On 10/28/2024 9:07 AM, Alexander Shishkin wrote: > In order to map the EFI runtime services, set_virtual_address_map > needs to be called, which resides in the lower half of the address > space. This means that LASS needs to be temporarily disabled around > this call. This can only be done before the CR pinning is set up. > ... > > /* > * This needs to follow the FPU initializtion, since EFI depends on it. > + * It also needs to precede the CR pinning setup, because we need to be > + * able to temporarily clear the CR4.LASS bit in order to execute the > + * set_virtual_address_map call, which resides in lower addresses and > + * would trip LASS if enabled. > */ It would be helpful to describe why lass_stac()/clac() doesn't work here and instead the heavy handed CR4 toggling is needed. > if (efi_enabled(EFI_RUNTIME_SERVICES)) > efi_enter_virtual_mode(); > > + setup_cr_pinning(); > +
