Re: [edk2-devel] [PATCH 0/6] Substract TME-MK KEY_ID_BITS from CPU max PA

["Ni, Ray" <ray.ni@intel.com>]

@Xu, Min M, can you check if Gerd's comment is valid?

Gerd,
This Bugzilla captures the same idea: https://bugzilla.tianocore.org/show_bug.cgi?id=3394
Originally from Laszlo. +@Liu, Zhiguang who will work on patch submission later.

Thanks,
Ray

> -----Original Message-----
> From: kraxel@redhat.com <kraxel@redhat.com>
> Sent: Thursday, March 30, 2023 5:03 PM
> To: Ni, Ray <ray.ni@intel.com>
> Cc: devel@edk2.groups.io; Tom Lendacky <thomas.lendacky@amd.com>
> Subject: Re: [edk2-devel] [PATCH 0/6] Substract TME-MK KEY_ID_BITS from CPU max PA
> 
>   Hi,
> 
> > For tdx, the actual max physical address bits is decreased by the KEY_ID_BITS bits.
> > But the max physical address bits reported from CPUID instruction don't change.
> 
> I guess the physical address bits calculation for tdx needs adjustment
> then.  Right now we have:
> 
>   if (TdIsEnabled ()) {
>     if (TdSharedPageMask () == (1ULL << 47)) {
>       PhysMemAddressWidth = 48;
>     } else {
>       PhysMemAddressWidth = 52;
>     }
>   }
> 
> 
> See PlatformAddressWidthInitialization() in PlatformInitLib/MemDetect.c
> 
> Which would be the third place needing the same logic.  Maybe worth
> thinking about a helper function in a library somewhere, so we don't
> cut&paste the same code snippet again and again ...
> 
> take care,
>   Gerd