Re: [Xen-devel] [edk2] [PATCH RFC 10/14] UefiCpuPkg/BaseXApicX2ApicLib: Fix initialisation on my system and ...

["Kinney, Michael D" <michael.d.kinney@xxxxxxxxx>]

Hi Anthony,

Can you provide more details on why you want to expose internal APIs
in the library class?

What is the specific issue?  Is the Local APIC in your environment 
not behaving the same as real HW?

Thanks,

Mike



> -----Original Message-----
> From: edk2-devel [mailto:edk2-devel-bounces@xxxxxxxxxxxx] On Behalf Of 
> Anthony PERARD
> Sent: Thursday, December 8, 2016 7:34 AM
> To: edk2-devel@xxxxxxxxxxxx; xen-devel@xxxxxxxxxxxxxxxxxxxx
> Cc: Anthony PERARD <anthony.perard@xxxxxxxxxx>
> Subject: [edk2] [PATCH RFC 10/14] UefiCpuPkg/BaseXApicX2ApicLib: Fix 
> initialisation
> on my system and ...
> 
> declare more exported function, ReadLocalApicReg and WriteLocalApicReg.
> 
> On my system (running OVMF inside a Xen PVH guest), writing the
> interrupt information (to XAPIC_LVT_TIMER_OFFSET) would also reset the
> init-count register, thus disabling the timer.
> ---
>  UefiCpuPkg/Include/Library/LocalApicLib.h          | 40 
> ++++++++++++++++++++++
>  .../BaseXApicX2ApicLib/BaseXApicX2ApicLib.c        | 10 +++---
>  2 files changed, 45 insertions(+), 5 deletions(-)
> 
> diff --git a/UefiCpuPkg/Include/Library/LocalApicLib.h
> b/UefiCpuPkg/Include/Library/LocalApicLib.h
> index fc980bc..ab621f2 100644
> --- a/UefiCpuPkg/Include/Library/LocalApicLib.h
> +++ b/UefiCpuPkg/Include/Library/LocalApicLib.h
> @@ -48,6 +48,46 @@ SetLocalApicBaseAddress (
>    );
> 
>  /**
> +  Read from a local APIC register.
> +
> +  This function reads from a local APIC register either in xAPIC or x2APIC 
> mode.
> +  It is required that in xAPIC mode wider registers (64-bit or 256-bit) must 
> be
> +  accessed using multiple 32-bit loads or stores, so this function only 
> performs
> +  32-bit read.
> +
> +  @param  MmioOffset  The MMIO offset of the local APIC register in xAPIC 
> mode.
> +                      It must be 16-byte aligned.
> +
> +  @return 32-bit      Value read from the register.
> +**/
> +UINT32
> +EFIAPI
> +ReadLocalApicReg (
> +  IN UINTN  MmioOffset
> +  );
> +
> +/**
> +  Write to a local APIC register.
> +
> +  This function writes to a local APIC register either in xAPIC or x2APIC 
> mode.
> +  It is required that in xAPIC mode wider registers (64-bit or 256-bit) must 
> be
> +  accessed using multiple 32-bit loads or stores, so this function only 
> performs
> +  32-bit write.
> +
> +  if the register index is invalid or unsupported in current APIC mode, then 
> ASSERT.
> +
> +  @param  MmioOffset  The MMIO offset of the local APIC register in xAPIC 
> mode.
> +                      It must be 16-byte aligned.
> +  @param  Value       Value to be written to the register.
> +**/
> +VOID
> +EFIAPI
> +WriteLocalApicReg (
> +  IN UINTN  MmioOffset,
> +  IN UINT32 Value
> +  );
> +
> +/**
>    Get the current local APIC mode.
> 
>    If local APIC is disabled, then ASSERT.
> diff --git a/UefiCpuPkg/Library/BaseXApicX2ApicLib/BaseXApicX2ApicLib.c
> b/UefiCpuPkg/Library/BaseXApicX2ApicLib/BaseXApicX2ApicLib.c
> index e690d2a..f84a40a 100644
> --- a/UefiCpuPkg/Library/BaseXApicX2ApicLib/BaseXApicX2ApicLib.c
> +++ b/UefiCpuPkg/Library/BaseXApicX2ApicLib/BaseXApicX2ApicLib.c
> @@ -820,11 +820,6 @@ InitializeApicTimer (
>    //
>    InitializeLocalApicSoftwareEnable (TRUE);
> 
> -  //
> -  // Program init-count register.
> -  //
> -  WriteLocalApicReg (XAPIC_TIMER_INIT_COUNT_OFFSET, InitCount);
> -
>    if (DivideValue != 0) {
>      ASSERT (DivideValue <= 128);
>      ASSERT (DivideValue == GetPowerOfTwo32((UINT32)DivideValue));
> @@ -848,6 +843,11 @@ InitializeApicTimer (
>    LvtTimer.Bits.Mask = 0;
>    LvtTimer.Bits.Vector = Vector;
>    WriteLocalApicReg (XAPIC_LVT_TIMER_OFFSET, LvtTimer.Uint32);
> +
> +  //
> +  // Program init-count register.
> +  //
> +  WriteLocalApicReg (XAPIC_TIMER_INIT_COUNT_OFFSET, InitCount);
>  }
> 
>  /**
> --
> Anthony PERARD
> 
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> edk2-devel@xxxxxxxxxxxx
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