Re: [PATCH v3 4/4] iommufd: Extend IOMMU_GET_HW_INFO to report PASID capability

Hi Yi,

On 9/12/2024 6:47 PM, Yi Liu wrote:

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, so it is reasonable to extend the IOMMU_GET_HW_INFO to report the PASID capability to userspace.

Signed-off-by: Yi Liu yi.l.liu@intel.com

drivers/iommu/iommufd/device.c | 27 ++++++++++++++++++++++++++- drivers/pci/ats.c | 32 ++++++++++++++++++++++++++++++++ include/linux/pci-ats.h | 3 +++ include/uapi/linux/iommufd.h | 14 +++++++++++++- 4 files changed, 74 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c index 18f94aa462ea..6b7e3e5f4598 100644 --- a/drivers/iommu/iommufd/device.c +++ b/drivers/iommu/iommufd/device.c @@ -4,6 +4,8 @@ #include <linux/iommufd.h> #include <linux/slab.h> #include <linux/iommu.h> +#include <linux/pci.h> +#include <linux/pci-ats.h> #include <uapi/linux/iommufd.h> #include "../iommu-priv.h" @@ -1185,7 +1187,8 @@ 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); @@ -1242,6 +1245,28 @@ 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;
• if (dev_is_pci(idev->dev)) {

• struct pci_dev *pdev = to_pci_dev(idev->dev);
  

• int ctrl;
  

• if (pdev->is_virtfn)
  

• 	pdev = pci_physfn(pdev);
  

• ctrl = pci_pasid_ctrl_status(pdev);
  

• if (ctrl >= 0 && (ctrl & PCI_PASID_CTRL_ENABLE)) {
  

• 	cmd->out_max_pasid_log2 =
  

• 			ilog2(idev->dev->iommu->max_pasids);
  

• 	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 c570892b2090..886f24e3999f 100644 --- a/drivers/pci/ats.c +++ b/drivers/pci/ats.c @@ -505,4 +505,36 @@ 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_ctrl_status - Check the PASID status
• • @pdev: PCI device structure
• • Returns a negative value when no PASI capability is present.

s/PASI/PASID/

• • 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_ctrl_status(struct pci_dev *pdev) +{

• u16 ctrl = 0;

No need to initialize ctrl.

-Vasant