On 24/01/2022 13:11, Yicong Yang wrote:
The DMA of HiSilicon PTT device can only work with identical
mapping. So add a quirk for the device to force the domain
passthrough.

This patch should be earlier in the series, before the PTT driver, and the comment on hisi_ptt_check_iommu_mapping() should mention what is going on here.


Signed-off-by: Yicong Yang <yangyic...@hisilicon.com>
---
  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 16 ++++++++++++++++
  1 file changed, 16 insertions(+)

diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c 
b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
index 6dc6d8b6b368..6f67a2b1dd27 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -2838,6 +2838,21 @@ static int arm_smmu_dev_disable_feature(struct device 
*dev,
        }
  }
+#define IS_HISI_PTT_DEVICE(pdev) ((pdev)->vendor == PCI_VENDOR_ID_HUAWEI && \
+                                        (pdev)->device == 0xa12e)

I assume that not all revisions will require this check, right?

+
+static int arm_smmu_def_domain_type(struct device *dev)
+{
+       if (dev_is_pci(dev)) {
+               struct pci_dev *pdev = to_pci_dev(dev);
+
+               if (IS_HISI_PTT_DEVICE(pdev))
+                       return IOMMU_DOMAIN_IDENTITY;
+       }
+
+       return 0;
+}
+
  static struct iommu_ops arm_smmu_ops = {
        .capable                = arm_smmu_capable,
        .domain_alloc           = arm_smmu_domain_alloc,
@@ -2863,6 +2878,7 @@ static struct iommu_ops arm_smmu_ops = {
        .sva_unbind             = arm_smmu_sva_unbind,
        .sva_get_pasid          = arm_smmu_sva_get_pasid,
        .page_response          = arm_smmu_page_response,
+       .def_domain_type        = arm_smmu_def_domain_type,
        .pgsize_bitmap          = -1UL, /* Restricted during device attach */
        .owner                  = THIS_MODULE,
  };

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