Re: [PATCH V2] MdeModulePkg/XhciPei: Unlinked XhciPei memory block

["Wu, Hao A" <hao.a.wu@intel.com>]

Hello,

My take is that unlike in DXE, the UsbHcFreeMemBlock() implementation in PEI phase does not perform freeing the memory.

So I think both the solution:
* Provided at https://edk2.groups.io/g/devel/topic/92833071#92165, which aligns with EhciPei
* Mentioned at the end of your previous reply, which aligns with XhciDxe
should work fine.

I will leave it to you for the final decision.

Best Regards,
Hao Wu

> -----Original Message-----
> From: He, Jiangang <Jiangang.He@amd.com>
> Sent: Friday, December 16, 2022 12:48 AM
> To: Chang, Abner <Abner.Chang@amd.com>; Wu, Hao A
> <hao.a.wu@intel.com>; devel@edk2.groups.io
> Cc: Lin, Kuei-Hung (Timothy) <Kuei-Hung.Lin@amd.com>; Ni, Ray
> <ray.ni@intel.com>; Zeng, Star <star.zeng@intel.com>; Sun, Zhikai
> <zhikai.sun@intel.com>; Kirkendall, Garrett <Garrett.Kirkendall@amd.com>
> Subject: RE: [PATCH V2] MdeModulePkg/XhciPei: Unlinked XhciPei memory
> block
> 
> [AMD Official Use Only - General]
> 
> Yes, it is the same issue discussed in
> https://edk2.groups.io/g/devel/topic/92833071#92165
> 
> MdeModulePkg\Bus\Pci\XhciPei\UsbHcMem.c
> 
>   for (Block = Pool->Head->Next; Block != NULL; Block = Pool->Head->Next) {
>     // UsbHcUnlinkMemBlock (Pool->Head, Block);
>     UsbHcFreeMemBlock (Pool, Block);
>   }
> Block = Pool->Head->Next never change without calling
> UsbHcUnlinkMemBlock (Pool->Head, Block), therefore dead loop.
> 
> Our proposed fix came from dxe version of the equivalent file
> MdeModulePkg\Bus\Pci\XhciDxe\UsbHcMem.c but swapped two routine call
> order (Now I think it is incorrect as clarified below).
>   for (Block = Pool->Head->Next; Block != NULL; Block = Pool->Head->Next) {
>     UsbHcFreeMemBlock (Pool, Block);
>     UsbHcUnlinkMemBlock (Pool->Head, Block);
>   }
> 
> https://edk2.groups.io/g/devel/topic/92833071#92165 proposed fix:
> 
>   for (Block = Pool->Head->Next; Block != NULL; Block = Block ->Next) {
>     // UsbHcUnlinkMemBlock (Pool->Head, Block);
>     UsbHcFreeMemBlock (Pool, Block);
>   }
> 
> I think it again, both proposals have problem of reading memory content in
> the buffer that has just been freed.
> 
>   for (Block = Pool->Head->Next; Block != NULL; Block = Pool->Head->Next) {
>      UsbHcUnlinkMemBlock (Pool->Head, Block);
>     UsbHcFreeMemBlock (Pool, Block);
>   }
> is right solution and matches dxe version of UsbHcMem.c.
> 
> Thanks,
> Jiangang
> 
> -----Original Message-----
> From: Chang, Abner <Abner.Chang@amd.com>
> Sent: Wednesday, December 14, 2022 8:12 PM
> To: Wu, Hao A <hao.a.wu@intel.com>; devel@edk2.groups.io
> Cc: Lin, Kuei-Hung (Timothy) <Kuei-Hung.Lin@amd.com>; Ni, Ray
> <ray.ni@intel.com>; Zeng, Star <star.zeng@intel.com>; Sun, Zhikai
> <zhikai.sun@intel.com>; Kirkendall, Garrett <Garrett.Kirkendall@amd.com>;
> He, Jiangang <Jiangang.He@amd.com>
> Subject: RE: [PATCH V2] MdeModulePkg/XhciPei: Unlinked XhciPei memory
> block
> 
> [AMD Official Use Only - General]
> 
> Hi Jiangang,
> Could you please provide the context of this patch?
> 
> Thanks
> Abner
> 
> > -----Original Message-----
> > From: Wu, Hao A <hao.a.wu@intel.com>
> > Sent: Monday, December 12, 2022 11:27 AM
> > To: Chang, Abner <Abner.Chang@amd.com>; devel@edk2.groups.io
> > Cc: Lin, Kuei-Hung (Timothy) <Kuei-Hung.Lin@amd.com>; Ni, Ray
> > <ray.ni@intel.com>; Zeng, Star <star.zeng@intel.com>; Sun, Zhikai
> > <zhikai.sun@intel.com>; Kirkendall, Garrett
> > <Garrett.Kirkendall@amd.com>
> > Subject: RE: [PATCH V2] MdeModulePkg/XhciPei: Unlinked XhciPei memory
> > block
> >
> > Caution: This message originated from an External Source. Use proper
> > caution when opening attachments, clicking links, or responding.
> >
> >
> > Sorry for a question, may I know what issue was met that leads to the
> > proposed patch?
> > Could you help to check if it is related with the topic discussed in
> >
> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fedk2
> > .gr
> >
> oups.io%2Fg%2Fdevel%2Ftopic%2F92833071%2392165&amp;data=05%7C0
> 1%7
> >
> Cabner.chang%40amd.com%7Ccac49c2820e741b8c48a08dadbf0cc24%7C3d
> d8
> >
> 961fe4884e608e11a82d994e183d%7C0%7C0%7C638064124512265992%7C
> Unk
> >
> nown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6I
> k1h
> >
> aWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&amp;sdata=z1Q7NRxN4GMA
> %2
> > FBxYd2D7Gnkc3aTD23mRnwNF3H5wE0k%3D&amp;reserved=0? Thanks in
> advance.
> >
> > Best Regards,
> > Hao Wu
> >
> > > -----Original Message-----
> > > From: abner.chang@amd.com <abner.chang@amd.com>
> > > Sent: Saturday, December 10, 2022 11:13 PM
> > > To: devel@edk2.groups.io
> > > Cc: Kuei-Hung.Lin@amd.com; Wu, Hao A <hao.a.wu@intel.com>; Ni, Ray
> > > <ray.ni@intel.com>; Garrett Kirkendall <garrett.kirkendall@amd.com>;
> > > Abner Chang <abner.chang@amd.com>
> > > Subject: [PATCH V2] MdeModulePkg/XhciPei: Unlinked XhciPei memory
> > > block
> > >
> > > From: Abner Chang <abner.chang@amd.com>
> > >
> > > In V2: Add AMD copyright.
> > >
> > > Unlink the XhciPei memory block when it has been freed.
> > >
> > > Signed-off-by: Kuei-Hung Lin <Kuei-Hung.Lin@amd.com>
> > > Cc: Hao A Wu <hao.a.wu@intel.com>
> > > Cc: Ray Ni <ray.ni@intel.com>
> > > Cc: Garrett Kirkendall <garrett.kirkendall@amd.com>
> > > Cc: Abner Chang <abner.chang@amd.com>
> > > ---
> > >  MdeModulePkg/Bus/Pci/XhciPei/UsbHcMem.c | 29
> > > ++++++++++++++++++++++++-
> > >  1 file changed, 28 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/MdeModulePkg/Bus/Pci/XhciPei/UsbHcMem.c
> > > b/MdeModulePkg/Bus/Pci/XhciPei/UsbHcMem.c
> > > index c64b38fcfc8..39ba31b0913 100644
> > > --- a/MdeModulePkg/Bus/Pci/XhciPei/UsbHcMem.c
> > > +++ b/MdeModulePkg/Bus/Pci/XhciPei/UsbHcMem.c
> > > @@ -3,6 +3,7 @@ PEIM to produce gPeiUsb2HostControllerPpiGuid
> based
> > > on gPeiUsbControllerPpiGuid  which is used to enable recovery
> > > function from USB Drivers.
> > >
> > >  Copyright (c) 2014 - 2016, Intel Corporation. All rights
> > > reserved.<BR>
> > > +Copyright (C) 2022 Advanced Micro Devices, Inc. All rights
> > > +reserved.<BR>
> > >
> > >  SPDX-License-Identifier: BSD-2-Clause-Patent
> > >
> > > @@ -365,6 +366,32 @@ UsbHcInitMemPool (
> > >    return Pool;
> > >  }
> > >
> > > +/**
> > > +  Unlink the memory block from the pool's list.
> > > +
> > > +  @param  Head           The block list head of the memory's pool.
> > > +  @param  BlockToUnlink  The memory block to unlink.
> > > +
> > > +**/
> > > +VOID
> > > +UsbHcUnlinkMemBlock (
> > > +  IN USBHC_MEM_BLOCK  *Head,
> > > +  IN USBHC_MEM_BLOCK  *BlockToUnlink
> > > +  )
> > > +{
> > > +  USBHC_MEM_BLOCK  *Block;
> > > +
> > > +  ASSERT ((Head != NULL) && (BlockToUnlink != NULL));
> > > +
> > > +  for (Block = Head; Block != NULL; Block = Block->Next) {
> > > +    if (Block->Next == BlockToUnlink) {
> > > +      Block->Next         = BlockToUnlink->Next;
> > > +      BlockToUnlink->Next = NULL;
> > > +      break;
> > > +    }
> > > +  }
> > > +}
> > > +
> > >  /**
> > >    Release the memory management pool.
> > >
> > > @@ -386,8 +413,8 @@ UsbHcFreeMemPool (
> > >    // first block.
> > >    //
> > >    for (Block = Pool->Head->Next; Block != NULL; Block =
> > > Pool->Head->Next) {
> > > -    // UsbHcUnlinkMemBlock (Pool->Head, Block);
> > >      UsbHcFreeMemBlock (Pool, Block);
> > > +    UsbHcUnlinkMemBlock (Pool->Head, Block);
> > >    }
> > >
> > >    UsbHcFreeMemBlock (Pool, Pool->Head);
> > > --
> > > 2.37.1.windows.1