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Re: [Xen-devel] [PATCH 0/5] x86: EPT/MTRR interaction adjustments and cleanup

>>> On 03.03.14 at 09:35, "Xu, Dongxiao" <dongxiao.xu@xxxxxxxxx> wrote:
>>  -----Original Message-----
>> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
>> Sent: Tuesday, February 25, 2014 6:21 PM
>> To: xen-devel
>> Cc: Xu, Dongxiao; Dong, Eddie; Nakajima, Jun; Zhang, Yang Z; Keir Fraser
>> Subject: [PATCH 0/5] x86: EPT/MTRR interaction adjustments and cleanup
>> 1: x86/hvm: refine the judgment on IDENT_PT for EMT
>> 2: x86/HVM: fix memory type merging in epte_get_entry_emt()
>> 3: x86/HVM: consolidate passthrough handling in epte_get_entry_emt()
>> 4: x86/HVM: use manifest constants / enumerators for memory types
>> 5: x86/HVM: adjust data definitions in mtrr.c
> For 1-3 (related to logic change), they look good to me.

Please be explicit here - I would _think_ that I can translate this to
a Reviewed-by, but I'm not sure.

Further, with you commenting on 1-3 only, do you have any
reservations towards 4 and/or 5?


>> With this series in place (or actually the first three patches thereof,
>> as the rest is cleanup), apart from the need to fully drop the
>> dependency on HVM_PARAM_IDENT_PT (see the discussion started
>> at http://lists.xenproject.org/archives/html/xen-devel/2014-02/msg02150.html)
>> the other main question is whether the dependency on iommu_snoop
>> is really correct: I don't see why the IOMMU's snooping capability
>> would affect the cachability of memory accesses - especially in the
>> GPU passthrough case, RAM pages may need mapping as UC/WC
>> if the GPU is permitted direct access to them - uniformly using WB
>> here seems to be calling for problems.
>> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

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