Re: [PATCH v9 04/11] x86/virt/tdx: Allocate refcounts for Dynamic PAMT memory

[Dave Hansen]

On 8/6/26 15:02, Edgecombe, Rick P wrote:
> On Thu, 2026-08-06 at 02:21 +0000, sashiko-bot@xxxxxxxxxx wrote:
>> [Severity: High]
>> Could this vzalloc() call trigger a kernel panic on systems with sparse
>> memory layouts instead of gracefully disabling TDX?
...
> I think this is a bit overblown. If there is a lot of memory such that this
> allocation is large, we can expect it be less likely to fail.

Yes, it could trigger a kernel panic. And, yes, sashiko's concern is
overblown.

This code only runs on the host side, so there's no exotic VM craziness.
In reality, today, there are not many TDX systems. The ones that do
exist don't have exotic sparse memory layouts either. TDX also doesn't
yet support any of the emerging memory technologies like CXL.mem that
might lead to bare-metal weirdo layouts.

But even in a future with a pathologically evil memory layout, is anyone
going to miss 8GB of memory on a server? Probably not.

So, yeah, I just don't see the point of going crazy over this. If
someone hits this in 10 years, we'll fix it then. Oooh, maybe I'll be
retired in 10 years. One can dream.