Re: [Xen-devel] [PATCH v4 07/17] x86/hvm: add length to mmio check op

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 24/06/15 12:24, Paul Durrant wrote:
> When memory mapped I/O is range checked by internal handlers, the length
> of the access should be taken into account.
>
> Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
> Cc: Keir Fraser <keir@xxxxxxx>
> Cc: Jan Beulich <jbeulich@xxxxxxxx>
> Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
>

For what purpose?  The length of the access doesn't affect which handler
should accept the IO.

This length check now causes an MMIO handler to not claim an access
which straddles the upper boundary.

It is probably fine to terminate such an access early, but it isn't fine
to pass such a straddled access to the default ioreq server.

~Andrew

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