[edk2-devel] [PATCH 2/2] OvmfPkg/ResetVector: Exclude SEV launch secrets page from pre-validation

[Gerd Hoffmann]

  Hi,

> >>>>>> Check if that page is defined; if it is, skip it in the metadata
> >>>>>> list.
> >>>>>> In such case, VMM should fill the page with the hashes content, or
> >>>>>> explicitly update it as a zero page (if kernel hashes are not used).
> >>>>>
> >>>>> Is it an option to just skip the page unconditionally?
> >>>>>
> >>>>> I think in the OvmfPkgX64 build the page is not used, so it probably
> >>>>> doesn't matter whenever it is included or not, and it would make
> >>>>> things
> >>>>> a bit less confusing ...

>   // The below address range was part of the SEV OVMF metadata, and range   
>   // should be pre-validated by the Hypervisor.                             
>   {                                                                         
>     FixedPcdGet32 (PcdOvmfSecPageTablesBase),                               
>     FixedPcdGet32 (PcdOvmfPeiMemFvBase),                                    
>   },                                                                        

> As the comment says, it assumes the entire range
> from PcdOvmfSecPageTablesBase (= 0x800000)
> to PcdOvmfPeiMemFvBase (= 0x820000) 
> is pre-validated by the Hypervisor.
> 
> How will it know to actually validate that page at 0x80F000 ?

Probably it doesn't unless we split the entry into two, so we are
effectively trading making the reset vector more complicated vs.
making this list more complicated.

I guess it's not worth the trouble then.

Acked-by: Gerd Hoffmann <kraxel at redhat.com>
for or the original patch (and thanks for investigating).

take care,
  Gerd



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