[PATCH RFCv1 08/14] iommufd: Add IOMMU_VIOMMU_SET_DEV_ID ioctl

Nicolin Chen
2024-04-13T03:47:58Z

Introduce a new ioctl to set a per-viommu device virtual id that should be
linked to the physical device id (or just a struct device pointer).

Since a viommu (user space IOMMU instance) can have multiple devices while
it's not ideal to confine a device to one single user space IOMMU instance
either, these two shouldn't just do a 1:1 mapping. Add two xarrays in their
structures to bind them bidirectionally.

Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
drivers/iommu/iommufd/device.c | 11 +++++
drivers/iommu/iommufd/iommufd_private.h | 10 +++++
drivers/iommu/iommufd/main.c | 2 +
drivers/iommu/iommufd/viommu.c | 58 +++++++++++++++++++++++++
include/linux/iommufd.h | 2 +
include/uapi/linux/iommufd.h | 20 +++++++++
6 files changed, 103 insertions(+)

diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
index 873630c111c1..68086f3074b6 100644
--- a/drivers/iommu/iommufd/device.c
+++ b/drivers/iommu/iommufd/device.c
@@ -135,7 +135,16 @@ void iommufd_device_destroy(struct iommufd_object *obj)
{
struct iommufd_device *idev =
container_of(obj, struct iommufd_device, obj);
+ struct iommufd_viommu *viommu;
+ unsigned long index;

+ xa_for_each(&idev->viommus, index, viommu) {
+ if (viommu->ops->unset_dev_id)
+ viommu->ops->unset_dev_id(viommu, idev->dev);
+ xa_erase(&viommu->idevs, idev->obj.id);
+ xa_erase(&idev->viommus, index);
+ }
+ xa_destroy(&idev->viommus);
iommu_device_release_dma_owner(idev->dev);
iommufd_put_group(idev->igroup);
if (!iommufd_selftest_is_mock_dev(idev->dev))
@@ -216,6 +225,8 @@ struct iommufd_device *iommufd_device_bind(struct iommufd_ctx *ictx,
/* igroup refcount moves into iommufd_device */
idev->igroup = igroup;

+ xa_init_flags(&idev->viommus, XA_FLAGS_ALLOC1);
+
/*
* If the caller fails after this success it must call
* iommufd_unbind_device() which is safe since we hold this refcount.
diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h
index ae90b4493109..9ba8f4ecc221 100644
--- a/drivers/iommu/iommufd/iommufd_private.h
+++ b/drivers/iommu/iommufd/iommufd_private.h
@@ -392,6 +392,7 @@ struct iommufd_device {
struct list_head group_item;
/* always the physical device */
struct device *dev;
+ struct xarray viommus;
bool enforce_cache_coherency;
};

@@ -424,8 +425,17 @@ void iopt_remove_access(struct io_pagetable *iopt,
u32 iopt_access_list_id);
void iommufd_access_destroy_object(struct iommufd_object *obj);

+static inline struct iommufd_viommu *
+iommufd_get_viommu(struct iommufd_ucmd *ucmd, u32 id)
+{
+ return container_of(iommufd_get_object(ucmd->ictx, id,
+ IOMMUFD_OBJ_VIOMMU),
+ struct iommufd_viommu, obj);
+}
+
int iommufd_viommu_alloc_ioctl(struct iommufd_ucmd *ucmd);
void iommufd_viommu_destroy(struct iommufd_object *obj);
+int iommufd_viommu_set_device_id(struct iommufd_ucmd *ucmd);

#ifdef CONFIG_IOMMUFD_TEST
int iommufd_test(struct iommufd_ucmd *ucmd);
diff --git a/drivers/iommu/iommufd/main.c b/drivers/iommu/iommufd/main.c
index 9de7e3e63ce4..16efc3346a2a 100644
--- a/drivers/iommu/iommufd/main.c
+++ b/drivers/iommu/iommufd/main.c
@@ -381,6 +381,8 @@ static const struct iommufd_ioctl_op iommufd_ioctl_ops[] = {
__reserved),
IOCTL_OP(IOMMU_VIOMMU_ALLOC, iommufd_viommu_alloc_ioctl,
struct iommu_viommu_alloc, out_viommu_id),
+ IOCTL_OP(IOMMU_VIOMMU_SET_DEV_ID, iommufd_viommu_set_device_id,
+ struct iommu_viommu_set_dev_id, id),
#ifdef CONFIG_IOMMUFD_TEST
IOCTL_OP(IOMMU_TEST_CMD, iommufd_test, struct iommu_test_cmd, last),
#endif
diff --git a/drivers/iommu/iommufd/viommu.c b/drivers/iommu/iommufd/viommu.c
index 079e0ff79942..71baca0c75de 100644
--- a/drivers/iommu/iommufd/viommu.c
+++ b/drivers/iommu/iommufd/viommu.c
@@ -69,6 +69,7 @@ int iommufd_viommu_alloc_ioctl(struct iommufd_ucmd *ucmd)
rc = PTR_ERR(viommu);
goto out_put_hwpt;
}
+ xa_init_flags(&viommu->idevs, XA_FLAGS_ALLOC1);

/* iommufd_object_finalize will store the viommu->obj.id */
rc = xa_alloc(&ucmd->ictx->objects, &viommu->obj.id, XA_ZERO_ENTRY,
@@ -102,3 +103,60 @@ int iommufd_viommu_alloc_ioctl(struct iommufd_ucmd *ucmd)
iommufd_put_object(ucmd->ictx, &idev->obj);
return rc;
}
+
+int iommufd_viommu_set_device_id(struct iommufd_ucmd *ucmd)
+{
+ struct iommu_viommu_set_dev_id *cmd = ucmd->cmd;
+ unsigned int dev_id, viommu_id;
+ struct iommufd_viommu *viommu;
+ struct iommufd_device *idev;
+ int rc;
+
+ idev = iommufd_get_device(ucmd, cmd->dev_id);
+ if (IS_ERR(idev))
+ return PTR_ERR(idev);
+ dev_id = idev->obj.id;
+
+ viommu = iommufd_get_viommu(ucmd, cmd->viommu_id);
+ if (IS_ERR(viommu)) {
+ rc = PTR_ERR(viommu);
+ goto out_put_idev;
+ }
+
+ if (viommu->iommu_dev != idev->dev->iommu->iommu_dev) {
+ rc = -EINVAL;
+ goto out_put_viommu;
+ }
+
+ if (!viommu->ops->set_dev_id || !viommu->ops->unset_dev_id) {
+ rc = -EOPNOTSUPP;
+ goto out_put_viommu;
+ }
+
+ rc = xa_alloc(&idev->viommus, &viommu_id, viommu,
+ XA_LIMIT(viommu->obj.id, viommu->obj.id),
+ GFP_KERNEL_ACCOUNT);
+ if (rc)
+ goto out_put_viommu;
+
+ rc = xa_alloc(&viommu->idevs, &dev_id, idev,
+ XA_LIMIT(dev_id, dev_id), GFP_KERNEL_ACCOUNT);
+ if (rc)
+ goto out_xa_erase_viommu;
+
+ rc = viommu->ops->set_dev_id(viommu, idev->dev, cmd->id);
+ if (rc)
+ goto out_xa_erase_idev;
+
+ goto out_put_viommu;
+
+out_xa_erase_idev:
+ xa_erase(&viommu->idevs, idev->obj.id);
+out_xa_erase_viommu:
+ xa_erase(&idev->viommus, viommu->obj.id);
+out_put_viommu:
+ iommufd_put_object(ucmd->ictx, &viommu->obj);
+out_put_idev:
+ iommufd_put_object(ucmd->ictx, &idev->obj);
+ return rc;
+}
diff --git a/include/linux/iommufd.h b/include/linux/iommufd.h
index ca6ac8a1ffd0..2be302b82f47 100644
--- a/include/linux/iommufd.h
+++ b/include/linux/iommufd.h
@@ -10,6 +10,7 @@
#include <linux/errno.h>
#include <linux/err.h>
#include <linux/refcount.h>
+#include <linux/xarray.h>

struct device;
struct iommufd_device;
@@ -88,6 +89,7 @@ struct iommufd_viommu {
const struct iommufd_viommu_ops *ops;

unsigned int type;
+ struct xarray idevs;
};

/**
diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h
index 2b0825d69846..eaa192de63d3 100644
--- a/include/uapi/linux/iommufd.h
+++ b/include/uapi/linux/iommufd.h
@@ -51,6 +51,7 @@ enum {
IOMMUFD_CMD_HWPT_GET_DIRTY_BITMAP,
IOMMUFD_CMD_HWPT_INVALIDATE,
IOMMUFD_CMD_VIOMMU_ALLOC,
+ IOMMUFD_CMD_VIOMMU_SET_DEV_ID,
};

/**
@@ -722,4 +723,23 @@ struct iommu_viommu_alloc {
__u32 out_viommu_id;
};
#define IOMMU_VIOMMU_ALLOC _IO(IOMMUFD_TYPE, IOMMUFD_CMD_VIOMMU_ALLOC)
+
+/**
+ * struct iommu_viommu_set_dev_id - ioctl(IOMMU_VIOMMU_SET_DEV_ID)
+ * @size: sizeof(struct iommu_viommu_set_dev_id)
+ * @viommu_id: viommu ID to associate with the device to store its virtual ID
+ * @dev_id: device ID to set a device virtual ID
+ * @__reserved: Must be 0
+ * @id: Device virtual ID
+ *
+ * Set a viommu-specific virtual ID of a device
+ */
+struct iommu_viommu_set_dev_id {
+ __u32 size;
+ __u32 viommu_id;
+ __u32 dev_id;
+ __u32 __reserved;
+ __aligned_u64 id;
+};
+#define IOMMU_VIOMMU_SET_DEV_ID _IO(IOMMUFD_TYPE, IOMMUFD_CMD_VIOMMU_SET_DEV_ID)
#endif
--
2.43.0