SICE is a novel framework to provide hardware-level isolation and protection for sensitive workloads running on ×86 platforms in compute clouds. Unlike existing isolation techniques, SICE does not rely on any software component in the host environment (i.e., an OS or a hypervisor). Instead, the security of the isolated environments is guaranteed by a trusted computing base that only includes the hardware, the BIOS, and the System Management Mode (SMM). SICE provides fast context switching to and from an isolated environment, allowing isolated workloads to time-share the physical platform with untrusted workloads. Moreover, SICE supports a large range (up to 4GB) of isolated memory. Finally, the most unique feature of SICE is the use of multi-core processors to allow the isolated environments to run concurrently and yet securely beside the untrusted host. We have implemented a SICE prototype using an AMD x86 hardware platform. Our experiments show that SICE performs fast context switching (67 μs) to and from the isolated environment and that it imposes a reasonable overhead (3% on all but one benchmark) on the operation of an isolated Linux virtual machine. Our prototype demonstrates that, subject to a careful security review of the BIOS software and the SMM hardware implementation, current hardware architecture already provides abstractions that can support building strong isolation mechanisms using a very small SMM software foundation of about 300 lines of code. © 2011 ACM.