iommufd: Extend IOMMU_GET_HW_INFO to report PASID capability

PASID usage requires PASID support in both device and IOMMU. Since the
iommu drivers always enable the PASID capability for the device if it
is supported, this extends the IOMMU_GET_HW_INFO to report the PASID
capability to userspace. Also, enhances the selftest accordingly.

Link: https://patch.msgid.link/r/20250321180143.8468-5-yi.l.liu@intel.com
Cc: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Tested-by: Zhangfei Gao <zhangfei.gao@linaro.org> #aarch64 platform
Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
index 1605f6c0e1eee5e01acee30c55f5837d0496ff9f..2307daad65c0fac6e5a4e7267ac8752b7ca67db9 100644 (file)
--- a/drivers/iommu/iommufd/device.c
+++ b/drivers/iommu/iommufd/device.c
@@ -3,6 +3,7 @@
  */
 #include <linux/iommu.h>
 #include <linux/iommufd.h>
+#include <linux/pci-ats.h>
 #include <linux/slab.h>
 #include <uapi/linux/iommufd.h>
 
@@ -1455,7 +1456,8 @@ int iommufd_get_hw_info(struct iommufd_ucmd *ucmd)
        void *data;
        int rc;
 
-       if (cmd->flags || cmd->__reserved)
+       if (cmd->flags || cmd->__reserved[0] || cmd->__reserved[1] ||
+           cmd->__reserved[2])
                return -EOPNOTSUPP;
 
        idev = iommufd_get_device(ucmd, cmd->dev_id);
@@ -1512,6 +1514,36 @@ int iommufd_get_hw_info(struct iommufd_ucmd *ucmd)
        if (device_iommu_capable(idev->dev, IOMMU_CAP_DIRTY_TRACKING))
                cmd->out_capabilities |= IOMMU_HW_CAP_DIRTY_TRACKING;
 
+       cmd->out_max_pasid_log2 = 0;
+       /*
+        * Currently, all iommu drivers enable PASID in the probe_device()
+        * op if iommu and device supports it. So the max_pasids stored in
+        * dev->iommu indicates both PASID support and enable status. A
+        * non-zero dev->iommu->max_pasids means PASID is supported and
+        * enabled. The iommufd only reports PASID capability to userspace
+        * if it's enabled.
+        */
+       if (idev->dev->iommu->max_pasids) {
+               cmd->out_max_pasid_log2 = ilog2(idev->dev->iommu->max_pasids);
+
+               if (dev_is_pci(idev->dev)) {
+                       struct pci_dev *pdev = to_pci_dev(idev->dev);
+                       int ctrl;
+
+                       ctrl = pci_pasid_status(pdev);
+
+                       WARN_ON_ONCE(ctrl < 0 ||
+                                    !(ctrl & PCI_PASID_CTRL_ENABLE));
+
+                       if (ctrl & PCI_PASID_CTRL_EXEC)
+                               cmd->out_capabilities |=
+                                               IOMMU_HW_CAP_PCI_PASID_EXEC;
+                       if (ctrl & PCI_PASID_CTRL_PRIV)
+                               cmd->out_capabilities |=
+                                               IOMMU_HW_CAP_PCI_PASID_PRIV;
+               }
+       }
+
        rc = iommufd_ucmd_respond(ucmd, sizeof(*cmd));
 out_free:
        kfree(data);

diff --git a/drivers/pci/ats.c b/drivers/pci/ats.c
index c6b266c772c81cfbe82fe6dd9d16a262140f818d..ec6c8dbdc5e9c9959e822e016ab301bf483713a5 100644 (file)
--- a/drivers/pci/ats.c
+++ b/drivers/pci/ats.c
@@ -538,4 +538,37 @@ int pci_max_pasids(struct pci_dev *pdev)
        return (1 << FIELD_GET(PCI_PASID_CAP_WIDTH, supported));
 }
 EXPORT_SYMBOL_GPL(pci_max_pasids);
+
+/**
+ * pci_pasid_status - Check the PASID status
+ * @pdev: PCI device structure
+ *
+ * Returns a negative value when no PASID capability is present.
+ * Otherwise the value of the control register is returned.
+ * Status reported are:
+ *
+ * PCI_PASID_CTRL_ENABLE - PASID enabled
+ * PCI_PASID_CTRL_EXEC - Execute permission enabled
+ * PCI_PASID_CTRL_PRIV - Privileged mode enabled
+ */
+int pci_pasid_status(struct pci_dev *pdev)
+{
+       int pasid;
+       u16 ctrl;
+
+       if (pdev->is_virtfn)
+               pdev = pci_physfn(pdev);
+
+       pasid = pdev->pasid_cap;
+       if (!pasid)
+               return -EINVAL;
+
+       pci_read_config_word(pdev, pasid + PCI_PASID_CTRL, &ctrl);
+
+       ctrl &= PCI_PASID_CTRL_ENABLE | PCI_PASID_CTRL_EXEC |
+               PCI_PASID_CTRL_PRIV;
+
+       return ctrl;
+}
+EXPORT_SYMBOL_GPL(pci_pasid_status);
 #endif /* CONFIG_PCI_PASID */

diff --git a/include/linux/pci-ats.h b/include/linux/pci-ats.h
index 0e8b74e63767a6f09d8f4110f0cd74cb417569c9..75c6c86cf09dcbf0515a4b04c496b679718df4ba 100644 (file)
--- a/include/linux/pci-ats.h
+++ b/include/linux/pci-ats.h
@@ -42,6 +42,7 @@ int pci_enable_pasid(struct pci_dev *pdev, int features);
 void pci_disable_pasid(struct pci_dev *pdev);
 int pci_pasid_features(struct pci_dev *pdev);
 int pci_max_pasids(struct pci_dev *pdev);
+int pci_pasid_status(struct pci_dev *pdev);
 #else /* CONFIG_PCI_PASID */
 static inline int pci_enable_pasid(struct pci_dev *pdev, int features)
 { return -EINVAL; }
@@ -50,6 +51,8 @@ static inline int pci_pasid_features(struct pci_dev *pdev)
 { return -EINVAL; }
 static inline int pci_max_pasids(struct pci_dev *pdev)
 { return -EINVAL; }
+static inline int pci_pasid_status(struct pci_dev *pdev)
+{ return -EINVAL; }
 #endif /* CONFIG_PCI_PASID */
 
 #endif /* LINUX_PCI_ATS_H */

diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h
index 6901804ec736ad4d553a43fefd675d9b6983224f..e2c04e58a997d81b444c569fdf35d64aa1ed7e94 100644 (file)
--- a/include/uapi/linux/iommufd.h
+++ b/include/uapi/linux/iommufd.h
@@ -612,9 +612,17 @@ enum iommu_hw_info_type {
  *                                   IOMMU_HWPT_GET_DIRTY_BITMAP
  *                                   IOMMU_HWPT_SET_DIRTY_TRACKING
  *
+ * @IOMMU_HW_CAP_PCI_PASID_EXEC: Execute Permission Supported, user ignores it
+ *                               when the struct
+ *                               iommu_hw_info::out_max_pasid_log2 is zero.
+ * @IOMMU_HW_CAP_PCI_PASID_PRIV: Privileged Mode Supported, user ignores it
+ *                               when the struct
+ *                               iommu_hw_info::out_max_pasid_log2 is zero.
  */
 enum iommufd_hw_capabilities {
        IOMMU_HW_CAP_DIRTY_TRACKING = 1 << 0,
+       IOMMU_HW_CAP_PCI_PASID_EXEC = 1 << 1,
+       IOMMU_HW_CAP_PCI_PASID_PRIV = 1 << 2,
 };
 
 /**
@@ -630,6 +638,9 @@ enum iommufd_hw_capabilities {
  *                 iommu_hw_info_type.
  * @out_capabilities: Output the generic iommu capability info type as defined
  *                    in the enum iommu_hw_capabilities.
+ * @out_max_pasid_log2: Output the width of PASIDs. 0 means no PASID support.
+ *                      PCI devices turn to out_capabilities to check if the
+ *                      specific capabilities is supported or not.
  * @__reserved: Must be 0
  *
  * Query an iommu type specific hardware information data from an iommu behind
@@ -653,7 +664,8 @@ struct iommu_hw_info {
        __u32 data_len;
        __aligned_u64 data_uptr;
        __u32 out_data_type;
-       __u32 __reserved;
+       __u8 out_max_pasid_log2;
+       __u8 __reserved[3];
        __aligned_u64 out_capabilities;
 };
 #define IOMMU_GET_HW_INFO _IO(IOMMUFD_TYPE, IOMMUFD_CMD_GET_HW_INFO)