RE: [PATCH 2/3] iommu/vt-d: Replace spin_lock with mutex to protect domain ida

[Tian, Kevin]

> From: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> Sent: Wednesday, April 23, 2025 11:10 AM
> 
> The domain ID allocator is currently protected by a spin_lock. However,
> ida_alloc_range can potentially block if it needs to allocate memory to
> grow its internal structures.
> 
> Replace the spin_lock with a mutex which allows sleep on block. Thus,
> the memory allocation flags can be updated from GFP_ATOMIC to
> GFP_KERNEL
> to allow blocking memory allocations if necessary.
> 
> Introduce a new mutex, did_lock, specifically for protecting the domain
> ida. The existing spinlock will remain for protecting other intel_iommu
> fields.
> 
> Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>

Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>