.3