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qemu: fix Windows installs stalling on USB storage timeouts - #7971
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QEMU's usb-storage could park a status (CSW) request that arrived while a command was completing and never answer it, so the guest timed out the transfer after 10 s, reset the device and retried. The window is narrow, but with the HVF in-kernel GICv3 from 5.0.7 Windows queues the CSW fast enough to hit it on nearly every burst of reads: installing from the default USB CD copied its files in ~1230 s instead of ~160 s. Pick up the fix from the UTM QEMU fork (ae92cdc41f), which releases the SCSI request before completing the packet. The install now copies its files in ~135 s with the in-kernel GIC. Resolves #7970 Assisted-by: Claude:claude-opus-5-5
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5.0.7 enabled the Hypervisor.framework in-kernel GICv3 for QEMU VMs. That exposed a latent race in QEMU's usb-storage: when a command completed, the guest's already-queued status (CSW) request could be handled re-entrantly while the request was still marked in flight. It was then parked and never answered. Windows times out USB storage transfers after 10 s, so an install from the default USB CD stalled ~10 s after every burst of reads (endpoint stop, device reset, retry). The emulated GIC was slow enough to dodge the window most of the time; the in-kernel GIC hits it on nearly every burst.
This picks up the fix from the UTM QEMU fork (utmapp/qemu@ae92cdc41f), which releases the SCSI request before completing the packet.
Measured on the "Installing Windows" copy phase of a Windows 11 24H2 ARM64 install from a USB CD:
-machine kernel-irqchip=offResolves #7970
Testing: Tested by a human on macOS 27.0, Apple M3. The author acknowledges that this change has been tested and/or reviewed by a human in accordance with UTM's AI contribution guidelines.