Re: [Qemu-devel] [RFC v5 0/8] ARM SMMUv3 Emulation Support

[Auger Eric]

Hi Geetha, Tomasz,

On 12/07/2017 19:24, Geetha Akula wrote:
> Hi Eric
> 
> 
>> This series implements the emulation code for ARM SMMUv3.
>> This is the continuation of Prem's work [1].
>>
>> This v5 mainly brings VFIO integration in DT mode. On guest kernel
>> side, this requires a quirk [1] to force TLB invalidation on map.
>>
>> The following changes also are noticeable:
>> - fix SMMU_CMDQ_CONS offset
>> - adds dma-coherent dt property which fixes the unhandled command
>>   opcode bug.
>> - implements block PTE
>>
>> The smmu is instantiated when passing the smmu option to machvirt:
>> "-M virt-2.10,smmu"
>>
>> As I haven't split the code yet so that it can be easily reviewable
>> I don't expect deep reviews at this stage. Also the implementation may
>> be largely sub-optimal.
>>
>> Tested Use Cases:
>> - booted a guest in dt and acpi mode with an iommu_platform
>>   virtio-net-pci device (using dma ops). Tested with the following
>>   guest combinations: 4K page - 39 bit VA, 4K - 48b, 64K - 39b,
>>   64K - 48b.
> 
> Verified patches with virtio-net-pci. Not observed any command queue
> issues like in V4 patch series.
Thank you for your comments and sorry for the delay, I was off.

Good to hear it fixes the command queue issues.

 There is a huge difference in iperf numbers
> on guest with and without SMMUv3 emulation i.e (1.5 Gbps with viommu
> and 9.0 Gbps without viommu). I think this is expected behaviour.
The perf can be definitively improved by setting the tlbi-on-map mode
for guest smmuv3 only when needed, as it is done with x86 qemu
intel-iommu,cache-mode=true explicit option.

> 
> Is there any plan to add device-iotlb and iotlb support in SMMUv3 emulation ?

What does both comprise exactly? do you mean PCI ATS support or vhost
device iotlb (ie. the use case exercised by Tomasz). Please can you
elaborate?

Thanks

Eric
> 
> 
> Thank you,
> Geetha.
> 
> 
>> - booted a guest (featuring [1]) with PCIe passthrough'ed PCIe devices:
>>   - AMD Overdrive and igbvf passthrough (using gsi direct mapping)
>>   - Cavium ThunderX and ixgbevf passthrough (using KVM MSI routing)
>>
>> Unfortunately I have not been able to run DPDK testpmd yet on guest side.
>> The problem I see is the user space driver dma-maps a huge area
>> and this causes plenty of CMDQ_OP_TLBI_NH_VA commands to be sent
>> (tlbi-on-map) which are sent for each page whereas the dma-map covers a
>> huge page. I will work on this issue for next version.
>>
>> Known limitations:
>> - no VMSAv8-32 suport
>> - no nested stage support (S1 + S2)
>> - no support for HYP mappings
>> - register fine emulation, commands, interrupts and errors were
>>   not accurately tested. Handling is sufficient to run use cases
>>   described hereafter though.
>>
>> Best Regards
>>
>> Eric
>>
>> This series can be found at:
>> v5: https://github.com/eauger/qemu/tree/v2.9-SMMU-v5
>> v4: https://github.com/eauger/qemu/tree/v2.9-SMMU-v4
>>
>> References:
>> [1] [RFC 0/2] arm-smmu-v3 tlbi-on-map option
>> [2] Prem's last iteration:
>> - https://lists.gnu.org/archive/html/qemu-devel/2016-08/msg03531.html
>>
>> History:
>> v4 -> v5:
>> - initial_level now part of SMMUTransCfg
>> - smmu_page_walk_64 takes into account the max input size
>> - implement sys->iommu_ops.replay and sys->iommu_ops.notify_flag_changed
>> - smmuv3_translate: bug fix: don't walk on bypass
>> - smmu_update_qreg: fix PROD index update
>> - I did not yet address Peter's comments as the code is not mature enough
>>   to be split into sub patches.
>>
>> v3 -> v4 [Eric]:
>> - page table walk rewritten to allow scan of the page table within a
>>   range of IOVA. This prepares for VFIO integration and replay.
>> - configuration parsing partially reworked.
>> - do not advertise unsupported/untested features: S2, S1 + S2, HYP,
>>   PRI, ATS, ..
>> - added ACPI table generation
>> - migrated to dynamic traces
>> - mingw compilation fix
>>
>> v2 -> v3 [Eric]:
>> - rebased on 2.9
>> - mostly code and patch reorganization to ease the review process
>> - optional patches removed. They may be handled separately. I am currently
>>   working on ACPI enablement.
>> - optional instantiation of the smmu in mach-virt
>> - removed [2/9] (fdt functions) since not mandated
>> - start splitting main patch into base and derived object
>> - no new function feature added
>>
>> v1 -> v2 [Prem]:
>> - Adopted review comments from Eric Auger
>>         - Make SMMU_DPRINTF to internally call qemu_log
>>             (since translation requests are too many, we need control
>>              on the type of log we want)
>>         - SMMUTransCfg modified to suite simplicity
>>         - Change RegInfo to uint64 register array
>>         - Code cleanup
>>         - Test cleanups
>> - Reshuffled patches
>>
>> v0 -> v1 [Prem]:
>> - As per SMMUv3 spec 16.0 (only is_ste_consistant() is noticeable)
>> - Reworked register access/update logic
>> - Factored out translation code for
>>         - single point bug fix
>>         - sharing/removal in future
>> - (optional) Unit tests added, with PCI test device
>>         - S1 with 4k/64k, S1+S2 with 4k/64k
>>         - (S1 or S2) only can be verified by Linux 4.7 driver
>>         - (optional) Priliminary ACPI support
>>
>> v0 [Prem]:
>> - Implements SMMUv3 spec 11.0
>> - Supported for PCIe devices,
>> - Command Queue and Event Queue supported
>> - LPAE only, S1 is supported and Tested, S2 not tested
>> - BE mode Translation not supported
>> - IRQ support (legacy, no MSI)
>> - Tested with DPDK and e1000
>>
>>
>> Eric Auger (5):
>>   hw/arm/smmu-common: smmu base class
>>   hw/arm/virt: Add 2.10 machine type
>>   hw/arm/virt: Add tlbi-on-map property to the smmuv3 node
>>   target/arm/kvm: Translate the MSI doorbell in kvm_arch_fixup_msi_route
>>   hw/arm/smmuv3: VFIO integration
>>
>> Prem Mallappa (3):
>>   hw/arm/smmuv3: smmuv3 emulation model
>>   hw/arm/virt: Add SMMUv3 to the virt board
>>   hw/arm/virt-acpi-build: Add smmuv3 node in IORT table
>>
>>  default-configs/aarch64-softmmu.mak |    1 +
>>  hw/arm/Makefile.objs                |    1 +
>>  hw/arm/smmu-common.c                |  474 +++++++++++++
>>  hw/arm/smmu-internal.h              |   89 +++
>>  hw/arm/smmuv3-internal.h            |  651 ++++++++++++++++++
>>  hw/arm/smmuv3.c                     | 1256 
>> +++++++++++++++++++++++++++++++++++
>>  hw/arm/trace-events                 |   54 ++
>>  hw/arm/virt-acpi-build.c            |   56 +-
>>  hw/arm/virt.c                       |  111 +++-
>>  include/hw/acpi/acpi-defs.h         |   15 +
>>  include/hw/arm/smmu-common.h        |  127 ++++
>>  include/hw/arm/smmuv3.h             |   87 +++
>>  include/hw/arm/virt.h               |    5 +
>>  target/arm/kvm.c                    |   28 +
>>  target/arm/trace-events             |    3 +
>>  15 files changed, 2949 insertions(+), 9 deletions(-)
>>  create mode 100644 hw/arm/smmu-common.c
>>  create mode 100644 hw/arm/smmu-internal.h
>>  create mode 100644 hw/arm/smmuv3-internal.h
>>  create mode 100644 hw/arm/smmuv3.c
>>  create mode 100644 include/hw/arm/smmu-common.h
>>  create mode 100644 include/hw/arm/smmuv3.h
>>
>> --
>> 2.5.5