[PATCH 8/8] iommu/arm-smmu-v3: Add support for PCI PASID

Jean-Philippe Brucker
2019-06-10T18:52:05Z

Enable PASID for PCI devices that support it. Since the SSID tables are
allocated by arm_smmu_attach_dev(), PASID has to be enabled early enough.
arm_smmu_dev_feature_enable() would be too late, since by that time the
main DMA domain has already been attached. Do it in add_device() instead.

Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
---
drivers/iommu/arm-smmu-v3.c | 51 ++++++++++++++++++++++++++++++++++++-
1 file changed, 50 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
index 972bfb80f964..a8a516d9ff10 100644
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -2197,6 +2197,49 @@ static void arm_smmu_disable_ats(struct arm_smmu_master *master)
master->ats_enabled = false;
}

+static int arm_smmu_enable_pasid(struct arm_smmu_master *master)
+{
+ int ret;
+ int features;
+ int num_pasids;
+ struct pci_dev *pdev;
+
+ if (!dev_is_pci(master->dev))
+ return -ENOSYS;
+
+ pdev = to_pci_dev(master->dev);
+
+ features = pci_pasid_features(pdev);
+ if (features < 0)
+ return -ENOSYS;
+
+ num_pasids = pci_max_pasids(pdev);
+ if (num_pasids <= 0)
+ return -ENOSYS;
+
+ ret = pci_enable_pasid(pdev, features);
+ if (!ret)
+ master->ssid_bits = min_t(u8, ilog2(num_pasids),
+ master->smmu->ssid_bits);
+ return ret;
+}
+
+static void arm_smmu_disable_pasid(struct arm_smmu_master *master)
+{
+ struct pci_dev *pdev;
+
+ if (!dev_is_pci(master->dev))
+ return;
+
+ pdev = to_pci_dev(master->dev);
+
+ if (!pdev->pasid_enabled)
+ return;
+
+ pci_disable_pasid(pdev);
+ master->ssid_bits = 0;
+}
+
static void arm_smmu_detach_dev(struct arm_smmu_master *master)
{
unsigned long flags;
@@ -2413,6 +2456,9 @@ static int arm_smmu_add_device(struct device *dev)

master->ssid_bits = min(smmu->ssid_bits, fwspec->num_pasid_bits);

+ /* Note that PASID must be enabled before, and disabled after ATS */
+ arm_smmu_enable_pasid(master);
+
/*
* If the SMMU doesn't support 2-stage CD, limit the linear
* tables to a reasonable number of contexts, let's say
@@ -2423,7 +2469,7 @@ static int arm_smmu_add_device(struct device *dev)

ret = iommu_device_link(&smmu->iommu, dev);
if (ret)
- goto err_free_master;
+ goto err_disable_pasid;

group = iommu_group_get_for_dev(dev);
if (IS_ERR(group)) {
@@ -2436,6 +2482,8 @@ static int arm_smmu_add_device(struct device *dev)

err_unlink:
iommu_device_unlink(&smmu->iommu, dev);
+err_disable_pasid:
+ arm_smmu_disable_pasid(master);
err_free_master:
kfree(master);
fwspec->iommu_priv = NULL;
@@ -2456,6 +2504,7 @@ static void arm_smmu_remove_device(struct device *dev)
arm_smmu_detach_dev(master);
iommu_group_remove_device(dev);
iommu_device_unlink(&smmu->iommu, dev);
+ arm_smmu_disable_pasid(master);
kfree(master);
iommu_fwspec_free(dev);
}
--
2.21.0