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Subject[PATCH v6 4/9] KVM: arm/arm64: vgic-its: Check GITS_BASER Valid bit before saving tables
Date
At the moment we don't properly check the GITS_BASER<n>.Valid
bit before saving the collection and device tables.

On vgic_its_save_collection_table() we use the GITS_BASER gpa
field whereas the Valid bit should be used.

On vgic_its_save_device_tables() there is no check. This can
cause various bugs, among which a subsequent fault when accessing
the table in guest memory.

Let's systematically check the Valid bit before doing anything.

We also uniformize the code between save and restore.

Signed-off-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>

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

v2 -> v3:
- slight rewording of the commit message
- added Andre's and Christoffer's R-b
---
virt/kvm/arm/vgic/vgic-its.c | 20 +++++++++++---------
1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
index c4758e6..9ba6f23 100644
--- a/virt/kvm/arm/vgic/vgic-its.c
+++ b/virt/kvm/arm/vgic/vgic-its.c
@@ -2071,11 +2071,12 @@ static int vgic_its_device_cmp(void *priv, struct list_head *a,
static int vgic_its_save_device_tables(struct vgic_its *its)
{
const struct vgic_its_abi *abi = vgic_its_get_abi(its);
+ u64 baser = its->baser_device_table;
struct its_device *dev;
int dte_esz = abi->dte_esz;
- u64 baser;

- baser = its->baser_device_table;
+ if (!(baser & GITS_BASER_VALID))
+ return 0;

list_sort(NULL, &its->device_list, vgic_its_device_cmp);

@@ -2219,17 +2220,17 @@ static int vgic_its_restore_cte(struct vgic_its *its, gpa_t gpa, int esz)
static int vgic_its_save_collection_table(struct vgic_its *its)
{
const struct vgic_its_abi *abi = vgic_its_get_abi(its);
+ u64 baser = its->baser_coll_table;
+ gpa_t gpa = BASER_ADDRESS(baser);
struct its_collection *collection;
u64 val;
- gpa_t gpa;
size_t max_size, filled = 0;
int ret, cte_esz = abi->cte_esz;

- gpa = BASER_ADDRESS(its->baser_coll_table);
- if (!gpa)
+ if (!(baser & GITS_BASER_VALID))
return 0;

- max_size = GITS_BASER_NR_PAGES(its->baser_coll_table) * SZ_64K;
+ max_size = GITS_BASER_NR_PAGES(baser) * SZ_64K;

list_for_each_entry(collection, &its->collection_list, coll_list) {
ret = vgic_its_save_cte(its, collection, gpa, cte_esz);
@@ -2260,17 +2261,18 @@ static int vgic_its_save_collection_table(struct vgic_its *its)
static int vgic_its_restore_collection_table(struct vgic_its *its)
{
const struct vgic_its_abi *abi = vgic_its_get_abi(its);
+ u64 baser = its->baser_coll_table;
int cte_esz = abi->cte_esz;
size_t max_size, read = 0;
gpa_t gpa;
int ret;

- if (!(its->baser_coll_table & GITS_BASER_VALID))
+ if (!(baser & GITS_BASER_VALID))
return 0;

- gpa = BASER_ADDRESS(its->baser_coll_table);
+ gpa = BASER_ADDRESS(baser);

- max_size = GITS_BASER_NR_PAGES(its->baser_coll_table) * SZ_64K;
+ max_size = GITS_BASER_NR_PAGES(baser) * SZ_64K;

while (read < max_size) {
ret = vgic_its_restore_cte(its, gpa, cte_esz);
--
2.5.5
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