Re: [PATCH v2] UefiCpuPkg: Fix SMM code hangs when InitPaging

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

Gerd,
I saw Zhiguang and you had some conversation in V1 mail thread.
Was below question answered in that conversation?

Any concern if I merge the patch?

Thanks,
Ray

> -----Original Message-----
> From: Gerd Hoffmann <kraxel@redhat.com>
> Sent: Wednesday, January 18, 2023 5:05 PM
> To: Liu, Zhiguang <zhiguang.liu@intel.com>
> Cc: devel@edk2.groups.io; Kumar, Rahul R <rahul.r.kumar@intel.com>; Zeng,
> Star <star.zeng@intel.com>; Wu@sirius.home.kraxel.org; Wu, Jiaxin
> <jiaxin.wu@intel.com>; Ni, Ray <ray.ni@intel.com>; Dong, Eric
> <eric.dong@intel.com>
> Subject: Re: [PATCH v2] UefiCpuPkg: Fix SMM code hangs when InitPaging
> 
> On Wed, Jan 18, 2023 at 09:23:48AM +0800, Zhiguang Liu wrote:
> > REF: https://bugzilla.tianocore.org/show_bug.cgi?id=4246
> >
> > In function InitPaging, NumberOfPml5Entries is calculated by below code
> > NumberOfPml5Entries = (UINTN)LShiftU64 (1, SizeOfMemorySpace - 48);
> > If the SizeOfMemorySpace is larger than 48, NumberOfPml5Entries will be
> > larger than 1. However, this doesn't make sense if the hardware doesn't
> > support 5 level page table.
> 
> ... if 5-level paging is not used.
> 
> Hardware which does not support 5-level paging is limited to 48 anyway.
> 
> This still does not explain why this fixes code hangs.
> 
> take care,
>   Gerd