On 3/14/19 3:50 AM, Paolo Bonzini wrote: > There is a prctl to query the state, ARCH_X86_CET_STATUS, but I'm a bit > wary of adding support for it before it hits the kernel; IBT only needs > compiler support because the instructions/prefixes are a nop if > disabled, unlike SHSTK which needs the "allocate shadow stack" prctl. > It's a small fixed cost per TB, it seemed not a big deal to me.
There's a cpuid bit though, leaf 7, ebx bit 20. If that's not set... It's a small fixed cost, and it's possible that it's lost in the padding between TB's. But per 256k TB's it's 1MB "wasted", worst case. r~
