iommufd: IOCTLs for the io_pagetable

Connect the IOAS to its IOCTL interface. This exposes most of the
functionality in the io_pagetable to userspace.

This is intended to be the core of the generic interface that IOMMUFD will
provide. Every IOMMU driver should be able to implement an iommu_domain
that is compatible with this generic mechanism.

It is also designed to be easy to use for simple non virtual machine
monitor users, like DPDK:
 - Universal simple support for all IOMMUs (no PPC special path)
 - An IOVA allocator that considers the aperture and the allowed/reserved
   ranges
 - io_pagetable allows any number of iommu_domains to be connected to the
   IOAS
 - Automatic allocation and re-use of iommu_domains

Along with room in the design to add non-generic features to cater to
specific HW functionality.

Link: https://lore.kernel.org/r/11-v6-a196d26f289e+11787-iommufd_jgg@nvidia.com
Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Tested-by: Yi Liu <yi.l.liu@intel.com>
Tested-by: Lixiao Yang <lixiao.yang@intel.com>
Tested-by: Matthew Rosato <mjrosato@linux.ibm.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

4 files changed, 474 insertions, 0 deletions

diff --git a/drivers/iommu/iommufd/Makefile b/drivers/iommu/iommufd/Makefile
index b66a8c47ff55..2b4f36f1b72f 100644
--- a/drivers/iommu/iommufd/Makefile
+++ b/drivers/iommu/iommufd/Makefile
@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0-only
 iommufd-y := \
 	io_pagetable.o \
+	ioas.o \
 	main.o \
 	pages.o
 
diff --git a/drivers/iommu/iommufd/ioas.c b/drivers/iommu/iommufd/ioas.c
new file mode 100644
index 000000000000..6ff97dafc891
--- /dev/null
+++ b/drivers/iommu/iommufd/ioas.c
@@ -0,0 +1,392 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2021-2022, NVIDIA CORPORATION & AFFILIATES
+ */
+#include <linux/interval_tree.h>
+#include <linux/iommufd.h>
+#include <linux/iommu.h>
+#include <uapi/linux/iommufd.h>
+
+#include "io_pagetable.h"
+
+void iommufd_ioas_destroy(struct iommufd_object *obj)
+{
+	struct iommufd_ioas *ioas = container_of(obj, struct iommufd_ioas, obj);
+	int rc;
+
+	rc = iopt_unmap_all(&ioas->iopt, NULL);
+	WARN_ON(rc && rc != -ENOENT);
+	iopt_destroy_table(&ioas->iopt);
+}
+
+struct iommufd_ioas *iommufd_ioas_alloc(struct iommufd_ctx *ictx)
+{
+	struct iommufd_ioas *ioas;
+
+	ioas = iommufd_object_alloc(ictx, ioas, IOMMUFD_OBJ_IOAS);
+	if (IS_ERR(ioas))
+		return ioas;
+
+	iopt_init_table(&ioas->iopt);
+	return ioas;
+}
+
+int iommufd_ioas_alloc_ioctl(struct iommufd_ucmd *ucmd)
+{
+	struct iommu_ioas_alloc *cmd = ucmd->cmd;
+	struct iommufd_ioas *ioas;
+	int rc;
+
+	if (cmd->flags)
+		return -EOPNOTSUPP;
+
+	ioas = iommufd_ioas_alloc(ucmd->ictx);
+	if (IS_ERR(ioas))
+		return PTR_ERR(ioas);
+
+	cmd->out_ioas_id = ioas->obj.id;
+	rc = iommufd_ucmd_respond(ucmd, sizeof(*cmd));
+	if (rc)
+		goto out_table;
+	iommufd_object_finalize(ucmd->ictx, &ioas->obj);
+	return 0;
+
+out_table:
+	iommufd_object_abort_and_destroy(ucmd->ictx, &ioas->obj);
+	return rc;
+}
+
+int iommufd_ioas_iova_ranges(struct iommufd_ucmd *ucmd)
+{
+	struct iommu_iova_range __user *ranges;
+	struct iommu_ioas_iova_ranges *cmd = ucmd->cmd;
+	struct iommufd_ioas *ioas;
+	struct interval_tree_span_iter span;
+	u32 max_iovas;
+	int rc;
+
+	if (cmd->__reserved)
+		return -EOPNOTSUPP;
+
+	ioas = iommufd_get_ioas(ucmd, cmd->ioas_id);
+	if (IS_ERR(ioas))
+		return PTR_ERR(ioas);
+
+	down_read(&ioas->iopt.iova_rwsem);
+	max_iovas = cmd->num_iovas;
+	ranges = u64_to_user_ptr(cmd->allowed_iovas);
+	cmd->num_iovas = 0;
+	cmd->out_iova_alignment = ioas->iopt.iova_alignment;
+	interval_tree_for_each_span(&span, &ioas->iopt.reserved_itree, 0,
+				    ULONG_MAX) {
+		if (!span.is_hole)
+			continue;
+		if (cmd->num_iovas < max_iovas) {
+			struct iommu_iova_range elm = {
+				.start = span.start_hole,
+				.last = span.last_hole,
+			};
+
+			if (copy_to_user(&ranges[cmd->num_iovas], &elm,
+					 sizeof(elm))) {
+				rc = -EFAULT;
+				goto out_put;
+			}
+		}
+		cmd->num_iovas++;
+	}
+	rc = iommufd_ucmd_respond(ucmd, sizeof(*cmd));
+	if (rc)
+		goto out_put;
+	if (cmd->num_iovas > max_iovas)
+		rc = -EMSGSIZE;
+out_put:
+	up_read(&ioas->iopt.iova_rwsem);
+	iommufd_put_object(&ioas->obj);
+	return rc;
+}
+
+static int iommufd_ioas_load_iovas(struct rb_root_cached *itree,
+				   struct iommu_iova_range __user *ranges,
+				   u32 num)
+{
+	u32 i;
+
+	for (i = 0; i != num; i++) {
+		struct iommu_iova_range range;
+		struct iopt_allowed *allowed;
+
+		if (copy_from_user(&range, ranges + i, sizeof(range)))
+			return -EFAULT;
+
+		if (range.start >= range.last)
+			return -EINVAL;
+
+		if (interval_tree_iter_first(itree, range.start, range.last))
+			return -EINVAL;
+
+		allowed = kzalloc(sizeof(*allowed), GFP_KERNEL_ACCOUNT);
+		if (!allowed)
+			return -ENOMEM;
+		allowed->node.start = range.start;
+		allowed->node.last = range.last;
+
+		interval_tree_insert(&allowed->node, itree);
+	}
+	return 0;
+}
+
+int iommufd_ioas_allow_iovas(struct iommufd_ucmd *ucmd)
+{
+	struct iommu_ioas_allow_iovas *cmd = ucmd->cmd;
+	struct rb_root_cached allowed_iova = RB_ROOT_CACHED;
+	struct interval_tree_node *node;
+	struct iommufd_ioas *ioas;
+	struct io_pagetable *iopt;
+	int rc = 0;
+
+	if (cmd->__reserved)
+		return -EOPNOTSUPP;
+
+	ioas = iommufd_get_ioas(ucmd, cmd->ioas_id);
+	if (IS_ERR(ioas))
+		return PTR_ERR(ioas);
+	iopt = &ioas->iopt;
+
+	rc = iommufd_ioas_load_iovas(&allowed_iova,
+				     u64_to_user_ptr(cmd->allowed_iovas),
+				     cmd->num_iovas);
+	if (rc)
+		goto out_free;
+
+	/*
+	 * We want the allowed tree update to be atomic, so we have to keep the
+	 * original nodes around, and keep track of the new nodes as we allocate
+	 * memory for them. The simplest solution is to have a new/old tree and
+	 * then swap new for old. On success we free the old tree, on failure we
+	 * free the new tree.
+	 */
+	rc = iopt_set_allow_iova(iopt, &allowed_iova);
+out_free:
+	while ((node = interval_tree_iter_first(&allowed_iova, 0, ULONG_MAX))) {
+		interval_tree_remove(node, &allowed_iova);
+		kfree(container_of(node, struct iopt_allowed, node));
+	}
+	iommufd_put_object(&ioas->obj);
+	return rc;
+}
+
+static int conv_iommu_prot(u32 map_flags)
+{
+	/*
+	 * We provide no manual cache coherency ioctls to userspace and most
+	 * architectures make the CPU ops for cache flushing privileged.
+	 * Therefore we require the underlying IOMMU to support CPU coherent
+	 * operation. Support for IOMMU_CACHE is enforced by the
+	 * IOMMU_CAP_CACHE_COHERENCY test during bind.
+	 */
+	int iommu_prot = IOMMU_CACHE;
+
+	if (map_flags & IOMMU_IOAS_MAP_WRITEABLE)
+		iommu_prot |= IOMMU_WRITE;
+	if (map_flags & IOMMU_IOAS_MAP_READABLE)
+		iommu_prot |= IOMMU_READ;
+	return iommu_prot;
+}
+
+int iommufd_ioas_map(struct iommufd_ucmd *ucmd)
+{
+	struct iommu_ioas_map *cmd = ucmd->cmd;
+	unsigned long iova = cmd->iova;
+	struct iommufd_ioas *ioas;
+	unsigned int flags = 0;
+	int rc;
+
+	if ((cmd->flags &
+	     ~(IOMMU_IOAS_MAP_FIXED_IOVA | IOMMU_IOAS_MAP_WRITEABLE |
+	       IOMMU_IOAS_MAP_READABLE)) ||
+	    cmd->__reserved)
+		return -EOPNOTSUPP;
+	if (cmd->iova >= ULONG_MAX || cmd->length >= ULONG_MAX)
+		return -EOVERFLOW;
+
+	ioas = iommufd_get_ioas(ucmd, cmd->ioas_id);
+	if (IS_ERR(ioas))
+		return PTR_ERR(ioas);
+
+	if (!(cmd->flags & IOMMU_IOAS_MAP_FIXED_IOVA))
+		flags = IOPT_ALLOC_IOVA;
+	rc = iopt_map_user_pages(ucmd->ictx, &ioas->iopt, &iova,
+				 u64_to_user_ptr(cmd->user_va), cmd->length,
+				 conv_iommu_prot(cmd->flags), flags);
+	if (rc)
+		goto out_put;
+
+	cmd->iova = iova;
+	rc = iommufd_ucmd_respond(ucmd, sizeof(*cmd));
+out_put:
+	iommufd_put_object(&ioas->obj);
+	return rc;
+}
+
+int iommufd_ioas_copy(struct iommufd_ucmd *ucmd)
+{
+	struct iommu_ioas_copy *cmd = ucmd->cmd;
+	struct iommufd_ioas *src_ioas;
+	struct iommufd_ioas *dst_ioas;
+	unsigned int flags = 0;
+	LIST_HEAD(pages_list);
+	unsigned long iova;
+	int rc;
+
+	if ((cmd->flags &
+	     ~(IOMMU_IOAS_MAP_FIXED_IOVA | IOMMU_IOAS_MAP_WRITEABLE |
+	       IOMMU_IOAS_MAP_READABLE)))
+		return -EOPNOTSUPP;
+	if (cmd->length >= ULONG_MAX || cmd->src_iova >= ULONG_MAX ||
+	    cmd->dst_iova >= ULONG_MAX)
+		return -EOVERFLOW;
+
+	src_ioas = iommufd_get_ioas(ucmd, cmd->src_ioas_id);
+	if (IS_ERR(src_ioas))
+		return PTR_ERR(src_ioas);
+	rc = iopt_get_pages(&src_ioas->iopt, cmd->src_iova, cmd->length,
+			    &pages_list);
+	iommufd_put_object(&src_ioas->obj);
+	if (rc)
+		return rc;
+
+	dst_ioas = iommufd_get_ioas(ucmd, cmd->dst_ioas_id);
+	if (IS_ERR(dst_ioas)) {
+		rc = PTR_ERR(dst_ioas);
+		goto out_pages;
+	}
+
+	if (!(cmd->flags & IOMMU_IOAS_MAP_FIXED_IOVA))
+		flags = IOPT_ALLOC_IOVA;
+	iova = cmd->dst_iova;
+	rc = iopt_map_pages(&dst_ioas->iopt, &pages_list, cmd->length, &iova,
+			    conv_iommu_prot(cmd->flags), flags);
+	if (rc)
+		goto out_put_dst;
+
+	cmd->dst_iova = iova;
+	rc = iommufd_ucmd_respond(ucmd, sizeof(*cmd));
+out_put_dst:
+	iommufd_put_object(&dst_ioas->obj);
+out_pages:
+	iopt_free_pages_list(&pages_list);
+	return rc;
+}
+
+int iommufd_ioas_unmap(struct iommufd_ucmd *ucmd)
+{
+	struct iommu_ioas_unmap *cmd = ucmd->cmd;
+	struct iommufd_ioas *ioas;
+	unsigned long unmapped = 0;
+	int rc;
+
+	ioas = iommufd_get_ioas(ucmd, cmd->ioas_id);
+	if (IS_ERR(ioas))
+		return PTR_ERR(ioas);
+
+	if (cmd->iova == 0 && cmd->length == U64_MAX) {
+		rc = iopt_unmap_all(&ioas->iopt, &unmapped);
+		if (rc)
+			goto out_put;
+	} else {
+		if (cmd->iova >= ULONG_MAX || cmd->length >= ULONG_MAX) {
+			rc = -EOVERFLOW;
+			goto out_put;
+		}
+		rc = iopt_unmap_iova(&ioas->iopt, cmd->iova, cmd->length,
+				     &unmapped);
+		if (rc)
+			goto out_put;
+	}
+
+	cmd->length = unmapped;
+	rc = iommufd_ucmd_respond(ucmd, sizeof(*cmd));
+
+out_put:
+	iommufd_put_object(&ioas->obj);
+	return rc;
+}
+
+int iommufd_option_rlimit_mode(struct iommu_option *cmd,
+			       struct iommufd_ctx *ictx)
+{
+	if (cmd->object_id)
+		return -EOPNOTSUPP;
+
+	if (cmd->op == IOMMU_OPTION_OP_GET) {
+		cmd->val64 = ictx->account_mode == IOPT_PAGES_ACCOUNT_MM;
+		return 0;
+	}
+	if (cmd->op == IOMMU_OPTION_OP_SET) {
+		int rc = 0;
+
+		if (!capable(CAP_SYS_RESOURCE))
+			return -EPERM;
+
+		xa_lock(&ictx->objects);
+		if (!xa_empty(&ictx->objects)) {
+			rc = -EBUSY;
+		} else {
+			if (cmd->val64 == 0)
+				ictx->account_mode = IOPT_PAGES_ACCOUNT_USER;
+			else if (cmd->val64 == 1)
+				ictx->account_mode = IOPT_PAGES_ACCOUNT_MM;
+			else
+				rc = -EINVAL;
+		}
+		xa_unlock(&ictx->objects);
+
+		return rc;
+	}
+	return -EOPNOTSUPP;
+}
+
+static int iommufd_ioas_option_huge_pages(struct iommu_option *cmd,
+					  struct iommufd_ioas *ioas)
+{
+	if (cmd->op == IOMMU_OPTION_OP_GET) {
+		cmd->val64 = !ioas->iopt.disable_large_pages;
+		return 0;
+	}
+	if (cmd->op == IOMMU_OPTION_OP_SET) {
+		if (cmd->val64 == 0)
+			return iopt_disable_large_pages(&ioas->iopt);
+		if (cmd->val64 == 1) {
+			iopt_enable_large_pages(&ioas->iopt);
+			return 0;
+		}
+		return -EINVAL;
+	}
+	return -EOPNOTSUPP;
+}
+
+int iommufd_ioas_option(struct iommufd_ucmd *ucmd)
+{
+	struct iommu_option *cmd = ucmd->cmd;
+	struct iommufd_ioas *ioas;
+	int rc = 0;
+
+	if (cmd->__reserved)
+		return -EOPNOTSUPP;
+
+	ioas = iommufd_get_ioas(ucmd, cmd->object_id);
+	if (IS_ERR(ioas))
+		return PTR_ERR(ioas);
+
+	switch (cmd->option_id) {
+	case IOMMU_OPTION_HUGE_PAGES:
+		rc = iommufd_ioas_option_huge_pages(cmd, ioas);
+		break;
+	default:
+		rc = -EOPNOTSUPP;
+	}
+
+	iommufd_put_object(&ioas->obj);
+	return rc;
+}
diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h
index f7ab6c6edafd..1a13c54a8def 100644
--- a/drivers/iommu/iommufd/iommufd_private.h
+++ b/drivers/iommu/iommufd/iommufd_private.h
@@ -11,6 +11,7 @@
 
 struct iommu_domain;
 struct iommu_group;
+struct iommu_option;
 
 struct iommufd_ctx {
 	struct file *file;
@@ -102,6 +103,7 @@ static inline int iommufd_ucmd_respond(struct iommufd_ucmd *ucmd,
 enum iommufd_object_type {
 	IOMMUFD_OBJ_NONE,
 	IOMMUFD_OBJ_ANY = IOMMUFD_OBJ_NONE,
+	IOMMUFD_OBJ_IOAS,
 };
 
 /* Base struct for all objects with a userspace ID handle. */
@@ -174,6 +176,37 @@ struct iommufd_object *_iommufd_object_alloc(struct iommufd_ctx *ictx,
 			     type),                                            \
 		     typeof(*(ptr)), obj)
 
+/*
+ * The IO Address Space (IOAS) pagetable is a virtual page table backed by the
+ * io_pagetable object. It is a user controlled mapping of IOVA -> PFNs. The
+ * mapping is copied into all of the associated domains and made available to
+ * in-kernel users.
+ */
+struct iommufd_ioas {
+	struct iommufd_object obj;
+	struct io_pagetable iopt;
+};
+
+static inline struct iommufd_ioas *iommufd_get_ioas(struct iommufd_ucmd *ucmd,
+						    u32 id)
+{
+	return container_of(iommufd_get_object(ucmd->ictx, id,
+					       IOMMUFD_OBJ_IOAS),
+			    struct iommufd_ioas, obj);
+}
+
+struct iommufd_ioas *iommufd_ioas_alloc(struct iommufd_ctx *ictx);
+int iommufd_ioas_alloc_ioctl(struct iommufd_ucmd *ucmd);
+void iommufd_ioas_destroy(struct iommufd_object *obj);
+int iommufd_ioas_iova_ranges(struct iommufd_ucmd *ucmd);
+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_ioas_option(struct iommufd_ucmd *ucmd);
+int iommufd_option_rlimit_mode(struct iommu_option *cmd,
+			       struct iommufd_ctx *ictx);
+
 struct iommufd_access {
 	unsigned long iova_alignment;
 	u32 iopt_access_list_id;
diff --git a/drivers/iommu/iommufd/main.c b/drivers/iommu/iommufd/main.c
index dfbc68b97506..1c0a1f499378 100644
--- a/drivers/iommu/iommufd/main.c
+++ b/drivers/iommu/iommufd/main.c
@@ -204,8 +204,39 @@ static int iommufd_fops_release(struct inode *inode, struct file *filp)
 	return 0;
 }
 
+static int iommufd_option(struct iommufd_ucmd *ucmd)
+{
+	struct iommu_option *cmd = ucmd->cmd;
+	int rc;
+
+	if (cmd->__reserved)
+		return -EOPNOTSUPP;
+
+	switch (cmd->option_id) {
+	case IOMMU_OPTION_RLIMIT_MODE:
+		rc = iommufd_option_rlimit_mode(cmd, ucmd->ictx);
+		break;
+	case IOMMU_OPTION_HUGE_PAGES:
+		rc = iommufd_ioas_option(ucmd);
+		break;
+	default:
+		return -EOPNOTSUPP;
+	}
+	if (rc)
+		return rc;
+	if (copy_to_user(&((struct iommu_option __user *)ucmd->ubuffer)->val64,
+			 &cmd->val64, sizeof(cmd->val64)))
+		return -EFAULT;
+	return 0;
+}
+
 union ucmd_buffer {
 	struct iommu_destroy destroy;
+	struct iommu_ioas_alloc alloc;
+	struct iommu_ioas_allow_iovas allow_iovas;
+	struct iommu_ioas_iova_ranges iova_ranges;
+	struct iommu_ioas_map map;
+	struct iommu_ioas_unmap unmap;
 };
 
 struct iommufd_ioctl_op {
@@ -226,6 +257,20 @@ struct iommufd_ioctl_op {
 	}
 static const struct iommufd_ioctl_op iommufd_ioctl_ops[] = {
 	IOCTL_OP(IOMMU_DESTROY, iommufd_destroy, struct iommu_destroy, id),
+	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,
+		 struct iommu_ioas_allow_iovas, allowed_iovas),
+	IOCTL_OP(IOMMU_IOAS_COPY, iommufd_ioas_copy, struct iommu_ioas_copy,
+		 src_iova),
+	IOCTL_OP(IOMMU_IOAS_IOVA_RANGES, iommufd_ioas_iova_ranges,
+		 struct iommu_ioas_iova_ranges, out_iova_alignment),
+	IOCTL_OP(IOMMU_IOAS_MAP, iommufd_ioas_map, struct iommu_ioas_map,
+		 iova),
+	IOCTL_OP(IOMMU_IOAS_UNMAP, iommufd_ioas_unmap, struct iommu_ioas_unmap,
+		 length),
+	IOCTL_OP(IOMMU_OPTION, iommufd_option, struct iommu_option,
+		 val64),
 };
 
 static long iommufd_fops_ioctl(struct file *filp, unsigned int cmd,
@@ -312,6 +357,9 @@ void iommufd_ctx_put(struct iommufd_ctx *ictx)
 EXPORT_SYMBOL_NS_GPL(iommufd_ctx_put, IOMMUFD);
 
 static const struct iommufd_object_ops iommufd_object_ops[] = {
+	[IOMMUFD_OBJ_IOAS] = {
+		.destroy = iommufd_ioas_destroy,
+	},
 };
 
 static struct miscdevice iommu_misc_dev = {