[PATCH v5 08/10] KVM: arm/arm64: vgic-its: Free caches when GITS_BASER Valid bit is cleared

Eric Auger
2017-10-23T14:09:26Z

When the GITS_BASER<n>.Valid gets cleared, the data structures in
guest RAM are not valid anymore. The device, collection
and LPI lists stored in the in-kernel ITS represent the same
information in some form of cache. So let's void the cache.

Signed-off-by: Eric Auger <eric.auger@redhat.com>

---
v4 -> v5:
- add comment about locking

v2 -> v3:
- add a comment and clear cache in if block
---
virt/kvm/arm/vgic/vgic-its.c | 27 +++++++++++++++++++++++----
1 file changed, 23 insertions(+), 4 deletions(-)

diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
index 8098f91..bdfceb4 100644
--- a/virt/kvm/arm/vgic/vgic-its.c
+++ b/virt/kvm/arm/vgic/vgic-its.c
@@ -1434,8 +1434,9 @@ static void vgic_mmio_write_its_baser(struct kvm *kvm,
unsigned long val)
{
const struct vgic_its_abi *abi = vgic_its_get_abi(its);
- u64 entry_size, device_type;
+ u64 entry_size;
u64 reg, *regptr, clearbits = 0;
+ int type;

/* When GITS_CTLR.Enable is 1, we ignore write accesses. */
if (its->enabled)
@@ -1445,12 +1446,12 @@ static void vgic_mmio_write_its_baser(struct kvm *kvm,
case 0:
regptr = &its->baser_device_table;
entry_size = abi->dte_esz;
- device_type = GITS_BASER_TYPE_DEVICE;
+ type = GITS_BASER_TYPE_DEVICE;
break;
case 1:
regptr = &its->baser_coll_table;
entry_size = abi->cte_esz;
- device_type = GITS_BASER_TYPE_COLLECTION;
+ type = GITS_BASER_TYPE_COLLECTION;
clearbits = GITS_BASER_INDIRECT;
break;
default:
@@ -1462,10 +1463,28 @@ static void vgic_mmio_write_its_baser(struct kvm *kvm,
reg &= ~clearbits;

reg |= (entry_size - 1) << GITS_BASER_ENTRY_SIZE_SHIFT;
- reg |= device_type << GITS_BASER_TYPE_SHIFT;
+ reg |= (u64)type << GITS_BASER_TYPE_SHIFT;
reg = vgic_sanitise_its_baser(reg);

*regptr = reg;
+
+ /*
+ * If the table is no longer valid, we clear the associated cached data.
+ * Note: there cannot be any race with save/restore code which locks
+ * all vcpus.
+ */
+ if (!(reg & GITS_BASER_VALID)) {
+ switch (type) {
+ case GITS_BASER_TYPE_DEVICE:
+ vgic_its_free_device_list(kvm, its);
+ break;
+ case GITS_BASER_TYPE_COLLECTION:
+ vgic_its_free_collection_list(kvm, its);
+ break;
+ default:
+ break;
+ }
+ }
}

static unsigned long vgic_mmio_read_its_ctlr(struct kvm *vcpu,
--
2.5.5