Re: [PATCH v3 09/35] OvmfPkg/OvmfXen: use a TimerLib instance that depends only on the CPU

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

On 07/04/19 16:42, Anthony PERARD wrote:
> ACPI Timer does not work in a PVH guest, but local APIC works on both
> PVH and HVM.
> 
> Note that the use of SecPeiDxeTimerLibCpu might be an issue with a
> driver of type DXE_RUNTIME_DRIVER. I've attemptde to find out which of
> the DXE_RUNTIME_DRIVER uses the TimerLib at runtime. I've done that by
> replacing the TimerLib evaluation in
> [LibraryClasses.common.DXE_RUNTIME_DRIVER] by a different one and
> check every module that uses it (with the --report-file=report build
> option).
> 
> ResetSystemRuntimeDxe is calling the TimerLib API at runtime to do the
> operation "EfiResetCold", so this may never complete if the OS have
> disabled the Local APIC Timer.
> 
> Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1689
> Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
> ---
> 
> Notes:
>     v3:
>     - cleanup .dsc, leave only one TimerLib resolution
>     - Added a note in the commit message regarding the use of the local apic
>       by runtime drivers

Good note -- yes, the warning in
"MdePkg/Library/SecPeiDxeTimerLibCpu/SecPeiDxeTimerLibCpu.inf" applies.
I guess Xen setups can live with that potential problem, for now.

Acked-by: Laszlo Ersek <lersek@redhat.com>

Thanks
Laszlo

> 
>  OvmfPkg/OvmfXen.dsc | 7 +------
>  1 file changed, 1 insertion(+), 6 deletions(-)
> 
> diff --git a/OvmfPkg/OvmfXen.dsc b/OvmfPkg/OvmfXen.dsc
> index 9f79d455fa..6288394eb8 100644
> --- a/OvmfPkg/OvmfXen.dsc
> +++ b/OvmfPkg/OvmfXen.dsc
> @@ -104,7 +104,7 @@ [SkuIds]
>  ################################################################################
>  [LibraryClasses]
>    PcdLib|MdePkg/Library/BasePcdLibNull/BasePcdLibNull.inf
> -  TimerLib|OvmfPkg/Library/AcpiTimerLib/BaseAcpiTimerLib.inf
> +  TimerLib|MdePkg/Library/SecPeiDxeTimerLibCpu/SecPeiDxeTimerLibCpu.inf
>    PrintLib|MdePkg/Library/BasePrintLib/BasePrintLib.inf
>    BaseMemoryLib|MdePkg/Library/BaseMemoryLibRepStr/BaseMemoryLibRepStr.inf
>    BaseLib|MdePkg/Library/BaseLib/BaseLib.inf
> @@ -202,7 +202,6 @@ [LibraryClasses.common]
>    BaseCryptLib|CryptoPkg/Library/BaseCryptLib/BaseCryptLib.inf
>  
>  [LibraryClasses.common.SEC]
> -  TimerLib|OvmfPkg/Library/AcpiTimerLib/BaseRomAcpiTimerLib.inf
>    QemuFwCfgLib|OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgSecLib.inf
>  !ifdef $(DEBUG_ON_SERIAL_PORT)
>    DebugLib|MdePkg/Library/BaseDebugLibSerialPort/BaseDebugLibSerialPort.inf
> @@ -281,7 +280,6 @@ [LibraryClasses.common.DXE_CORE]
>  
>  [LibraryClasses.common.DXE_RUNTIME_DRIVER]
>    PcdLib|MdePkg/Library/DxePcdLib/DxePcdLib.inf
> -  TimerLib|OvmfPkg/Library/AcpiTimerLib/DxeAcpiTimerLib.inf
>    HobLib|MdePkg/Library/DxeHobLib/DxeHobLib.inf
>    DxeCoreEntryPoint|MdePkg/Library/DxeCoreEntryPoint/DxeCoreEntryPoint.inf
>    MemoryAllocationLib|MdePkg/Library/UefiMemoryAllocationLib/UefiMemoryAllocationLib.inf
> @@ -298,7 +296,6 @@ [LibraryClasses.common.DXE_RUNTIME_DRIVER]
>  
>  [LibraryClasses.common.UEFI_DRIVER]
>    PcdLib|MdePkg/Library/DxePcdLib/DxePcdLib.inf
> -  TimerLib|OvmfPkg/Library/AcpiTimerLib/DxeAcpiTimerLib.inf
>    HobLib|MdePkg/Library/DxeHobLib/DxeHobLib.inf
>    DxeCoreEntryPoint|MdePkg/Library/DxeCoreEntryPoint/DxeCoreEntryPoint.inf
>    MemoryAllocationLib|MdePkg/Library/UefiMemoryAllocationLib/UefiMemoryAllocationLib.inf
> @@ -313,7 +310,6 @@ [LibraryClasses.common.UEFI_DRIVER]
>  
>  [LibraryClasses.common.DXE_DRIVER]
>    PcdLib|MdePkg/Library/DxePcdLib/DxePcdLib.inf
> -  TimerLib|OvmfPkg/Library/AcpiTimerLib/DxeAcpiTimerLib.inf
>    HobLib|MdePkg/Library/DxeHobLib/DxeHobLib.inf
>    MemoryAllocationLib|MdePkg/Library/UefiMemoryAllocationLib/UefiMemoryAllocationLib.inf
>    ReportStatusCodeLib|MdeModulePkg/Library/DxeReportStatusCodeLib/DxeReportStatusCodeLib.inf
> @@ -337,7 +333,6 @@ [LibraryClasses.common.DXE_DRIVER]
>  
>  [LibraryClasses.common.UEFI_APPLICATION]
>    PcdLib|MdePkg/Library/DxePcdLib/DxePcdLib.inf
> -  TimerLib|OvmfPkg/Library/AcpiTimerLib/DxeAcpiTimerLib.inf
>    HobLib|MdePkg/Library/DxeHobLib/DxeHobLib.inf
>    MemoryAllocationLib|MdePkg/Library/UefiMemoryAllocationLib/UefiMemoryAllocationLib.inf
>    ReportStatusCodeLib|MdeModulePkg/Library/DxeReportStatusCodeLib/DxeReportStatusCodeLib.inf
>