[PATCH RFC v2 12/13] iommufd: vfio container FD ioctl compatibility

Jason Gunthorpe
2022-09-02T20:00:06Z

iommufd can directly implement the /dev/vfio/vfio container IOCTLs by
mapping them into io_pagetable operations.

A userspace application can test against iommufd and confirm compatability
then simply make a small change to open /dev/iommu instead of
/dev/vfio/vfio.

For testing purposes /dev/vfio/vfio can be symlinked to /dev/iommu and
then all applications will use the compatability path with no code
changes. It is unclear if this could ever be a production configuration.

This series just provides the iommufd side of compatability. Actually
linking this to VFIO_SET_CONTAINER is a followup series, with a link in
the cover letter.

Internally the compatibility API uses a normal IOAS object that, like
vfio, is automatically allocated when the first device is
attached.

Userspace can also query or set this IOAS object directly using the
IOMMU_VFIO_IOAS ioctl. This allows mixing and matching new iommufd only
features while still using the VFIO style map/unmap ioctls.

While this is enough to operate qemu, it is still a bit of a WIP with a
few gaps:

- Only the TYPE1v2 mode is supported where unmap cannot punch holes or
split areas. The old mode can be implemented with a new operation to
split an iopt_area into two without disturbing the iopt_pages or the
domains, then unmapping a whole area as normal.

- Resource limits rely on memory cgroups to bound what userspace can do
instead of the module parameter dma_entry_limit.

- Pinned page accounting uses the same system as io_uring, not the
mm_struct based system vfio uses.

- VFIO P2P is not implemented. The DMABUF patches for vfio are a start at
a solution where iommufd would import a special DMABUF. This is to avoid
further propogating the follow_pfn() security problem.

- Indefinite suspend of SW access (VFIO_DMA_MAP_FLAG_VADDR) is not
implemented.

- A full audit for pedantic compatibility details (eg errnos, etc) has
not yet been done

- powerpc SPAPR is left out, as it is not connected to the iommu_domain
framework. My hope is that SPAPR will be moved into the iommu_domain
framework as a special HW specific type and would expect power to
support the generic interface through a normal iommu_domain.

The following are not going to be implemented and we expect to remove them
from VFIO type1:

- SW access 'dirty tracking'. As discussed in the cover letter this will
be done in VFIO.

- VFIO_TYPE1_NESTING_IOMMU
https://lore.kernel.org/all/0-v1-0093c9b0e345+19-vfio_no_nesting_jgg@nvidia.com/

Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
---
drivers/iommu/iommufd/Makefile | 3 +-
drivers/iommu/iommufd/iommufd_private.h | 6 +
drivers/iommu/iommufd/main.c | 16 +-
drivers/iommu/iommufd/vfio_compat.c | 423 ++++++++++++++++++++++++
include/linux/iommufd.h | 8 +
include/uapi/linux/iommufd.h | 36 ++
6 files changed, 486 insertions(+), 6 deletions(-)
create mode 100644 drivers/iommu/iommufd/vfio_compat.c

diff --git a/drivers/iommu/iommufd/Makefile b/drivers/iommu/iommufd/Makefile
index ca28a135b9675f..2fdff04000b326 100644
--- a/drivers/iommu/iommufd/Makefile
+++ b/drivers/iommu/iommufd/Makefile
@@ -5,6 +5,7 @@ iommufd-y := \
io_pagetable.o \
ioas.o \
main.o \
- pages.o
+ pages.o \
+ vfio_compat.o

obj-$(CONFIG_IOMMUFD) += iommufd.o
diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h
index 540b36c0befa5e..d87227cc08a47d 100644
--- a/drivers/iommu/iommufd/iommufd_private.h
+++ b/drivers/iommu/iommufd/iommufd_private.h
@@ -70,6 +70,8 @@ void iopt_remove_reserved_iova(struct io_pagetable *iopt, void *owner);
struct iommufd_ctx {
struct file *file;
struct xarray objects;
+
+ struct iommufd_ioas *vfio_ioas;
};

struct iommufd_ctx *iommufd_fget(int fd);
@@ -81,6 +83,9 @@ struct iommufd_ucmd {
void *cmd;
};

+int iommufd_vfio_ioctl(struct iommufd_ctx *ictx, unsigned int cmd,
+ unsigned long arg);
+
/* Copy the response in ucmd->cmd back to userspace. */
static inline int iommufd_ucmd_respond(struct iommufd_ucmd *ucmd,
size_t cmd_len)
@@ -208,6 +213,7 @@ int iommufd_ioas_allow_iovas(struct iommufd_ucmd *ucmd);
int iommufd_ioas_map(struct iommufd_ucmd *ucmd);
int iommufd_ioas_copy(struct iommufd_ucmd *ucmd);
int iommufd_ioas_unmap(struct iommufd_ucmd *ucmd);
+int iommufd_vfio_ioas(struct iommufd_ucmd *ucmd);

/*
* A HW pagetable is called an iommu_domain inside the kernel. This user object
diff --git a/drivers/iommu/iommufd/main.c b/drivers/iommu/iommufd/main.c
index ed64b84b3b9337..549d6a4c8f5575 100644
--- a/drivers/iommu/iommufd/main.c
+++ b/drivers/iommu/iommufd/main.c
@@ -134,6 +134,8 @@ bool iommufd_object_destroy_user(struct iommufd_ctx *ictx,
return false;
}
__xa_erase(&ictx->objects, obj->id);
+ if (ictx->vfio_ioas && &ictx->vfio_ioas->obj == obj)
+ ictx->vfio_ioas = NULL;
xa_unlock(&ictx->objects);
up_write(&obj->destroy_rwsem);

@@ -241,27 +243,31 @@ static struct iommufd_ioctl_op iommufd_ioctl_ops[] = {
__reserved),
IOCTL_OP(IOMMU_IOAS_UNMAP, iommufd_ioas_unmap, struct iommu_ioas_unmap,
length),
+ IOCTL_OP(IOMMU_VFIO_IOAS, iommufd_vfio_ioas, struct iommu_vfio_ioas,
+ __reserved),
};

static long iommufd_fops_ioctl(struct file *filp, unsigned int cmd,
unsigned long arg)
{
+ struct iommufd_ctx *ictx = filp->private_data;
struct iommufd_ucmd ucmd = {};
struct iommufd_ioctl_op *op;
union ucmd_buffer buf;
unsigned int nr;
int ret;

- ucmd.ictx = filp->private_data;
+ nr = _IOC_NR(cmd);
+ if (nr < IOMMUFD_CMD_BASE ||
+ (nr - IOMMUFD_CMD_BASE) >= ARRAY_SIZE(iommufd_ioctl_ops))
+ return iommufd_vfio_ioctl(ictx, cmd, arg);
+
+ ucmd.ictx = ictx;
ucmd.ubuffer = (void __user *)arg;
ret = get_user(ucmd.user_size, (u32 __user *)ucmd.ubuffer);
if (ret)
return ret;

- nr = _IOC_NR(cmd);
- if (nr < IOMMUFD_CMD_BASE ||
- (nr - IOMMUFD_CMD_BASE) >= ARRAY_SIZE(iommufd_ioctl_ops))
- return -ENOIOCTLCMD;
op = &iommufd_ioctl_ops[nr - IOMMUFD_CMD_BASE];
if (op->ioctl_num != cmd)
return -ENOIOCTLCMD;
diff --git a/drivers/iommu/iommufd/vfio_compat.c b/drivers/iommu/iommufd/vfio_compat.c
new file mode 100644
index 00000000000000..57ef97aa309985
--- /dev/null
+++ b/drivers/iommu/iommufd/vfio_compat.c
@@ -0,0 +1,423 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (c) 2021-2022, NVIDIA CORPORATION & AFFILIATES
+ */
+#include <linux/file.h>
+#include <linux/interval_tree.h>
+#include <linux/iommu.h>
+#include <linux/iommufd.h>
+#include <linux/slab.h>
+#include <linux/vfio.h>
+#include <uapi/linux/vfio.h>
+#include <uapi/linux/iommufd.h>
+
+#include "iommufd_private.h"
+
+static struct iommufd_ioas *get_compat_ioas(struct iommufd_ctx *ictx)
+{
+ struct iommufd_ioas *ioas = ERR_PTR(-ENODEV);
+
+ xa_lock(&ictx->objects);
+ if (!ictx->vfio_ioas || !iommufd_lock_obj(&ictx->vfio_ioas->obj))
+ goto out_unlock;
+ ioas = ictx->vfio_ioas;
+out_unlock:
+ xa_unlock(&ictx->objects);
+ return ioas;
+}
+
+/**
+ * iommufd_vfio_compat_ioas_id - Return the IOAS ID that vfio should use
+ * @ictx - Context to operate on
+ *
+ * The compatability IOAS is the IOAS that the vfio compatability ioctls operate
+ * on since they do not have an IOAS ID input in their ABI. Only attaching a
+ * group should cause a default creation of the internal ioas, this returns the
+ * existing ioas if it has already been assigned somehow.
+ */
+int iommufd_vfio_compat_ioas_id(struct iommufd_ctx *ictx, u32 *out_ioas_id)
+{
+ struct iommufd_ioas *ioas = NULL;
+ struct iommufd_ioas *out_ioas;
+
+ ioas = iommufd_ioas_alloc(ictx);
+ if (IS_ERR(ioas))
+ return PTR_ERR(ioas);
+
+ xa_lock(&ictx->objects);
+ if (ictx->vfio_ioas && iommufd_lock_obj(&ictx->vfio_ioas->obj))
+ out_ioas = ictx->vfio_ioas;
+ else {
+ out_ioas = ioas;
+ ictx->vfio_ioas = ioas;
+ }
+ xa_unlock(&ictx->objects);
+
+ *out_ioas_id = out_ioas->obj.id;
+ if (out_ioas != ioas) {
+ iommufd_put_object(&out_ioas->obj);
+ iommufd_object_abort(ictx, &ioas->obj);
+ return 0;
+ }
+ iommufd_object_finalize(ictx, &ioas->obj);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(iommufd_vfio_compat_ioas_id);
+
+int iommufd_vfio_ioas(struct iommufd_ucmd *ucmd)
+{
+ struct iommu_vfio_ioas *cmd = ucmd->cmd;
+ struct iommufd_ioas *ioas;
+
+ if (cmd->__reserved)
+ return -EOPNOTSUPP;
+ switch (cmd->op) {
+ case IOMMU_VFIO_IOAS_GET:
+ ioas = get_compat_ioas(ucmd->ictx);
+ if (IS_ERR(ioas))
+ return PTR_ERR(ioas);
+ cmd->ioas_id = ioas->obj.id;
+ iommufd_put_object(&ioas->obj);
+ return iommufd_ucmd_respond(ucmd, sizeof(*cmd));
+
+ case IOMMU_VFIO_IOAS_SET:
+ ioas = iommufd_get_ioas(ucmd, cmd->ioas_id);
+ if (IS_ERR(ioas))
+ return PTR_ERR(ioas);
+ xa_lock(&ucmd->ictx->objects);
+ ucmd->ictx->vfio_ioas = ioas;
+ xa_unlock(&ucmd->ictx->objects);
+ iommufd_put_object(&ioas->obj);
+ return 0;
+
+ case IOMMU_VFIO_IOAS_CLEAR:
+ xa_lock(&ucmd->ictx->objects);
+ ucmd->ictx->vfio_ioas = NULL;
+ xa_unlock(&ucmd->ictx->objects);
+ return 0;
+ default:
+ return -EOPNOTSUPP;
+ }
+}
+
+static int iommufd_vfio_map_dma(struct iommufd_ctx *ictx, unsigned int cmd,
+ void __user *arg)
+{
+ u32 supported_flags = VFIO_DMA_MAP_FLAG_READ | VFIO_DMA_MAP_FLAG_WRITE;
+ size_t minsz = offsetofend(struct vfio_iommu_type1_dma_map, size);
+ struct vfio_iommu_type1_dma_map map;
+ int iommu_prot = IOMMU_CACHE;
+ struct iommufd_ioas *ioas;
+ unsigned long iova;
+ int rc;
+
+ if (copy_from_user(&map, arg, minsz))
+ return -EFAULT;
+
+ if (map.argsz < minsz || map.flags & ~supported_flags)
+ return -EINVAL;
+
+ if (map.flags & VFIO_DMA_MAP_FLAG_READ)
+ iommu_prot |= IOMMU_READ;
+ if (map.flags & VFIO_DMA_MAP_FLAG_WRITE)
+ iommu_prot |= IOMMU_WRITE;
+
+ ioas = get_compat_ioas(ictx);
+ if (IS_ERR(ioas))
+ return PTR_ERR(ioas);
+
+ iova = map.iova;
+ rc = iopt_map_user_pages(&ioas->iopt, &iova,
+ u64_to_user_ptr(map.vaddr), map.size,
+ iommu_prot, 0);
+ iommufd_put_object(&ioas->obj);
+ return rc;
+}
+
+static int iommufd_vfio_unmap_dma(struct iommufd_ctx *ictx, unsigned int cmd,
+ void __user *arg)
+{
+ size_t minsz = offsetofend(struct vfio_iommu_type1_dma_unmap, size);
+
+ /* VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP is obsoleted by the new
+ * dirty tracking direction:
+ * https://lore.kernel.org/kvm/20220731125503.142683-1-yishaih@nvidia.com/
+ * https://lore.kernel.org/kvm/20220428210933.3583-1-joao.m.martins@oracle.com/
+ */
+ u32 supported_flags = VFIO_DMA_UNMAP_FLAG_ALL;
+ struct vfio_iommu_type1_dma_unmap unmap;
+ struct iommufd_ioas *ioas;
+ unsigned long unmapped;
+ int rc;
+
+ if (copy_from_user(&unmap, arg, minsz))
+ return -EFAULT;
+
+ if (unmap.argsz < minsz || unmap.flags & ~supported_flags)
+ return -EINVAL;
+
+ ioas = get_compat_ioas(ictx);
+ if (IS_ERR(ioas))
+ return PTR_ERR(ioas);
+
+ if (unmap.flags & VFIO_DMA_UNMAP_FLAG_ALL)
+ rc = iopt_unmap_all(&ioas->iopt, &unmapped);
+ else
+ rc = iopt_unmap_iova(&ioas->iopt, unmap.iova,
+ unmap.size, &unmapped);
+ iommufd_put_object(&ioas->obj);
+ unmap.size = unmapped;
+
+ return rc;
+}
+
+static int iommufd_vfio_cc_iommu(struct iommufd_ctx *ictx)
+{
+ struct iommufd_ioas *ioas;
+ bool rc;
+
+ ioas = get_compat_ioas(ictx);
+ if (IS_ERR(ioas))
+ return PTR_ERR(ioas);
+ rc = iommufd_ioas_enforced_coherent(ioas);
+ iommufd_put_object(&ioas->obj);
+ return rc;
+}
+
+static int iommufd_vfio_check_extension(struct iommufd_ctx *ictx,
+ unsigned long type)
+{
+ switch (type) {
+ case VFIO_TYPE1v2_IOMMU:
+ case VFIO_UNMAP_ALL:
+ return 1;
+
+ /*
+ * This is obsolete, and to be removed from VFIO. It was an incomplete
+ * idea that got merged.
+ * https://lore.kernel.org/kvm/0-v1-0093c9b0e345+19-vfio_no_nesting_jgg@nvidia.com/
+ */
+ case VFIO_TYPE1_NESTING_IOMMU:
+ return 0;
+
+ case VFIO_DMA_CC_IOMMU:
+ return iommufd_vfio_cc_iommu(ictx);
+
+ /*
+ * FIXME: The type1 iommu allows splitting of maps, which can fail. This is doable but
+ * is a bunch of extra code that is only for supporting this case.
+ */
+ case VFIO_TYPE1_IOMMU:
+ /*
+ * FIXME: VFIO_DMA_MAP_FLAG_VADDR
+ * https://lore.kernel.org/kvm/1611939252-7240-1-git-send-email-steven.sistare@oracle.com/
+ * Wow, what a wild feature. This should have been implemented by
+ * allowing a iopt_pages to be associated with a memfd. It can then
+ * source mapping requests directly from a memfd without going through a
+ * mm_struct and thus doesn't care that the original qemu exec'd itself.
+ * The idea that userspace can flip a flag and cause kernel users to
+ * block indefinately is unacceptable.
+ *
+ * For VFIO compat we should implement this in a slightly different way,
+ * Creating a access_user that spans the whole area will immediately
+ * stop new faults as they will be handled from the xarray. We can then
+ * reparent the iopt_pages to the new mm_struct and undo the
+ * access_user. No blockage of kernel users required, does require
+ * filling the xarray with pages though.
+ */
+ case VFIO_UPDATE_VADDR:
+ default:
+ return 0;
+ }
+}
+
+static int iommufd_vfio_set_iommu(struct iommufd_ctx *ictx, unsigned long type)
+{
+ struct iommufd_ioas *ioas = NULL;
+
+ if (type != VFIO_TYPE1v2_IOMMU)
+ return -EINVAL;
+
+ /* VFIO fails the set_iommu if there is no group */
+ ioas = get_compat_ioas(ictx);
+ if (IS_ERR(ioas))
+ return PTR_ERR(ioas);
+ iommufd_put_object(&ioas->obj);
+ return 0;
+}
+
+static u64 iommufd_get_pagesizes(struct iommufd_ioas *ioas)
+{
+ /* FIXME: See vfio_update_pgsize_bitmap(), for compat this should return
+ * the high bits too, and we need to decide if we should report that
+ * iommufd supports less than PAGE_SIZE alignment or stick to strict
+ * compatibility. qemu only cares about the first set bit.
+ */
+ return ioas->iopt.iova_alignment;
+}
+
+static int iommufd_fill_cap_iova(struct iommufd_ioas *ioas,
+ struct vfio_info_cap_header __user *cur,
+ size_t avail)
+{
+ struct vfio_iommu_type1_info_cap_iova_range __user *ucap_iovas =
+ container_of(cur,
+ struct vfio_iommu_type1_info_cap_iova_range __user,
+ header);
+ struct vfio_iommu_type1_info_cap_iova_range cap_iovas = {
+ .header = {
+ .id = VFIO_IOMMU_TYPE1_INFO_CAP_IOVA_RANGE,
+ .version = 1,
+ },
+ };
+ struct interval_tree_span_iter span;
+
+ interval_tree_for_each_span (&span, &ioas->iopt.reserved_itree,
+ 0, ULONG_MAX) {
+ struct vfio_iova_range range;
+
+ if (!span.is_hole)
+ continue;
+ range.start = span.start_hole;
+ range.end = span.last_hole;
+ if (avail >= struct_size(&cap_iovas, iova_ranges,
+ cap_iovas.nr_iovas + 1) &&
+ copy_to_user(&ucap_iovas->iova_ranges[cap_iovas.nr_iovas],
+ &range, sizeof(range)))
+ return -EFAULT;
+ cap_iovas.nr_iovas++;
+ }
+ if (avail >= struct_size(&cap_iovas, iova_ranges, cap_iovas.nr_iovas) &&
+ copy_to_user(ucap_iovas, &cap_iovas, sizeof(cap_iovas)))
+ return -EFAULT;
+ return struct_size(&cap_iovas, iova_ranges, cap_iovas.nr_iovas);
+}
+
+static int iommufd_fill_cap_dma_avail(struct iommufd_ioas *ioas,
+ struct vfio_info_cap_header __user *cur,
+ size_t avail)
+{
+ struct vfio_iommu_type1_info_dma_avail cap_dma = {
+ .header = {
+ .id = VFIO_IOMMU_TYPE1_INFO_DMA_AVAIL,
+ .version = 1,
+ },
+ /* iommufd has no limit, return the same value as VFIO. */
+ .avail = U16_MAX,
+ };
+
+ if (avail >= sizeof(cap_dma) &&
+ copy_to_user(cur, &cap_dma, sizeof(cap_dma)))
+ return -EFAULT;
+ return sizeof(cap_dma);
+}
+
+static int iommufd_vfio_iommu_get_info(struct iommufd_ctx *ictx,
+ void __user *arg)
+{
+ typedef int (*fill_cap_fn)(struct iommufd_ioas *ioas,
+ struct vfio_info_cap_header __user *cur,
+ size_t avail);
+ static const fill_cap_fn fill_fns[] = {
+ iommufd_fill_cap_iova,
+ iommufd_fill_cap_dma_avail,
+ };
+ size_t minsz = offsetofend(struct vfio_iommu_type1_info, iova_pgsizes);
+ struct vfio_info_cap_header __user *last_cap = NULL;
+ struct vfio_iommu_type1_info info;
+ struct iommufd_ioas *ioas;
+ size_t total_cap_size;
+ int rc;
+ int i;
+
+ if (copy_from_user(&info, arg, minsz))
+ return -EFAULT;
+
+ if (info.argsz < minsz)
+ return -EINVAL;
+ minsz = min_t(size_t, info.argsz, sizeof(info));
+
+ ioas = get_compat_ioas(ictx);
+ if (IS_ERR(ioas))
+ return PTR_ERR(ioas);
+
+ down_read(&ioas->iopt.iova_rwsem);
+ info.flags = VFIO_IOMMU_INFO_PGSIZES;
+ info.iova_pgsizes = iommufd_get_pagesizes(ioas);
+ info.cap_offset = 0;
+
+ total_cap_size = sizeof(info);
+ for (i = 0; i != ARRAY_SIZE(fill_fns); i++) {
+ int cap_size;
+
+ if (info.argsz > total_cap_size)
+ cap_size = fill_fns[i](ioas, arg + total_cap_size,
+ info.argsz - total_cap_size);
+ else
+ cap_size = fill_fns[i](ioas, NULL, 0);
+ if (cap_size < 0) {
+ rc = cap_size;
+ goto out_put;
+ }
+ if (last_cap && info.argsz >= total_cap_size &&
+ put_user(total_cap_size, &last_cap->next)) {
+ rc = -EFAULT;
+ goto out_put;
+ }
+ last_cap = arg + total_cap_size;
+ total_cap_size += cap_size;
+ }
+
+ /*
+ * If the user did not provide enough space then only some caps are
+ * returned and the argsz will be updated to the correct amount to get
+ * all caps.
+ */
+ if (info.argsz >= total_cap_size)
+ info.cap_offset = sizeof(info);
+ info.argsz = total_cap_size;
+ info.flags |= VFIO_IOMMU_INFO_CAPS;
+ if (copy_to_user(arg, &info, minsz))
+ rc = -EFAULT;
+ rc = 0;
+
+out_put:
+ up_read(&ioas->iopt.iova_rwsem);
+ iommufd_put_object(&ioas->obj);
+ return rc;
+}
+
+/* FIXME TODO:
+PowerPC SPAPR only:
+#define VFIO_IOMMU_ENABLE _IO(VFIO_TYPE, VFIO_BASE + 15)
+#define VFIO_IOMMU_DISABLE _IO(VFIO_TYPE, VFIO_BASE + 16)
+#define VFIO_IOMMU_SPAPR_TCE_GET_INFO _IO(VFIO_TYPE, VFIO_BASE + 12)
+#define VFIO_IOMMU_SPAPR_REGISTER_MEMORY _IO(VFIO_TYPE, VFIO_BASE + 17)
+#define VFIO_IOMMU_SPAPR_UNREGISTER_MEMORY _IO(VFIO_TYPE, VFIO_BASE + 18)
+#define VFIO_IOMMU_SPAPR_TCE_CREATE _IO(VFIO_TYPE, VFIO_BASE + 19)
+#define VFIO_IOMMU_SPAPR_TCE_REMOVE _IO(VFIO_TYPE, VFIO_BASE + 20)
+*/
+
+int iommufd_vfio_ioctl(struct iommufd_ctx *ictx, unsigned int cmd,
+ unsigned long arg)
+{
+ void __user *uarg = (void __user *)arg;
+
+ switch (cmd) {
+ case VFIO_GET_API_VERSION:
+ return VFIO_API_VERSION;
+ case VFIO_SET_IOMMU:
+ return iommufd_vfio_set_iommu(ictx, arg);
+ case VFIO_CHECK_EXTENSION:
+ return iommufd_vfio_check_extension(ictx, arg);
+ case VFIO_IOMMU_GET_INFO:
+ return iommufd_vfio_iommu_get_info(ictx, uarg);
+ case VFIO_IOMMU_MAP_DMA:
+ return iommufd_vfio_map_dma(ictx, cmd, uarg);
+ case VFIO_IOMMU_UNMAP_DMA:
+ return iommufd_vfio_unmap_dma(ictx, cmd, uarg);
+ case VFIO_IOMMU_DIRTY_PAGES:
+ default:
+ return -ENOIOCTLCMD;
+ }
+ return -ENOIOCTLCMD;
+}
diff --git a/include/linux/iommufd.h b/include/linux/iommufd.h
index c072e400f3e645..050024ff68142d 100644
--- a/include/linux/iommufd.h
+++ b/include/linux/iommufd.h
@@ -72,6 +72,8 @@ void iommufd_ctx_get(struct iommufd_ctx *ictx);
struct iommufd_ctx *iommufd_ctx_from_file(struct file *file);
void iommufd_ctx_put(struct iommufd_ctx *ictx);

+int iommufd_vfio_compat_ioas_id(struct iommufd_ctx *ictx, u32 *out_ioas_id);
+
int iommufd_access_rw(struct iommufd_access *access, unsigned long iova,
void *data, size_t len, bool write);
#else /* !CONFIG_IOMMUFD */
@@ -84,6 +86,12 @@ static inline void iommufd_ctx_put(struct iommufd_ctx *ictx)
{
}

+static inline int iommufd_vfio_compat_ioas_id(struct iommufd_ctx *ictx,
+ u32 *out_ioas_id)
+{
+ return -EOPNOTSUPP;
+}
+
static inline int iommufd_access_rw(struct iommufd_access *access, unsigned long iova,
void *data, size_t len, bool write)
{
diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h
index b7b0ac4016bb70..48c290505844d8 100644
--- a/include/uapi/linux/iommufd.h
+++ b/include/uapi/linux/iommufd.h
@@ -43,6 +43,7 @@ enum {
IOMMUFD_CMD_IOAS_IOVA_RANGES,
IOMMUFD_CMD_IOAS_MAP,
IOMMUFD_CMD_IOAS_UNMAP,
+ IOMMUFD_CMD_VFIO_IOAS,
};

/**
@@ -240,4 +241,39 @@ struct iommu_ioas_unmap {
__aligned_u64 length;
};
#define IOMMU_IOAS_UNMAP _IO(IOMMUFD_TYPE, IOMMUFD_CMD_IOAS_UNMAP)
+
+/**
+ * enum iommufd_vfio_ioas_op
+ * @IOMMU_VFIO_IOAS_GET: Get the current compatibility IOAS
+ * @IOMMU_VFIO_IOAS_SET: Change the current compatibility IOAS
+ * @IOMMU_VFIO_IOAS_CLEAR: Disable VFIO compatibility
+ */
+enum iommufd_vfio_ioas_op {
+ IOMMU_VFIO_IOAS_GET = 0,
+ IOMMU_VFIO_IOAS_SET = 1,
+ IOMMU_VFIO_IOAS_CLEAR = 2,
+};
+
+/**
+ * struct iommu_vfio_ioas - ioctl(IOMMU_VFIO_IOAS)
+ * @size: sizeof(struct iommu_ioas_copy)
+ * @ioas_id: For IOMMU_VFIO_IOAS_SET the input IOAS ID to set
+ * For IOMMU_VFIO_IOAS_GET will output the IOAS ID
+ * @op: One of enum iommufd_vfio_ioas_op
+ * @__reserved: Must be 0
+ *
+ * The VFIO compatibility support uses a single ioas because VFIO APIs do not
+ * support the ID field. Set or Get the IOAS that VFIO compatibility will use.
+ * When VFIO_GROUP_SET_CONTAINER is used on an iommufd it will get the
+ * compatibility ioas, either by taking what is already set, or auto creating
+ * one. From then on VFIO will continue to use that ioas and is not effected by
+ * this ioctl. SET or CLEAR does not destroy any auto-created IOAS.
+ */
+struct iommu_vfio_ioas {
+ __u32 size;
+ __u32 ioas_id;
+ __u16 op;
+ __u16 __reserved;
+};
+#define IOMMU_VFIO_IOAS _IO(IOMMUFD_TYPE, IOMMUFD_CMD_VFIO_IOAS)
#endif
--
2.37.3