[PATCH v2 2/3] KVM: arm64: vgic-its: Clear dte when mapd unmaps a device

[Kunkun Jiang]

vgic_its_save_device_tables will traverse its->device_list to
save dte for each device. vgic_its_restore_device_tables will
traverse each entry of device table and check if it is valid.
Restore if valid.

But when mapd unmaps a devices, we do not invalidate the
corresponding dte. In the scenario of continuous save
and restore, there may be a situation where a device's dte
is not saved but is restored. This is unreasonable and may
cause restore to fail. This patch clears the corresponding
dte when mapd unmaps a device.

Co-developed-by: Shusen Li <lishusen2 at huawei.com>
Singed-off-by: Shusen Li <lishusen2 at huawei.com>
Signed-off-by: Kunkun Jiang <jiangkunkun at huawei.com>
---
 arch/arm64/kvm/vgic/vgic-its.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kvm/vgic/vgic-its.c b/arch/arm64/kvm/vgic/vgic-its.c
index 344bd8c20f67..223a5f1d6a3d 100644
--- a/arch/arm64/kvm/vgic/vgic-its.c
+++ b/arch/arm64/kvm/vgic/vgic-its.c
@@ -1140,8 +1140,9 @@ static int vgic_its_cmd_handle_mapd(struct kvm *kvm, struct vgic_its *its,
 	u8 num_eventid_bits = its_cmd_get_size(its_cmd);
 	gpa_t itt_addr = its_cmd_get_ittaddr(its_cmd);
 	struct its_device *device;
+	gpa_t gpa;
 
-	if (!vgic_its_check_id(its, its->baser_device_table, device_id, NULL))
+	if (!vgic_its_check_id(its, its->baser_device_table, device_id, &gpa))
 		return E_ITS_MAPD_DEVICE_OOR;
 
 	if (valid && num_eventid_bits > VITS_TYPER_IDBITS)
@@ -1161,8 +1162,17 @@ static int vgic_its_cmd_handle_mapd(struct kvm *kvm, struct vgic_its *its,
 	 * The spec does not say whether unmapping a not-mapped device
 	 * is an error, so we are done in any case.
 	 */
-	if (!valid)
+	if (!valid) {
+		struct kvm *kvm = its->dev->kvm;
+		int dte_esz = vgic_its_get_abi(its)->dte_esz;
+		u64 val = 0;
+
+		if (KVM_BUG_ON(dte_esz != sizeof(val), kvm))
+			return -EINVAL;
+
+		vgic_write_guest_lock(kvm, gpa, &val, dte_esz);
 		return 0;
+	}
 
 	device = vgic_its_alloc_device(its, device_id, itt_addr,
 				       num_eventid_bits);
-- 
2.27.0