[PATCH 12/17] iommufd: Add user-managed hw_pagetable allocation

Yi Liu
2023-02-09T04:35:39Z

As the introduction of nested translation, there are page tables managed
by userspace. hw_pagetables can be stage-1 pagetable, stage-2 pagetable or
just standalone pagetable.

Stage-2 page table and standalone pagetable are kernel-managed for security.
iommufd has already supported it.

Stage-1 pagetable is user-managed and needs to work with a stage-2 page table.
Hence, userspace should provide a hw_pagetable ID that points to a stage-2
hw_pagetable. Since stage-1 is user-managed, so an ioctl is added to sync
the IOTLB when there is modification in the stage-1 page table.

The first available user-managed hw_pagtable type is the Intel VT-d stage-1
pagetable for nested translation.

Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
---
drivers/iommu/iommufd/device.c | 3 +-
drivers/iommu/iommufd/hw_pagetable.c | 71 ++++++++++++++++++++++++-
drivers/iommu/iommufd/iommufd_private.h | 1 +
drivers/iommu/iommufd/main.c | 8 +++
include/uapi/linux/iommufd.h | 34 ++++++++++++
5 files changed, 114 insertions(+), 3 deletions(-)

diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
index 6d948fa418d5..c19e2f54a44f 100644
--- a/drivers/iommu/iommufd/device.c
+++ b/drivers/iommu/iommufd/device.c
@@ -164,7 +164,8 @@ struct device *iommufd_obj_dev(struct iommufd_object *obj)
* indexed by the members defined in enum iommu_device_data_type.
*/
const u64 iommufd_supported_pgtbl_types[] = {
- [IOMMU_DEVICE_DATA_INTEL_VTD] = BIT_ULL(IOMMU_PGTBL_DATA_NONE),
+ [IOMMU_DEVICE_DATA_INTEL_VTD] = BIT_ULL(IOMMU_PGTBL_DATA_NONE) |
+ BIT_ULL(IOMMU_PGTBL_DATA_VTD_S1),
};

int iommufd_device_get_info(struct iommufd_ucmd *ucmd)
diff --git a/drivers/iommu/iommufd/hw_pagetable.c b/drivers/iommu/iommufd/hw_pagetable.c
index 02dee8e8d958..44a75ccc8e08 100644
--- a/drivers/iommu/iommufd/hw_pagetable.c
+++ b/drivers/iommu/iommufd/hw_pagetable.c
@@ -108,11 +108,12 @@ iommufd_hw_pagetable_alloc(struct iommufd_ctx *ictx, struct iommufd_ioas *ioas,
*/
static const size_t iommufd_hwpt_info_size[] = {
[IOMMU_PGTBL_DATA_NONE] = 0,
+ [IOMMU_PGTBL_DATA_VTD_S1] = sizeof(struct iommu_hwpt_intel_vtd),
};

int iommufd_hwpt_alloc(struct iommufd_ucmd *ucmd)
{
- struct iommufd_hw_pagetable *hwpt;
+ struct iommufd_hw_pagetable *hwpt, *parent = NULL;
struct iommu_hwpt_alloc *cmd = ucmd->cmd;
struct iommufd_ctx *ictx = ucmd->ictx;
struct iommufd_object *pt_obj = NULL;
@@ -160,6 +161,19 @@ int iommufd_hwpt_alloc(struct iommufd_ucmd *ucmd)
}

switch (pt_obj->type) {
+ case IOMMUFD_OBJ_HW_PAGETABLE:
+ parent = container_of(pt_obj, struct iommufd_hw_pagetable, obj);
+ /*
+ * Cannot allocate user-managed hwpt linking to auto_created
+ * hwpt. If the parent hwpt is already a user-managed hwpt,
+ * don't allocate another user-managed hwpt linking to it.
+ */
+ if (parent->auto_domain || parent->parent) {
+ rc = -EINVAL;
+ goto out_put_pt;
+ }
+ ioas = parent->ioas;
+ break;
case IOMMUFD_OBJ_IOAS:
ioas = container_of(pt_obj, struct iommufd_ioas, obj);
break;
@@ -189,7 +203,7 @@ int iommufd_hwpt_alloc(struct iommufd_ucmd *ucmd)
}

mutex_lock(&ioas->mutex);
- hwpt = __iommufd_hw_pagetable_alloc(ictx, ioas, dev, NULL, data);
+ hwpt = __iommufd_hw_pagetable_alloc(ictx, ioas, dev, parent, data);
mutex_unlock(&ioas->mutex);
if (IS_ERR(hwpt)) {
rc = PTR_ERR(hwpt);
@@ -217,3 +231,56 @@ int iommufd_hwpt_alloc(struct iommufd_ucmd *ucmd)
iommufd_put_object(dev_obj);
return rc;
}
+
+static u32 iommufd_hwpt_invalidate_info_size[] = {
+ [IOMMU_PGTBL_DATA_VTD_S1] = sizeof(struct iommu_hwpt_invalidate_intel_vtd),
+};
+
+int iommufd_hwpt_invalidate(struct iommufd_ucmd *ucmd)
+{
+ struct iommu_hwpt_invalidate *cmd = ucmd->cmd;
+ struct iommufd_hw_pagetable *hwpt;
+ u64 user_ptr;
+ u32 user_data_len, klen;
+ int rc = 0;
+
+ /*
+ * No invalidation needed for type==IOMMU_PGTBL_DATA_NONE.
+ * data_len should not exceed the size of iommufd_invalidate_buffer.
+ */
+ if (cmd->data_type == IOMMU_PGTBL_DATA_NONE || !cmd->data_len)
+ return -EOPNOTSUPP;
+
+ hwpt = iommufd_get_hwpt(ucmd, cmd->hwpt_id);
+ if (IS_ERR(hwpt))
+ return PTR_ERR(hwpt);
+
+ /* Do not allow any kernel-managed hw_pagetable */
+ if (!hwpt->parent) {
+ rc = -EINVAL;
+ goto out_put_hwpt;
+ }
+
+ klen = iommufd_hwpt_invalidate_info_size[cmd->data_type];
+ if (!klen) {
+ rc = -EINVAL;
+ goto out_put_hwpt;
+ }
+
+ /*
+ * copy the needed fields before reusing the ucmd buffer, this
+ * avoids memory allocation in this path.
+ */
+ user_ptr = cmd->data_uptr;
+ user_data_len = cmd->data_len;
+
+ rc = copy_struct_from_user(cmd, klen,
+ u64_to_user_ptr(user_ptr), user_data_len);
+ if (rc)
+ goto out_put_hwpt;
+
+ hwpt->domain->ops->iotlb_sync_user(hwpt->domain, cmd);
+out_put_hwpt:
+ iommufd_put_object(&hwpt->obj);
+ return rc;
+}
diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h
index 5ef034451f4b..bb341e633c18 100644
--- a/drivers/iommu/iommufd/iommufd_private.h
+++ b/drivers/iommu/iommufd/iommufd_private.h
@@ -267,6 +267,7 @@ iommufd_get_hwpt(struct iommufd_ucmd *ucmd, u32 id)
}

int iommufd_hwpt_alloc(struct iommufd_ucmd *ucmd);
+int iommufd_hwpt_invalidate(struct iommufd_ucmd *ucmd);

struct device *iommufd_obj_dev(struct iommufd_object *obj);

diff --git a/drivers/iommu/iommufd/main.c b/drivers/iommu/iommufd/main.c
index 831303d64abe..6e2d8805daf3 100644
--- a/drivers/iommu/iommufd/main.c
+++ b/drivers/iommu/iommufd/main.c
@@ -252,6 +252,12 @@ union ucmd_buffer {
struct iommu_destroy destroy;
struct iommu_device_info info;
struct iommu_hwpt_alloc hwpt;
+ struct iommu_hwpt_invalidate cache;
+ /*
+ * data_type specific structure used in the cache invalidation
+ * path.
+ */
+ struct iommu_hwpt_invalidate_intel_vtd vtd;
struct iommu_ioas_alloc alloc;
struct iommu_ioas_allow_iovas allow_iovas;
struct iommu_ioas_copy ioas_copy;
@@ -287,6 +293,8 @@ static const struct iommufd_ioctl_op iommufd_ioctl_ops[] = {
__reserved),
IOCTL_OP(IOMMU_HWPT_ALLOC, iommufd_hwpt_alloc, struct iommu_hwpt_alloc,
__reserved),
+ IOCTL_OP(IOMMU_HWPT_INVALIDATE, iommufd_hwpt_invalidate,
+ struct iommu_hwpt_invalidate, data_uptr),
IOCTL_OP(IOMMU_IOAS_ALLOC, iommufd_ioas_alloc_ioctl,
struct iommu_ioas_alloc, out_ioas_id),
IOCTL_OP(IOMMU_IOAS_ALLOW_IOVAS, iommufd_ioas_allow_iovas,
diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h
index f501add5ffe9..cb6a9ee215f4 100644
--- a/include/uapi/linux/iommufd.h
+++ b/include/uapi/linux/iommufd.h
@@ -47,6 +47,7 @@ enum {
IOMMUFD_CMD_VFIO_IOAS,
IOMMUFD_CMD_DEVICE_GET_INFO,
IOMMUFD_CMD_HWPT_ALLOC,
+ IOMMUFD_CMD_HWPT_INVALIDATE,
};

/**
@@ -377,9 +378,11 @@ struct iommu_device_info_vtd {
/**
* enum iommu_pgtbl_data_type - IOMMU Page Table User Data type
* @IOMMU_PGTBL_DATA_NONE: no user data
+ * @IOMMU_PGTBL_DATA_VTD_S1: Data for Intel VT-d stage-1 page table
*/
enum iommu_pgtbl_data_type {
IOMMU_PGTBL_DATA_NONE,
+ IOMMU_PGTBL_DATA_VTD_S1,
};

/**
@@ -495,6 +498,8 @@ struct iommu_hwpt_intel_vtd {
* +------------------------------+-------------------------------------+
* | IOMMU_PGTBL_DATA_NONE | N/A |
* +------------------------------+-------------------------------------+
+ * | IOMMU_PGTBL_DATA_VTD_S1 | struct iommu_hwpt_intel_vtd |
+ * +------------------------------+-------------------------------------+
*/
struct iommu_hwpt_alloc {
__u32 size;
@@ -562,4 +567,33 @@ struct iommu_hwpt_invalidate_intel_vtd {
__u64 granule_size;
__u64 nb_granules;
};
+
+/**
+ * struct iommu_hwpt_invalidate - ioctl(IOMMU_HWPT_INVALIDATE)
+ * @size: sizeof(struct iommu_hwpt_invalidate)
+ * @hwpt_id: HWPT ID of target hardware page table for the invalidation
+ * @data_type: One of enum iommu_pgtbl_data_type
+ * @data_len: Length of the type specific data
+ * @data_uptr: User pointer to the type specific data
+ *
+ * Invalidate the iommu cache for user-managed page table. Modifications
+ * on user-managed page table should be followed with this operation to
+ * sync the userspace with the kernel and underlying hardware. This operation
+ * is only needed by user-managed hw_pagetables, so the @data_type should
+ * never be IOMMU_PGTBL_DATA_NONE.
+ *
+ * +==============================+========================================+
+ * | @data_type | Data structure in @data_uptr |
+ * +------------------------------+----------------------------------------+
+ * | IOMMU_PGTBL_DATA_VTD_S1 | struct iommu_hwpt_invalidate_intel_vtd |
+ * +------------------------------+----------------------------------------+
+ */
+struct iommu_hwpt_invalidate {
+ __u32 size;
+ __u32 hwpt_id;
+ __u32 data_type;
+ __u32 data_len;
+ __aligned_u64 data_uptr;
+};
+#define IOMMU_HWPT_INVALIDATE _IO(IOMMUFD_TYPE, IOMMUFD_CMD_HWPT_INVALIDATE)
#endif
--
2.34.1