linux-kernel - Re: [PATCH v3 02/24] x86/virt/tdx: Add SEAMCALL wrapper tdh_mem_page

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Message-ID: <aW3MyZ3M0ugyfsLb@yzhao56-desk.sh.intel.com>
Date: Mon, 19 Jan 2026 14:18:49 +0800
From: Yan Zhao <yan.y.zhao@...el.com>
To: "Huang, Kai" <kai.huang@...el.com>
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Subject: Re: [PATCH v3 02/24] x86/virt/tdx: Add SEAMCALL wrapper
 tdh_mem_page_demote()

On Fri, Jan 16, 2026 at 07:22:33PM +0800, Huang, Kai wrote:
> 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.
LGTM. Thanks!