Re: [edk2-devel] [PATCH] MdeModulePkg/UefiBootManagerLib: Signal ReadyToBoot on platform recovery

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

On 10/26/23 18:19, Laszlo Ersek wrote:
> On 10/26/23 15:53, Neal Gompa wrote:
>> From: Neal Gompa <ngompa@fedoraproject.org>
>>
>> Currently, the ReadyToBoot event is only signaled when a formal Boot
>> Manager option is executed (in BmBoot.c -> EfiBootManagerBoot ()).
>>
>> However, the introduction of Platform Recovery in UEFI 2.5 makes it
>> necessary to signal ReadyToBoot when a Platform Recovery boot loader
>> runs because otherwise it may lead to the execution of a boot loader
>> that has similar requirements to a regular one that is not launched
>> as a Boot Manager option.
>>
>> This is especially critical to ensuring that the graphical console
>> is actually usable during platform recovery, as some platforms do
>> rely on the ConsolePrefDxe driver, which only performs console
>> initialization after ReadyToBoot is triggered.
>>
>> This patch fixes that behavior by calling EfiSignalEventReadyToBoot ()
>> in EfiBootManagerProcessLoadOption (), which is the function that sets
>> up the platform recovery boot process.
>>
>> The expected behavior has been clarified in the UEFI 2.10 specification
>> to explicitly indicate this behavior is required for correct operation.
>>
>> This is a rebased version of the patch originally written by Pete Batard.
>>
>> Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=2831
>>
>> Cc: Pete Batard <pete@akeo.ie>
>> Cc: Daniel P. Berrangé <berrange@redhat.com>
>> Cc: Gerd Hoffmann <kraxel@redhat.com>
>> Cc: Samer El-Haj-Mahmoud <samer.el-haj-mahmoud@arm.com>
>>
>> Co-authored-by: Pete Batard <pete@akeo.ie>
>> Signed-off-by: Neal Gompa <ngompa@fedoraproject.org>
>> ---
>>  MdeModulePkg/Library/UefiBootManagerLib/BmLoadOption.c | 9 +++++++++
>>  1 file changed, 9 insertions(+)
>>
>> diff --git a/MdeModulePkg/Library/UefiBootManagerLib/BmLoadOption.c b/MdeModulePkg/Library/UefiBootManagerLib/BmLoadOption.c
>> index 2087f0b91d..31ed608817 100644
>> --- a/MdeModulePkg/Library/UefiBootManagerLib/BmLoadOption.c
>> +++ b/MdeModulePkg/Library/UefiBootManagerLib/BmLoadOption.c
>> @@ -1416,6 +1416,15 @@ EfiBootManagerProcessLoadOption (
>>      return EFI_SUCCESS;
>>    }
>>  
>> +  //
>> +  // Signal the EVT_SIGNAL_READY_TO_BOOT event when we are about to load and execute the boot option.
>> +  //
>> +  EfiSignalEventReadyToBoot ();
>> +  //
>> +  // Report Status Code to indicate ReadyToBoot was signalled
>> +  //
>> +  REPORT_STATUS_CODE (EFI_PROGRESS_CODE, (EFI_SOFTWARE_DXE_BS_DRIVER | EFI_SW_DXE_BS_PC_READY_TO_BOOT_EVENT));
>> +
>>    //
>>    // Load and start the load option.
>>    //
> 
> While the patch does the right thing for the latest UEFI spec language,
> it does a bit too much.
> 
> The spec says (v2.10), under 7.1.2 "EFI_BOOT_SERVICES.CreateEventEx()":
> 
> -----------
> EFI_EVENT_GROUP_READY_TO_BOOT
> 
> This event group is notified by the system right before notifying
> EFI_EVENT_GROUP_AFTER_READY_TO_BOOT event group when the Boot Manager is
> about to load and execute a boot option or a platform or OS recovery
> option. The event group presents the last chance to modify device or
> system configuration prior to passing control to a boot option.
> -----------
> 
> NB "boot option", or "platform or OS recovery option".
> 
> However, EfiBootManagerProcessLoadOption() is also used for launching
> Driver#### and SysPrep#### options.
> 
> EfiBootManagerProcessLoadOption() has two call sites:
> 
> (1) in ProcessLoadOptions() [MdeModulePkg/Universal/BdsDxe/BdsEntry.c]
> 
> (2) near the end of BdsEntry() [MdeModulePkg/Universal/BdsDxe/BdsEntry.c]
> 
> Call site (2) bears the comment "When platform recovery is not enabled,
> still boot to platform default file path", so I figure signaling
> ready-to-boot at that point is fine.
> 
> Call site (1) requires further investigation. Namely,
> ProcessLoadOptions() itself is called from three locations, all inside
> BdsEntry() [MdeModulePkg/Universal/BdsDxe/BdsEntry.c]:
> 
> (1.1) under comment "Execute Driver Options", for "LoadOptionTypeDriver"
> type load options
> 
> (1.2) under comment "Execute SysPrep####", for "LoadOptionTypeSysPrep"
> type load options
> 
> (1.3) for "LoadOptionTypePlatformRecovery" type load options.
> 
> I figure the intended extension is for case (1.3), but the patch, as
> proposed, will also affect (1.1) and (1.2); that is, when Driver#### and
> SysPrep#### options are processes. That's beyond what the spec says, in
> my opinion.
> 
> Now, EfiBootManagerProcessLoadOption() takes a pointer to an
> EFI_BOOT_MANAGER_LOAD_OPTION structure. This structure has a field
> called OptionType (of type EFI_BOOT_MANAGER_LOAD_OPTION_TYPE). You might
> want to restrict the signaling and the status code reporting to when
> LoadOption->OptionType is either LoadOptionTypeBoot or
> LoadOptionTypePlatformRecovery (i.e., exclude LoadOptionTypeDriver and
> LoadOptionTypeSysPrep).

In fact,

EfiBootManagerProcessLoadOption() already checks
"LoadOption->OptionType" higher up, and if its LoadOptionTypeBoot, then
the function returns early, with EFI_UNSUPPORTED.

Therefore, IMO, you need to restrict the logic you are proposing to

  LoadOption->OptionType == LoadOptionTypePlatformRecovery

exclusively.

Laszlo

> 
> (
> 
> I've made an attempt to check the above-noted four call paths (i.e.,
> (1.1) through (1.3), and (2)), and I *think* the OptionType field is
> populated on all of them; thus, the check I recommend should be safe.
> 
> Call paths (1.1) through (1.3) call EfiBootManagerGetLoadOptions(),
> which sets the OptionType field in each returned structure according to
> the input parameter "LoadOptionType" (note the tricky call to
> EfiBootManagerVariableToLoadOption()).
> 
> And (2) relies on "PlatformDefaultBootOption", which is created in
> BdsEntry() with LoadOptionTypePlatformRecovery.
> 
> )
> 
> Laszlo
> 
> 
> 
> 
> 
> 



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