On Thu, Dec 19, 2024 at 10:05:53AM +0800, Baolu Lu wrote: > On 12/18/24 13:00, Nicolin Chen wrote: > > This is a reverse search v.s. iommufd_viommu_find_dev, as drivers may want > > to convert a struct device pointer (physical) to its virtual device ID for > > an event injection to the user space VM. > > > > Again, this avoids exposing more core structures to the drivers, than the > > iommufd_viommu alone. > > > > Signed-off-by: Nicolin Chen<nicolinc@xxxxxxxxxx> > > --- > > include/linux/iommufd.h | 8 ++++++++ > > drivers/iommu/iommufd/driver.c | 20 ++++++++++++++++++++ > > 2 files changed, 28 insertions(+) > > > > diff --git a/include/linux/iommufd.h b/include/linux/iommufd.h > > index b082676c9e43..ac1f1897d290 100644 > > --- a/include/linux/iommufd.h > > +++ b/include/linux/iommufd.h > > @@ -190,6 +190,8 @@ struct iommufd_object *_iommufd_object_alloc(struct iommufd_ctx *ictx, > > enum iommufd_object_type type); > > struct device *iommufd_viommu_find_dev(struct iommufd_viommu *viommu, > > unsigned long vdev_id); > > +unsigned long iommufd_viommu_get_vdev_id(struct iommufd_viommu *viommu, > > + struct device *dev); > > Hi Nicolin, > > This series overall looks good to me. But I have a question that might > be irrelevant to this series itself. > > The iommufd provides both IOMMUFD_OBJ_DEVICE and IOMMUFD_OBJ_VDEVICE > objects. What is the essential difference between these two from > userspace's perspective? A quick answer is an IOMMUFD_OBJ_DEVICE being a host physical device and an IOMMUFD_OBJ_VDEVICE being an IOMMUFD_OBJ_DEVICE related to IOMMUFD_OBJ_VIOMMU. Two of them can be seen in two different layers. May refer to this graph: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/userspace-api/iommufd.rst?h=v6.13-rc3#n150 > And, which object ID should the IOMMU device > driver provide when reporting other events in the future? > > Currently, the IOMMUFD uAPI reports IOMMUFD_OBJ_DEVICE in the page > fault message, and IOMMUFD_OBJ_VDEVICE (if I understand it correctly) in > the vIRQ message. It will be more future-proof if this could be defined > clearly. A vIRQ is actually reported per-vIOMMU in this design. Although in the this series the SMMU driver seems to report a per-device vIRQ, it internally converts the vDEVICE to a virtual device ID and packs the virtual device ID into a per-vIOMMU event: +/** + * struct iommu_virq_arm_smmuv3 - ARM SMMUv3 Virtual IRQ + * (IOMMU_VIRQ_TYPE_ARM_SMMUV3) + * @evt: 256-bit ARM SMMUv3 Event record, little-endian. + * (Refer to "7.3 Event records" in SMMUv3 HW Spec) + * + * StreamID field reports a virtual device ID. To receive a virtual IRQ for a + * device, a vDEVICE must be allocated via IOMMU_VDEVICE_ALLOC. + */ +struct iommu_virq_arm_smmuv3 { + __aligned_le64 evt[4]; }; Thanks Nicolin
