Re: [RFC,05/10] x86/speculation: Add basic IBRS support infrastructure

[Dr. David Alan Gilbert]

* Borislav Petkov (bp@xxxxxxx) wrote:
> On Wed, Jan 31, 2018 at 12:30:36PM +0000, Dr. David Alan Gilbert wrote:
> > Indeed, it's only for this weird case where you suddenly need to change
> > it.
> 
> No, there's more:
> 
> 	.name = "Broadwell-noTSX",
> 	.name = "Haswell-noTSX",

Haswell came out and we made the CPU definition, and then got a
microcode update that removed the feature.

So the common feature of noTSX and IBRS is that they're the only two
cases where a CPU has released and then the flags have changed later.

Dave

> -- 
> Regards/Gruss,
>     Boris.
> 
> SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
> -- 
--
Dr. David Alan Gilbert / dgilbert@xxxxxxxxxx / Manchester, UK