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Date: Tue, 14 Aug 2018 09:49:11 +0800 From: "Leizhen (ThunderTown)" <thunder.leizhen@...wei.com> To: Robin Murphy <robin.murphy@....com>, Will Deacon <will.deacon@....com>, Joerg Roedel <joro@...tes.org>, linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>, iommu <iommu@...ts.linux-foundation.org>, linux-kernel <linux-kernel@...r.kernel.org> CC: LinuxArm <linuxarm@...wei.com>, Hanjun Guo <guohanjun@...wei.com>, Libin <huawei.libin@...wei.com> Subject: Re: [PATCH v4 4/5] iommu/arm-smmu-v3: add support for non-strict mode On 2018/8/9 19:06, Robin Murphy wrote: > On 06/08/18 13:27, Zhen Lei wrote: >> Dynamically choose strict or non-strict mode for page table config based >> on the iommu domain type. >> >> Signed-off-by: Zhen Lei <thunder.leizhen@...wei.com> >> --- >> drivers/iommu/arm-smmu-v3.c | 7 ++++++- >> 1 file changed, 6 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c >> index 2f1304b..904bc1e 100644 >> --- a/drivers/iommu/arm-smmu-v3.c >> +++ b/drivers/iommu/arm-smmu-v3.c >> @@ -1622,6 +1622,11 @@ static int arm_smmu_domain_finalise(struct iommu_domain *domain) >> if (smmu->features & ARM_SMMU_FEAT_COHERENCY) >> pgtbl_cfg.quirks = IO_PGTABLE_QUIRK_NO_DMA; >> >> + if (domain->type == IOMMU_DOMAIN_DMA) { >> + domain->non_strict = 1; >> + pgtbl_cfg.quirks |= IO_PGTABLE_QUIRK_NON_STRICT; >> + } >> + >> pgtbl_ops = alloc_io_pgtable_ops(fmt, &pgtbl_cfg, smmu_domain); >> if (!pgtbl_ops) >> return -ENOMEM; >> @@ -1782,7 +1787,7 @@ static void arm_smmu_iotlb_sync(struct iommu_domain *domain) >> { >> struct arm_smmu_device *smmu = to_smmu_domain(domain)->smmu; >> >> - if (smmu) >> + if (smmu && !domain->non_strict) > > That doesn't smell right - even in non-strict domains we still need stuff like walk cache invalidations for non-leaf unmaps to be synchronous, so we can't just ignore all sync operations at the driver level. I think the right thing to do to elide the "normal" sync on unmap is to first convert __iommu_dma_unmap to use iommu_unmap_fast()/iommu_tlb_sync(), then make it not issue that sync at all for non-strict domains. OK, I will try it. > > Robin. > >> __arm_smmu_tlb_sync(smmu); >> } >> >> -- >> 1.8.3 >> >> > > . > -- Thanks! BestRegards
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