Messages in this thread | | | Date | Wed, 15 Jul 2020 11:26:38 +0200 | From | Joerg Roedel <> | Subject | Re: [PATCH v4 70/75] x86/head/64: Don't call verify_cpu() on starting APs |
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Hi Kees,
thanks for your reviews!
On Tue, Jul 14, 2020 at 06:40:30PM -0700, Kees Cook wrote: > Eek, no. MSR_IA32_MISC_ENABLE_XD_DISABLE needs to be cleared very early > during CPU startup; this can't just be skipped.
That MSR is Intel-only, right? The boot-path installed here is only used for SEV-ES guests, running on AMD systems, so this MSR is not even accessed during boot on those VMs.
The alternative is to set up exception handling prior to calling verify_cpu, including segments, stack and IDT. Given that verify_cpu() does not add much value to SEV-ES guests, I'd like to avoid adding this complexity.
> Also, is UNWIND_HINT_EMPTY needed for the new target?
Yes, I think it is, will add it in the next version.
Regards,
Joerg
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