Quoting Gerd Hoffmann (2023-11-13 04:48:10)
> On Fri, Nov 10, 2023 at 08:14:39PM -0600, Michael Roth wrote:
> > The struct used for GHCB-based page-state change requests uses a 40-bit
> > bit-field for the GFN, which is shifted by PAGE_SHIFT to generate a
> > 64-bit address. However, anything beyond 40-bits simply gets shifted off
> > when doing this, which will cause issues when dealing with 1TB+
> > addresses. Fix this by casting the 40-bit GFN values to 64-bit ones
> > prior to shifting it by PAGE_SHIFT.
> >
> > Fixes: ade62c18f474 ("OvmfPkg/MemEncryptSevLib: add support to validate
> > system RAM")
> > Signed-off-by: Michael Roth <michael.r...@amd.com>
> > ---
> > .../BaseMemEncryptSevLib/X64/SnpPageStateChangeInternal.c | 5 +++--
> > 1 file changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git
> > a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/SnpPageStateChangeInternal.c
> > b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/SnpPageStateChangeInternal.c
> > index 85eb41585b..d52d2940e9 100644
> > --- a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/SnpPageStateChangeInternal.c
> > +++ b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/SnpPageStateChangeInternal.c
> > @@ -78,13 +78,14 @@ PvalidateRange (
> > IN BOOLEAN Validate
> > )
> > {
> > - UINTN Address, RmpPageSize, Ret, i;
> > + UINTN RmpPageSize, Ret, i;
> > + EFI_PHYSICAL_ADDRESS Address;
> >
> > for ( ; StartIndex <= EndIndex; StartIndex++) {
> > //
> > // Get the address and the page size from the Info.
> > //
> > - Address = Info->Entry[StartIndex].GuestFrameNumber <<
> > EFI_PAGE_SHIFT;
> > + Address = ((UINT64)Info->Entry[StartIndex].GuestFrameNumber) <<
> > EFI_PAGE_SHIFT;
>
> Minor nit: why cast to UINT64 not EFI_PHYSICAL_ADDRESS?
My original thinking was that we were originally shifting a 40-bit
bit-field of a UINT64, so the minimal change is to cast it to a
normal UINT64 to fix the bit-field overflow. So I thought casting
to another type might obfuscate the fix a bit.
EFI_PHYSICAL_ADDRESS seems more correct all around though, so I've
sent a v2 with the suggested change.
Thanks!
-Mike
>
> Otherwise looks good to me.
>
> take care,
> Gerd
>
-=-=-=-=-=-=-=-=-=-=-=-
Groups.io Links: You receive all messages sent to this group.
View/Reply Online (#111284): https://edk2.groups.io/g/devel/message/111284
Mute This Topic: https://groups.io/mt/102520474/21656
Group Owner: devel+ow...@edk2.groups.io
Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com]
-=-=-=-=-=-=-=-=-=-=-=-
