On Mon, Feb 20, 2023 at 11:02 AM Borislav Petkov bp@alien8.de wrote:
On Mon, Feb 20, 2023 at 10:56:38AM -0800, KP Singh wrote:
Sure, it looks like an omission to me, we wrote a POC on Skylake that was able to do cross-thread training with the current set of mitigations.
Right.
STIBP with IBRS is still correct if spectre_v2=ibrs had really meant IBRS everywhere,
Yeah, IBRS everywhere got shot down as a no-no very early in the game, for apparent reasons.
As you said in the other thread, this needs to be documented both in the code and the kernel documentation.
but just means KERNEL_IBRS, which means only kernel is protected, userspace is still unprotected.
Yes, that was always the intent with IBRS: enable on kernel entry and disable on exit.
Thx.
-- Regards/Gruss, Boris.