[edk2-devel] [PATCH] Revert "UefiCpuPkg/CpuDxe: Fix boot error"
Laszlo Ersek
lersek at redhat.com
Thu Dec 17 14:40:12 UTC 2020
On 12/17/20 09:50, Laszlo Ersek wrote:
> This reverts commit cee5b0441af39dd6f76cc4e0447a1c7f788cbb00.
>
> Commit cee5b0441af3 ("UefiCpuPkg/CpuDxe: Fix boot error", 2020-12-08)
> breaks CpuDxe (and with it, OVMF boot) on AMD processors. AMD processors
> cannot do far jumps to 64-bit targets, as documented in the AMD64
> Architecture Programmer's Manual.
>
> Revert the patch until a RETFQ-based substitute is posted.
>
> Cc: Eric Dong <eric.dong at intel.com>
> Cc: Guo Dong <guo.dong at intel.com>
> Cc: James Bottomley <James.Bottomley at HansenPartnership.com>
> Cc: Rahul Kumar <rahul1.kumar at intel.com>
> Cc: Ray Ni <ray.ni at intel.com>
> Cc: Thomas Lendacky <thomas.lendacky at amd.com>
> Ref: https://edk2.groups.io/g/devel/message/68597
> Ref: https://www.redhat.com/archives/edk2-devel-archive/2020-December/msg00493.html
> Reported-by: Thomas Lendacky <thomas.lendacky at amd.com>
> Ref: https://edk2.groups.io/g/devel/message/68832
> Ref: https://www.redhat.com/archives/edk2-devel-archive/2020-December/msg00737.html
> Reported-by: James Bottomley <James.Bottomley at HansenPartnership.com>
> Signed-off-by: Laszlo Ersek <lersek at redhat.com>
Ticket:
https://bugzilla.tianocore.org/show_bug.cgi?id=3121
Thanks
Laszlo
> ---
>
> Notes:
> The broken patch was committed on December 8th; Tom reported the
> regression the next day, and James reported it independently on Dec
> 14th/15th (dependent on one's time zone).
>
> Nine days after merging the broken patch, I've only seen "pondering" of
> how we should fix the issue. I'll tell you how: I'm going to merge this
> revert later today unless I see a patch that implements the RETFQ-based
> replacement.
>
> Regressing code and not working diligently to address the problem is
> unacceptable.
>
> UefiCpuPkg/CpuDxe/X64/CpuAsm.nasm | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/UefiCpuPkg/CpuDxe/X64/CpuAsm.nasm b/UefiCpuPkg/CpuDxe/X64/CpuAsm.nasm
> index 6ad32b49f4ef..c3489bcc3e89 100644
> --- a/UefiCpuPkg/CpuDxe/X64/CpuAsm.nasm
> +++ b/UefiCpuPkg/CpuDxe/X64/CpuAsm.nasm
> @@ -23,8 +23,8 @@ ASM_PFX(SetCodeSelector):
> sub rsp, 0x10
> lea rax, [setCodeSelectorLongJump]
> mov [rsp], rax
> - mov [rsp+8], cx
> - jmp qword far [rsp]
> + mov [rsp+4], cx
> + jmp dword far [rsp]
> setCodeSelectorLongJump:
> add rsp, 0x10
> ret
>
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