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author | 2023-02-21 18:24:12 -0800 | |
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committer | 2023-02-21 18:24:12 -0800 | |
commit | 5b7c4cabbb65f5c469464da6c5f614cbd7f730f2 (patch) | |
tree | cc5c2d0a898769fd59549594fedb3ee6f84e59a0 /Documentation/userspace-api/iommu.rst | |
download | linux-5b7c4cabbb65f5c469464da6c5f614cbd7f730f2.tar.gz linux-5b7c4cabbb65f5c469464da6c5f614cbd7f730f2.zip |
Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-nextgrafted
Pull networking updates from Jakub Kicinski:
"Core:
- Add dedicated kmem_cache for typical/small skb->head, avoid having
to access struct page at kfree time, and improve memory use.
- Introduce sysctl to set default RPS configuration for new netdevs.
- Define Netlink protocol specification format which can be used to
describe messages used by each family and auto-generate parsers.
Add tools for generating kernel data structures and uAPI headers.
- Expose all net/core sysctls inside netns.
- Remove 4s sleep in netpoll if carrier is instantly detected on
boot.
- Add configurable limit of MDB entries per port, and port-vlan.
- Continue populating drop reasons throughout the stack.
- Retire a handful of legacy Qdiscs and classifiers.
Protocols:
- Support IPv4 big TCP (TSO frames larger than 64kB).
- Add IP_LOCAL_PORT_RANGE socket option, to control local port range
on socket by socket basis.
- Track and report in procfs number of MPTCP sockets used.
- Support mixing IPv4 and IPv6 flows in the in-kernel MPTCP path
manager.
- IPv6: don't check net.ipv6.route.max_size and rely on garbage
collection to free memory (similarly to IPv4).
- Support Penultimate Segment Pop (PSP) flavor in SRv6 (RFC8986).
- ICMP: add per-rate limit counters.
- Add support for user scanning requests in ieee802154.
- Remove static WEP support.
- Support minimal Wi-Fi 7 Extremely High Throughput (EHT) rate
reporting.
- WiFi 7 EHT channel puncturing support (client & AP).
BPF:
- Add a rbtree data structure following the "next-gen data structure"
precedent set by recently added linked list, that is, by using
kfunc + kptr instead of adding a new BPF map type.
- Expose XDP hints via kfuncs with initial support for RX hash and
timestamp metadata.
- Add BPF_F_NO_TUNNEL_KEY extension to bpf_skb_set_tunnel_key to
better support decap on GRE tunnel devices not operating in collect
metadata.
- Improve x86 JIT's codegen for PROBE_MEM runtime error checks.
- Remove the need for trace_printk_lock for bpf_trace_printk and
bpf_trace_vprintk helpers.
- Extend libbpf's bpf_tracing.h support for tracing arguments of
kprobes/uprobes and syscall as a special case.
- Significantly reduce the search time for module symbols by
livepatch and BPF.
- Enable cpumasks to be used as kptrs, which is useful for tracing
programs tracking which tasks end up running on which CPUs in
different time intervals.
- Add support for BPF trampoline on s390x and riscv64.
- Add capability to export the XDP features supported by the NIC.
- Add __bpf_kfunc tag for marking kernel functions as kfuncs.
- Add cgroup.memory=nobpf kernel parameter option to disable BPF
memory accounting for container environments.
Netfilter:
- Remove the CLUSTERIP target. It has been marked as obsolete for
years, and we still have WARN splats wrt races of the out-of-band
/proc interface installed by this target.
- Add 'destroy' commands to nf_tables. They are identical to the
existing 'delete' commands, but do not return an error if the
referenced object (set, chain, rule...) did not exist.
Driver API:
- Improve cpumask_local_spread() locality to help NICs set the right
IRQ affinity on AMD platforms.
- Separate C22 and C45 MDIO bus transactions more clearly.
- Introduce new DCB table to control DSCP rewrite on egress.
- Support configuration of Physical Layer Collision Avoidance (PLCA)
Reconciliation Sublayer (RS) (802.3cg-2019). Modern version of
shared medium Ethernet.
- Support for MAC Merge layer (IEEE 802.3-2018 clause 99). Allowing
preemption of low priority frames by high priority frames.
- Add support for controlling MACSec offload using netlink SET.
- Rework devlink instance refcounts to allow registration and
de-registration under the instance lock. Split the code into
multiple files, drop some of the unnecessarily granular locks and
factor out common parts of netlink operation handling.
- Add TX frame aggregation parameters (for USB drivers).
- Add a new attr TCA_EXT_WARN_MSG to report TC (offload) warning
messages with notifications for debug.
- Allow offloading of UDP NEW connections via act_ct.
- Add support for per action HW stats in TC.
- Support hardware miss to TC action (continue processing in SW from
a specific point in the action chain).
- Warn if old Wireless Extension user space interface is used with
modern cfg80211/mac80211 drivers. Do not support Wireless
Extensions for Wi-Fi 7 devices at all. Everyone should switch to
using nl80211 interface instead.
- Improve the CAN bit timing configuration. Use extack to return
error messages directly to user space, update the SJW handling,
including the definition of a new default value that will benefit
CAN-FD controllers, by increasing their oscillator tolerance.
New hardware / drivers:
- Ethernet:
- nVidia BlueField-3 support (control traffic driver)
- Ethernet support for imx93 SoCs
- Motorcomm yt8531 gigabit Ethernet PHY
- onsemi NCN26000 10BASE-T1S PHY (with support for PLCA)
- Microchip LAN8841 PHY (incl. cable diagnostics and PTP)
- Amlogic gxl MDIO mux
- WiFi:
- RealTek RTL8188EU (rtl8xxxu)
- Qualcomm Wi-Fi 7 devices (ath12k)
- CAN:
- Renesas R-Car V4H
Drivers:
- Bluetooth:
- Set Per Platform Antenna Gain (PPAG) for Intel controllers.
- Ethernet NICs:
- Intel (1G, igc):
- support TSN / Qbv / packet scheduling features of i226 model
- Intel (100G, ice):
- use GNSS subsystem instead of TTY
- multi-buffer XDP support
- extend support for GPIO pins to E823 devices
- nVidia/Mellanox:
- update the shared buffer configuration on PFC commands
- implement PTP adjphase function for HW offset control
- TC support for Geneve and GRE with VF tunnel offload
- more efficient crypto key management method
- multi-port eswitch support
- Netronome/Corigine:
- add DCB IEEE support
- support IPsec offloading for NFP3800
- Freescale/NXP (enetc):
- support XDP_REDIRECT for XDP non-linear buffers
- improve reconfig, avoid link flap and waiting for idle
- support MAC Merge layer
- Other NICs:
- sfc/ef100: add basic devlink support for ef100
- ionic: rx_push mode operation (writing descriptors via MMIO)
- bnxt: use the auxiliary bus abstraction for RDMA
- r8169: disable ASPM and reset bus in case of tx timeout
- cpsw: support QSGMII mode for J721e CPSW9G
- cpts: support pulse-per-second output
- ngbe: add an mdio bus driver
- usbnet: optimize usbnet_bh() by avoiding unnecessary queuing
- r8152: handle devices with FW with NCM support
- amd-xgbe: support 10Mbps, 2.5GbE speeds and rx-adaptation
- virtio-net: support multi buffer XDP
- virtio/vsock: replace virtio_vsock_pkt with sk_buff
- tsnep: XDP support
- Ethernet high-speed switches:
- nVidia/Mellanox (mlxsw):
- add support for latency TLV (in FW control messages)
- Microchip (sparx5):
- separate explicit and implicit traffic forwarding rules, make
the implicit rules always active
- add support for egress DSCP rewrite
- IS0 VCAP support (Ingress Classification)
- IS2 VCAP filters (protos, L3 addrs, L4 ports, flags, ToS
etc.)
- ES2 VCAP support (Egress Access Control)
- support for Per-Stream Filtering and Policing (802.1Q,
8.6.5.1)
- Ethernet embedded switches:
- Marvell (mv88e6xxx):
- add MAB (port auth) offload support
- enable PTP receive for mv88e6390
- NXP (ocelot):
- support MAC Merge layer
- support for the the vsc7512 internal copper phys
- Microchip:
- lan9303: convert to PHYLINK
- lan966x: support TC flower filter statistics
- lan937x: PTP support for KSZ9563/KSZ8563 and LAN937x
- lan937x: support Credit Based Shaper configuration
- ksz9477: support Energy Efficient Ethernet
- other:
- qca8k: convert to regmap read/write API, use bulk operations
- rswitch: Improve TX timestamp accuracy
- Intel WiFi (iwlwifi):
- EHT (Wi-Fi 7) rate reporting
- STEP equalizer support: transfer some STEP (connection to radio
on platforms with integrated wifi) related parameters from the
BIOS to the firmware.
- Qualcomm 802.11ax WiFi (ath11k):
- IPQ5018 support
- Fine Timing Measurement (FTM) responder role support
- channel 177 support
- MediaTek WiFi (mt76):
- per-PHY LED support
- mt7996: EHT (Wi-Fi 7) support
- Wireless Ethernet Dispatch (WED) reset support
- switch to using page pool allocator
- RealTek WiFi (rtw89):
- support new version of Bluetooth co-existance
- Mobile:
- rmnet: support TX aggregation"
* tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1872 commits)
page_pool: add a comment explaining the fragment counter usage
net: ethtool: fix __ethtool_dev_mm_supported() implementation
ethtool: pse-pd: Fix double word in comments
xsk: add linux/vmalloc.h to xsk.c
sefltests: netdevsim: wait for devlink instance after netns removal
selftest: fib_tests: Always cleanup before exit
net/mlx5e: Align IPsec ASO result memory to be as required by hardware
net/mlx5e: TC, Set CT miss to the specific ct action instance
net/mlx5e: Rename CHAIN_TO_REG to MAPPED_OBJ_TO_REG
net/mlx5: Refactor tc miss handling to a single function
net/mlx5: Kconfig: Make tc offload depend on tc skb extension
net/sched: flower: Support hardware miss to tc action
net/sched: flower: Move filter handle initialization earlier
net/sched: cls_api: Support hardware miss to tc action
net/sched: Rename user cookie and act cookie
sfc: fix builds without CONFIG_RTC_LIB
sfc: clean up some inconsistent indentings
net/mlx4_en: Introduce flexible array to silence overflow warning
net: lan966x: Fix possible deadlock inside PTP
net/ulp: Remove redundant ->clone() test in inet_clone_ulp().
...
Diffstat (limited to 'Documentation/userspace-api/iommu.rst')
-rw-r--r-- | Documentation/userspace-api/iommu.rst | 209 |
1 files changed, 209 insertions, 0 deletions
diff --git a/Documentation/userspace-api/iommu.rst b/Documentation/userspace-api/iommu.rst new file mode 100644 index 000000000..d3108c151 --- /dev/null +++ b/Documentation/userspace-api/iommu.rst @@ -0,0 +1,209 @@ +.. SPDX-License-Identifier: GPL-2.0 +.. iommu: + +===================================== +IOMMU Userspace API +===================================== + +IOMMU UAPI is used for virtualization cases where communications are +needed between physical and virtual IOMMU drivers. For baremetal +usage, the IOMMU is a system device which does not need to communicate +with userspace directly. + +The primary use cases are guest Shared Virtual Address (SVA) and +guest IO virtual address (IOVA), wherein the vIOMMU implementation +relies on the physical IOMMU and for this reason requires interactions +with the host driver. + +.. contents:: :local: + +Functionalities +=============== +Communications of user and kernel involve both directions. The +supported user-kernel APIs are as follows: + +1. Bind/Unbind guest PASID (e.g. Intel VT-d) +2. Bind/Unbind guest PASID table (e.g. ARM SMMU) +3. Invalidate IOMMU caches upon guest requests +4. Report errors to the guest and serve page requests + +Requirements +============ +The IOMMU UAPIs are generic and extensible to meet the following +requirements: + +1. Emulated and para-virtualised vIOMMUs +2. Multiple vendors (Intel VT-d, ARM SMMU, etc.) +3. Extensions to the UAPI shall not break existing userspace + +Interfaces +========== +Although the data structures defined in IOMMU UAPI are self-contained, +there are no user API functions introduced. Instead, IOMMU UAPI is +designed to work with existing user driver frameworks such as VFIO. + +Extension Rules & Precautions +----------------------------- +When IOMMU UAPI gets extended, the data structures can *only* be +modified in two ways: + +1. Adding new fields by re-purposing the padding[] field. No size change. +2. Adding new union members at the end. May increase the structure sizes. + +No new fields can be added *after* the variable sized union in that it +will break backward compatibility when offset moves. A new flag must +be introduced whenever a change affects the structure using either +method. The IOMMU driver processes the data based on flags which +ensures backward compatibility. + +Version field is only reserved for the unlikely event of UAPI upgrade +at its entirety. + +It's *always* the caller's responsibility to indicate the size of the +structure passed by setting argsz appropriately. +Though at the same time, argsz is user provided data which is not +trusted. The argsz field allows the user app to indicate how much data +it is providing; it's still the kernel's responsibility to validate +whether it's correct and sufficient for the requested operation. + +Compatibility Checking +---------------------- +When IOMMU UAPI extension results in some structure size increase, +IOMMU UAPI code shall handle the following cases: + +1. User and kernel has exact size match +2. An older user with older kernel header (smaller UAPI size) running on a + newer kernel (larger UAPI size) +3. A newer user with newer kernel header (larger UAPI size) running + on an older kernel. +4. A malicious/misbehaving user passing illegal/invalid size but within + range. The data may contain garbage. + +Feature Checking +---------------- +While launching a guest with vIOMMU, it is strongly advised to check +the compatibility upfront, as some subsequent errors happening during +vIOMMU operation, such as cache invalidation failures cannot be nicely +escalated to the guest due to IOMMU specifications. This can lead to +catastrophic failures for the users. + +User applications such as QEMU are expected to import kernel UAPI +headers. Backward compatibility is supported per feature flags. +For example, an older QEMU (with older kernel header) can run on newer +kernel. Newer QEMU (with new kernel header) may refuse to initialize +on an older kernel if new feature flags are not supported by older +kernel. Simply recompiling existing code with newer kernel header should +not be an issue in that only existing flags are used. + +IOMMU vendor driver should report the below features to IOMMU UAPI +consumers (e.g. via VFIO). + +1. IOMMU_NESTING_FEAT_SYSWIDE_PASID +2. IOMMU_NESTING_FEAT_BIND_PGTBL +3. IOMMU_NESTING_FEAT_BIND_PASID_TABLE +4. IOMMU_NESTING_FEAT_CACHE_INVLD +5. IOMMU_NESTING_FEAT_PAGE_REQUEST + +Take VFIO as example, upon request from VFIO userspace (e.g. QEMU), +VFIO kernel code shall query IOMMU vendor driver for the support of +the above features. Query result can then be reported back to the +userspace caller. Details can be found in +Documentation/driver-api/vfio.rst. + + +Data Passing Example with VFIO +------------------------------ +As the ubiquitous userspace driver framework, VFIO is already IOMMU +aware and shares many key concepts such as device model, group, and +protection domain. Other user driver frameworks can also be extended +to support IOMMU UAPI but it is outside the scope of this document. + +In this tight-knit VFIO-IOMMU interface, the ultimate consumer of the +IOMMU UAPI data is the host IOMMU driver. VFIO facilitates user-kernel +transport, capability checking, security, and life cycle management of +process address space ID (PASID). + +VFIO layer conveys the data structures down to the IOMMU driver. It +follows the pattern below:: + + struct { + __u32 argsz; + __u32 flags; + __u8 data[]; + }; + +Here data[] contains the IOMMU UAPI data structures. VFIO has the +freedom to bundle the data as well as parse data size based on its own flags. + +In order to determine the size and feature set of the user data, argsz +and flags (or the equivalent) are also embedded in the IOMMU UAPI data +structures. + +A "__u32 argsz" field is *always* at the beginning of each structure. + +For example: +:: + + struct iommu_cache_invalidate_info { + __u32 argsz; + #define IOMMU_CACHE_INVALIDATE_INFO_VERSION_1 1 + __u32 version; + /* IOMMU paging structure cache */ + #define IOMMU_CACHE_INV_TYPE_IOTLB (1 << 0) /* IOMMU IOTLB */ + #define IOMMU_CACHE_INV_TYPE_DEV_IOTLB (1 << 1) /* Device IOTLB */ + #define IOMMU_CACHE_INV_TYPE_PASID (1 << 2) /* PASID cache */ + #define IOMMU_CACHE_INV_TYPE_NR (3) + __u8 cache; + __u8 granularity; + __u8 padding[6]; + union { + struct iommu_inv_pasid_info pasid_info; + struct iommu_inv_addr_info addr_info; + } granu; + }; + +VFIO is responsible for checking its own argsz and flags. It then +invokes appropriate IOMMU UAPI functions. The user pointers are passed +to the IOMMU layer for further processing. The responsibilities are +divided as follows: + +- Generic IOMMU layer checks argsz range based on UAPI data in the + current kernel version. + +- Generic IOMMU layer checks content of the UAPI data for non-zero + reserved bits in flags, padding fields, and unsupported version. + This is to ensure not breaking userspace in the future when these + fields or flags are used. + +- Vendor IOMMU driver checks argsz based on vendor flags. UAPI data + is consumed based on flags. Vendor driver has access to + unadulterated argsz value in case of vendor specific future + extensions. Currently, it does not perform the copy_from_user() + itself. A __user pointer can be provided in some future scenarios + where there's vendor data outside of the structure definition. + +IOMMU code treats UAPI data in two categories: + +- structure contains vendor data + (Example: iommu_uapi_cache_invalidate()) + +- structure contains only generic data + (Example: iommu_uapi_sva_bind_gpasid()) + + + +Sharing UAPI with in-kernel users +--------------------------------- +For UAPIs that are shared with in-kernel users, a wrapper function is +provided to distinguish the callers. For example, + +Userspace caller :: + + int iommu_uapi_sva_unbind_gpasid(struct iommu_domain *domain, + struct device *dev, + void __user *udata) + +In-kernel caller :: + + int iommu_sva_unbind_gpasid(struct iommu_domain *domain, + struct device *dev, ioasid_t ioasid); |