RE: [Xen-devel] string mmio/pio across page boundaries

["Li, Xin B" <xin.b.li@xxxxxxxxx>]

>
>When preparing arguments for send_mmio_req() or send_pio_req() in hvm
>where a single iteration crosses a page boundary, the value to 
>be written is copied from guest memory, but I can't see where the value

>read is copied to guest memory. Is this case simply missing?
>

in send_mmio_req or send_pio_req, there is no request crossing a page
boundary, since it's already converted.


>Also, a long while back the logic to calculate when wrapping occurs was
>changed with two subsequent patches. As I'm looking at the code now it
>seems like - only the first patch got applied to handle_mmio() (i.e.,
the 
>logic is still broken - neither patch got applied to
{svm,vmx}_io_instruction().
>
>Further, there is a comment in handle_mmio() now saying "We need to
>make sure we advance to the point where the next request will be on a
>different page.  If we're going down, that means advancing until one
>byte before the start of the page, hence +1." This wasn't applied
>similarly to {svm,vmx}_io_instruction(). And the actual code seems
>wrong: If e.g. addr is on a page boundary, count will become zero. I
>would think that the +1 must be outside of the division.
>
>Was this intentional in some way? Otherwise, I'll prepare a patch to
>address all of these.
>

Are you using an old source tree, I don't see such code, and we have
sent a patch to clean that code before xen 3.0.3.
I think the logic is correct now.
-Xin

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