Re: [Xen-devel] [PATCH 0/2] MMIO emulation fixes

[Olaf Hering <olaf@xxxxxxxxx>]

On Mon, Aug 13, Jan Beulich wrote:

> And hence the consideration of mapping in an all zeros page
> instead. This is because of the way __hvmemul_read() /
> __hvm_copy() work: The latter doesn't tell its caller how many
> bytes it was able to read, and hence the former considers the
> entire range MMIO (and forwards the request for emulation).
> Of course all of this is an issue only because
> hvmemul_virtual_to_linear() sees no need to split the request
> at the page boundary, due to the balloon driver having left in
> place the mapping of the ballooned out page.

Should perhaps __hvm_copy detect the fault and copy 0xf for the
unavailable page into 'buf', and finally return success?

Clearly something must be done at the Xen level.

Olaf

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