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由 Avi Kivity 提交于
When trying to map an alias of a ram region, where the alias starts at address A and we map it into address B, and A > B, we had an arithmetic underflow. Because we use unsigned arithmetic, the underflow converted into a large number which failed addrrange_intersects() tests. The concrete example which triggered this was cirrus vga mapping the framebuffer at offsets 0xc0000-0xc7fff (relative to the start of the framebuffer) into offsets 0xa0000 (relative to system addres space start). With our favorite analogy of a windowing system, this is equivalent to dragging a subwindow off the left edge of the screen, and failing to clip it into its parent window which is on screen. Fix by switching to signed arithmetic. Signed-off-by: NRichard Henderson <rth@twiddle.net> Signed-off-by: NAvi Kivity <avi@redhat.com> Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>
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