Re: [PATCH v8] Preserve the EFI System Resource Table for dom0

[Julien Grall <julien@xxxxxxx>]

Hi Andrew,

On 06/07/2022 11:44, Andrew Cooper wrote:
> On 06/07/2022 11:32, Luca Fancellu wrote:
> > @@ -1051,6 +1110,70 @@ static void __init 
> > efi_set_gop_mode(EFI_GRAPHICS_OUTPUT_PROTOCOL *gop, UINTN gop
> > #define INVALID_VIRTUAL_ADDRESS (0xBAAADUL << \
> >                                   (EFI_PAGE_SHIFT + BITS_PER_LONG - 32))
> >
> > +static void __init efi_relocate_esrt(EFI_SYSTEM_TABLE *SystemTable)
> > +{
> > +    EFI_STATUS status;
> > +    UINTN info_size = 0, map_key, mdesc_size;
> > +    void *memory_map = NULL;
> > +    UINT32 ver;
> > +    unsigned int i;
> > +
> > +    for ( ; ; ) {
> > +        status = efi_bs->GetMemoryMap(&info_size, memory_map, &map_key,
> > +                                      &mdesc_size, &ver);
> > +        if ( status == EFI_SUCCESS && memory_map != NULL )
> > +            break;
> > +        if ( status == EFI_BUFFER_TOO_SMALL || memory_map == NULL )
> > +        {
> > +            info_size += 8 * efi_mdesc_size;
> > +            if ( memory_map != NULL )
> > +                efi_bs->FreePool(memory_map);
> > +            memory_map = NULL;
> > +            status = efi_bs->AllocatePool(EfiLoaderData, info_size, 
> > &memory_map);
> > +            if ( status == EFI_SUCCESS )
> > +                continue;
> > +            PrintErr(L"Cannot allocate memory to relocate ESRT\r\n");
> > +        }
> > +        else
> > +            PrintErr(L"Cannot obtain memory map to relocate ESRT\r\n");
> > +        return;
> > +    }
> > +
> > +    /* Try to obtain the ESRT.  Errors are not fatal. */
> > +    for ( i = 0; i < info_size; i += efi_mdesc_size )
> > +    {
> > +        /*
> > +         * ESRT needs to be moved to memory of type EfiRuntimeServicesData
> > +         * so that the memory it is in will not be used for other purposes.
> > +         */
> > +        void *new_esrt = NULL;
> > +        size_t esrt_size = get_esrt_size(efi_memmap + i);
> ... a NULL pointer here.  And the only way that could happen is if
> efi_memmap is NULL.
>
> Which perhaps isn't surprising because presumably ARM gets memory
> information from the DT, not EFI?
We are always using the EFI memory map on Arm. The information from the 
DT used to be removed, but now kept just to get the NUMA information 
outside of the EFI stub.
Cheers,

--
Julien Grall