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Draft: efi/x86: Free EFI memory map only when installing a new one.

Lenny Szubowicz requested to merge lszubowi/centos-stream-9:rhel-41172 into main

JIRA: https://issues.redhat.com/browse/RHEL-41172

commit 75dde792d6f6c2d0af50278bd374bf0c512fe196
Author: Ard Biesheuvel ardb@kernel.org
Date: Mon Jun 10 16:02:13 2024 +0200

efi/x86: Free EFI memory map only when installing a new one.  

The logic in __efi_memmap_init() is shared between two different  
execution flows:  
- mapping the EFI memory map early or late into the kernel VA space, so  
  that its entries can be accessed;  
- the x86 specific cloning of the EFI memory map in order to insert new  
  entries that are created as a result of making a memory reservation  
  via a call to efi_mem_reserve().  

In the former case, the underlying memory containing the kernel's view  
of the EFI memory map (which may be heavily modified by the kernel  
itself on x86) is not modified at all, and the only thing that changes  
is the virtual mapping of this memory, which is different between early  
and late boot.  

In the latter case, an entirely new allocation is created that carries a  
new, updated version of the kernel's view of the EFI memory map. When  
installing this new version, the old version will no longer be  
referenced, and if the memory was allocated by the kernel, it will leak  
unless it gets freed.  

The logic that implements this freeing currently lives on the code path  
that is shared between these two use cases, but it should only apply to  
the latter. So move it to the correct spot.  

While at it, drop the dummy definition for non-x86 architectures, as  
that is no longer needed.  

Cc: <stable@vger.kernel.org>  
Fixes: f0ef6523475f ("efi: Fix efi_memmap_alloc() leaks")  
Tested-by: Ashish Kalra <Ashish.Kalra@amd.com>  
Link: https://lore.kernel.org/all/36ad5079-4326-45ed-85f6-928ff76483d3@amd.com  
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

Signed-off-by: Lenny Szubowicz lszubowi@redhat.com

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