Re: [patch v3 31/36] x86/apic: Provide cpu_primary_thread mask

Kirill A. Shutemov
2023-05-29T02:39:59Z

On Sat, May 27, 2023 at 03:40:02PM +0200, Thomas Gleixner wrote:
> On Fri, May 26 2023 at 12:14, Thomas Gleixner wrote:
> > On Wed, May 24 2023 at 23:48, Kirill A. Shutemov wrote:
> >> This patch causes boot regression on TDX guest. The guest crashes on SMP
> >> bring up.
>
> The below should fix that. Sigh...

Okay, this gets me fixes the boot for TDX guest:

Tested-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>

But it gets broken again on "x86/smpboot: Implement a bit spinlock to
protect the realmode stack" with

[ 0.554079] .... node #0, CPUs: #1 #2
[ 0.738071] Callback from call_rcu_tasks() invoked.
[ 10.562065] CPU2 failed to report alive state
[ 10.566337] #3
[ 20.570066] CPU3 failed to report alive state
[ 20.574268] #4
...

Notably CPU1 is missing from "failed to report" list. So CPU1 takes the
lock fine, but seems never unlocks it.

Maybe trampoline_lock(%rip) in head_64.S somehow is not the same as
&tr_lock in trampoline_64.S. I donno.

I haven't find the root cause yet. But bypassing locking in
LOAD_REALMODE_ESP makes the issue go away.

I will look more into it.

--
Kiryl Shutsemau / Kirill A. Shutemov