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Subject[PATCH v6 7/9] KVM: arm/arm64: vgic-its: Free caches when GITS_BASER Valid bit is cleared
Date
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>

---
v5 -> v6:
- rename type into device_type and revert tthe u64 -> int change
- remove the default clause
- take the its mutex lock around vgic_its_free_device/collection_list

v4 -> v5:
- add comment about locking

v2 -> v3:
- add a comment and clear cache in if block
---
virt/kvm/arm/vgic/vgic-its.c | 26 ++++++++++++++++++++++----
1 file changed, 22 insertions(+), 4 deletions(-)

diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
index 5b7be85..2a92d4d 100644
--- a/virt/kvm/arm/vgic/vgic-its.c
+++ b/virt/kvm/arm/vgic/vgic-its.c
@@ -1428,7 +1428,7 @@ 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. */
@@ -1439,12 +1439,12 @@ 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:
@@ -1456,10 +1456,28 @@ 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 |= table_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+ * If the table is no longer valid, we clear the associated cached data.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)) {
+ 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,
--
2.5.5
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