1. A system for supporting virtual machine live migration in a subnet, comprising: one or more microprocessors; one or more switches, the one or more switches comprising at least a leaf switch, wherein each of the one or more switches comprise a plurality of ports and a linear forwarding table, wherein the linear forwarding table (LFT) of each switch designates a specific port through which incoming subnet traffic having a specific destination local identifier is forwarded; a first host channel adapter and a second host channel adapter, wherein the first and the second host channel adapters each comprise at least one virtual function, and wherein the first and the second host channel adapters are interconnected via the one or more switches; a first hypervisor and a second hypervisor, wherein the first hypervisor is associated with the first host channel adapter and the second hypervisor is associated with the second host channel adapter; and a virtual machine running on the first hypervisor, wherein the virtual machine is associated with a local identifier (LID) and with the virtual function of the first host channel adapter; wherein the virtual machine running on the first hypervisor operates to perform a live migration to the second hypervisor associated with the second host channel adapter, and wherein the live migration configures the one or more processors to: send a subnet management packet (SMP) to at least one switch of the one or more switches, wherein the subnet management packet instructs the at least one switch to update a block of destination local identifiers (LIDs) in the linear forwarding table that includes the LID associated with the virtual machine, the updating of the block including changing the port through which incoming subnet traffic specifying the LID associated with the virtual machine as the destination LID is forwarded.