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Re: [PATCH v7 8/8] AMD/IOMMU: respect AtsDisabled device flag


  • To: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
  • From: Jan Beulich <jbeulich@xxxxxxxx>
  • Date: Thu, 26 Aug 2021 16:33:29 +0200
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  • Cc: Paul Durrant <paul@xxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>
  • Delivery-date: Thu, 26 Aug 2021 14:33:40 +0000
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On 26.08.2021 16:27, Andrew Cooper wrote:
> On 26/08/2021 08:26, Jan Beulich wrote:
>> TBD: I find the ordering in amd_iommu_disable_domain_device()
>>      suspicious: amd_iommu_enable_domain_device() sets up the DTE first
>>      and then enables ATS on the device. It would seem to me that
>>      disabling would better be done the other way around (disable ATS on
>>      device, then adjust DTE).
> 
> I'd hope that the worst which goes wrong, given the problematic order,
> is a master abort.
> 
> But yes - ATS wants disabling on the device first, before the DTE is
> updated.

Okay, I'll add another patch.

Jan




 


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