[PATCH v6 2/4] iommufd: Add iommufd_access_replace() API

Nicolin Chen
2023-03-27T18:05:41Z

Extract all common procedure, between the iommufd_access_attach() API and
the new iommufd_access_replace() API, to an iommufd_access_change_pt()
helper.

Add iommufd_access_replace() function for VFIO emulated pathway to use.

Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
drivers/iommu/iommufd/device.c | 53 +++++++++++++++++++------
include/linux/iommufd.h | 1 +
tools/testing/selftests/iommu/iommfd*.c | 0
3 files changed, 42 insertions(+), 12 deletions(-)
create mode 100644 tools/testing/selftests/iommu/iommfd*.c

diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
index 6f7b349ba8f5..b6d61e886fbb 100644
--- a/drivers/iommu/iommufd/device.c
+++ b/drivers/iommu/iommufd/device.c
@@ -752,38 +752,67 @@ void iommufd_access_detach(struct iommufd_access *access)
}
EXPORT_SYMBOL_NS_GPL(iommufd_access_detach, IOMMUFD);

-int iommufd_access_attach(struct iommufd_access *access, u32 ioas_id)
+static int iommufd_access_change_pt(struct iommufd_access *access, u32 ioas_id)
{
struct iommufd_ioas *new_ioas;
- int rc = 0;
+ int rc;

- mutex_lock(&access->ioas_lock);
- if (access->ioas != NULL && access->ioas->obj.id != ioas_id) {
- mutex_unlock(&access->ioas_lock);
- return -EINVAL;
- }
+ lockdep_assert_held(&access->ioas_lock);

new_ioas = iommufd_get_ioas(access->ictx, ioas_id);
- if (IS_ERR(new_ioas)) {
- mutex_unlock(&access->ioas_lock);
+ if (IS_ERR(new_ioas))
return PTR_ERR(new_ioas);
- }

rc = iopt_add_access(&new_ioas->iopt, access);
if (rc) {
- mutex_unlock(&access->ioas_lock);
iommufd_put_object(&new_ioas->obj);
return rc;
}
iommufd_ref_to_users(&new_ioas->obj);

+ if (access->ioas)
+ __iommufd_access_detach(access);
access->ioas = new_ioas;
access->ioas_unpin = new_ioas;
- mutex_unlock(&access->ioas_lock);
return 0;
}
+
+int iommufd_access_attach(struct iommufd_access *access, u32 ioas_id)
+{
+ int rc;
+
+ mutex_lock(&access->ioas_lock);
+ if (access->ioas != NULL && access->ioas->obj.id != ioas_id) {
+ mutex_unlock(&access->ioas_lock);
+ return -EINVAL;
+ }
+
+ rc = iommufd_access_change_pt(access, ioas_id);
+ mutex_unlock(&access->ioas_lock);
+ return rc;
+}
EXPORT_SYMBOL_NS_GPL(iommufd_access_attach, IOMMUFD);

+int iommufd_access_replace(struct iommufd_access *access, u32 ioas_id)
+{
+ int rc;
+
+ mutex_lock(&access->ioas_lock);
+ if (!access->ioas) {
+ mutex_unlock(&access->ioas_lock);
+ return -ENOENT;
+ }
+ if (access->ioas->obj.id == ioas_id) {
+ mutex_unlock(&access->ioas_lock);
+ return 0;
+ }
+
+ rc = iommufd_access_change_pt(access, ioas_id);
+ mutex_unlock(&access->ioas_lock);
+ return rc;
+}
+EXPORT_SYMBOL_NS_GPL(iommufd_access_replace, IOMMUFD);
+
/**
* iommufd_access_notify_unmap - Notify users of an iopt to stop using it
* @iopt: iopt to work on
diff --git a/include/linux/iommufd.h b/include/linux/iommufd.h
index 135dc2a28156..6752c58226d1 100644
--- a/include/linux/iommufd.h
+++ b/include/linux/iommufd.h
@@ -48,6 +48,7 @@ iommufd_access_create(struct iommufd_ctx *ictx,
const struct iommufd_access_ops *ops, void *data, u32 *id);
void iommufd_access_destroy(struct iommufd_access *access);
int iommufd_access_attach(struct iommufd_access *access, u32 ioas_id);
+int iommufd_access_replace(struct iommufd_access *access, u32 ioas_id);
void iommufd_access_detach(struct iommufd_access *access);

void iommufd_ctx_get(struct iommufd_ctx *ictx);
diff --git a/tools/testing/selftests/iommu/iommfd*.c b/tools/testing/selftests/iommu/iommfd*.c
new file mode 100644
index 000000000000..e69de29bb2d1
--
2.40.0