On Sat, 10 Feb 2024 at 11:41, Borislav Petkov <bp@xxxxxxxxx> wrote: > > On Fri, Feb 09, 2024 at 01:55:02PM +0000, Ard Biesheuvel wrote: > > I was trying to get rid of global variable assignments and accesses > > from the 1:1 mapping, but since we cannot get rid of those entirely, > > we might just keep __pgtable_l5_enabled but use RIP_REL_REF() in the > > accessors, and move the assignment to the asm startup code. > > Yeah. > > > asm(ALTERNATIVE_TERNARY( > > "movq %%cr4, %[reg] \n\t btl %[la57], %k[reg]" CC_SET(c), > > %P[feat], "stc", "clc") > > : [reg] "=r" (r), CC_OUT(c) (ret) > > : [feat] "i" (X86_FEATURE_LA57), > > [la57] "i" (X86_CR4_LA57_BIT) > > : "cc"); > > Creative :) > > > but we'd still have two versions in that case. > > Yap. RIP_REL_REF() ain't too bad ... > We can actually rip all of that stuff out, and have only a single implementation of pgtable_l5_enabled() that is not based on a variable at all. It results in a nice cleanup, but I'll keep it as a separate patch in the next revision so we can easily drop it if preferred.
