On Thu, Jun 26, 2025 at 12:34:51PM -0700, Nicolin Chen wrote: > The iommu_hw_info can output via the out_data_type field the vendor data > type from a driver, but this only allows driver to report one data type. > > Now, with SMMUv3 having a Tegra241 CMDQV implementation, it has two sets > of types and data structs to report. > > One way to support that is to use the same type field bidirectionally. > > Reuse the same field by adding an "in_data_type", allowing user space to > request for a specific type and to get the corresponding data. > > For backward compatibility, since the ioctl handler has never checked an > input value, add an IOMMU_HW_INFO_FLAG_INPUT_TYPE to switch between the > old output-only field and the new bidirectional field. > > Reviewed-by: Kevin Tian <[email protected]> > Reviewed-by: Jason Gunthorpe <[email protected]> > Reviewed-by: Lu Baolu <[email protected]> > Signed-off-by: Nicolin Chen <[email protected]> > --- > include/uapi/linux/iommufd.h | 20 +++++++++++++++++++- > drivers/iommu/iommufd/device.c | 9 ++++++--- > 2 files changed, 25 insertions(+), 4 deletions(-) > > diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h > index 6ad361ff9b06..6ae9d2102154 100644 > --- a/include/uapi/linux/iommufd.h > +++ b/include/uapi/linux/iommufd.h > @@ -628,6 +628,15 @@ enum iommufd_hw_capabilities { > IOMMU_HW_CAP_PCI_PASID_PRIV = 1 << 2, > }; > > +/** > + * enum iommufd_hw_info_flags - Flags for iommu_hw_info > + * @IOMMU_HW_INFO_FLAG_INPUT_TYPE: If set, @in_data_type carries an input > type > + * for user space to request for a specific > info > + */ > +enum iommufd_hw_info_flags { > + IOMMU_HW_INFO_FLAG_INPUT_TYPE = 1 << 0, > +}; > + > /** > * struct iommu_hw_info - ioctl(IOMMU_GET_HW_INFO) > * @size: sizeof(struct iommu_hw_info) > @@ -637,6 +646,12 @@ enum iommufd_hw_capabilities { > * data that kernel supports > * @data_uptr: User pointer to a user-space buffer used by the kernel to fill > * the iommu type specific hardware information data > + * @in_data_type: This shares the same field with @out_data_type, making it > be > + * a bidirectional field. When IOMMU_HW_INFO_FLAG_INPUT_TYPE > is > + * set, an input type carried via this @in_data_type field > will > + * be valid, requesting for the info data to the given type. > If > + * IOMMU_HW_INFO_FLAG_INPUT_TYPE is unset, any input value > will > + * be seen as IOMMU_HW_INFO_TYPE_DEFAULT > * @out_data_type: Output the iommu hardware info type as defined in the enum > * iommu_hw_info_type. > * @out_capabilities: Output the generic iommu capability info type as > defined > @@ -666,7 +681,10 @@ struct iommu_hw_info { > __u32 dev_id; > __u32 data_len; > __aligned_u64 data_uptr; > - __u32 out_data_type; > + union { > + __u32 in_data_type; > + __u32 out_data_type; > + }; > __u8 out_max_pasid_log2; > __u8 __reserved[3]; > __aligned_u64 out_capabilities; > diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c > index 64a51993e6a1..cbd86aabdd1c 100644 > --- a/drivers/iommu/iommufd/device.c > +++ b/drivers/iommu/iommufd/device.c > @@ -1506,6 +1506,7 @@ EXPORT_SYMBOL_NS_GPL(iommufd_access_rw, "IOMMUFD"); > > int iommufd_get_hw_info(struct iommufd_ucmd *ucmd) > { > + const u32 SUPPORTED_FLAGS = IOMMU_HW_INFO_FLAG_INPUT_TYPE; > struct iommu_hw_info *cmd = ucmd->cmd; > void __user *user_ptr = u64_to_user_ptr(cmd->data_uptr); > const struct iommu_ops *ops; > @@ -1515,12 +1516,14 @@ int iommufd_get_hw_info(struct iommufd_ucmd *ucmd) > void *data; > int rc; > > - if (cmd->flags || cmd->__reserved[0] || cmd->__reserved[1] || > - cmd->__reserved[2]) > + if (cmd->flags & ~SUPPORTED_FLAGS) > + return -EOPNOTSUPP; > + if (cmd->__reserved[0] || cmd->__reserved[1] || cmd->__reserved[2]) > return -EOPNOTSUPP; > > /* Clear the type field since drivers don't support a random input */ > - cmd->out_data_type = IOMMU_HW_INFO_TYPE_DEFAULT; > + if (!(cmd->flags & IOMMU_HW_INFO_FLAG_INPUT_TYPE)) > + cmd->in_data_type = IOMMU_HW_INFO_TYPE_DEFAULT; > > idev = iommufd_get_device(ucmd, cmd->dev_id); > if (IS_ERR(idev))
Reviewed-by: Pranjal Shrivastava <[email protected]> > -- > 2.43.0 >
