Re: [PATCH v2 06/25] x86/virt/tdx: Add SEAMCALL wrappers for TDX TD creation

From: Dave Hansen
Date: Tue Nov 12 2024 - 16:40:41 EST


On 11/12/24 13:21, Edgecombe, Rick P wrote:
> On Tue, 2024-11-12 at 12:17 -0800, Dave Hansen wrote:
>> On 10/30/24 12:00, Rick Edgecombe wrote:
>>> +u64 tdh_mng_create(u64 tdr, u64 hkid)
>>> +{
>>> + struct tdx_module_args args = {
>>> + .rcx = tdr,
>>> + .rdx = hkid,
>>> + };
>>> + clflush_cache_range(__va(tdr), PAGE_SIZE);
>>> + return seamcall(TDH_MNG_CREATE, &args);
>>> +}
>>> +EXPORT_SYMBOL_GPL(tdh_mng_create);
>> I'd _prefer_ that this explain why the clflush is there.
> How about:
> /*
> * The TDX module exposes a CLFLUSH_BEFORE_ALLOC bit to specify whether
> * a CLFLUSH of pages is required before handing them to the TDX module.
> * Be conservative and make the code simpler by doing the CLFLUSH
> * unconditionally.
> */

Is there a chance we could put this in a helper so the "be conservative"
policy is centralized in one location? The comment could also go there.