On 08.08.2025 22:23, Andrew Cooper wrote:
> Under FRED, SETSSBSY is unavailable, and we want to be setting up FRED prior
> to setting up shadow stacks. As we still need Supervisor Tokens in IDT mode,
> we need mode-specific logic to establish SSP.
>
> In FRED mode, write a Restore Token, RSTORSSP it, and discard the resulting
> Previous-SSP token.
>
> No change outside of FRED mode.
>
> Signed-off-by: Andrew Cooper <andrew.coop...@citrix.com>
Why is it that in patch 17 you could use identical code, but here you can't?
> @@ -912,10 +913,30 @@ static void __init noreturn reinit_bsp_stack(void)
>
> if ( cpu_has_xen_shstk )
> {
> - wrmsrl(MSR_PL0_SSP,
> - (unsigned long)stack + (PRIMARY_SHSTK_SLOT + 1) * PAGE_SIZE -
> 8);
Does this removal perhaps belong elsewhere, especially with "No change
outside of FRED mode" in the description?
Jan
