Re: [patch] x86/smpboot: Disable parallel bootup if cc_vendor != NONE

Kirill A. Shutemov
2023-05-30T12:30:55Z

On Tue, May 30, 2023 at 02:09:17PM +0200, Thomas Gleixner wrote:
> The decision to allow parallel bringup of secondary CPUs checks
> CC_ATTR_GUEST_STATE_ENCRYPT to detect encrypted guests. Those cannot use
> parallel bootup because accessing the local APIC is intercepted and raises
> a #VC or #VE, which cannot be handled at that point.
>
> The check works correctly, but only for AMD encrypted guests. TDX does not
> set that flag.
>
> Check for cc_vendor != CC_VENDOR_NONE instead. That might be overbroad, but
> definitely works for both AMD and Intel.

It boots fine with TDX, but I think it is wrong. cc_get_vendor() will
report CC_VENDOR_AMD even on bare metal if SME is enabled. I don't think
we want it.

--
Kiryl Shutsemau / Kirill A. Shutemov