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Re: [Xen-devel] GPU passthrough performance regression in >4GB vms due to XSA-60 changes

>>> On 15.05.14 at 15:39, <tomasz.wroblewski@xxxxxxxxx> wrote:

> On 05/15/2014 03:23 PM, Jan Beulich wrote:
>>>>> On 15.05.14 at 14:10, <tomasz.wroblewski@xxxxxxxxx> wrote:
>>> Not really sure why it only affects 64bit vms but I've just noticed the
>>> pci BARs for the card are being relocated by hvmloader as per some logs:
>>> (XEN) HVM3: Relocating guest memory for lowmem MMIO space enabled
>>> (XEN) HVM3: Relocating 0xffff pages from 0e0001000 to 14dc00000 for
>>> lowmem MMIO hole
>>> (XEN) HVM3: Relocating 0x1 pages from 0e0000000 to 15dbff000 for lowmem
>>> MMIO hole
>>> So it might be also related to that.
>> Indeed it might - what are the (guest) MTRR types for those regions?
> It's writeback for both the 32bit and 64bit above ranges.

Which seems rather wrong - it should at best be WC. Did you try to
find out why it is WB?


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