Re: [PATCH 1/2] x86/virt/tdx: Drop tdx_clflush_*()

[Binbin Wu]

On 9/23/2026 1:25 PM, Yan Zhao wrote:
> On Tue, Sep 22, 2026 at 01:52:14PM -0700, Rick Edgecombe wrote:
>> The TDX module exposes a bit (CLFLUSH_BEFORE_ALLOC) to say whether it
>> requires some memory to be flushed from the cache before being handed
> Drop "some"?
> 
>> to the TDX module.
>>
>> During the initial TDX upstreaming, it was decided it would be simplest
>> to just always flush in these cases, rather than checking for the bit and
> "in these cases" is ambiguous.

I assume "some memory" and "these cases" refer to memory pages allocated for
TD private memory or TD control structures. I agree with Yan that it would be
better to just state that explicitly.

> 
>> having conditional logic. So currently the kernel flushes in several
>> places when handing memory to the TDX module.
>>
>> In practice this bit has never been set by any TDX module, so flushing
>> is unneeded. Going forward the TDX docs will be updated to clarify that
> "Going forward, ...".
> 
>> CLFLUSH_BEFORE_ALLOC will never be set in any future TDX module either.
>>
>> So make code even simpler by just deleting all the CLFLUSH_BEFORE_ALLOC
>> handling.
>>
>> AI was used to review the change.
>>
>> Signed-off-by: Rick Edgecombe <rick.p.edgecombe@xxxxxxxxx>

Reviewed-by: Binbin Wu <binbin.wu@xxxxxxxxxxxxxxx>