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Re: [Xen-devel] [Q] Is qemu used when we use VTd?

To: Jean Guyader <jean.guyader@xxxxxxxxx>
Subject: Re: [Xen-devel] [Q] Is qemu used when we use VTd?
From: Akio Takebe <takebe_akio@xxxxxxxxxxxxxx>
Date: Thu, 11 Sep 2008 20:48:02 +0900
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Jean Guyader wrote:
On Thu, Sep 11, 2008 at 11:46 AM, Akio Takebe
<takebe_akio@xxxxxxxxxxxxxx> wrote:

If we assign a device to HVM guest,
HVM guest can do directry DMA transfer.
But how about accessing pci configuration register
of the pass through device? Do we still access
pci configuration register through qemu?

Yes, you should have a look at the function pt_pci_read_config in

HVM guest use PCI BIOS of rombios at access pci configuration register,
and the accesses are trapped by qemu. qemu do their access instead, right?

Can we directly use MMCONFIG for PCI-Express card pass-throughed by VT-d on HVM?

Best Regards,

Akio Takebe

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