[v3,2/4] KVM: arm64: vgic-its: Clear DTE when MAPD unmaps a device

Commit Message

Jing Zhang Nov. 6, 2024, 8:30 a.m. UTC

From: Kunkun Jiang <[e-mail]>

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 device, it does not invalidate the
corresponding DTE. In the scenario of continuous saves
and restores, 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 <[e-mail]>
Signed-off-by: Shusen Li <[e-mail]>
Signed-off-by: Kunkun Jiang <[e-mail]>
Signed-off-by: Jing Zhang <[e-mail]>
---
 arch/arm64/kvm/vgic/vgic-its.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

Patch

diff --git a/arch/arm64/kvm/vgic/vgic-its.c b/arch/arm64/kvm/vgic/vgic-its.c
index 2381bc5ce544..7c57c7c6fbff 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);