On 01/09/2025 10:28 am, Jan Beulich wrote:
> On 28.08.2025 17:03, Andrew Cooper wrote:
>> @@ -908,7 +909,29 @@ static void __init noreturn reinit_bsp_stack(void)
>> if ( cpu_has_xen_shstk )
>> {
>> wrmsrl(MSR_S_CET, xen_msr_s_cet_value());
>> - asm volatile ("setssbsy" ::: "memory");
>> +
>> + /*
>> + * IDT and FRED differ by a Supervisor Token on the shadow stack,
>> and
>> + * therefore by the value in MSR_PL0_SSP.
> Beside not being overly relevant here afaict, is this last part of the
> sentence
> actually correct? Patch 06 doesn't write different values into the MSR.
It is correct, but also well hidden.
#define MSR_FRED_SSP_SL0 MSR_PL0_SSP
I suppose I should should write MSR_PL0_SSP/MSR_FRED_SSP_SL0 here to
highlight the logically different names for the two modes.
~Andrew
