Re: [edk2-devel] [PATCH for-edk2-stable201905 0/6] work around a QEMU issue triggered by the original TianoCore#1814 fix

["Laszlo Ersek" <lersek@redhat.com>]

On 05/29/19 17:12, Laszlo Ersek wrote:
> Bugzilla: https://bugzilla.tianocore.org/show_bug.cgi?id=1859
> Repo:     https://github.com/lersek/edk2.git
> Branch:   exbar_mtrr_bz_1859
> 
> The fix (commit range 3b7a897cd8e3..39b9a5ffe661) for
> <https://bugzilla.tianocore.org/show_bug.cgi?id=1814> is technically
> correct, but it tickles an (arguably unjustified) assumption in QEMU the
> wrong way. For end users, this makes the original fix for TianoCore#1814
> a regression, under certain circumstances.
> 
> In theory, the assumption should be eliminated in QEMU, but in practice,
> that could be quite intrusive and/or take long. It seems possible to
> work around the problem in OVMF, satisfying the assumption again; for
> that, OVMF needs a different fix (and a different trade-off) for the
> original problem described in TianoCore#1814.
> 
> Please see the detailed problem statement and the workaround's idea in
> TianoCore#1859.
> 
> If possible, I'd like to get this into edk2-stable201905 (which we're
> postponing by two weeks anyway, for the sake of the OpenSSL 1.1.1b
> upgrade).
> 
> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> Cc: Gerd Hoffmann <kraxel@redhat.com>
> Cc: Jordan Justen <jordan.l.justen@intel.com>

Thank you everyone for the feedback; I've pushed the series as commit
range f03859ea6c8f..49edde15230a.

Laszlo

> Laszlo Ersek (6):
>   Revert "OvmfPkg/PlatformPei: fix MTRR for low-RAM sizes that have many
>     bits clear"
>   Revert "OvmfPkg/PlatformPei: reorder the 32-bit PCI window vs. the
>     PCIEXBAR on q35"
>   Revert "OvmfPkg/PlatformPei: hoist PciBase assignment above the
>     i440fx/q35 branching"
>   Revert "OvmfPkg/PlatformPei: assign PciSize on both i440fx/q35
>     branches explicitly"
>   OvmfPkg: raise the PCIEXBAR base to 2816 MB on Q35
>   OvmfPkg/PlatformPei: set 32-bit UC area at PciBase / PciExBarBase
>     (pc/q35)
> 
>  OvmfPkg/OvmfPkgIa32.dsc         |  5 +-
>  OvmfPkg/OvmfPkgIa32X64.dsc      |  5 +-
>  OvmfPkg/OvmfPkgX64.dsc          |  5 +-
>  OvmfPkg/PlatformPei/Platform.h  |  5 ++
>  OvmfPkg/PlatformPei/MemDetect.c | 70 +++++++++++++++-----
>  OvmfPkg/PlatformPei/Platform.c  | 17 +++--
>  6 files changed, 80 insertions(+), 27 deletions(-)
>