On Fri, Mar 06, 2026 at 05:00:55PM +0000, Mark Brown wrote: > Some parts of the SME state are optional, enabled by additional features > on top of the base FEAT_SME and controlled with enable bits in SMCR_ELx. We > unconditionally enable these for the host but for KVM we will allow the > feature set exposed to guests to be restricted by the VMM. These are the > FFR register (FEAT_SME_FA64) and ZT0 (FEAT_SME2). > > We defer saving of guest floating point state for non-protected guests to > the host kernel. We also want to avoid having to reconfigure the guest > floating point state if nothing used the floating point state while running > the host. If the guest was running with the optional features disabled then > traps will be enabled for them so the host kernel will need to skip > accessing that state when saving state for the guest. > > Support this by moving the decision about saving this state to the point > where we bind floating point state to the CPU, adding a new variable to > the cpu_fp_state which uses the enable bits in SMCR_ELx to flag which > features are enabled. > > Reviewed-by: Fuad Tabba <[email protected]> > Signed-off-by: Mark Brown <[email protected]>
Reviewed-by: Catalin Marinas <[email protected]>
