Intel LASS In Good Shape For Linux 7.1
In addition to Linux 7.1 supporting FRED by default for Flexible Return and Event Delivery, another Intel CPU feature now in good shape for this next kernel version is Linear Address Space Separation (LASS).
Linear Address Space Separation is a new CPU security feature found with newer Intel processors. LASS is able to mitigate a class of side-channel attacks relying on speculative access across the user/kernel space boundary. LASS was initially upstreamed in Linux 6.19 but some corner cases ended up remaining that are now addressed for Linux 7.1. On the hardware side, LASS is supported by Xeon 6 server processors and Lunar Lake and newer on the client side.
For Linux 7.1 the LASS enablement is now considered "complete" with removing a LASS restriction dependent on EFI services and also vsyscall handling around LASS.
The x86/cpu pull that was merged to Linux 7.1 Git is what formally completes the Intel LASS enablement with the EFI and vsyscall restrictions removed. The patches also include now deferring LAS enablement until the user-space is brought up.
Linear Address Space Separation is a new CPU security feature found with newer Intel processors. LASS is able to mitigate a class of side-channel attacks relying on speculative access across the user/kernel space boundary. LASS was initially upstreamed in Linux 6.19 but some corner cases ended up remaining that are now addressed for Linux 7.1. On the hardware side, LASS is supported by Xeon 6 server processors and Lunar Lake and newer on the client side.
For Linux 7.1 the LASS enablement is now considered "complete" with removing a LASS restriction dependent on EFI services and also vsyscall handling around LASS.
The x86/cpu pull that was merged to Linux 7.1 Git is what formally completes the Intel LASS enablement with the EFI and vsyscall restrictions removed. The patches also include now deferring LAS enablement until the user-space is brought up.