On Tue, Jun 04, 2024 at 11:15:03AM +0200, Borislav Petkov wrote: > On Mon, Jun 03, 2024 at 05:24:00PM -0700, H. Peter Anvin wrote: > > Trying one more time; sorry (again) if someone receives this in duplicate. > > > > > > > > > > > > diff --git a/arch/x86/kernel/relocate_kernel_64.S b/arch/x86/kernel/relocate_kernel_64.S > > > > > index 56cab1bb25f5..085eef5c3904 100644 > > > > > --- a/arch/x86/kernel/relocate_kernel_64.S > > > > > +++ b/arch/x86/kernel/relocate_kernel_64.S > > > > > @@ -148,9 +148,10 @@ SYM_CODE_START_LOCAL_NOALIGN(identity_mapped) > > > > > */ > > > > > movl $X86_CR4_PAE, %eax > > > > > testq $X86_CR4_LA57, %r13 > > > > > - jz 1f > > > > > + jz .Lno_la57 > > > > > orl $X86_CR4_LA57, %eax > > > > > -1: > > > > > +.Lno_la57: > > > > > + > > > > > movq %rax, %cr4 > > > > If we are cleaning up this code... the above can simply be: > > > > andl $(X86_CR4_PAE | X86_CR4_LA54), %r13 > > movq %r13, %cr4 > > > > %r13 is dead afterwards, and the PAE bit *will* be set in %r13 anyway. > > Yeah, with a proper comment. The testing of bits is not really needed. I think it is better fit the next patch. What about this?
