On Mon, Aug 26, 2024 at 1:33 PM Pawan Gupta <pawan.kumar.gupta@xxxxxxxxxxxxxxx> wrote: > > On Fri, Aug 23, 2024 at 11:53:10AM -0700, Jim Mattson wrote: > > Since this synthetic feature bit is set on AMD CPUs that don't flush > > the RSB on an IBPB, indicate as much in the comment, to avoid > > potential confusion with the Intel IBPB semantics. > > > > Signed-off-by: Jim Mattson <jmattson@xxxxxxxxxx> > > --- > > arch/x86/include/asm/cpufeatures.h | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h > > index dd4682857c12..cabd6b58e8ec 100644 > > --- a/arch/x86/include/asm/cpufeatures.h > > +++ b/arch/x86/include/asm/cpufeatures.h > > @@ -215,7 +215,7 @@ > > #define X86_FEATURE_SPEC_STORE_BYPASS_DISABLE ( 7*32+23) /* Disable Speculative Store Bypass. */ > > #define X86_FEATURE_LS_CFG_SSBD ( 7*32+24) /* AMD SSBD implementation via LS_CFG MSR */ > > #define X86_FEATURE_IBRS ( 7*32+25) /* "ibrs" Indirect Branch Restricted Speculation */ > > -#define X86_FEATURE_IBPB ( 7*32+26) /* "ibpb" Indirect Branch Prediction Barrier */ > > +#define X86_FEATURE_IBPB ( 7*32+26) /* "ibpb" Indirect Branch Prediction Barrier without RSB flush */ > > I don't think the comment is accurate for Intel. Maybe you meant to modify > X86_FEATURE_AMD_IBPB? It's perhaps a bit terse, but this is what I meant. Perhaps better would be "without guaranteed RSB flush"?
