Re: [PATCH v2] xen/device-tree: Allow region overlapping with /memreserve/ ranges

[Shawn Anastasio <sanastasio@xxxxxxxxxxxxxxxxxxxxx>]

Hi Luca,

On 11/14/24 4:28 AM, Luca Fancellu wrote:
> There are some cases where the device tree exposes a memory range
> in both /memreserve/ and reserved-memory node, in this case the
> current code will stop Xen to boot since it will find that the
> latter range is clashing with the already recorded /memreserve/
> ranges.
> 
> Furthermore, u-boot lists boot modules ranges, such as ramdisk,
> in the /memreserve/ part and even in this case this will prevent
> Xen to boot since it will see that the module memory range that
> it is going to add in 'add_boot_module' clashes with a /memreserve/
> range.
> 
> When Xen populate the data structure that tracks the memory ranges,
> it also adds a memory type described in 'enum membank_type', so
> in order to fix this behavior, allow overlapping with the /memreserve/
> ranges in the 'check_reserved_regions_overlap' function when a flag
> is set.
> 
> In order to implement this solution, there is a distinction between
> the 'struct membanks *' handled by meminfo_overlap_check(...) that
> needs to be done, because the static shared memory banks doesn't have
> a usable bank[].type field and so it can't be accessed, hence now
> the 'struct membanks_hdr' have a 'enum region_type type' field in order
> to be able to identify static shared memory banks in 
> meminfo_overlap_check(...).
> 
> While there, set a type for the memory recorded using meminfo_add_bank()
> from efi-boot.h.
> 
> Fixes: 53dc37829c31 ("xen/arm: Add DT reserve map regions to 
> bootinfo.reserved_mem")
> Reported-by: Shawn Anastasio <sanastasio@xxxxxxxxxxxxxxxxxxxxx>
> Reported-by: Grygorii Strashko <grygorii_strashko@xxxxxxxx>
> Signed-off-by: Luca Fancellu <luca.fancellu@xxxxxxx>

Sorry for the late response on this and I know it has already gone in,
but I just wanted to confirm that this fixes the original issue I
observed with overlapping regions in skiboot's generated DT.

Thanks!