Re: [PATCH v2 0/3] Put AP into safe hlt-loop code on S3 path

["Yao, Jiewen" <jiewen.yao@intel.com>]

Yes. I think it is good to check in because it did fix an existing issue.
I suggest we describe the remaining issue honestly in our checkin log.

Thank you
Yao Jiewen

From: Fan, Jeff
Sent: Sunday, November 13, 2016 8:52 PM
To: Laszlo Ersek <lersek@redhat.com>
Cc: edk2-devel@ml01.01.org; Yao, Jiewen <jiewen.yao@intel.com>; Paolo Bonzini <pbonzini@redhat.com>
Subject: RE: [edk2] [PATCH v2 0/3] Put AP into safe hlt-loop code on S3 path

Laszlo,

Thanks your testing. It seems that there is still some unknown issue existing.

I suggest to push this serial of patches firstly, because they have big progress to solve the AP crashed issue in https://bugzilla.tianocore.org/show_bug.cgi?id=216.

I could submit another bug to handle "AP lost" issue.  Thus, JIewen's  or others' patches could be push as long as they have no additional issue except for "AP Lost:".

I could follow up to fix "AP Lost" issue.

Thanks!
Jeff


-----Original Message-----
From: Laszlo Ersek [mailto:lersek@redhat.com]
Sent: Saturday, November 12, 2016 3:49 AM
To: Fan, Jeff
Cc: edk2-devel@ml01.01.org<mailto:edk2-devel@ml01.01.org>; Yao, Jiewen; Paolo Bonzini
Subject: Re: [edk2] [PATCH v2 0/3] Put AP into safe hlt-loop code on S3 path

On 11/11/16 06:45, Jeff Fan wrote:
> On S3 path, we will wake up APs to restore CPU context in
> PiSmmCpuDxeSmm driver. In case, one NMI or SMI happens, APs may exit
> from hlt state and execute the instruction after HLT instruction.
>
> But APs are not running on safe code, it leads OVMF S3 boot unstable.
>
> https://bugzilla.tianocore.org/show_bug.cgi?id=216
>
> I tested real platform with 64bit DXE.
>
> v2:
>   1. Make stack alignment per Laszlo's comment.
>   2. Trim whitespace at end of end per Laszlo's comment.
>   3. Update year mark in file header.
>   4. Enhancement on InterlockedDecrement() per Paolo's comment.
>
> Jeff Fan (3):
>   UefiCpuPkg/PiSmmCpuDxeSmm: Put AP into safe hlt-loop code on S3 path
>   UefiCpuPkg/PiSmmCpuDxeSmm: Place AP to 32bit protected mode on S3 path
>   UefiCpuPkg/PiSmmCpuDxeSmm: Decrease mNumberToFinish in AP safe code
>
>  UefiCpuPkg/PiSmmCpuDxeSmm/CpuS3.c             | 33 +++++++++++++-
>  UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmmFuncsArch.c | 29 +++++++++++-
>  UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h    | 15 +++++++
>  UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmmFuncsArch.c  | 63
> ++++++++++++++++++++++++++-
>  4 files changed, 136 insertions(+), 4 deletions(-)
>

Applied this locally to master (ffd6b0b1b65e) for testing. I tested the series with a suspend-resume loop -- not a busy loop, just manually. (So there was always one second or so between adjacent steps.)

No crashes or emulation failures, but the "AP going lost" issue remains present -- sometimes Linux cannot bring up one of the four VCPUs after resume.

In the Ia32 case, this "AP lost" symptom surfaced after the 6th resume.

In the Ia32X64 case, I experienced the symptom after the 89th resume.

Thanks
Laszlo