[PATCH v6 1/9] KVM: arm/arm64: vgic-its: Fix return value for device table restore

[Eric Auger <eric.auger@redhat.com>]

From: wanghaibin <wanghaibin.wang@huawei.com>

If ITT only contains invalid entries, vgic_its_restore_itt
returns 1 and this is considered as an an error in
vgic_its_restore_dte.

Also in case the device table only contains invalid entries,
the table restore fails and this is not correct.

This patch fixes those 2 issues:
- vgic_its_restore_itt now returns <= 0 values. If all
  ITEs are invalid, this is considered as successful.
- vgic_its_restore_device_tables also returns <= 0 values.

We also simplify the returned value computation in
handle_l1_dte.

Signed-off-by: wanghaibin <wanghaibin.wang@huawei.com>
Signed-off-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>

---

v5 -> v6:
- added Christoffer's R-b

v2 -> v3:
- add comments
- vgic_its_restore_itt don't return +1 anymore
- reword the commit message

v1 -> v2:
- if (ret > 0) ret = 0
---
 virt/kvm/arm/vgic/vgic-its.c | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
index f51c1e1..d27a301 100644
--- a/virt/kvm/arm/vgic/vgic-its.c
+++ b/virt/kvm/arm/vgic/vgic-its.c
@@ -1940,6 +1940,14 @@ static int vgic_its_save_itt(struct vgic_its *its, struct its_device *device)
 	return 0;
 }
 
+/**
+ * vgic_its_restore_itt - restore the ITT of a device
+ *
+ * @its: its handle
+ * @dev: device handle
+ *
+ * Return 0 on success, < 0 on error
+ */
 static int vgic_its_restore_itt(struct vgic_its *its, struct its_device *dev)
 {
 	const struct vgic_its_abi *abi = vgic_its_get_abi(its);
@@ -1951,6 +1959,10 @@ static int vgic_its_restore_itt(struct vgic_its *its, struct its_device *dev)
 	ret = scan_its_table(its, base, max_size, ite_esz, 0,
 			     vgic_its_restore_ite, dev);
 
+	/* scan_its_table returns +1 if all ITEs are invalid */
+	if (ret > 0)
+		ret = 0;
+
 	return ret;
 }
 
@@ -2107,10 +2119,7 @@ static int handle_l1_dte(struct vgic_its *its, u32 id, void *addr,
 	ret = scan_its_table(its, gpa, SZ_64K, dte_esz,
 			     l2_start_id, vgic_its_restore_dte, NULL);
 
-	if (ret <= 0)
-		return ret;
-
-	return 1;
+	return ret;
 }
 
 /**
@@ -2140,8 +2149,9 @@ static int vgic_its_restore_device_tables(struct vgic_its *its)
 				     vgic_its_restore_dte, NULL);
 	}
 
+	/* scan_its_table returns +1 if all entries are invalid */
 	if (ret > 0)
-		ret = -EINVAL;
+		ret = 0;
 
 	return ret;
 }
-- 
2.5.5