vfio-user: Implement sparse mmap capability for Server#132
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likebreath merged 2 commits intorust-vmm:mainfrom Mar 2, 2026
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vfio-user: Implement sparse mmap capability for Server#132likebreath merged 2 commits intorust-vmm:mainfrom
likebreath merged 2 commits intorust-vmm:mainfrom
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Manage the server socket better by removing the socket path when the server is dropped. Also, remove a possible leftover socket path when starting the server. Signed-off-by: Sebastien Boeuf <sboeuf@meta.com>
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LGTM. Just one nit below.
The vfio-user client already supports the sparse mmap capability but this was missing from the server implementation. Adding this feature so that a vfio-user server relying on this crate can use the sparse mmap capability to define subregions which must be memory mapped within standard PCI regions. As stated in the vfio-user spec here https://www.qemu.org/docs/master/interop/vfio-user.html#sparse-regions in the context of an NVMe emulated device, having the doorbell region memory mapped allows for great performance since the backend can poll the doorbells directly and catch any new entry in the submission queues. Signed-off-by: Sebastien Boeuf <sboeuf@meta.com>
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The vfio-user client already supports the sparse mmap capability but
this was missing from the server implementation.
Adding this feature so that a vfio-user server relying on this crate can
use the sparse mmap capability to define subregions which must be memory
mapped within standard PCI regions.
As stated in the vfio-user spec here
https://www.qemu.org/docs/master/interop/vfio-user.html#sparse-regions
in the context of an NVMe emulated device, having the doorbell region
memory mapped allows for great performance since the backend can poll
the doorbells directly and catch any new entry in the submission queues.