Collect the IO page table usage statistics from each paging HWPT object within an iommufd context and expose that data to userspace via the new iommu-nr-pages field in fdinfo.
Implement a show_fdinfo hook for iommufd_fops that iterates over the context's object xarray, identifies paging HWPTs, and aggregates their nr_pages counters. Nested HWPTs are skipped as their stage-1 page tables are owned by userspace. Only domains whose page table is implemented by the generic_pt library account their page table memory. If the domain of any paging HWPT does not, the field is omitted instead of reporting a partial count. Document the new field in Documentation/filesystems/proc.rst. Signed-off-by: Pranjal Shrivastava <[email protected]> --- Documentation/filesystems/proc.rst | 17 +++++++++++++ drivers/iommu/iommufd/main.c | 38 ++++++++++++++++++++++++++++++ 2 files changed, 55 insertions(+) diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems/proc.rst index 2d06c9930fcf..90ba32e9e3b1 100644 --- a/Documentation/filesystems/proc.rst +++ b/Documentation/filesystems/proc.rst @@ -2217,6 +2217,23 @@ IOMMU backend is set, or when any attached domain does not account its IO page table memory. Currently only domains using the generic_pt page table library account their IO page table memory. +IOMMUFD files +~~~~~~~~~~~~~ + +:: + + pos: 0 + flags: 02000002 + mnt_id: 17 + ino: 1104 + iommu-nr-pages: 11 + +where 'iommu-nr-pages' is the number of pages of memory used by the IO page +tables of all paging HW pagetables owned by the iommufd context. Nested HW +pagetables are not included since their page tables are owned by userspace. +The field is omitted when any paging HW pagetable does not account its IO page +table memory. + 3.9 /proc/<pid>/map_files - Information about memory mapped files --------------------------------------------------------------------- This directory contains symbolic links which represent memory mapped files diff --git a/drivers/iommu/iommufd/main.c b/drivers/iommu/iommufd/main.c index 9a921b153162..51d0d100dc91 100644 --- a/drivers/iommu/iommufd/main.c +++ b/drivers/iommu/iommufd/main.c @@ -11,6 +11,7 @@ #include <linux/bug.h> #include <linux/file.h> #include <linux/fs.h> +#include <linux/seq_file.h> #include <linux/iommufd.h> #include <linux/miscdevice.h> #include <linux/module.h> @@ -633,12 +634,49 @@ static int iommufd_fops_mmap(struct file *filp, struct vm_area_struct *vma) return rc; } +#ifdef CONFIG_PROC_FS +static void iommufd_fops_show_fdinfo(struct seq_file *m, struct file *filep) +{ + struct iommufd_ctx *ictx = filep->private_data; + struct iommufd_object *obj; + unsigned long nr_pages = 0; + bool supported = true; + unsigned long index; + + xa_lock(&ictx->objects); + xa_for_each(&ictx->objects, index, obj) { + struct iommufd_hw_pagetable *hwpt; + + /* Nested stage-1 page tables are owned by the guest */ + if (obj->type != IOMMUFD_OBJ_HWPT_PAGING) + continue; + + hwpt = container_of(obj, struct iommufd_hw_pagetable, obj); + if (!hwpt->domain) + continue; + /* Only generic_pt page tables account their pages */ + if (!hwpt->domain->is_iommupt) { + supported = false; + break; + } + nr_pages += atomic_long_read(&hwpt->domain->nr_pages); + } + xa_unlock(&ictx->objects); + + if (supported) + seq_printf(m, "iommu-nr-pages:\t%lu\n", nr_pages); +} +#endif + static const struct file_operations iommufd_fops = { .owner = THIS_MODULE, .open = iommufd_fops_open, .release = iommufd_fops_release, .unlocked_ioctl = iommufd_fops_ioctl, .mmap = iommufd_fops_mmap, +#ifdef CONFIG_PROC_FS + .show_fdinfo = iommufd_fops_show_fdinfo, +#endif }; /** -- 2.56.0.rc1.315.gc6ed9934b7-goog
