From: Jason Gunthorpe jgg@nvidia.com Sent: Monday, May 15, 2023 10:00 PM
Replace allows all the devices in a group to move in one step to a new HWPT. Further, the HWPT move is done without going through a blocking domain so that the IOMMU driver can implement some level of non-distruption to ongoing DMA if that has meaning for it (eg for future special driver domains)
Replace uses a lot of the same logic as normal attach, except the actual domain change over has different restrictions, and we are careful to sequence things so that failure is going to leave everything the way it was, and not get trapped in a blocking domain or something if there is ENOMEM.
Reviewed-by: Lu Baolu baolu.lu@linux.intel.com Reviewed-by: Kevin Tian kevin.tian@intel.com Signed-off-by: Jason Gunthorpe jgg@nvidia.com
drivers/iommu/iommufd/device.c | 99 ++++++++++++++++++++++++++++++++++ drivers/iommu/iommufd/main.c | 1 + 2 files changed, 100 insertions(+)
diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c index b7868c877d1c1c..ce758fbe3c525d 100644 --- a/drivers/iommu/iommufd/device.c +++ b/drivers/iommu/iommufd/device.c @@ -4,6 +4,7 @@ #include <linux/iommufd.h> #include <linux/slab.h> #include <linux/iommu.h> +#include "../iommu-priv.h"
#include "io_pagetable.h" #include "iommufd_private.h" @@ -365,6 +366,84 @@ iommufd_device_do_attach(struct iommufd_device *idev, return NULL; }
+static struct iommufd_hw_pagetable * +iommufd_device_do_replace(struct iommufd_device *idev,
struct iommufd_hw_pagetable *hwpt)+{
- struct iommufd_group *igroup = idev->igroup;
- struct iommufd_hw_pagetable *old_hwpt;
- unsigned int num_devices = 0;
- struct iommufd_device *cur;
- int rc;
- mutex_lock(&idev->igroup->lock);
- if (igroup->hwpt == NULL) {
rc = -EINVAL;goto err_unlock;- }
- if (hwpt == igroup->hwpt) {
mutex_unlock(&idev->igroup->lock);return NULL;- }
- /* Try to upgrade the domain we have */
- list_for_each_entry(cur, &igroup->device_list, group_item) {
num_devices++;if (cur->enforce_cache_coherency) {rc = iommufd_hw_pagetable_enforce_cc(hwpt);if (rc)goto err_unlock;}- }
- old_hwpt = igroup->hwpt;
- if (hwpt->ioas != old_hwpt->ioas) {
list_for_each_entry(cur, &igroup->device_list, group_item) {rc = iopt_table_enforce_dev_resv_regions(&hwpt->ioas->iopt, cur->dev, NULL);if (rc)goto err_unresv;}- }
- rc = iommufd_group_setup_msi(idev->igroup, hwpt);
- if (rc)
goto err_unresv;- rc = iommu_group_replace_domain(igroup->group, hwpt->domain);
- if (rc)
goto err_unresv;- if (hwpt->ioas != old_hwpt->ioas) {
list_for_each_entry(cur, &igroup->device_list, group_item)iopt_remove_reserved_iova(&old_hwpt->ioas->iopt,cur->dev);- }
- igroup->hwpt = hwpt;
- /*
* Move the refcounts held by the device_list to the new hwpt. Retain a* refcount for this thread as the caller will free it.*/- refcount_add(num_devices, &hwpt->obj.users);
- if (num_devices > 1)
WARN_ON(refcount_sub_and_test(num_devices - 1,&old_hwpt->obj.users));- mutex_unlock(&idev->igroup->lock);
- /* Caller must destroy old_hwpt */
- return old_hwpt;
+err_unresv:
- list_for_each_entry(cur, &igroup->device_list, group_item)
iopt_remove_reserved_iova(&hwpt->ioas->iopt, cur->dev);+err_unlock:
- mutex_unlock(&idev->igroup->lock);
- return ERR_PTR(rc);
+}
typedef struct iommufd_hw_pagetable *(*attach_fn)( struct iommufd_device *idev, struct iommufd_hw_pagetable *hwpt);
@@ -523,6 +602,26 @@ int iommufd_device_attach(struct iommufd_device *idev, u32 *pt_id) } EXPORT_SYMBOL_NS_GPL(iommufd_device_attach, IOMMUFD);
+/**
- iommufd_device_replace - Change the device's iommu_domain
- @idev: device to change
- @pt_id: Input a IOMMUFD_OBJ_IOAS, or IOMMUFD_OBJ_HW_PAGETABLE
Output the IOMMUFD_OBJ_HW_PAGETABLE ID
- This is the same as
- iommufd_device_detach();
- iommufd_device_attach();
One blank line here would fix a warning as below in "make htmldocs".
Documentation/userspace-api/iommufd:184: ./drivers/iommu/iommufd/device.c:665: WARNING: Definition list ends without a blank line; unexpected unindent.
Regards, Yi Liu
- If it fails then no change is made to the attachment. The iommu driver may
- implement this so there is no disruption in translation. This can only be
- called if iommufd_device_attach() has already succeeded.
- */
+int iommufd_device_replace(struct iommufd_device *idev, u32 *pt_id) +{
- return iommufd_device_change_pt(idev, pt_id,
&iommufd_device_do_replace);+} +EXPORT_SYMBOL_NS_GPL(iommufd_device_replace, IOMMUFD);
/**
- iommufd_device_detach - Disconnect a device to an iommu_domain
- @idev: device to detach
diff --git a/drivers/iommu/iommufd/main.c b/drivers/iommu/iommufd/main.c index 24f30f384df6f9..5b7f70543adb24 100644 --- a/drivers/iommu/iommufd/main.c +++ b/drivers/iommu/iommufd/main.c @@ -466,5 +466,6 @@ module_exit(iommufd_exit); MODULE_ALIAS_MISCDEV(VFIO_MINOR); MODULE_ALIAS("devname:vfio/vfio"); #endif +MODULE_IMPORT_NS(IOMMUFD_INTERNAL); MODULE_DESCRIPTION("I/O Address Space Management for passthrough devices"); MODULE_LICENSE("GPL"); -- 2.40.1