Re: [Qemu-devel] [V9 0/4] AMD IOMMU

[Jan Kiszka]

On 2016-05-04 09:05, David Kiarie wrote:
> On Wed, May 4, 2016 at 9:12 AM, Jan Kiszka <address@hidden> wrote:
>> On 2016-04-30 00:42, David Kiarie wrote:
>>> These series adds AMD IOMMU support to Qemu. It's currently in the 9th 
>>> version.
>>>
>>> In this series I have (hopefully) addressed all the comments made in the 
>>> previous version.
>>> I have also tested and successfully passed-through PCI device 'ac97' with 
>>> more devices to be tested.
>>>
>>
>> I've done some basic testing with a Jailhouse setup and found it
>> working. The ACPI table is now properly parsed and the DMA remapping was
>> not disturbing the system after Jailhouse was activated.
>>
>> However, it was also still not intervening after I started to corrupt
>> the configuration, removed DMA target properties from most of the RAM or
>> dropped PCI devices.
> 
> This means you're invalidating DTEs ?

No, it's either enabling the IOMMU with only a partially filled or
completely empty page table or not listing a specific device that
continues to do DMA (pattern: Linux boots with IOMMU off, Jailhouse
configures 1:1 mappings afterwards and enables IOMMU).

Jan

> 
>>
>> You are not dropping invalid remapping requests, are you? According to
>> the logs, you are detecting them at least:
>>
>> (amd-iommu)amd_iommu_get_dte: Device Table at 0x3b0d4000
>> (amd-iommu)amd_iommu_get_dte: Pte entry at 0x0 is invalid
>> (amd-iommu)amd_iommu_translate: devid: 00:02.0 gpa 0x32f39480 hpa 0x32f39000
>>
>> It's a bit hard to test right now if remapping is actually properly
>> working in all important cases if you do not reject invalid ones.
>>
>> Jan
>>