Re: [PATCH v3 02/24] x86/virt/tdx: Add SEAMCALL wrapper tdh_mem_page_demote()

[Huang, Kai]

On Fri, 2026-01-16 at 11:10 +0000, Huang, Kai wrote:
> W/o the WARN(), the caller _can_ call this wrapper (i.e., not a kernel
> bug) but it always get a SW-defined error.  Again, maybe it has value for
> the case where the caller wants to use this to tell whether DEMOTE is
> available.
> 
> With the WARN(), it's a kernel bug to call the wrapper, and the caller
> needs to use other way (i.e., tdx_supports_demote_nointerrupt()) to tell
> whether DEMOTE is available.
> 
> So if you want the check, probably WARN() is a better idea since I suppose
> we always want users to use tdx_supports_demote_nointerrupt() to know
> whether DEMOTE can be done, and the WARN() is just to catch bug.

Forgot to say, the name tdx_supports_demote_nointerrupt() somehow only
tells the TDX module *supports* non-interruptible DEMOTE, it doesn't tell
whether TDX module has *enabled* that.

So while we know for this DEMOTE case, there's no need to *enable* this
feature (i.e., DEMOTE is non-interruptible when this feature is reported
as *supported*), from kernel's point of view, is it better to just use a
clearer name?

E.g., tdx_huge_page_demote_uninterruptible()?

A bonus is the name contains "huge_page" so it's super clear what's the
demote about.