On Tue, Jul 08, 2025 at 06:19:03PM -0700, Sohil Mehta wrote: > On 7/7/2025 1:03 AM, Kirill A. Shutemov wrote: > > From: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx> > > > > 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. > > > > Instead of moving setup_cr_pinning() below efi_enter_virtual_mode() in > > arch_cpu_finalize_init(), defer it until core initcall. > > > > Wrapping efi_enter_virtual_mode() into lass_stac()/clac() is not enough > > because AC flag gates data accesses, but not instruction fetch. Clearing > > the CR4 bit is required. > > > > I think the wording might need to be reordered. How about? > > 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. > > Wrapping efi_enter_virtual_mode() into lass_stac()/clac() is not enough > because AC flag gates data accesses, but not instruction fetch. Clearing > the CR4 bit is required. > > However, this must be done before the CR pinning is set up. Instead of > arbitrarily moving setup_cr_pinning() after efi_enter_virtual_mode() in > arch_cpu_finalize_init(), defer it until core initcall. > > Other than that, > Reviewed-by: Sohil Mehta <sohil.mehta@xxxxxxxxx> Okay, looks good, thanks! -- Kiryl Shutsemau / Kirill A. Shutemov
