[PATCH v4 02/11] KVM: arm/arm64: vgic-its: fix vgic_its_restore_collection_table returned value

Eric Auger
2017-10-17T07:10:35Z

vgic_its_restore_cte returns +1 if the collection table entry
is valid and properly decoded. As a consequence, if the
collection table is fully filled with valid data that are
decoded without error, vgic_its_restore_collection_table()
returns +1. This is wrong.

Let's use the standard C convention for both vgic_its_restore_cte
and vgic_its_restore_collection_table. vgic_its_restore_cte now
returns whether we have reached the end of the table in the @last
output parameter. vgic_its_restore_collection_table aborts in case
of error or if the end is found. Otherwise, it now returns 0.

Fixes: ea1ad53e1e31a3 (KVM: arm64: vgic-its: Collection table save/restore)
Signed-off-by: Eric Auger <eric.auger@redhat.com>

---

v2 -> v3: creation
---
virt/kvm/arm/vgic/vgic-its.c | 40 +++++++++++++++++++++++++++++++---------
1 file changed, 31 insertions(+), 9 deletions(-)

diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
index eea14a1..a4ff8f7 100644
--- a/virt/kvm/arm/vgic/vgic-its.c
+++ b/virt/kvm/arm/vgic/vgic-its.c
@@ -2204,7 +2204,19 @@ static int vgic_its_save_cte(struct vgic_its *its,
return kvm_write_guest(its->dev->kvm, gpa, &val, esz);
}

-static int vgic_its_restore_cte(struct vgic_its *its, gpa_t gpa, int esz)
+/**
+ * vgic_its_restore_cte - Restore a collection table entry
+ *
+ * @its: its handle
+ * @gpa: guest physical address of the entry
+ * @esz: entry size
+ * @last: output boolean indicating whether we have reached the
+ * end of the collection table (ie. an invalid entry was decoded)
+ *
+ * Return: 0 upon success, < 0 on error
+ */
+static int vgic_its_restore_cte(struct vgic_its *its, gpa_t gpa, int esz,
+ bool *last)
{
struct its_collection *collection;
struct kvm *kvm = its->dev->kvm;
@@ -2217,7 +2229,8 @@ static int vgic_its_restore_cte(struct vgic_its *its, gpa_t gpa, int esz)
if (ret)
return ret;
val = le64_to_cpu(val);
- if (!(val & KVM_ITS_CTE_VALID_MASK))
+ *last = !(val & KVM_ITS_CTE_VALID_MASK);
+ if (*last)
return 0;

target_addr = (u32)(val >> KVM_ITS_CTE_RDBASE_SHIFT);
@@ -2233,7 +2246,7 @@ static int vgic_its_restore_cte(struct vgic_its *its, gpa_t gpa, int esz)
if (ret)
return ret;
collection->target_addr = target_addr;
- return 1;
+ return 0;
}

/**
@@ -2278,8 +2291,13 @@ static int vgic_its_save_collection_table(struct vgic_its *its)

/**
* vgic_its_restore_collection_table - reads the collection table
- * in guest memory and restores the ITS internal state. Requires the
- * BASER registers to be restored before.
+ * in guest memory and restores the ITS collection cache.
+ *
+ * @its: its handle
+ *
+ * Requires the Collection BASER to be previously restored.
+ *
+ * Returns 0 on success or < 0 on error
*/
static int vgic_its_restore_collection_table(struct vgic_its *its)
{
@@ -2297,13 +2315,17 @@ static int vgic_its_restore_collection_table(struct vgic_its *its)
max_size = GITS_BASER_NR_PAGES(its->baser_coll_table) * SZ_64K;

while (read < max_size) {
- ret = vgic_its_restore_cte(its, gpa, cte_esz);
- if (ret <= 0)
- break;
+ bool last;
+
+ ret = vgic_its_restore_cte(its, gpa, cte_esz, &last);
+ if (ret < 0 || last)
+ return ret;
gpa += cte_esz;
read += cte_esz;
}
- return ret;
+
+ /* table was fully filled with valid entries, decoded without error */
+ return 0;
}

/**
--
2.5.5