Re: [PATCH 6/7] xen/arm: Implement the logic for static shared memory from Xen heap

[Michal Orzel <michal.orzel@xxxxxxx>]

Hi Luca,

On 23/04/2024 10:25, Luca Fancellu wrote:
> 
> 
> This commit implements the logic to have the static shared memory banks
> from the Xen heap instead of having the host physical address passed from
> the user.
> 
> When the host physical address is not supplied, the physical memory is
> taken from the Xen heap using allocate_domheap_memory, the allocation
> needs to occur at the first handled DT node and the allocated banks
> need to be saved somewhere, so introduce the 'shm_heap_banks' static
> global variable of type 'struct meminfo' that will hold the banks
> allocated from the heap, its field .shmem_extra will be used to point
> to the bootinfo shared memory banks .shmem_extra space, so that there
> is not further allocation of memory and every bank in shm_heap_banks
> can be safely identified by the shm_id to reconstruct its traceability
> and if it was allocated or not.
> 
> A search into 'shm_heap_banks' will reveal if the banks were allocated
> or not, in case the host address is not passed, and the callback given
> to allocate_domheap_memory will store the banks in the structure and
> map them to the current domain, to do that, some changes to
> acquire_shared_memory_bank are made to let it differentiate if the bank
> is from the heap and if it is, then assign_pages is called for every
> bank.
> 
> When the bank is already allocated, for every bank allocated with the
> corresponding shm_id, handle_shared_mem_bank is called and the mapping
> are done.
> 
> Signed-off-by: Luca Fancellu <luca.fancellu@xxxxxxx>

I tested this patch and it resulted in assertion:
Assertion 's <= e' failed at common/rangeset.c:189

I checked and in find_unallocated_memory(), given that start is ~0UL (host 
address not provided),
start + size would overflow. Did you test this patch?

~Michal