KVM: arm64: Allow no running vcpu on restoring vgic3 LPI pending status

We don't have a running VCPU context to restore vgic3 LPI pending status
due to command KVM_DEV_ARM_{VGIC_GRP_CTRL, ITS_RESTORE_TABLES} on KVM
device "kvm-arm-vgic-its".

Use vgic_write_guest_lock() to restore vgic3 LPI pending status.

Signed-off-by: Gavin Shan <[email protected]>
Reviewed-by: Oliver Upton <[email protected]>
Signed-off-by: Marc Zyngier <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

Author: Gavin Shan

Documentation/virt/kvm/api.rst

@@ -8070,9 +8070,11 @@ considering the state as complete. VMM needs to ensure that the dirty
 state is final and avoid missing dirty pages from another ioctl ordered
 after the bitmap collection.
 
-NOTE: One example of using the backup bitmap is saving arm64 vgic/its
-tables through KVM_DEV_ARM_{VGIC_GRP_CTRL, ITS_SAVE_TABLES} command on
-KVM device "kvm-arm-vgic-its" when dirty ring is enabled.
+NOTE: Multiple examples of using the backup bitmap: (1) save vgic/its
+tables through command KVM_DEV_ARM_{VGIC_GRP_CTRL, ITS_SAVE_TABLES} on
+KVM device "kvm-arm-vgic-its". (2) restore vgic/its tables through
+command KVM_DEV_ARM_{VGIC_GRP_CTRL, ITS_RESTORE_TABLES} on KVM device
+"kvm-arm-vgic-its". VGICv3 LPI pending status is restored.
 
 8.30 KVM_CAP_XEN_HVM
 --------------------

arch/arm64/kvm/vgic/vgic-v3.c

@@ -339,7 +339,7 @@ int vgic_v3_lpi_sync_pending_status(struct kvm *kvm, struct vgic_irq *irq)
 	if (status) {
 		/* clear consumed data */
 		val &= ~(1 << bit_nr);
-		ret = kvm_write_guest_lock(kvm, ptr, &val, 1);
+		ret = vgic_write_guest_lock(kvm, ptr, &val, 1);
 		if (ret)
 			return ret;
 	}