Messages in this thread | | | Subject | Re: [PATCH v2 00/24] iommu: Refactor DMA domain strictness | From | "chenxiang (M)" <> | Date | Fri, 30 Jul 2021 09:21:18 +0800 |
| |
在 2021/7/29 18:59, Robin Murphy 写道: > On 2021-07-29 03:55, chenxiang (M) wrote: >> Hi Robin, >> >> >> 在 2021/7/28 23:58, Robin Murphy 写道: >>> Hi all, >>> >>> Here's v2 where things start to look more realistic, hence the expanded >>> CC list. The patches are now based on the current iommu/core branch to >>> take John's iommu_set_dma_strict() cleanup into account. >>> >>> The series remiains in two (or possibly 3) logical parts - for people >>> CC'd on cookie cleanup patches, the later parts should not affect you >>> since your drivers don't implement non-strict mode anyway; the cleanup >>> is all pretty straightforward, but please do yell at me if I've managed >>> to let a silly mistake slip through and broken your driver. >>> >>> This time I have also build-tested x86 as well as arm64 :) >> >> I have tested those patchset on ARM64 with SMMUV3, and the testcases >> are as follows: >> - Boot with iommu.strict=0, running fio and it works well; >> - Boot with iommu.strict=1, running fio and it works well; >> - Change strict mode to lazy mode when building, the change takes >> effect; >> - Boot without iommu.strict(default strict mode), change the sysfs >> interface type from DMA to DMA-FQ dynamically during running fio, and >> it works well; >> - Boot without iommu.strict(default strict mode), change the sysfs >> interface type from DMA-FQ to DMA dynamically, and it is not allowed >> and print "Device or resource busy" >> (i know it is qualified, and we can change no-strict mode to strict >> by unbind the driver -> change the sysfs interface (type)->bind the >> driver (tested this and it works well), >> but i have a small question: is it also possible to change from >> DMA-FQ to DMA dynamically? ) > > As patch #22 mentions, I think it's possible in principle, but it's > certainly trickier. When enabling a flush queue, it doesn't matter if > it takes a while for other threads to notice that cookie->fq_domain is > now set and stop doing synchronous invalidations (and in the SMMU case > it seems like there are probably enough dependencies to additionally > prevent the io_pgtable quirk being observable before that). However > when disabling, we'd need to be absolutely sure that the driver *has* > started invalidating strictly before we stop queueing freed IOVAs, > plus we need to be absolutely sure that we've stopped queueing freed > IOVAs before we attempt to tear down the flush queue itself. I'm not > sure off-hand how feasible it would be to put all that synchronisation > in the right places without it also impacting normal operation. > > Furthermore, as also noted, there doesn't seem to be a good reason for > ever actually needing to do that. If a device isn't trusted, it should > be given a strict domain *before* any driver has a chance to start > doing anything, or your trust model is broken and pretty useless. I > can imagine some niche debugging/benchmarking cases where it might > help save a bit of effort, but nothing with a strong enough > justification to be worth supporting in mainline.
Ok, thanks.
> >> Anyway, please feel free to add : >> Tested-by: Xiang Chen <chenxiang66@hisilicon.com> > > That's great, thanks! > > Robin. > >>> Changes in v2: >>> >>> - Add iommu_is_dma_domain() helper to abstract flag check (and help >>> avoid silly typos like the one in v1). >>> - Tweak a few commit messages for spelling and (hopefully) clarity. >>> - Move the iommu_create_device_direct_mappings() update to patch #14 >>> where it should have been. >>> - Rewrite patch #20 as a conversion of the now-existing option. >>> - Clean up the ops->flush_iotlb_all check which is also made redundant >>> by the new domain type >>> - Add patch #24, which is arguably tangential, but it was something I >>> spotted during the rebase, so... >>> >>> Once again, the whole lot is available on a branch here: >>> >>> https://gitlab.arm.com/linux-arm/linux-rm/-/tree/iommu/fq >>> >>> Thanks, >>> Robin. >>> >>> >>> CC: Marek Szyprowski <m.szyprowski@samsung.com> >>> CC: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com> >>> CC: Geert Uytterhoeven <geert+renesas@glider.be> >>> CC: Yong Wu <yong.wu@mediatek.com> >>> CC: Heiko Stuebner <heiko@sntech.de> >>> CC: Chunyan Zhang <chunyan.zhang@unisoc.com> >>> CC: Chunyan Zhang <chunyan.zhang@unisoc.com> >>> CC: Maxime Ripard <mripard@kernel.org> >>> CC: Jean-Philippe Brucker <jean-philippe@linaro.org> >>> >>> Robin Murphy (24): >>> iommu: Pull IOVA cookie management into the core >>> iommu/amd: Drop IOVA cookie management >>> iommu/arm-smmu: Drop IOVA cookie management >>> iommu/vt-d: Drop IOVA cookie management >>> iommu/exynos: Drop IOVA cookie management >>> iommu/ipmmu-vmsa: Drop IOVA cookie management >>> iommu/mtk: Drop IOVA cookie management >>> iommu/rockchip: Drop IOVA cookie management >>> iommu/sprd: Drop IOVA cookie management >>> iommu/sun50i: Drop IOVA cookie management >>> iommu/virtio: Drop IOVA cookie management >>> iommu/dma: Unexport IOVA cookie management >>> iommu/dma: Remove redundant "!dev" checks >>> iommu: Introduce explicit type for non-strict DMA domains >>> iommu/amd: Prepare for multiple DMA domain types >>> iommu/arm-smmu: Prepare for multiple DMA domain types >>> iommu/vt-d: Prepare for multiple DMA domain types >>> iommu: Express DMA strictness via the domain type >>> iommu: Expose DMA domain strictness via sysfs >>> iommu: Merge strictness and domain type configs >>> iommu/dma: Factor out flush queue init >>> iommu: Allow enabling non-strict mode dynamically >>> iommu/arm-smmu: Allow non-strict in pgtable_quirks interface >>> iommu: Only log strictness for DMA domains >>> >>> .../ABI/testing/sysfs-kernel-iommu_groups | 2 + >>> drivers/iommu/Kconfig | 80 >>> +++++++++---------- >>> drivers/iommu/amd/iommu.c | 21 +---- >>> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 25 ++++-- >>> drivers/iommu/arm/arm-smmu/arm-smmu.c | 29 ++++--- >>> drivers/iommu/arm/arm-smmu/qcom_iommu.c | 8 -- >>> drivers/iommu/dma-iommu.c | 44 +++++----- >>> drivers/iommu/exynos-iommu.c | 18 +---- >>> drivers/iommu/intel/iommu.c | 23 ++---- >>> drivers/iommu/iommu.c | 53 +++++++----- >>> drivers/iommu/ipmmu-vmsa.c | 27 +------ >>> drivers/iommu/mtk_iommu.c | 6 -- >>> drivers/iommu/rockchip-iommu.c | 11 +-- >>> drivers/iommu/sprd-iommu.c | 6 -- >>> drivers/iommu/sun50i-iommu.c | 12 +-- >>> drivers/iommu/virtio-iommu.c | 8 -- >>> include/linux/dma-iommu.h | 9 ++- >>> include/linux/iommu.h | 15 +++- >>> 18 files changed, 171 insertions(+), 226 deletions(-) >>> >> >> > > . >
| |