Hi Star, This logic seems much complicated than mine. Also after CSM retired from EDKII, we will change this code back to only require allocate buffer below 1M. I will add such notes in the code comments. So I prefer to use my change.
Thanks, Eric > -----Original Message----- > From: Zeng, Star > Sent: Tuesday, March 5, 2019 3:33 PM > To: Dong, Eric <[email protected]>; [email protected] > Cc: Ni, Ray <[email protected]>; Laszlo Ersek ([email protected]) > <[email protected]>; Zeng, Star <[email protected]> > Subject: RE: [edk2] [Patch] UefiCpuPkg/MpInitLib: Direct allocate buffer for > Wake up Buffer. > > Just an idea to avoid hard code value 0x88000. > > Before EndOfDxe: Allocate buffer in AllocateResetVector(), and free buffer > in FreeResetVector(). > At EndOfDxe (it is after LegacyBiosDxe driver entry point) callback: Allocate > buffer and record it to CpuMpData->WakeupBuffer, and always occupy the > buffer, that means no free. > After EndOfDxe: Use CpuMpData->WakeupBuffer. > > > Thanks, > Star > -----Original Message----- > From: edk2-devel [mailto:[email protected]] On Behalf Of > Eric Dong > Sent: Tuesday, March 5, 2019 10:07 AM > To: [email protected] > Subject: [edk2] [Patch] UefiCpuPkg/MpInitLib: Direct allocate buffer for > Wake up Buffer. > > https://bugzilla.tianocore.org/show_bug.cgi?id=1538 > > Current CpuDxe driver "borrows" Wakeup Buffer (through Allocate & free to > get the buffer pointer, backup the buffer data before using it and restore it > after using). Now this logic met a problem described in the above BZ > because the test tool and the CpuDxe both use the same memory at the > same time. > > In order to fix the above issue, CpuDxe changed to allocate the buffer below > 1M instead of borrow it. After investigation, we found below > 0x88000 is the possible space which can be used. For now, range > 0x60000 ~ 0x88000 used for Legacy OPROMs by LegacyBios driver. And it tries > to allocate these range page(4K size) by page. It just reports warning > message if specific page been used by others already. > > Also CpuDxe driver will produce CPU arch protocol and LegacyBios driver has > dependency for this protocol. So CpuDxe driver will start before LegacyBios > driver and CpuDxe driver can allocate that space successful. > > With this change, CpuDxe driver will use 0x87000 ~ 0x88000 as wakeup buffer. > > Cc: Ray Ni <[email protected]> > Contributed-under: TianoCore Contribution Agreement 1.1 > Signed-off-by: Eric Dong <[email protected]> > --- > UefiCpuPkg/Library/MpInitLib/DxeMpLib.c | 30 +++++++++++++++++++---- > ------- > 1 file changed, 19 insertions(+), 11 deletions(-) > > diff --git a/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c > b/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c > index b2307cbb61..5bc9a47efb 100644 > --- a/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c > +++ b/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c > @@ -76,7 +76,7 @@ SaveCpuMpData ( > } > > /** > - Get available system memory below 1MB by specified size. > + Get available system memory below 0x88000 by specified size. > > @param[in] WakeupBufferSize Wakeup buffer size required > > @@ -91,7 +91,19 @@ GetWakeupBuffer ( > EFI_STATUS Status; > EFI_PHYSICAL_ADDRESS StartAddress; > > - StartAddress = BASE_1MB; > + // > + // Current "Borrow" space mechanism caused potential race condition > + if both // AP and the original owner use the share space. > + // > + // LegacyBios driver tries to allocate 4K pages between 0x60000 ~ > + 0x88000 // space. It will just report an waring message if the page > + has been allocate // by other drivers. > + // LagacyBios driver depends on CPU Arch protocol, so it will start > + after // CpuDxe driver which produce Cpu Arch Protocol and use this > library. > + // So below allocate logic will be trigged before LegacyBios driver > + and it // will always return success. > + // > + StartAddress = BASE_512KB + BASE_32KB; > Status = gBS->AllocatePages ( > AllocateMaxAddress, > EfiBootServicesData, > @@ -99,17 +111,13 @@ GetWakeupBuffer ( > &StartAddress > ); > ASSERT_EFI_ERROR (Status); > - if (!EFI_ERROR (Status)) { > - Status = gBS->FreePages( > - StartAddress, > - EFI_SIZE_TO_PAGES (WakeupBufferSize) > - ); > - ASSERT_EFI_ERROR (Status); > - DEBUG ((DEBUG_INFO, "WakeupBufferStart = %x, WakeupBufferSize > = %x\n", > - (UINTN) StartAddress, WakeupBufferSize)); > - } else { > + if (EFI_ERROR (Status)) { > StartAddress = (EFI_PHYSICAL_ADDRESS) -1; > } > + > + DEBUG ((DEBUG_INFO, "WakeupBufferStart = %x, WakeupBufferSize > = %x\n", > + (UINTN) StartAddress, WakeupBufferSize)); > + > return (UINTN) StartAddress; > } > > -- > 2.15.0.windows.1 > > _______________________________________________ > edk2-devel mailing list > [email protected] > https://lists.01.org/mailman/listinfo/edk2-devel _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
