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Message-ID: <7be26560c604b0cbc2fd218997b97a47e4ed11ff.1745646960.git.nicolinc@nvidia.com>
Date: Fri, 25 Apr 2025 22:58:08 -0700
From: Nicolin Chen <nicolinc@...dia.com>
To: <jgg@...dia.com>, <kevin.tian@...el.com>, <corbet@....net>,
<will@...nel.org>
CC: <bagasdotme@...il.com>, <robin.murphy@....com>, <joro@...tes.org>,
<thierry.reding@...il.com>, <vdumpa@...dia.com>, <jonathanh@...dia.com>,
<shuah@...nel.org>, <jsnitsel@...hat.com>, <nathan@...nel.org>,
<peterz@...radead.org>, <yi.l.liu@...el.com>, <mshavit@...gle.com>,
<praan@...gle.com>, <zhangzekun11@...wei.com>, <iommu@...ts.linux.dev>,
<linux-doc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<linux-arm-kernel@...ts.infradead.org>, <linux-tegra@...r.kernel.org>,
<linux-kselftest@...r.kernel.org>, <patches@...ts.linux.dev>,
<mochs@...dia.com>, <alok.a.tiwari@...cle.com>, <vasant.hegde@....com>
Subject: [PATCH v2 13/22] iommufd: Add mmap interface
For vIOMMU passing through HW resources to user space (VMs), add an mmap
infrastructure to map a region of hardware MMIO pages.
Maintain an mt_mmap per ictx for validations. To allow IOMMU drivers to
add and delete mmappable regions to/from the mt_mmap, add a pair of new
helpers: iommufd_ctx_alloc_mmap() and iommufd_ctx_free_mmap().
Signed-off-by: Nicolin Chen <nicolinc@...dia.com>
---
drivers/iommu/iommufd/iommufd_private.h | 8 +++++
include/linux/iommufd.h | 15 ++++++++++
drivers/iommu/iommufd/driver.c | 39 +++++++++++++++++++++++++
drivers/iommu/iommufd/main.c | 39 +++++++++++++++++++++++++
4 files changed, 101 insertions(+)
diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h
index b974c207ae8a..db5b62ec4abb 100644
--- a/drivers/iommu/iommufd/iommufd_private.h
+++ b/drivers/iommu/iommufd/iommufd_private.h
@@ -7,6 +7,7 @@
#include <linux/iommu.h>
#include <linux/iommufd.h>
#include <linux/iova_bitmap.h>
+#include <linux/maple_tree.h>
#include <linux/rwsem.h>
#include <linux/uaccess.h>
#include <linux/xarray.h>
@@ -44,6 +45,7 @@ struct iommufd_ctx {
struct xarray groups;
wait_queue_head_t destroy_wait;
struct rw_semaphore ioas_creation_lock;
+ struct maple_tree mt_mmap;
struct mutex sw_msi_lock;
struct list_head sw_msi_list;
@@ -55,6 +57,12 @@ struct iommufd_ctx {
struct iommufd_ioas *vfio_ioas;
};
+/* Entry for iommufd_ctx::mt_mmap */
+struct iommufd_mmap {
+ unsigned long pfn_start;
+ unsigned long pfn_end;
+};
+
/*
* The IOVA to PFN map. The map automatically copies the PFNs into multiple
* domains and permits sharing of PFNs between io_pagetable instances. This
diff --git a/include/linux/iommufd.h b/include/linux/iommufd.h
index 5dff154e8ce1..d63e2d91be0d 100644
--- a/include/linux/iommufd.h
+++ b/include/linux/iommufd.h
@@ -236,6 +236,9 @@ int iommufd_object_depend(struct iommufd_object *obj_dependent,
struct iommufd_object *obj_depended);
void iommufd_object_undepend(struct iommufd_object *obj_dependent,
struct iommufd_object *obj_depended);
+int iommufd_ctx_alloc_mmap(struct iommufd_ctx *ictx, phys_addr_t base,
+ size_t size, unsigned long *immap_id);
+void iommufd_ctx_free_mmap(struct iommufd_ctx *ictx, unsigned long immap_id);
struct device *iommufd_viommu_find_dev(struct iommufd_viommu *viommu,
unsigned long vdev_id);
int iommufd_viommu_get_vdev_id(struct iommufd_viommu *viommu,
@@ -262,11 +265,23 @@ static inline int iommufd_object_depend(struct iommufd_object *obj_dependent,
return -EOPNOTSUPP;
}
+static inline int iommufd_ctx_alloc_mmap(struct iommufd_ctx *ictx,
+ phys_addr_t base, size_t size,
+ unsigned long *immap_id)
+{
+ return -EOPNOTSUPP;
+}
+
static inline void iommufd_object_undepend(struct iommufd_object *obj_dependent,
struct iommufd_object *obj_depended)
{
}
+static inline void iommufd_ctx_free_mmap(struct iommufd_ctx *ictx,
+ unsigned long immap_id)
+{
+}
+
static inline struct device *
iommufd_viommu_find_dev(struct iommufd_viommu *viommu, unsigned long vdev_id)
{
diff --git a/drivers/iommu/iommufd/driver.c b/drivers/iommu/iommufd/driver.c
index fb7f8fe40f95..c55336c580dc 100644
--- a/drivers/iommu/iommufd/driver.c
+++ b/drivers/iommu/iommufd/driver.c
@@ -78,6 +78,45 @@ void iommufd_object_undepend(struct iommufd_object *obj_dependent,
}
EXPORT_SYMBOL_NS_GPL(iommufd_object_undepend, "IOMMUFD");
+/* Driver should report the output @immap_id to user space for mmap() syscall */
+int iommufd_ctx_alloc_mmap(struct iommufd_ctx *ictx, phys_addr_t base,
+ size_t size, unsigned long *immap_id)
+{
+ struct iommufd_mmap *immap;
+ int rc;
+
+ if (WARN_ON_ONCE(!immap_id))
+ return -EINVAL;
+ if (base & ~PAGE_MASK)
+ return -EINVAL;
+ if (!size || size & ~PAGE_MASK)
+ return -EINVAL;
+
+ immap = kzalloc(sizeof(*immap), GFP_KERNEL);
+ if (!immap)
+ return -ENOMEM;
+ immap->pfn_start = base >> PAGE_SHIFT;
+ immap->pfn_end = immap->pfn_start + (size >> PAGE_SHIFT) - 1;
+
+ rc = mtree_alloc_range(&ictx->mt_mmap, immap_id, immap, sizeof(immap),
+ 0, LONG_MAX >> PAGE_SHIFT, GFP_KERNEL);
+ if (rc < 0) {
+ kfree(immap);
+ return rc;
+ }
+
+ /* mmap() syscall will right-shift the immap_id to vma->vm_pgoff */
+ *immap_id <<= PAGE_SHIFT;
+ return 0;
+}
+EXPORT_SYMBOL_NS_GPL(iommufd_ctx_alloc_mmap, "IOMMUFD");
+
+void iommufd_ctx_free_mmap(struct iommufd_ctx *ictx, unsigned long immap_id)
+{
+ kfree(mtree_erase(&ictx->mt_mmap, immap_id >> PAGE_SHIFT));
+}
+EXPORT_SYMBOL_NS_GPL(iommufd_ctx_free_mmap, "IOMMUFD");
+
/* Caller should xa_lock(&viommu->vdevs) to protect the return value */
struct device *iommufd_viommu_find_dev(struct iommufd_viommu *viommu,
unsigned long vdev_id)
diff --git a/drivers/iommu/iommufd/main.c b/drivers/iommu/iommufd/main.c
index ac51d5cfaa61..4b46ea47164d 100644
--- a/drivers/iommu/iommufd/main.c
+++ b/drivers/iommu/iommufd/main.c
@@ -213,6 +213,7 @@ static int iommufd_fops_open(struct inode *inode, struct file *filp)
xa_init_flags(&ictx->objects, XA_FLAGS_ALLOC1 | XA_FLAGS_ACCOUNT);
xa_init(&ictx->groups);
ictx->file = filp;
+ mt_init_flags(&ictx->mt_mmap, MT_FLAGS_ALLOC_RANGE);
init_waitqueue_head(&ictx->destroy_wait);
mutex_init(&ictx->sw_msi_lock);
INIT_LIST_HEAD(&ictx->sw_msi_list);
@@ -410,11 +411,49 @@ static long iommufd_fops_ioctl(struct file *filp, unsigned int cmd,
return ret;
}
+/*
+ * Kernel driver must first do iommufd_ctx_alloc_mmap() to register an mmappable
+ * MMIO region to the iommufd core to receive an "immap_id". Then, driver should
+ * report to user space this immap_id and the size of the registered MMIO region
+ * for @vm_pgoff and @size of an mmap() call, via an IOMMU_VIOMMU_ALLOC ioctl in
+ * the output fields of its driver-type data structure.
+ *
+ * Note the @size is allowed to be smaller than the registered size as a partial
+ * mmap starting from the registered base address.
+ */
+static int iommufd_fops_mmap(struct file *filp, struct vm_area_struct *vma)
+{
+ struct iommufd_ctx *ictx = filp->private_data;
+ size_t size = vma->vm_end - vma->vm_start;
+ struct iommufd_mmap *immap;
+
+ if (size & ~PAGE_MASK)
+ return -EINVAL;
+ if (!(vma->vm_flags & VM_SHARED))
+ return -EINVAL;
+ if (vma->vm_flags & VM_EXEC)
+ return -EPERM;
+
+ /* vm_pgoff carries an index (immap_id) to an mtree entry (immap) */
+ immap = mtree_load(&ictx->mt_mmap, vma->vm_pgoff);
+ if (!immap)
+ return -ENXIO;
+ if (size >> PAGE_SHIFT > immap->pfn_end - immap->pfn_start + 1)
+ return -ENXIO;
+
+ vma->vm_pgoff = 0;
+ vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+ vm_flags_set(vma, VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP | VM_IO);
+ return remap_pfn_range(vma, vma->vm_start, immap->pfn_start, size,
+ vma->vm_page_prot);
+}
+
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,
};
/**
--
2.43.0
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