RHEL 7 and RHEL 8 will fail to boot with SEV enabled and 8 or more NIC Virtual Functions(VF)

Issue

• When SEV is enabled, all DMA operations inside the guest need to be performed using shared memory. To make this transparent to the guest, SEV uses the Linux kernel SWIOTLB pool, which has a default size of 64MB. A guest panic will occur if the Linux kernel exhausts the SWIOTLB pool. The number of devices used by the guest and the utilization of these devices has a direct impact on the amount of SWIOTLB required. It is recommended to increase the SWIOTLB pool that the Linux kernel allocates for SEV guests. A recommended starting size is 512MB.