vmm: interrupt: Allocate GSIs for MSI/MSI-X interrupt vectors lazily - #7940
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likebreath merged 2 commits intoApr 1, 2026
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Signed-off-by: Bo Chen <[email protected]>
Previously, GSIs were eagerly allocated for all MSI-X vectors a device advertises (i.e. the maximum the device can support). This can easily exhaust KVM_MAX_IRQ_ROUTES (4096) with modern NVMe devices that support up to 2048 MSI-X vectors. Defer GSI allocation to the first time an interrupt vector is unmasked. The EventFd is still created eagerly since external components (e.g. VFIO) need it at device init time. Signed-off-by: Bo Chen <[email protected]>
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FYI: My colleague @amphi build properly GSI free'ing, e.g. on device unplug. Although not directly related, I think you'd be very interested in that as well. We hadn't have the time to upstream yet. |
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March 31, 2026 22:20
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Previously, GSIs were eagerly allocated for all MSI-X vectors a device
advertises (i.e. the maximum the device can support). This can easily
exhaust
KVM_MAX_IRQ_ROUTES (4096)with modern NVMe devicesthat support up to 2048 MSI-X vectors.
Defer GSI allocation to the first time an interrupt vector is
unmasked. The EventFd is still created eagerly since external
components (e.g. VFIO) need it at device init time.