Re: [PATCH QEMU HCI-8.0 v8 14/14] usb-host: make CPR migration blocker conditional #VSTOR-137800

[no-reply@sashiko.virtuozzo.com]

> A previous commit added an unconditional blocker for CPR migrations.
> That is to refuse CPR gracefully instead of crashing and for the previous
> commits to remain bisectable.
> 
> Now the restore path is complete: the FD is preserved, in-flight URBs
> are drained and replayed, the device is handed off across cpr-transfer,
> and the endpoints and isochronous streams are reconstructed on the
> target.  So let's lift the CPR blocker for the devices which satisfy the
> preconditions.
> 
> Still, the remaining preconditions for CPR to work are:
> 
>   * We must open host device FD ourselves, so that libusb owns the FD.
>     This way we're able to preserve the FD during CPR;
>   * Device ID must be provided as a unique stable key for CPR FD registry.
> 
> Use them to guard the blocker addition.  Apart from that, prohibit CPR on
> WIN32 platform and on hosts with older libusb versions.
> 
> Signed-off-by: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com>

Sashiko has reviewed this patch and found no issues. It looks great!

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Sashiko AI review · https://sashiko.vzint.dev/#/patchset/20261006-usb-host_v3-v8-0-72ae4fb8977b@virtuozzo.com?part=14