Merge patch series "IOMMUFD Generic interface"

Jason Gunthorpe <jgg@nvidia.com> says:

==================
iommufd is the user API to control the IOMMU subsystem as it relates to
managing IO page tables that point at user space memory.

It takes over from drivers/vfio/vfio_iommu_type1.c (aka the VFIO
container) which is the VFIO specific interface for a similar idea.

We see a broad need for extended features, some being highly IOMMU device
specific:
 - Binding iommu_domain's to PASID/SSID
 - Userspace IO page tables, for ARM, x86 and S390
 - Kernel bypassed invalidation of user page tables
 - Re-use of the KVM page table in the IOMMU
 - Dirty page tracking in the IOMMU
 - Runtime Increase/Decrease of IOPTE size
 - PRI support with faults resolved in userspace

Many of these HW features exist to support VM use cases - for instance the
combination of PASID, PRI and Userspace IO Page Tables allows an
implementation of DMA Shared Virtual Addressing (vSVA) within a
guest. Dirty tracking enables VM live migration with SRIOV devices and
PASID support allow creating "scalable IOV" devices, among other things.

As these features are fundamental to a VM platform they need to be
uniformly exposed to all the driver families that do DMA into VMs, which
is currently VFIO and VDPA.

The pre-v1 series proposed re-using the VFIO type 1 data structure,
however it was suggested that if we are doing this big update then we
should also come with an improved data structure that solves the
limitations that VFIO type1 has. Notably this addresses:

 - Multiple IOAS/'containers' and multiple domains inside a single FD

 - Single-pin operation no matter how many domains and containers use
   a page

 - A fine grained locking scheme supporting user managed concurrency for
   multi-threaded map/unmap

 - A pre-registration mechanism to optimize vIOMMU use cases by
   pre-pinning pages

 - Extended ioctl API that can manage these new objects and exposes
   domains directly to user space

 - domains are sharable between subsystems, eg VFIO and VDPA

The bulk of this code is a new data structure design to track how the
IOVAs are mapped to PFNs.

iommufd intends to be general and consumable by any driver that wants to
DMA to userspace. From a driver perspective it can largely be dropped in
in-place of iommu_attach_device() and provides a uniform full feature set
to all consumers.

As this is a larger project this series is the first step. This series
provides the iommfd "generic interface" which is designed to be suitable
for applications like DPDK and VMM flows that are not optimized to
specific HW scenarios. It is close to being a drop in replacement for the
existing VFIO type 1 and supports existing qemu based VM flows.

Several follow-on series are being prepared:

- Patches integrating with qemu in native mode:
  https://github.com/yiliu1765/qemu/commits/qemu-iommufd-6.0-rc2

- A completed integration with VFIO now exists that covers "emulated" mdev
  use cases now, and can pass testing with qemu/etc in compatability mode:
  https://github.com/jgunthorpe/linux/commits/vfio_iommufd

- A draft providing system iommu dirty tracking on top of iommufd,
  including iommu driver implementations:
  https://github.com/jpemartins/linux/commits/x86-iommufd

  This pairs with patches for providing a similar API to support VFIO-device
  tracking to give a complete vfio solution:
  https://lore.kernel.org/kvm/20220901093853.60194-1-yishaih@nvidia.com/

- Userspace page tables aka 'nested translation' for ARM and Intel iommu
  drivers:
  https://github.com/nicolinc/iommufd/commits/iommufd_nesting

- "device centric" vfio series to expose the vfio_device FD directly as a
  normal cdev, and provide an extended API allowing dynamically changing
  the IOAS binding:
  https://github.com/yiliu1765/iommufd/commits/iommufd-v6.0-rc2-nesting-0901

- Drafts for PASID and PRI interfaces are included above as well

Overall enough work is done now to show the merit of the new API design
and at least draft solutions to many of the main problems.

Several people have contributed directly to this work: Eric Auger, Joao
Martins, Kevin Tian, Lu Baolu, Nicolin Chen, Yi L Liu. Many more have
participated in the discussions that lead here, and provided ideas. Thanks
to all!

The v1/v2 iommufd series has been used to guide a large amount of preparatory
work that has now been merged. The general theme is to organize things in
a way that makes injecting iommufd natural:

 - VFIO live migration support with mlx5 and hisi_acc drivers.
   These series need a dirty tracking solution to be really usable.
   https://lore.kernel.org/kvm/20220224142024.147653-1-yishaih@nvidia.com/
   https://lore.kernel.org/kvm/20220308184902.2242-1-shameerali.kolothum.thodi@huawei.com/

 - Significantly rework the VFIO gvt mdev and remove struct
   mdev_parent_ops
   https://lore.kernel.org/lkml/20220411141403.86980-1-hch@lst.de/

 - Rework how PCIe no-snoop blocking works
   https://lore.kernel.org/kvm/0-v3-2cf356649677+a32-intel_no_snoop_jgg@nvidia.com/

 - Consolidate dma ownership into the iommu core code
   https://lore.kernel.org/linux-iommu/20220418005000.897664-1-baolu.lu@linux.intel.com/

 - Make all vfio driver interfaces use struct vfio_device consistently
   https://lore.kernel.org/kvm/0-v4-8045e76bf00b+13d-vfio_mdev_no_group_jgg@nvidia.com/

 - Remove the vfio_group from the kvm/vfio interface
   https://lore.kernel.org/kvm/0-v3-f7729924a7ea+25e33-vfio_kvm_no_group_jgg@nvidia.com/

 - Simplify locking in vfio
   https://lore.kernel.org/kvm/0-v2-d035a1842d81+1bf-vfio_group_locking_jgg@nvidia.com/

 - Remove the vfio notifiter scheme that faces drivers
   https://lore.kernel.org/kvm/0-v4-681e038e30fd+78-vfio_unmap_notif_jgg@nvidia.com/

 - Improve the driver facing API for vfio pin/unpin pages to make the
   presence of struct page clear
   https://lore.kernel.org/kvm/20220723020256.30081-1-nicolinc@nvidia.com/

 - Clean up in the Intel IOMMU driver
   https://lore.kernel.org/linux-iommu/20220301020159.633356-1-baolu.lu@linux.intel.com/
   https://lore.kernel.org/linux-iommu/20220510023407.2759143-1-baolu.lu@linux.intel.com/
   https://lore.kernel.org/linux-iommu/20220514014322.2927339-1-baolu.lu@linux.intel.com/
   https://lore.kernel.org/linux-iommu/20220706025524.2904370-1-baolu.lu@linux.intel.com/
   https://lore.kernel.org/linux-iommu/20220702015610.2849494-1-baolu.lu@linux.intel.com/

 - Rework s390 vfio drivers
   https://lore.kernel.org/kvm/20220707135737.720765-1-farman@linux.ibm.com/

 - Normalize vfio ioctl handling
   https://lore.kernel.org/kvm/0-v2-0f9e632d54fb+d6-vfio_ioctl_split_jgg@nvidia.com/

 - VFIO API for dirty tracking (aka dma logging) managed inside a PCI
   device, with mlx5 implementation
   https://lore.kernel.org/kvm/20220901093853.60194-1-yishaih@nvidia.com

 - Introduce a struct device sysfs presence for struct vfio_device
   https://lore.kernel.org/kvm/20220901143747.32858-1-kevin.tian@intel.com/

 - Complete restructuring the vfio mdev model
   https://lore.kernel.org/kvm/20220822062208.152745-1-hch@lst.de/

 - Isolate VFIO container code in preperation for iommufd to provide an
   alternative implementation of it all
   https://lore.kernel.org/kvm/0-v1-a805b607f1fb+17b-vfio_container_split_jgg@nvidia.com

 - Simplify and consolidate iommu_domain/device compatability checking
   https://lore.kernel.org/linux-iommu/cover.1666042872.git.nicolinc@nvidia.com/

 - Align iommu SVA support with the domain-centric model
   https://lore.kernel.org/all/20221031005917.45690-1-baolu.lu@linux.intel.com/

This is about 233 patches applied since March, thank you to everyone
involved in all this work!

Currently there are a number of supporting series still in progress:

 - DMABUF exporter support for VFIO to allow PCI P2P with VFIO
   https://lore.kernel.org/r/0-v2-472615b3877e+28f7-vfio_dma_buf_jgg@nvidia.com

 - Start to provide iommu_domain ops for POWER
   https://lore.kernel.org/all/20220714081822.3717693-1-aik@ozlabs.ru/

However, these are not necessary for this series to advance.

Syzkaller coverage has been merged and is now running in the syzbot
environment on linux-next:

https://github.com/google/syzkaller/pull/3515
https://github.com/google/syzkaller/pull/3521
==================

Link: https://lore.kernel.org/r/0-v6-a196d26f289e+11787-iommufd_jgg@nvidia.com
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

4 files changed, 174 insertions, 1 deletions

diff --git a/include/linux/interval_tree.h b/include/linux/interval_tree.h
index 288c26f50732..2b8026a39906 100644
--- a/include/linux/interval_tree.h
+++ b/include/linux/interval_tree.h
@@ -27,4 +27,62 @@ extern struct interval_tree_node *
 interval_tree_iter_next(struct interval_tree_node *node,
 			unsigned long start, unsigned long last);
 
+/**
+ * struct interval_tree_span_iter - Find used and unused spans.
+ * @start_hole: Start of an interval for a hole when is_hole == 1
+ * @last_hole: Inclusive end of an interval for a hole when is_hole == 1
+ * @start_used: Start of a used interval when is_hole == 0
+ * @last_used: Inclusive end of a used interval when is_hole == 0
+ * @is_hole: 0 == used, 1 == is_hole, -1 == done iteration
+ *
+ * This iterator travels over spans in an interval tree. It does not return
+ * nodes but classifies each span as either a hole, where no nodes intersect, or
+ * a used, which is fully covered by nodes. Each iteration step toggles between
+ * hole and used until the entire range is covered. The returned spans always
+ * fully cover the requested range.
+ *
+ * The iterator is greedy, it always returns the largest hole or used possible,
+ * consolidating all consecutive nodes.
+ *
+ * Use interval_tree_span_iter_done() to detect end of iteration.
+ */
+struct interval_tree_span_iter {
+	/* private: not for use by the caller */
+	struct interval_tree_node *nodes[2];
+	unsigned long first_index;
+	unsigned long last_index;
+
+	/* public: */
+	union {
+		unsigned long start_hole;
+		unsigned long start_used;
+	};
+	union {
+		unsigned long last_hole;
+		unsigned long last_used;
+	};
+	int is_hole;
+};
+
+void interval_tree_span_iter_first(struct interval_tree_span_iter *state,
+				   struct rb_root_cached *itree,
+				   unsigned long first_index,
+				   unsigned long last_index);
+void interval_tree_span_iter_advance(struct interval_tree_span_iter *iter,
+				     struct rb_root_cached *itree,
+				     unsigned long new_index);
+void interval_tree_span_iter_next(struct interval_tree_span_iter *state);
+
+static inline bool
+interval_tree_span_iter_done(struct interval_tree_span_iter *state)
+{
+	return state->is_hole == -1;
+}
+
+#define interval_tree_for_each_span(span, itree, first_index, last_index)      \
+	for (interval_tree_span_iter_first(span, itree,                        \
+					   first_index, last_index);           \
+	     !interval_tree_span_iter_done(span);                              \
+	     interval_tree_span_iter_next(span))
+
 #endif	/* _LINUX_INTERVAL_TREE_H */
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 68d7d304cdb7..1690c334e516 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -124,6 +124,11 @@ enum iommu_cap {
 	IOMMU_CAP_NOEXEC,		/* IOMMU_NOEXEC flag */
 	IOMMU_CAP_PRE_BOOT_PROTECTION,	/* Firmware says it used the IOMMU for
 					   DMA protection and we should too */
+	/*
+	 * Per-device flag indicating if enforce_cache_coherency() will work on
+	 * this device.
+	 */
+	IOMMU_CAP_ENFORCE_CACHE_COHERENCY,
 };
 
 /* These are the possible reserved region types */
@@ -702,6 +707,9 @@ int iommu_group_claim_dma_owner(struct iommu_group *group, void *owner);
 void iommu_group_release_dma_owner(struct iommu_group *group);
 bool iommu_group_dma_owner_claimed(struct iommu_group *group);
 
+int iommu_device_claim_dma_owner(struct device *dev, void *owner);
+void iommu_device_release_dma_owner(struct device *dev);
+
 struct iommu_domain *iommu_sva_domain_alloc(struct device *dev,
 					    struct mm_struct *mm);
 int iommu_attach_device_pasid(struct iommu_domain *domain,
@@ -1059,6 +1067,15 @@ static inline bool iommu_group_dma_owner_claimed(struct iommu_group *group)
 	return false;
 }
 
+static inline void iommu_device_release_dma_owner(struct device *dev)
+{
+}
+
+static inline int iommu_device_claim_dma_owner(struct device *dev, void *owner)
+{
+	return -ENODEV;
+}
+
 static inline struct iommu_domain *
 iommu_sva_domain_alloc(struct device *dev, struct mm_struct *mm)
 {
diff --git a/include/linux/iommufd.h b/include/linux/iommufd.h
new file mode 100644
index 000000000000..650d45629647
--- /dev/null
+++ b/include/linux/iommufd.h
@@ -0,0 +1,98 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2021 Intel Corporation
+ * Copyright (c) 2021-2022, NVIDIA CORPORATION & AFFILIATES
+ */
+#ifndef __LINUX_IOMMUFD_H
+#define __LINUX_IOMMUFD_H
+
+#include <linux/types.h>
+#include <linux/errno.h>
+#include <linux/err.h>
+
+struct device;
+struct iommufd_device;
+struct page;
+struct iommufd_ctx;
+struct iommufd_access;
+struct file;
+
+struct iommufd_device *iommufd_device_bind(struct iommufd_ctx *ictx,
+					   struct device *dev, u32 *id);
+void iommufd_device_unbind(struct iommufd_device *idev);
+
+int iommufd_device_attach(struct iommufd_device *idev, u32 *pt_id);
+void iommufd_device_detach(struct iommufd_device *idev);
+
+struct iommufd_access_ops {
+	u8 needs_pin_pages : 1;
+	void (*unmap)(void *data, unsigned long iova, unsigned long length);
+};
+
+enum {
+	IOMMUFD_ACCESS_RW_READ = 0,
+	IOMMUFD_ACCESS_RW_WRITE = 1 << 0,
+	/* Set if the caller is in a kthread then rw will use kthread_use_mm() */
+	IOMMUFD_ACCESS_RW_KTHREAD = 1 << 1,
+
+	/* Only for use by selftest */
+	__IOMMUFD_ACCESS_RW_SLOW_PATH = 1 << 2,
+};
+
+struct iommufd_access *
+iommufd_access_create(struct iommufd_ctx *ictx, u32 ioas_id,
+		      const struct iommufd_access_ops *ops, void *data);
+void iommufd_access_destroy(struct iommufd_access *access);
+
+void iommufd_ctx_get(struct iommufd_ctx *ictx);
+
+#if IS_ENABLED(CONFIG_IOMMUFD)
+struct iommufd_ctx *iommufd_ctx_from_file(struct file *file);
+void iommufd_ctx_put(struct iommufd_ctx *ictx);
+
+int iommufd_access_pin_pages(struct iommufd_access *access, unsigned long iova,
+			     unsigned long length, struct page **out_pages,
+			     unsigned int flags);
+void iommufd_access_unpin_pages(struct iommufd_access *access,
+				unsigned long iova, unsigned long length);
+int iommufd_access_rw(struct iommufd_access *access, unsigned long iova,
+		      void *data, size_t len, unsigned int flags);
+int iommufd_vfio_compat_ioas_id(struct iommufd_ctx *ictx, u32 *out_ioas_id);
+#else /* !CONFIG_IOMMUFD */
+static inline struct iommufd_ctx *iommufd_ctx_from_file(struct file *file)
+{
+	return ERR_PTR(-EOPNOTSUPP);
+}
+
+static inline void iommufd_ctx_put(struct iommufd_ctx *ictx)
+{
+}
+
+static inline int iommufd_access_pin_pages(struct iommufd_access *access,
+					   unsigned long iova,
+					   unsigned long length,
+					   struct page **out_pages,
+					   unsigned int flags)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline void iommufd_access_unpin_pages(struct iommufd_access *access,
+					      unsigned long iova,
+					      unsigned long length)
+{
+}
+
+static inline int iommufd_access_rw(struct iommufd_access *access, unsigned long iova,
+		      void *data, size_t len, unsigned int flags)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int iommufd_vfio_compat_ioas_id(struct iommufd_ctx *ictx,
+					      u32 *out_ioas_id)
+{
+	return -EOPNOTSUPP;
+}
+#endif /* CONFIG_IOMMUFD */
+#endif
diff --git a/include/linux/sched/user.h b/include/linux/sched/user.h
index f054d0360a75..4cc52698e214 100644
--- a/include/linux/sched/user.h
+++ b/include/linux/sched/user.h
@@ -25,7 +25,7 @@ struct user_struct {
 
 #if defined(CONFIG_PERF_EVENTS) || defined(CONFIG_BPF_SYSCALL) || \
 	defined(CONFIG_NET) || defined(CONFIG_IO_URING) || \
-	defined(CONFIG_VFIO_PCI_ZDEV_KVM)
+	defined(CONFIG_VFIO_PCI_ZDEV_KVM) || IS_ENABLED(CONFIG_IOMMUFD)
 	atomic_long_t locked_vm;
 #endif
 #ifdef CONFIG_WATCH_QUEUE