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

["Kay, Allen M" <allen.m.kay@xxxxxxxxx>]

Hi Wei,

I thought the originally code already handles sizing of the BAR operations 
(writing all 1's and reading the size back). How did it work before? Did it 
work because we are relying on the a well behaved guest to restore the original 
value of the BAR after the sizing operation?

By reading the code, it is not obvious to me how does not doing r->addr = 
cfg_entry->data operation prevents calling of pt_bar_mapping_one() to create 
p2m mapping.

Allen

-----Original Message-----
From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx 
[mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Wei Wang2
Sent: Monday, July 20, 2009 7:04 AM
To: xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-devel] [PATCH] passthru: Fix pci bar remapping for passthru 
devices

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>
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