Re: [PATCH 1/2] vfio-ccw: sort out physical vs virtual pointers usage

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Quoting Eric Farman (2022-11-09 21:21:56)
> From: Alexander Gordeev <agordeev@xxxxxxxxxxxxx>
> 
> The ORB is a construct that is sent to the real hardware,
> so should contain a physical address in its interrupt
> parameter field. Let's clarify that.

Maybe I don't get it, but I think the commit description is inaccurate. The PoP
says (p. 15-25):

> Bits 0-31 of word 0 are
> preserved unmodified in the subchannel until
> replaced by a subsequent START SUBCHANNEL or
> MODIFY SUBCHANNEL instruction. These bits are
> placed in word 1 of the interruption code when an I/O
> interruption occurs and when an interruption request
> is cleared by the execution of TEST PENDING
> INTERRUPTION.

So the hardware actually doesn't care what kind of address this is. Rather, the
CIO driver expects the intparam to be a physical address - probably so it fits
32 bits -, see do_cio_interrupt.




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