Re: [PATCH v2 6/6] x86: limit amount of INT3 in IND_THUNK_*

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Mon, Sep 28, 2020 at 02:32:24PM +0200, Jan Beulich wrote:
> There's no point having every replacement variant to also specify the
> INT3 - just have it once in the base macro. When patching, NOPs will get
> inserted, which are fine to speculate through (until reaching the INT3).
> 
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

Acked-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>

> ---
> I also wonder whether the LFENCE in IND_THUNK_RETPOLINE couldn't be
> replaced by INT3 as well. Of course the effect will be marginal, as the
> size of the thunk will still be 16 bytes when including tail padding
> resulting from alignment.

I think Andrew is the best one to have an opinion on this.

Thanks, Roger.