Re: Memory space entry is not removed after calling FreeMemorySpace and RemoveMemorySpace

["Zeng, Star" <star.zeng@intel.com>]

There are two cases here.

Case 1:
1. gDS->AddMemorySpace
  The  memory range is automatically allocated for use by the UEFI memory services.
2. No any driver allocates memory at this memory range by gBS->AllocatePages()/AllocatePool().
3. gDS->FreeMemorySpace
4. gDS->RemoveMemorySpace

Case 2:
1. gDS->AddMemorySpace
  The  memory range is automatically allocated for use by the UEFI memory services.
2. There are driver(s) allocate memory at this memory range by gBS->AllocatePages()/AllocatePool.
3. gDS->FreeMemorySpace
4. gDS->RemoveMemorySpace

For case 1, the memory range could be removed safely from UEFI memory map at step 3, and step 3 and 4 could return success.
For case 2, the memory range could be not removed from UEFI memory map at step3 as the memory range is still been used by drivers, then step 3 and 4 should return failure.


Thanks,
Star
-----Original Message-----
From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of Wasim Khan
Sent: Monday, January 8, 2018 8:48 PM
To: Zeng, Star <star.zeng@intel.com>; edk2-devel@lists.01.org
Cc: Gao, Liming <liming.gao@intel.com>
Subject: Re: [edk2] Memory space entry is not removed after calling FreeMemorySpace and RemoveMemorySpace

Hi Star,

I agree with you that 'gDS->AddMemorySpace' should always pass, but if these functions are made to return the Status, we should ideally check the Status and take necessary actions upon failure.

After going through the code, if a memory space for EfiGcdMemoryTypeSystemMemory (or EfiGcdMemoryTypeMoreReliable) is added then memory  range is automatically allocated for use by the UEFI memory services by adding a memory descriptor to gMemoryMap .
But when we call 'gDS->FreeMemorySpace' and ''gDS->RemoveMemorySpace' , memory space is only removed from GCD map and it is not removed from UEFI Services map.

So ideally while when a call to gDS->AddMemorySpace (for memory type EfiGcdMemoryTypeSystemMemory) automatically allocates it for use by UEFI memory services. It should also free the memory when 'gDS->FreeMemorySpace' call is made.

I have opened a ticket for this issue (https://bugzilla.tianocore.org/show_bug.cgi?id=841) .


Regards,
Wasim

> -----Original Message-----
> From: Zeng, Star [mailto:star.zeng@intel.com]
> Sent: Monday, January 08, 2018 6:37 AM
> To: Wasim Khan <wasim.khan@nxp.com>; edk2-devel@lists.01.org
> Cc: Gao, Liming <liming.gao@intel.com>; Zeng, Star 
> <star.zeng@intel.com>
> Subject: RE: Memory space entry is not removed after calling 
> FreeMemorySpace and RemoveMemorySpace
> 
> Hi Wasim,
> 
> Got the point.
> 
> Yes, gDS->AddMemorySpace should return success normally, you may can 
> assume it.
> Or a little tricky method if you only want the memory space to be used 
> by OS kernel, but not post, I think you may can hook the 
> gBS->GetMemoryMap() with your own GetMemoryMap() function, it will 
> call original GetMemoryMap() function, and then append one entry for 
> the memory space you want to add for OS kernel.
> 
> 
> 
> Thanks,
> Star
> -----Original Message-----
> From: Wasim Khan [mailto:wasim.khan@nxp.com]
> Sent: Monday, January 8, 2018 3:03 AM
> To: Zeng, Star <star.zeng@intel.com>; edk2-devel@lists.01.org
> Cc: Gao, Liming <liming.gao@intel.com>
> Subject: RE: Memory space entry is not removed after calling 
> FreeMemorySpace and RemoveMemorySpace
> 
> Hi Star,
> 
> Thank you for your reply.
> 
> I cannot add memory space as EfiGcdMemoryTypeReserved because for my 
> use case, i am exposing memory space of an extended DDR memory to 
> kernel. If I add this memory space as EfiGcdMemoryTypeReserved, then 
> linux is not able to allocate memory from this region to applications 
> (a simple application requesting memory from this region fails). So I 
> have to add the memory space as EfiGcdMemoryTypeSystemMemory only.
> 
> > What is the usage that the memory space needs to be added first and 
> > removed
> later?
> No specific use case, I am checking the status of 
> 'gDS->AddMemorySpace' and 'gDS->SetMemorySpaceAttributes', if any of 
> these calls fails, I want to remove the added memory space. Ideally it should work.
> 
> 
> 
> Regards,
> Wasim
> 
> 
> 
> > -----Original Message-----
> > From: Zeng, Star [mailto:star.zeng@intel.com]
> > Sent: Friday, January 05, 2018 4:35 PM
> > To: Wasim Khan <wasim.khan@nxp.com>; edk2-devel@lists.01.org
> > Cc: Zeng, Star <star.zeng@intel.com>; Gao, Liming 
> > <liming.gao@intel.com>
> > Subject: RE: Memory space entry is not removed after calling 
> > FreeMemorySpace and RemoveMemorySpace
> >
> > PI spec has clear description below in AddMemorySpace().
> >
> > "If the memory range specified by BaseAddress and Length is of type 
> > EfiGcdMemoryTypeSystemMemory or EfiGcdMemoryTypeMoreReliable, then
> the
> > memory range may be *automatically allocated for use by the UEFI 
> > memory services*."
> >
> > But PI spec has no clear description about removing the use from the 
> > UEFI memory services in FreeMemorySpace() and RemoveMemorySpace().
> > I think it is very hard (may be not possible) as the added memory 
> > space may have been used by UEFI memory (page) services for drivers 
> > after the memory space is added by AddMemorySpace().
> >
> > What is the usage that the memory space needs to be added first and 
> > removed later?
> > Could the memory space be added as EfiGcdMemoryTypeReserved type 
> > instead of EfiGcdMemoryTypeSystemMemory type?
> >
> >
> > Thanks,
> > Star
> > -----Original Message-----
> > From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf 
> > Of Wasim Khan
> > Sent: Friday, January 5, 2018 5:59 PM
> > To: edk2-devel@lists.01.org
> > Subject: [edk2] Memory space entry is not removed after calling 
> > FreeMemorySpace and RemoveMemorySpace
> >
> > Hi All,
> >
> > I am facing a problem that if a add a memory space using 'gDS-
> > >AddMemorySpace'  and then remove it using 'gDS->FreeMemorySpace'
> > followed by 'gDS->RemoveMemorySpace'.
> > I can still see the entry of added memory space in the table shown 
> > by
> 'memmap'
> > command.
> >
> > I enabled DEBUG_GCD and as per logs , the entry is removed from 
> > GcdMemorySpaceMap , but when I run 'memmap' command which gets the 
> > memory map using 'gBS->GetMemoryMap', I can see that entry for the 
> > added memory space is still present. Steps and Logs are below for 
> > reference
> >
> > Do I need to perform any other steps in order to cleanly remove the 
> > memory space entry ?
> >
> > Regards,
> > Wasim
> >
> >
> >
> > Below are the steps and GCD debug logs.
> > Steps 1 : Add a memory space . We can see that an entry from system 
> > memory is added.
> >
> > Status = gDS->AddMemorySpace (
> >                                             EfiGcdMemoryTypeSystemMemory,
> >                                             FixedPcdGet64(PcdSystemMemoryExBase),
> >                                             SystemMemoryExSize,
> >                                             EFI_MEMORY_WC | EFI_MEMORY_WT |
> >                                             EFI_MEMORY_WB
> >                                             );
> >
> >                Logs:
> >
> >
> GCD:AddMemorySpace(Base=0000008080000000,Length=0000000380000000)
> >                               GcdMemoryType   = SystemMem
> >                               Capabilities    = 000000000000000E
> > CoreConvertSpace 774
> >                               Status = Success
> > GCDMemType Range                             Capabilities     Attributes
> > ========== ================================= ================ 
> > ================
> > NonExist   0000000000000000-000000009FFFFFFF 0000000000000000
> > 0000000000000000
> > SystemMem  00000000A0000000-00000000DFFFFFFF 800000000000000E
> > 0000000000000008*
> > NonExist   00000000E0000000-00000000E01BFFFF 0000000000000000
> > 0000000000000000
> > SystemMem  00000000E01C0000-00000000FFFFFFFF 800000000000000E
> > 0000000000000008*
> > NonExist   0000000100000000-000000807FFFFFFF 0000000000000000
> > 0000000000000000
> > SystemMem  0000008080000000-00000083FFFFFFFF 800000000000000E
> > 0000000000000000
> > NonExist   0000008400000000-0000FFFFFFFFFFFF 0000000000000000
> > 0000000000000000
> >
> >
> GCD:AllocateMemorySpace(Base=0000008080000000,Length=00000003800000
> > 00)
> >   GcdAllocateType = AtAddress
> >   GcdMemoryType   = SystemMem
> >   Alignment       = 0000000000001000
> >   ImageHandle     = FED1FF98
> >   DeviceHandle    = 0
> >   Status = Success  (BaseAddress = 0000008080000000)
> > GCDMemType Range                             Capabilities     Attributes
> > ========== ================================= ================ 
> > ================
> > NonExist   0000000000000000-000000009FFFFFFF 0000000000000000
> > 0000000000000000
> > SystemMem  00000000A0000000-00000000DFFFFFFF 800000000000000E
> > 0000000000000008*
> > NonExist   00000000E0000000-00000000E01BFFFF 0000000000000000
> > 0000000000000000
> > SystemMem  00000000E01C0000-00000000FFFFFFFF 800000000000000E
> > 0000000000000008*
> > NonExist   0000000100000000-000000807FFFFFFF 0000000000000000
> > 0000000000000000
> > SystemMem  0000008080000000-00000083FFFFFFFF 800000000000000E
> > 0000000000000000*
> > NonExist   0000008400000000-0000FFFFFFFFFFFF 0000000000000000
> > 0000000000000000
> >
> >
> > Step2: Free the memory space
> >                Status = gDS->FreeMemorySpace (
> >                FixedPcdGet64(PcdSystemMemoryExBase),
> >                SystemMemoryExSize
> >                );
> >
> >                Logs:
> >
> >
> GCD:FreeMemorySpace(Base=0000008080000000,Length=0000000380000000)
> > Status = Success
> > GCDMemType Range                             Capabilities     Attributes
> > ========== ================================= ================ 
> > ================
> > NonExist   0000000000000000-000000009FFFFFFF 0000000000000000
> > 0000000000000000
> > SystemMem  00000000A0000000-00000000DFFFFFFF 800000000000000E
> > 0000000000000008*
> > NonExist   00000000E0000000-00000000E01BFFFF 0000000000000000
> > 0000000000000000
> > SystemMem  00000000E01C0000-00000000FFFFFFFF 800000000000000E
> > 0000000000000008*
> > NonExist   0000000100000000-000000807FFFFFFF 0000000000000000
> > 0000000000000000
> > SystemMem  0000008080000000-00000083FFFFFFFF 800000000000000E
> > 0000000000000000
> > NonExist   0000008400000000-0000FFFFFFFFFFFF 0000000000000000
> > 0000000000000000
> >
> >
> > Step3: Remove the memory space , As we can see that entry 'SystemMem 
> > 0000008080000000-00000083FFFFFFFF' is removed.
> >                Status = gDS->RemoveMemorySpace (
> >                FixedPcdGet64(PcdSystemMemoryExBase),
> >                SystemMemoryExSize
> >                );
> >
> >                Logs:
> >
> >
> GCD:RemoveMemorySpace(Base=0000008080000000,Length=00000003800000
> > 00)
> > Status = Success
> > GCDMemType Range                             Capabilities     Attributes
> > ========== ================================= ================ 
> > ================
> > NonExist   0000000000000000-000000009FFFFFFF 0000000000000000
> > 0000000000000000
> > SystemMem  00000000A0000000-00000000DFFFFFFF 800000000000000E
> > 0000000000000008*
> > NonExist   00000000E0000000-00000000E01BFFFF 0000000000000000
> > 0000000000000000
> > SystemMem  00000000E01C0000-00000000FFFFFFFF 800000000000000E
> > 0000000000000008*
> > NonExist   0000000100000000-0000FFFFFFFFFFFF 0000000000000000
> > 0000000000000000
> >
> > Step4 : Run the 'memmap' command. As we can see that entry is still present.
> >                Shell> memmap
> > Type       Start            End              # Pages          Attributes
> > Available  00000000A0000000-00000000DFFFFFFF 0000000000040000 
> > 000000000000000E Available  00000000E01C0000-00000000E53C0FFF
> > 0000000000005201 000000000000000E
> > BS_Data    00000000E53C1000-00000000E5D99FFF 00000000000009D9
> > 000000000000000E
> > ...
> > Available  0000008080000000-00000083FFFFFFFF 0000000000380000 
> > 000000000000000E
> >                               ...
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