target-i386: add i440fx 0xcf8portascoalesced_pio

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Quoted 8 lines · On Mon, Aug 27, 2018 at 04:25:00PM +0800, [email protected] wrote:

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Is there a reason to not register this port as coalesced PIO also for Q35? In q35_host_realize()?
If not, I would do that as an extra patch as part of this series.

Just as I mentioned in patch [0/4] , you can add pci-
host config port as coalesecd pio. I think it works for q35 port 0xcf8.

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-Liran

What's the performance improvement for q35?

q35 also has the same pci-host config port 0xcf8 as piix. I test the coalesced pio for q35 pci-host config port 0xcf8. It spent less VM-exit avg time from 3us to 0.6us.

so pls include that patch too. piix is mostly feature frozen, piix only features aren't likely to be merged.