Re: issue about booting centos fail with edk2

[Laszlo Ersek <lersek@redhat.com>]

On 08/01/17 19:23, Ard Biesheuvel wrote:
> On 1 August 2017 at 16:42, Laszlo Ersek <lersek@redhat.com> wrote:
>> On 08/01/17 10:34, Zhu Yijun wrote:
>>> Thanks for your reply!
>>>
>>> On 2017/8/1 3:02, Laszlo Ersek wrote:
>>>> On 07/31/17 02:27, Zhu Yijun wrote:
>>>>> Hi all,
>>>>>
>>>>>     I install a CentOS-7-aarch64 guest img by qemu cdrom, but it hung at UEFI probability.
>>>>>
>>>>>     Basic info:
>>>>>     libvirt 1.3.5
>>>>>     QEMU 2.6.2
>>>>>     UEFI: master branch with commit "688c7d2 BaseTools: Fix the bug that warn() function with only 1 argument"
>>>>>
>>>>>     Config pflash and two disks in xml:
>>>>>
>>>>>     ...
>>>>>     <os>
>>>>>     <type arch='aarch64' machine='virt-2.6'>hvm</type>
>>>>>     <loader readonly='yes' type='pflash'>/usr/share/edk2/aarch64/QEMU_EFI-pflash.raw</loader>
>>>>>     <boot dev='hd'/>
>>>>>   </os>
>>>>>   ...
>>>>>   <disk type='file' device='disk'>
>>>>>       <driver name='qemu' type='qcow2' cache='none' io='native'/>
>>>>>       <source file='/CentOS-7-aarch64/centos.qcow2'/>
>>>>>       <backingStore/>
>>>>>       <target dev='sda' bus='scsi'/>
>>>>>     </disk>
>>>>>     <disk type='file' device='cdrom'>
>>>>>       <driver name='qemu' type='raw' cache='none' io='native'/>
>>>>>       <source file='/CentOS-7-aarch64/CentOS-7-aarch64-Everything.iso'/>
>>>>>       <backingStore/>
>>>>>       <target dev='sdb' bus='scsi'/>
>>>>>     </disk>
>>>>>     ...
>>>>>
>>>>>     I found it failed at "Match (Translated, TranslatedSize, ActiveOption[Idx].BootOption->FilePath)" function in "SetBootOrderFromQemu", the UEFI debug info as follow:
>>>> No, that's not where the problem is. See below:
>>>>
>>>>> start-console-fail.log
>>>>> FSOpen: Open '\EFI\BOOT\fallback.efi' Success
>>>>> FSOpen: Open '\EFI\BOOT\fallback.efi' Success
>>>>>
>>>>>
>>>>> Synchronous Exception at 0x00000002384B1104
>>>>> PC 0x0002384B1104
>>>>> PC 0x0002384A916C
>>>>> PC 0x0002384CA2D0
>>>>> PC 0x00023EEB7DF8 (0x00023EEB1000+0x00006DF8) [ 1] DxeCore.dll
>>>>> PC 0x00023BD1568C (0x00023BD02000+0x0001368C) [ 2] BdsDxe.dll
>>>>> PC 0x00023BD03F98 (0x00023BD02000+0x00001F98) [ 2] BdsDxe.dll
>>>>> PC 0x00023BD05640 (0x00023BD02000+0x00003640) [ 2] BdsDxe.dll
>>>>> PC 0x00023EEB3704 (0x00023EEB1000+0x00002704) [ 3] DxeCore.dll
>>>>> PC 0x00023EEB27C8 (0x00023EEB1000+0x000017C8) [ 3] DxeCore.dll
>>>>> PC 0x00023EEB2024 (0x00023EEB1000+0x00001024) [ 3] DxeCore.dll
>>>>> [ 1] /root/rpmbuild/BUILD/edk2-2.6.0/Build/ArmVirtQemu-AARCH64/DEBUG_GCC49/AARCH64/MdeModulePkg/Core/Dxe/DxeMain/DEBUG/DxeCore.dll
>>>>> [ 2] /root/rpmbuild/BUILD/edk2-2.6.0/Build/ArmVirtQemu-AARCH64/DEBUG_GCC49/AARCH64/MdeModulePkg/Universal/BdsDxe/BdsDxe/DEBUG/BdsDxe.dll
>>>>> [ 3] /root/rpmbuild/BUILD/edk2-2.6.0/Build/ArmVirtQemu-AARCH64/DEBUG_GCC49/AARCH64/MdeModulePkg/Core/Dxe/DxeMain/DEBUG/DxeCore.dll
>>>>>
>>>>>   X0 0x00000002384A9000   X1 0x00000002384B2990   X2 0x000000023AAFDF98   X3 0x000000023BFF0018
>>>>>   X4 0x0000000000000000   X5 0x0000000000000007   X6 0x0000000238533300   X7 0x0000000000000000
>>>>>   X8 0x000000023C01F548   X9 0x0000000200000000  X10 0x00000002384A8000  X11 0x00000002384C5FFF
>>>>>  X12 0x0000000000000000  X13 0x0000000000000008  X14 0x259511BDAEB1F36C  X15 0x1378CC1DF3F5DDBB
>>>>>  X16 0x000000023EEB0BE0  X17 0x0000000000000000  X18 0x0000000000000000  X19 0x0000000000000013
>>>>>  X20 0x0000000000000000  X21 0x0000000000000000  X22 0x0000000000000000  X23 0x0000000000000000
>>>>>  X24 0x0000000000000000  X25 0x0000000000000000  X26 0x0000000000000000  X27 0x0000000000000000
>>>>>  X28 0x0000000000000000   FP 0x000000023EEB0A40   LR 0x00000002384A916C
>>>>>
>>>>>   V0 0xAFAFAFAFAFAFAFAF AFAFAFAFAFAFAFAF   V1 0x63702F6666666666 6666666666666666
>>>>>   V2 0x40697363732F3340 6567646972622D69   V3 0x0000000000000000 0000000000000000
>>>>>   V4 0x0000000000000000 0000000000000000   V5 0x4010040140100401 4010040140100401
>>>>>   V6 0x0000000000000000 0000000000000000   V7 0x0000000000000000 0000000000000000
>>>>>   V8 0x0000000000000000 0000000000000000   V9 0x0000000000000000 0000000000000000
>>>>>  V10 0x0000000000000000 0000000000000000  V11 0x0000000000000000 0000000000000000
>>>>>  V12 0x0000000000000000 0000000000000000  V13 0x0000000000000000 0000000000000000
>>>>>  V14 0x0000000000000000 0000000000000000  V15 0x0000000000000000 0000000000000000
>>>>>  V16 0x0000000000000000 0000000000000000  V17 0x0000000000000000 0000000000000000
>>>>>  V18 0x0000000000000000 0000000000000000  V19 0x0000000000000000 0000000000000000
>>>>>  V20 0x0000000000000000 0000000000000000  V21 0x0000000000000000 0000000000000000
>>>>>  V22 0x0000000000000000 0000000000000000  V23 0x0000000000000000 0000000000000000
>>>>>  V24 0x0000000000000000 0000000000000000  V25 0x0000000000000000 0000000000000000
>>>>>  V26 0x0000000000000000 0000000000000000  V27 0x0000000000000000 0000000000000000
>>>>>  V28 0x0000000000000000 0000000000000000  V29 0x0000000000000000 0000000000000000
>>>>>  V30 0x0000000000000000 0000000000000000  V31 0x0000000000000000 0000000000000000
>>>>>
>>>>>   SP 0x000000023EEB0A40  ELR 0x00000002384B1104  SPSR 0x60000205  FPSR 0x00000000
>>>>>  ESR 0x02000000          FAR 0x1DE7EC7EDBADC0DE
>>>>>
>>>>>  ESR : EC 0x00  IL 0x1  ISS 0x00000000
>>>>>
>>>>> Stack dump:
>>>>>   000023EEB0940: 0000C0E000000148 00000002384A9000 00000002384CA254 0000000000000000
>>>>>   000023EEB0960: 000000023EEB0BC0 000000023AC006C0 0000F2503EEB0BC0 00000002384B6018
>>>>>   000023EEB0980: 000000023EEB0BC0 0000000000000000 000000000000C0E0 0000000000000148
>>>>>   000023EEB09A0: 0000000000000148 0000100000020A8C 00000002384B6110 00000002384B6108
>>>>>   000023EEB09C0: 00000002384B6100 0000000000000006 00000002384B6058 00000002384B50DF
>>>>>   000023EEB09E0: 00000002384A9148 0000000000000000 00000002384A9000 00000002384A9000
>>>>>   000023EEB0A00: 0000000000000000 00000002398DA518 00000002385375B2 00000002385629A0
>>>>>   000023EEB0A20: 000000023854C1C0 00000002398DA518 000000023EEB0BC0 0000000000000000
>>>>>> 000023EEB0A40: 000000023EEB0BC0 00000002384CA2D0 000000023AAFDF98 000000023BFF0018
>>>>>   000023EEB0A60: 00000002384CA360 000000023EEC8348 00000002385375B0 000000023AAFDF98
>>>>>   000023EEB0A80: 000000023EEB0AC0 0000F25038533338 00000002384B6018 0000000000000000
>>>>>   000023EEB0AA0: 0000000000000000 0000000238B63D18 0000000000001000 0000000000000000
>>>>>   000023EEB0AC0: 000000023BFF0018 00000002398DA518 00000002398CE598 0000000000000000
>>>>>   000023EEB0AE0: 0000000000000000 0000000000000000 00000002384C6000 00000000000C99C0
>>>>>   000023EEB0B00: 0000000200000001 0000000000000000 000000023AC006C0 11D295625B1B31A1
>>>>>   000023EEB0B20: 3B7269C9A0003F8E 0000000000000000 0000000238B63F98 000000163EEB0B68
>>>>> ASSERT [ArmCpuDxe] /root/rpmbuild/BUILD/edk2-2.6.0/ArmPkg/Library/DefaultExceptionHandlerLib/AArch64/DefaultExceptionHandler.c(271): ((BOOLEAN)(0==1))
>>>> This is a guest that you didn't install from installer media. I think
>>>> you may have gotten the preinstalled disk image from some image provider
>>>> service. The UEFI boot variable(s) are not set up to boot the CentOS
>>>> installation, in your nvram / pflash file.
>>> Yes, the boot variable must store in domain's nvram file("/var/lib/libvirt/qemu/nvram/centos_VARS.fd").  After installed, it generates an new boot menu
>>> called "CentOS Linux AltArch "  which device path is "HD(1,GPT,D562CAA6-F61B-4F93-87FB-22DDADF6CAE2,0x800,0x64000)/\EFI\centos\shim.efi".
>>>
>>> such like:
>>> Boot Manager Menu
>>>    CentOS Linux AltArch                          -> device path:  PciRoot(0x0)/Pci(0x3,0x0)/Pci(0x0,0x0)/Scsi(0x0,0x0) /HD(1,GPT,D562CAA6-F61B-4F93-87FB-22DDADF6CAE2,0x800,0x64000)/\EFI\centos\shim.efi
>>>    UEFI Misc Device
>>>    UEFI Misc Device 2
>>>    EFI Internal Shell
>>>    UEFI QEMU QEMU CD-ROM               -> device path:  PciRoot(0x0)/Pci(0x3,0x0)/Pci(0x0,0x0)/Scsi(0x0,0x1)
>>>    UEFI QEMU QEMU HARDDISK            -> device path:  PciRoot(0x0)/Pci(0x3,0x0)/Pci(0x0,0x0)/Scsi(0x0,0x0)
>>>    UEFI PXEv4 (MAC:5254002D2EB6)
>>>
>>> But when I shutdown &undefine this domain, and virsh create an new domain with the disk centos.qcow2 which installed just before, the UEFI boot manager
>>> menu is:
>>> Boot Manager Menu
>>>    UEFI QEMU QEMU HARDDISK               -> device path:  PciRoot(0x0)/Pci(0x3,0x0)/Pci(0x0,0x0)/Scsi(0x0,0x0)
>>>    UEFI Misc Device
>>>    UEFI Misc Device 2
>>>    EFI Internal Shell
>>>    UEFI PXEv4 (MAC:5254002D2EB6)
>>
>> Right. In this case you have lost your original nvram contents, and you
>> only have the boot options that are auto-generated by the
>> EfiBootManagerRefreshAllBootOption() function. This function lives in
>> UefiBootManagerLib, and is called from OVMF's PlatformBootManagerLib
>> instance.
>>
>> The filtering and reordering still occurs in OVMF, but now the first
>> boot option that matches QEMU's fw_cfg bootorder specification is not
>> the "CentOS Linux AltArch" boot option that you originally had. Instead,
>> now QemuBootOrderLib encounters the "UEFI QEMU QEMU HARDDISK"
>> auto-generated boot option first as a match.
>>
>> This boot option in turn means "fallback.efi", according to the blog
>> post I linked earlier.
>>
>> When "fallback.efi" executes successfully, your original "CentOS Linux
>> AltArch" boot option is restored / recreated (at the top of the boot
>> option list). But, when "fallback.efi" crashes, you get a crash instead.
>>
>>> I am confused about two points:
>>> 1) The new domain still have chance to load the "EFI\centos\shim.efi" and boot kernel successful, it means that sometimes the system firmware launches
>>> the BOOTAA64.EFI, sometimes lauches shim.efi.  It is probabilistic.
>>
>> "EFI\centos\shim.efi" is never automatically loaded. It needs a
>> dedicated UEFI boot option. Thus, it can be loaded in your "new" domain
>> *only* if "fallback.efi" runs first, successfully.
>>
>> So what you are seeing is that "fallback.efi" sometimes works, and
>> sometimes crashes. That's the nature of memory corruption bugs.
>>
>>>
>>> 2) Is there a way to make the "CentOS Linux AltArch " boot menu persistent?
>>
>> There isn't. If you lose your nvram, you lose the non-auto-generated
>> boot options with it.
>>
>> Remedying such situations is what "fallback.efi" exists for.
>>
>>>>
>>>> In such cases, the "fallback.efi" utility is invoked (called
>>>> "\EFI\BOOT\BOOTAA64.EFI). Please refer to:
>>>>
>>>> https://blog.uncooperative.org/blog/2014/02/06/the-efi-system-partition/
>>>>
>>>> Unfortunately, "fallback.efi" (from the shim package) used to have a few
>>>> bugs over time and sometimes it would crash. See for example:
>>>>
>>>>   https://bugzilla.redhat.com/show_bug.cgi?id=1196114
>>>>
>>>> I'm unsure what version of shim / fallback.efi is in the installed
>>>> CentOS image, but it looks like the same (or another similar)
>>>> fallback.efi issue to me.
>>>
>>> shim version in my side is shim-0.9-2.el7.aarch64.
>>
>> This confirms that you are not seeing the exact bug described in
>> RHBZ#1196114, because that bug was fixed in shim-0.9 (see
>> <https://bugzilla.redhat.com/show_bug.cgi?id=1196114#c16>).
>>
>> It remains a fact that your original log contains a crash register dump
>> after fallback.efi is launched. The V0 register contains
>> 0xAFAFAFAFAFAFAFAF AFAFAFAFAFAFAFAF; the pattern 0xAF is used to fill
>> released (freed) pages in debug builds. So this seems to be an
>> use-after-free issue. I suggest adding debug instrumentation to
>> fallback.efi, and seeing where exactly it blows up.
>>
> 
> The presence of the 0xAF pattern in register v0 by itself does not
> suggest anything at all: V0 is a SIMD register, which is used by the
> SetMem() routine to poison the memory. There is very little other code
> (if any) that actually uses the SIMD registers otherwise.

Thanks for pointing this out.

Can you perhaps deduce more info from the stack / register dump? The
topmost three stack frames don't have edk2 module names associated with
them -- does that confirm that the synchronous exception is raised in a
non-edk2 module?

(I still think the only way forward is to instrument fallback.efi, and I
won't be doing that.)

Thanks
Laszlo