On multiple SR-IOV cars it is possible for VF's assigned to guests to send ethernet flow control pause frames via the PF. This includes Linux kernel ixgbe driver before commit f079fa005aae08ee0e1bc32699874ff4f02e11c1, the Linux Kernel i40e/i40evf driver before e7358f54a3954df16d4f87e3cad35063f1c17de5 and the DPDK before commit 3f12b9f23b6499ff66ec8b0de941fb469297e5d0, additionally Multiple vendor NIC firmware is affected.