On Tue, Oct 27, 2020 at 09:04:46AM -0400, Michael S. Tsirkin wrote: > It's not a waste of time, it's just a lot of work > within guests.
Luckily it does no harm to set the NEEDS_RESET bit even if the guest doesn't handle it. If the guest driver is unaware it may continue to submit requests to the device for a while. The device emulation code stops accepting new requests though. This means the device will become unresponsive until reset, which is not ideal but okay in the case where the device was put into an invalid state. I agree that supporting NEEDS_RESET transparently inside guests is difficult. The driver needs to reset and resume the device without reporting errors to applications. In some cases drivers may not have enough state in order to do that. It's also tricky to test all code paths. I guess this is why no one has done it: drivers shouldn't enter the NEEDS_RESET state anyway and handling it is complex. Stefan
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