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Re: [PATCH for-5.2 v4 00/11] SMMUv3.2 Range-based TLB Invalidation Suppo
From: |
Peter Maydell |
Subject: |
Re: [PATCH for-5.2 v4 00/11] SMMUv3.2 Range-based TLB Invalidation Support |
Date: |
Thu, 30 Jul 2020 14:39:42 +0100 |
On Tue, 28 Jul 2020 at 16:08, Eric Auger <eric.auger@redhat.com> wrote:
>
> SMMU3.2 brings the support of range-based TLB invalidation and
> level hint. When this feature is supported, the SMMUv3 driver
> is allowed to send TLB invalidations for a range of IOVAs instead
> of using page based invalidation.
>
> Implementing this feature in the virtual SMMUv3 device is
> mandated for DPDK on guest use case: DPDK uses hugepage
> buffers and guest sends invalidations for blocks. Without
> this feature, a guest invalidation of a block of 1GB for instance
> translates into a storm of page invalidations. Each of them
> is trapped by the VMM and cascaded downto the physical IOMMU.
> This completely stalls the execution. This integration issue
> was initially reported in [1].
>
> Now SMMUv3.2 specifies additional parameters to NH_VA and NH_VAA
> stage 1 invalidation commands so we can support those extensions.
>
> Supporting block mappings in the IOTLB look sensible in terms of
> TLB entry consumption. However looking at virtio/vhost device usage,
> without block mapping and without range invalidation (< 5.7 kernels
> it may be less performant. However for recent guest kernels
> supporting range invalidations [2], the performance should be similar.
I think this is all reviewed now; I've put it on my list
of series to apply to target-arm.next in once 5.1 is out
and we reopen the trunk for 5.2.
thanks
-- PMM
- [PATCH for-5.2 v4 03/11] hw/arm/smmu: Introduce smmu_get_iotlb_key(), (continued)
- [PATCH for-5.2 v4 03/11] hw/arm/smmu: Introduce smmu_get_iotlb_key(), Eric Auger, 2020/07/28
- [PATCH for-5.2 v4 04/11] hw/arm/smmu: Introduce SMMUTLBEntry for PTW and IOTLB value, Eric Auger, 2020/07/28
- [PATCH for-5.2 v4 05/11] hw/arm/smmu-common: Manage IOTLB block entries, Eric Auger, 2020/07/28
- [PATCH for-5.2 v4 07/11] hw/arm/smmuv3: Get prepared for range invalidation, Eric Auger, 2020/07/28
- [PATCH for-5.2 v4 08/11] hw/arm/smmuv3: Fix IIDR offset, Eric Auger, 2020/07/28
- [PATCH for-5.2 v4 09/11] hw/arm/smmuv3: Let AIDR advertise SMMUv3.0 support, Eric Auger, 2020/07/28
- [PATCH for-5.2 v4 10/11] hw/arm/smmuv3: Support HAD and advertise SMMUv3.1 support, Eric Auger, 2020/07/28
- [PATCH for-5.2 v4 06/11] hw/arm/smmuv3: Introduce smmuv3_s1_range_inval() helper, Eric Auger, 2020/07/28
- [PATCH for-5.2 v4 11/11] hw/arm/smmuv3: Advertise SMMUv3.2 range invalidation, Eric Auger, 2020/07/28
- Re: [PATCH for-5.2 v4 00/11] SMMUv3.2 Range-based TLB Invalidation Support,
Peter Maydell <=