Re: [PATCH v2 5/8] x86/speculation: Add basic support for IBPB

[David Woodhouse]

On Sun, 2018-01-21 at 20:04 +0100, Borislav Petkov wrote:
> On Sun, Jan 21, 2018 at 06:54:22PM +0000, David Woodhouse wrote:
> > Because we're backporting this to every stable kernel under the
> sun,
> > and they don't already require asm-goto.
> 
> Considering the cost of the barrier, I'd simplify the whole endeavor
> *considerably* for backporting:
> 
> ÂÂÂÂÂÂÂÂif (boot_cpu_has(X86_FEATURE_IBPB))
> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂwrmsr(MSR_IA32_PRED_CMD, PRED_CMD_IBPB, 0);
> 
> Problem solved.

Nope. Plenty of patch sets *did* have the bug above though, until it
was spotted.

Attachment: smime.p7s
Description: S/MIME cryptographic signature