Re: [PATCH 1/1] OvmfPkg: Reserve the Ovmf work area as RT_DATA

["Min Xu" <min.m.xu@intel.com>]

On August 22, 2022 9:19 PM, Tom Lendacky wrote:
> On 8/21/22 21:23, Min Xu wrote:
> > From: Min M Xu <min.m.xu@intel.com>
> >
> > BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3974
> >
> > Ovmf work-area (PcdOvmfWorkArea) was designed to store the
> > Confidential Computing guest information, including the CC guest type.
> > This information will be probed by CcProbeLib so that the CC guest
> > type can be determined in run-time. But the Ovmf work-area was
> > reserved as BT_Data so that it cannot be accessed after
> > ExitBootService. Please see the detailed analysis in BZ#3974.
> >
> > RH also reports a similar bug. Please see:
> > https://bugzilla.redhat.com/show_bug.cgi?id=2114858
> >
> > This patch reserves the work-area as RT_Data to fix this bug.
> 
> The work area was never meant to be kept around. When first introduced,
> Laszlo had said it could be used early, but that global structures should be
> represented by PCDs. So the code is correct. It seems that the CcProbeLib
> should be setting some PCDs during the start of DXE or similar for use during
> run time services.
> 
Hi, Tom
The dynamic PCD is not thread-safe. Will IoLib be used in multi-thread scenario?

Thanks
Min