Re: [RFC v3 00/10] KVM PCIe/MSI passthrough on ARM/ARM64 and IOVA reserved regions

[Robin Murphy <robin.murphy@arm.com>]

On 30/11/16 10:52, Ganapatrao Kulkarni wrote:
> On Wed, Nov 30, 2016 at 3:44 PM, Auger Eric <eric.auger@redhat.com> wrote:
>> Hi Ganapat,
>>
>> On 30/11/2016 11:04, Ganapatrao Kulkarni wrote:
>>> Hi Eric,
>>>
>>> in you repo "https://github.com/eauger/linux/tree/v4.9-rc5-reserved-rfc-v3"
>>> there is 11th patch "pci: Enable overrides for missing ACS capabilities"
>>> is this patch part of some other series?
>>
>> Actually this is a very old patch from Alex aimed at working around lack
>> of PCIe ACS support: https://lkml.org/lkml/2013/5/30/513
>>
> 
> i have tried this patchset on thunderx-83xx for vfio and it works for me!
> i was wondering is this patch required? i guess not.

If your system and devices actually support and properly advertise ACS
then there's nothing to override. Conversely, if you're happy assigning
everything behind a single RC to the same guest then ACS doesn't really
matter. It's only the in-between case - when the host still wants to
keep control of one or more devices, but they all get grouped together
due to lack of ACS - that warrants working around.

Robin.

> 
> please cc me when you respin this patchset.
> 
> thanks
> Ganapat
> 
>> Thanks
>>
>> Eric
>>>
>>> thanks
>>> Ganapat
>>>
>>> On Wed, Nov 30, 2016 at 3:19 PM, Auger Eric <eric.auger@redhat.com> wrote:
>>>> Hi,
>>>>
>>>> On 15/11/2016 14:09, Eric Auger wrote:
>>>>> Following LPC discussions, we now report reserved regions through
>>>>> iommu-group sysfs reserved_regions attribute file.
>>>>>
>>>>> Reserved regions are populated through the IOMMU get_resv_region callback
>>>>> (former get_dm_regions), now implemented by amd-iommu, intel-iommu and
>>>>> arm-smmu.
>>>>>
>>>>> The intel-iommu reports the [FEE0_0000h - FEF0_000h] MSI window as an
>>>>> IOMMU_RESV_NOMAP reserved region.
>>>>>
>>>>> arm-smmu reports the MSI window (arbitrarily located at 0x8000000 and
>>>>> 1MB large) and the PCI host bridge windows.
>>>>>
>>>>> The series integrates a not officially posted patch from Robin:
>>>>> "iommu/dma: Allow MSI-only cookies".
>>>>>
>>>>> This series currently does not address IRQ safety assessment.
>>>>
>>>> I will respin this series taking into account Joerg's comment. Does
>>>> anyone have additional comments or want to put forward some conceptual
>>>> issues with the current direction and with this implementation?
>>>>
>>>> As for the IRQ safety assessment, in a first step I would propose to
>>>> remove the IOMMU_CAP_INTR_REMAP from arm-smmus and consider the
>>>> assignment as unsafe. Any objection?
>>>>
>>>> Thanks
>>>>
>>>> Eric
>>>>
>>>>
>>>>> Best Regards
>>>>>
>>>>> Eric
>>>>>
>>>>> Git: complete series available at
>>>>> https://github.com/eauger/linux/tree/v4.9-rc5-reserved-rfc-v3
>>>>>
>>>>> History:
>>>>> RFC v2 -> v3:
>>>>> - switch to an iommu-group sysfs API
>>>>> - use new dummy allocator provided by Robin
>>>>> - dummy allocator initialized by vfio-iommu-type1 after enumerating
>>>>>   the reserved regions
>>>>> - at the moment ARM MSI base address/size is left unchanged compared
>>>>>   to v2
>>>>> - we currently report reserved regions and not usable IOVA regions as
>>>>>   requested by Alex
>>>>>
>>>>> RFC v1 -> v2:
>>>>> - fix intel_add_reserved_regions
>>>>> - add mutex lock/unlock in vfio_iommu_type1
>>>>>
>>>>>
>>>>> Eric Auger (10):
>>>>>   iommu/dma: Allow MSI-only cookies
>>>>>   iommu: Rename iommu_dm_regions into iommu_resv_regions
>>>>>   iommu: Add new reserved IOMMU attributes
>>>>>   iommu: iommu_alloc_resv_region
>>>>>   iommu: Do not map reserved regions
>>>>>   iommu: iommu_get_group_resv_regions
>>>>>   iommu: Implement reserved_regions iommu-group sysfs file
>>>>>   iommu/vt-d: Implement reserved region get/put callbacks
>>>>>   iommu/arm-smmu: Implement reserved region get/put callbacks
>>>>>   vfio/type1: Get MSI cookie
>>>>>
>>>>>  drivers/iommu/amd_iommu.c       |  20 +++---
>>>>>  drivers/iommu/arm-smmu.c        |  52 +++++++++++++++
>>>>>  drivers/iommu/dma-iommu.c       | 116 ++++++++++++++++++++++++++-------
>>>>>  drivers/iommu/intel-iommu.c     |  50 ++++++++++----
>>>>>  drivers/iommu/iommu.c           | 141 ++++++++++++++++++++++++++++++++++++----
>>>>>  drivers/vfio/vfio_iommu_type1.c |  26 ++++++++
>>>>>  include/linux/dma-iommu.h       |   7 ++
>>>>>  include/linux/iommu.h           |  49 ++++++++++----
>>>>>  8 files changed, 391 insertions(+), 70 deletions(-)
>>>>>
>>>>
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