Re: [Xen-devel] [PATCH] passthru: Fix pci bar remapping for passthru devices

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

Are you questioning whether this patch should be applied?

 -- Keir

On 20/07/2009 15:26, "Jiang, Yunhong" <yunhong.jiang@xxxxxxxxx> wrote:

> I assume guest should disable the MMIO in PCI_COMMAND before writing all "1"s
> to bar register. Otherwise, what will happen on native if guest try to access
> 0xFFFFFFF0? 
> And if we do update the P2M, will it cause trouble to Xen HV?
> 
> Thanks
> Yunhong Jiang
> 
> xen-devel-bounces@xxxxxxxxxxxxxxxxxxx wrote:
>> Hi,
>> When guest code tries to get the block size of mmio, it will write
>> all "1"s into pci bar register and then qemu will return all "0"s to
>> the don't care
>> bits in the emulated bar register to indicate the block size
>> to guest code.
>> In this case, we should not create p2m mapping in
>> pt_bar_reg_write() and
>> pt_exp_rom_bar_reg_write(). Attached patch fixes this issue,
>> additional comment can be found in the patch.
>> 
>> Thanks,
>> Wei
>> 
>> Signed-off-by: Wei Wang <wei.wang2@xxxxxxx>
>> --
>> AMD GmbH, Germany
>> Operating System Research Center
>> 
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