KVM: arm/arm64: vgic-its: Free caches when GITS_BASER Valid bit is cleared

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.

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

1 files changed, 18 insertions, 4 deletions

diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
index d46256c07ba5..1732e08a4375 100644
--- a/virt/kvm/arm/vgic/vgic-its.c
+++ b/virt/kvm/arm/vgic/vgic-its.c
@@ -1431,7 +1431,7 @@ 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, table_type;
         u64 reg, *regptr, clearbits = 0;
 
         /* When GITS_CTLR.Enable is 1, we ignore write accesses. */
@@ -1442,12 +1442,12 @@ 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;
+                table_type = GITS_BASER_TYPE_DEVICE;
                 break;
         case 1:
                 regptr = &its->baser_coll_table;
                 entry_size = abi->cte_esz;
-                device_type = GITS_BASER_TYPE_COLLECTION;
+                table_type = GITS_BASER_TYPE_COLLECTION;
                 clearbits = GITS_BASER_INDIRECT;
                 break;
         default:
@@ -1459,10 +1459,24 @@ 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 |= table_type << GITS_BASER_TYPE_SHIFT;
         reg = vgic_sanitise_its_baser(reg);
 
         *regptr = reg;
+
+        if (!(reg & GITS_BASER_VALID)) {
+                /* Take the its_lock to prevent a race with a save/restore */
+                mutex_lock(&its->its_lock);
+                switch (table_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;
+                }
+                mutex_unlock(&its->its_lock);
+        }
 }
 
 static unsigned long vgic_mmio_read_its_ctlr(struct kvm *vcpu,