Re: [PATCH v2 1/2] x86/cpu: Disable CR pinning during CPU bringup

[Nikunj A. Dadhania]

On 3/12/2026 7:50 PM, Dave Hansen wrote:
> On 3/12/26 07:08, Nikunj A. Dadhania wrote:
>> 1) Back-porting complexity: The current issue affects kernels (6.9+) 
>>    where SEV-SNP guests fail to boot with FRED enabled. A simpler fix would
>>    be easier to backport and verify across stable branches.
> 
> The simplest fix is to disable FRED on those kernels, fwiw.

That would work, but disabling FRED means LTS users will not be able to use 
FRED with confidential computing—that's not really a fix.

This isn't just SEV-SNP. Xin Li confirmed Intel TDX has the same issue: FRED
is enabled before exception handling is ready, and #VC/#VE can't be handled on
secondary CPUs.

The initialization order is wrong for both SEV-SNP and TDX. The fixes are small
and targeted—just ensuring FRED state is set up before it's needed.

Regards,
Nikunj