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[PATCH net-next v10 0/7] netconsole: support automatic target recovery

by Andre Carvalho

This patchset introduces target resume capability to netconsole allowing it to recover targets when underlying low-level interface comes back online. The patchset starts by refactoring netconsole state representation in order to allow representing deactivated targets (targets that are disabled due to interfaces unregister). It then modifies netconsole to handle NETDEV_REGISTER events for such targets, setups netpoll and forces the device UP. Targets are matched with incoming interfaces depending on how they were bound in netconsole (by mac or interface name). For these reasons, we also attempt resuming on NETDEV_CHANGENAME. The patchset includes a selftest that validates netconsole target state transitions and that target is functional after resumed. Signed-off-by: Andre Carvalho <asantostc(a)gmail.com> --- Changes in v10: - Define wrappers around dynamic_netconsole_mutex lock/unlock and use them on process_resume_target to avoid build failures and #ifdefs inside callsite (suggested by Breno). - Refactored other dynamic_netconsole_mutex to use the wrappers for consistency. - Ensure we cancel pending working during removal of dynamic targets, which requires also holding dynamic_netconsole_mutex. - Introduce standalone workqueue to avoid potential leaks during module cleanup, flushing all pending resume events before removing all targets. - Link to v9: https://lore.kernel.org/r/20260104-netcons-retrigger-v9-0-38aa643d2283@gmai… Changes in v9: - Hold dynamic_netconsole_mutex on process_resume_target. - Cleanup dev_name as part of netconsole_process_cleanups_core to ensure we correctly resume by mac (for targets bound by mac) - Link to v8: https://lore.kernel.org/r/20251128-netcons-retrigger-v8-0-0bccbf4c6385@gmai… Changes in v8: - Handle NETDEV_REGISTER/CHANGENAME instead of NETDEV_UP (and force the device UP), to increase the chances of succesfully resuming a target. This requires using a workqueue instead of inline in the event notifier as we can't UP the device otherwise. - Link to v7: https://lore.kernel.org/r/20251126-netcons-retrigger-v7-0-1d86dba83b1c@gmai… Changes in v7: - selftest: use ${EXIT_STATUS} instead of ${ksft_pass} to avoid shellcheck warning - Link to v6: https://lore.kernel.org/r/20251121-netcons-retrigger-v6-0-9c03f5a2bd6f@gmai… Changes in v6: - Rebase on top of net-next to resolve conflicts, no functional changes. - Link to v5: https://lore.kernel.org/r/20251119-netcons-retrigger-v5-0-2c7dda6055d6@gmai… Changes in v5: - patch 3: Set (de)enslaved target as DISABLED instead of DEACTIVATED to prevent resuming it. - selftest: Fix test cleanup by moving trap line to outside of loop and remove unneeded 'local' keyword - Rename maybe_resume_target to resume_target, add netconsole_ prefix to process_resumable_targets. - Hold device reference before calling __netpoll_setup. - Link to v4: https://lore.kernel.org/r/20251116-netcons-retrigger-v4-0-5290b5f140c2@gmai… Changes in v4: - Simplify selftest cleanup, removing trap setup in loop. - Drop netpoll helper (__setup_netpoll_hold) and manage reference inside netconsole. - Move resume_list processing logic to separate function. - Link to v3: https://lore.kernel.org/r/20251109-netcons-retrigger-v3-0-1654c280bbe6@gmai… Changes in v3: - Resume by mac or interface name depending on how target was created. - Attempt to resume target without holding target list lock, by moving the target to a temporary list. This is required as netpoll may attempt to allocate memory. - Link to v2: https://lore.kernel.org/r/20250921-netcons-retrigger-v2-0-a0e84006237f@gmai… Changes in v2: - Attempt to resume target in the same thread, instead of using workqueue . - Add wrapper around __netpoll_setup (patch 4). - Renamed resume_target to maybe_resume_target and moved conditionals to inside its implementation, keeping code more clear. - Verify that device addr matches target mac address when target was setup using mac. - Update selftest to cover targets bound by mac and interface name. - Fix typo in selftest comment and sort tests alphabetically in Makefile. - Link to v1: https://lore.kernel.org/r/20250909-netcons-retrigger-v1-0-3aea904926cf@gmai… --- Andre Carvalho (5): netconsole: convert 'enabled' flag to enum for clearer state management netconsole: clear dev_name for devices bound by mac netconsole: introduce helpers for dynamic_netconsole_mutex lock/unlock netconsole: resume previously deactivated target selftests: netconsole: validate target resume Breno Leitao (2): netconsole: add target_state enum netconsole: add STATE_DEACTIVATED to track targets disabled by low level drivers/net/netconsole.c | 305 ++++++++++++++++----- tools/testing/selftests/drivers/net/Makefile | 1 + .../selftests/drivers/net/lib/sh/lib_netcons.sh | 35 ++- .../selftests/drivers/net/netcons_resume.sh | 97 +++++++ 4 files changed, 364 insertions(+), 74 deletions(-) --- base-commit: 60d8484c4cec811f5ceb6550655df74490d1a165 change-id: 20250816-netcons-retrigger-a4f547bfc867 Best regards, -- Andre Carvalho <asantostc(a)gmail.com>

1 hour, 31 minutes

[PATCH net-next v2 0/1] PSP self test improvements

by Cosmin Ratiu

Changes since v1: - Used ifindex in psp_responder to select the PSP device - Merged the two patches since they started overlapping too much. Cosmin Ratiu (1): selftests: drv-net: psp: Better control the used PSP dev .../selftests/drivers/net/lib/py/env.py | 1 + tools/testing/selftests/drivers/net/psp.py | 4 +- .../selftests/drivers/net/psp_responder.c | 50 +++++++++---------- 3 files changed, 26 insertions(+), 29 deletions(-) -- 2.45.0

2 hours, 27 minutes

[PATCH net-next v9 0/5] net: devmem: improve cpu cost of RX token management

by Bobby Eshleman

This series improves the CPU cost of RX token management by adding an attribute to NETDEV_CMD_BIND_RX that configures sockets using the binding to avoid the xarray allocator and instead use a per-binding niov array and a uref field in niov. Improvement is ~13% cpu util per RX user thread. Using kperf, the following results were observed: Before: Average RX worker idle %: 13.13, flows 4, test runs 11 After: Average RX worker idle %: 26.32, flows 4, test runs 11 Two other approaches were tested, but with no improvement. Namely, 1) using a hashmap for tokens and 2) keeping an xarray of atomic counters but using RCU so that the hotpath could be mostly lockless. Neither of these approaches proved better than the simple array in terms of CPU. The attribute NETDEV_A_DMABUF_AUTORELEASE is added to toggle the optimization. It is an optional attribute and defaults to 0 (i.e., optimization on). Signed-off-by: Bobby Eshleman <bobbyeshleman(a)meta.com> Changes in v9: - fixed build with NET_DEVMEM=n - fixed bug in rx bindings count logic - Link to v8: https://lore.kernel.org/r/20260107-scratch-bobbyeshleman-devmem-tcp-token-u… Changes in v8: - change static branch logic (only set when enabled, otherwise just always revert back to disabled) - fix missing tests - Link to v7: https://lore.kernel.org/r/20251119-scratch-bobbyeshleman-devmem-tcp-token-u… Changes in v7: - use netlink instead of sockopt (Stan) - restrict system to only one mode, dmabuf bindings can not co-exist with different modes (Stan) - use static branching to enforce single system-wide mode (Stan) - Link to v6: https://lore.kernel.org/r/20251104-scratch-bobbyeshleman-devmem-tcp-token-u… Changes in v6: - renamed 'net: devmem: use niov array for token management' to refer to optionality of new config - added documentation and tests - make autorelease flag per-socket sockopt instead of binding field / sysctl - many per-patch changes (see Changes sections per-patch) - Link to v5: https://lore.kernel.org/r/20251023-scratch-bobbyeshleman-devmem-tcp-token-u… Changes in v5: - add sysctl to opt-out of performance benefit, back to old token release - Link to v4: https://lore.kernel.org/all/20250926-scratch-bobbyeshleman-devmem-tcp-token… Changes in v4: - rebase to net-next - Link to v3: https://lore.kernel.org/r/20250926-scratch-bobbyeshleman-devmem-tcp-token-u… Changes in v3: - make urefs per-binding instead of per-socket, reducing memory footprint - fallback to cleaning up references in dmabuf unbind if socket leaked tokens - drop ethtool patch - Link to v2: https://lore.kernel.org/r/20250911-scratch-bobbyeshleman-devmem-tcp-token-u… Changes in v2: - net: ethtool: prevent user from breaking devmem single-binding rule (Mina) - pre-assign niovs in binding->vec for RX case (Mina) - remove WARNs on invalid user input (Mina) - remove extraneous binding ref get (Mina) - remove WARN for changed binding (Mina) - always use GFP_ZERO for binding->vec (Mina) - fix length of alloc for urefs - use atomic_set(, 0) to initialize sk_user_frags.urefs - Link to v1: https://lore.kernel.org/r/20250902-scratch-bobbyeshleman-devmem-tcp-token-u… --- Bobby Eshleman (5): net: devmem: rename tx_vec to vec in dmabuf binding net: devmem: refactor sock_devmem_dontneed for autorelease split net: devmem: implement autorelease token management net: devmem: document NETDEV_A_DMABUF_AUTORELEASE netlink attribute selftests: drv-net: devmem: add autorelease test Documentation/netlink/specs/netdev.yaml | 12 +++ Documentation/networking/devmem.rst | 70 +++++++++++++ include/net/netmem.h | 1 + include/net/sock.h | 7 +- include/uapi/linux/netdev.h | 1 + net/core/devmem.c | 116 ++++++++++++++++++---- net/core/devmem.h | 29 +++++- net/core/netdev-genl-gen.c | 5 +- net/core/netdev-genl.c | 10 +- net/core/sock.c | 103 ++++++++++++++----- net/ipv4/tcp.c | 76 +++++++++++--- net/ipv4/tcp_ipv4.c | 11 +- net/ipv4/tcp_minisocks.c | 3 +- tools/include/uapi/linux/netdev.h | 1 + tools/testing/selftests/drivers/net/hw/devmem.py | 21 +++- tools/testing/selftests/drivers/net/hw/ncdevmem.c | 19 ++-- 16 files changed, 407 insertions(+), 78 deletions(-) --- base-commit: 6ad078fa0ababa8de2a2b39f476d2abd179a3cf6 change-id: 20250829-scratch-bobbyeshleman-devmem-tcp-token-upstream-292be174d503 Best regards, -- Bobby Eshleman <bobbyeshleman(a)meta.com>

3 hours, 28 minutes

[PATCH net-next 0/2] selftests: net: improve error handling in passive TFO test

by Yohei Kojima

This series improves error handling in the passive TFO test by (1) fixing a broken behavior when the child processes failed (or timed out), and (2) adding more error handlng code in the test program. The first patch fixes the behavior that the test didn't report failure even if the server or the client process exited with non-zero status. The second patch adds error handling code in the test program to improve reliability of the test. This series was split out from the following series to address the feedback from Andrew Lunn: https://lore.kernel.org/netdev/cover.1767032397.git.yk@y-koj.net/ Yohei Kojima (2): selftests: net: fix passive TFO test to fail if child processes failed selftests: net: improve error handling in passive TFO test tools/testing/selftests/net/tfo.c | 10 +++++++--- tools/testing/selftests/net/tfo_passive.sh | 13 ++++++++++++- 2 files changed, 19 insertions(+), 4 deletions(-) -- 2.52.0

3 hours, 29 minutes

[PATCH v4 00/19] ublk: add support for integrity data

by Caleb Sander Mateos

Much work has recently gone into supporting block device integrity data (sometimes called "metadata") in Linux. Many NVMe devices these days support metadata transfers and/or automatic protection information generation and verification. However, ublk devices can't yet advertise integrity data capabilities. This patch series wires up support for integrity data in ublk. The ublk feature is referred to as "integrity" rather than "metadata" to match the block layer's name for it and to avoid confusion with the existing and unrelated UBLK_IO_F_META. To advertise support for integrity data, a ublk server fills out the struct ublk_params's integrity field and sets UBLK_PARAM_TYPE_INTEGRITY. The struct ublk_param_integrity flags and csum_type fields use the existing LBMD_PI_* constants from the linux/fs.h UAPI header. The ublk driver fills out a corresponding struct blk_integrity. When a request with integrity data is issued to the ublk device, the ublk driver sets UBLK_IO_F_INTEGRITY in struct ublksrv_io_desc's op_flags field. This is necessary for a ublk server for which bi_offload_capable() returns true to distinguish requests with integrity data from those without. Integrity data transfers can currently only be performed via the ublk user copy mechanism. The overhead of zero-copy buffer registration makes it less appealing for the small transfers typical of integrity data. Additionally, neither io_uring NVMe passthru nor IORING_RW_ATTR_FLAG_PI currently allow an io_uring registered buffer for the integrity data. The ki_pos field of the struct kiocb passed to the user copy ->{read,write}_iter() callback gains a bit UBLKSRV_IO_INTEGRITY_FLAG for a ublk server to indicate whether to access the request's data or integrity data. Not yet supported is an analogue for the IO_INTEGRITY_CHK_*/BIP_CHECK_* flags to ask the ublk server to verify the guard, reftag, and/or apptag of a request's protection information. The user copy mechanism currently forbids a ublk server from reading the data/integrity buffer of a read-direction request. We could potentially relax this restriction for integrity data on reads. Alternatively, the ublk driver could verify the requested fields as part of the user copy operation. v4: - Add max_integrity_segments to struct ublk_param_integrity (Ming) - Move UBLKSRV_IO_INTEGRITY_FLAG to avoid overflow from QID + UBLKSRV_IO_BUF_OFFSET (Ming) - Check UBLK_F_INTEGRITY when UBLKSRV_IO_INTEGRITY_FLAG is used (Ming) - Initialize integrity backing file to disable integrity checks (Ming) v3: - Drop support for communicating BIP_CHECK_* for now until the interface is decided - Add Reviewed-by tags v2: - Communicate BIP_CHECK_* flags and expected reftag seed and app tag to ublk server - Add UBLK_F_INTEGRITY feature flag (Ming) - Don't change the definition of UBLKSRV_IO_BUF_TOTAL_BITS (Ming) - Drop patches already applied - Add Reviewed-by tags Caleb Sander Mateos (16): blk-integrity: take const pointer in blk_integrity_rq() ublk: move ublk flag check functions earlier ublk: set UBLK_IO_F_INTEGRITY in ublksrv_io_desc ublk: split out ublk_copy_user_bvec() helper ublk: split out ublk_user_copy() helper ublk: inline ublk_check_and_get_req() into ublk_user_copy() ublk: move offset check out of __ublk_check_and_get_req() ublk: optimize ublk_user_copy() on daemon task selftests: ublk: display UBLK_F_INTEGRITY support selftests: ublk: add utility to get block device metadata size selftests: ublk: add kublk support for integrity params selftests: ublk: implement integrity user copy in kublk selftests: ublk: support non-O_DIRECT backing files selftests: ublk: add integrity data support to loop target selftests: ublk: add integrity params test selftests: ublk: add end-to-end integrity test Stanley Zhang (3): ublk: support UBLK_PARAM_TYPE_INTEGRITY in device creation ublk: implement integrity user copy ublk: support UBLK_F_INTEGRITY drivers/block/ublk_drv.c | 358 +++++++++++++------ include/linux/blk-integrity.h | 6 +- include/uapi/linux/ublk_cmd.h | 25 ++ tools/testing/selftests/ublk/Makefile | 7 +- tools/testing/selftests/ublk/common.c | 4 +- tools/testing/selftests/ublk/fault_inject.c | 1 + tools/testing/selftests/ublk/file_backed.c | 90 ++++- tools/testing/selftests/ublk/kublk.c | 90 ++++- tools/testing/selftests/ublk/kublk.h | 37 +- tools/testing/selftests/ublk/metadata_size.c | 36 ++ tools/testing/selftests/ublk/null.c | 1 + tools/testing/selftests/ublk/stripe.c | 6 +- tools/testing/selftests/ublk/test_common.sh | 10 + tools/testing/selftests/ublk/test_loop_08.sh | 111 ++++++ tools/testing/selftests/ublk/test_null_04.sh | 166 +++++++++ 15 files changed, 817 insertions(+), 131 deletions(-) create mode 100644 tools/testing/selftests/ublk/metadata_size.c create mode 100755 tools/testing/selftests/ublk/test_loop_08.sh create mode 100755 tools/testing/selftests/ublk/test_null_04.sh -- 2.45.2

3 hours, 40 minutes

[PATCH 0/3] selftests/mm: add memory failure selftests

by Miaohe Lin

Introduce selftests to validate the functionality of memory failure. These tests help ensure that memory failure handling for anonymous pages, pagecaches pages works correctly, including proper SIGBUS delivery to user processes, page isolation, and recovery paths. Currently madvise syscall is used to inject memory failures. And only anonymous pages and pagecaches are tested. More test scenarios, e.g. hugetlb, shmem, thp, will be added. Also more memory failure injecting methods will be supported, e.g. APEI Error INJection, if required. Thanks! Miaohe Lin (3): selftests/mm: add memory failure anonymous page test selftests/mm: add memory failure clean pagecache test selftests/mm: add memory failure dirty pagecache test MAINTAINERS | 1 + tools/testing/selftests/mm/.gitignore | 1 + tools/testing/selftests/mm/Makefile | 1 + tools/testing/selftests/mm/memory-failure.c | 335 ++++++++++++++++++++ tools/testing/selftests/mm/run_vmtests.sh | 21 ++ tools/testing/selftests/mm/vm_util.c | 41 +++ tools/testing/selftests/mm/vm_util.h | 3 + 7 files changed, 403 insertions(+) create mode 100644 tools/testing/selftests/mm/memory-failure.c -- 2.33.0

3 hours, 46 minutes

[GIT PULL] kselftest fixes update for Linux 6.19-rc5

by Shuah Khan

Hi Linus, Please pull the fixes kselftest fixes update for Linux 6.19-rc5. Fixes tracing test_multiple_writes stalls when buffer_size_kb is less than 12KB. diff is attached. thanks, -- Shuah ---------------------------------------------------------------- The following changes since commit 9ace4753a5202b02191d54e9fdf7f9e3d02b85eb: Linux 6.19-rc4 (2026-01-04 14:41:55 -0800) are available in the Git repository at: git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest tags/linux_kselftest-fixes-6.19-rc5 for you to fetch changes up to 6e39903c73df08b256322d04c4dfe4a82ec63a45: selftests/tracing: Fix test_multiple_writes stall (2026-01-09 15:49:32 -0700) ---------------------------------------------------------------- linux_kselftest-fixes-6.19-rc5 Fixes tracing test_multiple_writes stalls when buffer_size_kb is less than 12KB. ---------------------------------------------------------------- Fushuai Wang (1): selftests/tracing: Fix test_multiple_writes stall .../ftrace/test.d/00basic/trace_marker_raw.tc | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-) ----------------------------------------------------------------

3 hours, 46 minutes

[PATCH cgroup/for-6.20 v5 0/5] cgroup/cpuset: Don't invalidate sibling partitions on cpuset.cpus conflict

by Waiman Long

v5: - Fix patch 4 doc change as reported by Michael. v4: - Add tags and fix patch 4 commit log v3: - Patch 2: Change the condition for calling reset_partition_data() to (new_prs <= 0). - Patch 4: Update commit log and code comment to clarify the change. - Add a new patch 5 to move the empty cpus/mems check to cpuset1_validate_change(). v2: - Patch 1: additional comment - Patch 2: simplify the conditions for triggering call to compute_excpus(). - Patch 3: update description of cpuset.cpus.exclusive in cgroup-v2.rst to reflect the new behavior and change the name of the new cpus_excl_conflict() parameter to xcpus_changed. - Patch 4: update description of cpuset.cpus.partition in cgroup-v2.rst to clarify what exclusive CPUs will be used when a partition is created. This patch series is inspired by the cpuset patch sent by Sun Shaojie [1]. The idea is to avoid invalidating sibling partitions when there is a cpuset.cpus conflict. However this patch series does it in a slightly different way to make its behavior more consistent with other cpuset properties. The first 3 patches are just some cleanup and minor bug fixes on issues found during the investigation process. The last one is the major patch that changes the way cpuset.cpus is being handled during the partition creation process. Instead of invalidating sibling partitions when there is a conflict, it will strip out the conflicting exclusive CPUs and assign the remaining non-conflicting exclusive CPUs to the new partition unless there is no more CPU left which will fail the partition creation process. It is similar to the idea that cpuset.cpus.effective may only contain a subset of CPUs specified in cpuset.cpus. So cpuset.cpus.exclusive.effective may contain only a subset of cpuset.cpus when a partition is created without setting cpuset.cpus.exclusive. Even setting cpuset.cpus.exclusive instead of cpuset.cpus may not guarantee all the requested CPUs can be granted if parent doesn't have access to some of those exclusive CPUs. The difference is that conflicts from siblings is not possible with cpuset.cpus.exclusive as long as it can be set successfully without failure. [1] https://lore.kernel.org/lkml/20251117015708.977585-1-sunshaojie@kylinos.cn/ Waiman Long (5): cgroup/cpuset: Streamline rm_siblings_excl_cpus() cgroup/cpuset: Consistently compute effective_xcpus in update_cpumasks_hier() cgroup/cpuset: Don't fail cpuset.cpus change in v2 cgroup/cpuset: Don't invalidate sibling partitions on cpuset.cpus conflict cgroup/cpuset: Move the v1 empty cpus/mems check to cpuset1_validate_change() Documentation/admin-guide/cgroup-v2.rst | 41 +++-- kernel/cgroup/cpuset-internal.h | 12 ++ kernel/cgroup/cpuset-v1.c | 33 ++++ kernel/cgroup/cpuset.c | 163 ++++++------------ .../selftests/cgroup/test_cpuset_prs.sh | 29 +++- 5 files changed, 151 insertions(+), 127 deletions(-) -- 2.52.0

3 hours, 53 minutes

[PATCH v9 00/30] KVM: arm64: Implement support for SME

by Mark Brown

I've removed the RFC tag from this version of the series, but the items that I'm looking for feedback on remains the same: - The userspace ABI, in particular: - The vector length used for the SVE registers, access to the SVE registers and access to ZA and (if available) ZT0 depending on the current state of PSTATE.{SM,ZA}. - The use of a single finalisation for both SVE and SME. - The addition of control for enabling fine grained traps in a similar manner to FGU but without the UNDEF, I'm not clear if this is desired at all and at present this requires symmetric read and write traps like FGU. That seemed like it might be desired from an implementation point of view but we already have one case where we enable an asymmetric trap (for ARM64_WORKAROUND_AMPERE_AC03_CPU_38) and it seems generally useful to enable asymmetrically. This series implements support for SME use in non-protected KVM guests. Much of this is very similar to SVE, the main additional challenge that SME presents is that it introduces a new vector length similar to the SVE vector length and two new controls which change the registers seen by guests: - PSTATE.ZA enables the ZA matrix register and, if SME2 is supported, the ZT0 LUT register. - PSTATE.SM enables streaming mode, a new floating point mode which uses the SVE register set with the separately configured SME vector length. In streaming mode implementation of the FFR register is optional. It is also permitted to build systems which support SME without SVE, in this case when not in streaming mode no SVE registers or instructions are available. Further, there is no requirement that there be any overlap in the set of vector lengths supported by SVE and SME in a system, this is expected to be a common situation in practical systems. Since there is a new vector length to configure we introduce a new feature parallel to the existing SVE one with a new pseudo register for the streaming mode vector length. Due to the overlap with SVE caused by streaming mode rather than finalising SME as a separate feature we use the existing SVE finalisation to also finalise SME, a new define KVM_ARM_VCPU_VEC is provided to help make user code clearer. Finalising SVE and SME separately would introduce complication with register access since finalising SVE makes the SVE registers writeable by userspace and doing multiple finalisations results in an error being reported. Dealing with a state where the SVE registers are writeable due to one of SVE or SME being finalised but may have their VL changed by the other being finalised seems like needless complexity with minimal practical utility, it seems clearer to just express directly that only one finalisation can be done in the ABI. Access to the floating point registers follows the architecture: - When both SVE and SME are present: - If PSTATE.SM == 0 the vector length used for the Z and P registers is the SVE vector length. - If PSTATE.SM == 1 the vector length used for the Z and P registers is the SME vector length. - If only SME is present: - If PSTATE.SM == 0 the Z and P registers are inaccessible and the floating point state accessed via the encodings for the V registers. - If PSTATE.SM == 1 the vector length used for the Z and P registers - The SME specific ZA and ZT0 registers are only accessible if SVCR.ZA is 1. The VMM must understand this, in particular when loading state SVCR should be configured before other state. It should be noted that while the architecture refers to PSTATE.SM and PSTATE.ZA these PSTATE bits are not preserved in SPSR_ELx, they are only accessible via SVCR. There are a large number of subfeatures for SME, most of which only offer additional instructions but some of which (SME2 and FA64) add architectural state. These are configured via the ID registers as per usual. Protected KVM supported, with the implementation maintaining the existing restriction that the hypervisor will refuse to run if streaming mode or ZA is enabled. This both simplfies the code and avoids the need to allocate storage for host ZA and ZT0 state, there seems to be little practical use case for supporting this and the memory usage would be non-trivial. The new KVM_ARM_VCPU_VEC feature and ZA and ZT0 registers have not been added to the get-reg-list selftest, the idea of supporting additional features there without restructuring the program to generate all possible feature combinations has been rejected. I will post a separate series which does that restructuring. Signed-off-by: Mark Brown <broonie(a)kernel.org> --- Changes in v9: - Rebase onto v6.19-rc1. - ABI document clarifications. - Add changes dropping asserts on single bit wide bitfields in set_id_regs. - Link to v8: https://lore.kernel.org/r/20250902-kvm-arm64-sme-v8-0-2cb2199c656c@kernel.o… Changes in v8: - Small fixes in ABI documentation. - Link to v7: https://lore.kernel.org/r/20250822-kvm-arm64-sme-v7-0-7a65d82b8b10@kernel.o… Changes in v7: - Rebase onto v6.17-rc1. - Handle SMIDR_EL1 as a VM wide ID register and use this in feat_sme_smps(). - Expose affinity fields in SMIDR_EL1. - Remove SMPRI_EL1 from vcpu_sysreg, the value is always 0 currently. - Prevent userspace writes to SMPRIMAP_EL2. - Link to v6: https://lore.kernel.org/r/20250625-kvm-arm64-sme-v6-0-114cff4ffe04@kernel.o… Changes in v6: - Rebase onto v6.16-rc3. - Link to v5: https://lore.kernel.org/r/20250417-kvm-arm64-sme-v5-0-f469a2d5f574@kernel.o… Changes in v5: - Rebase onto v6.15-rc2. - Add pKVM guest support. - Always restore SVCR. - Link to v4: https://lore.kernel.org/r/20250214-kvm-arm64-sme-v4-0-d64a681adcc2@kernel.o… Changes in v4: - Rebase onto v6.14-rc2 and Mark Rutland's fixes. - Expose SME to nested guests. - Additional cleanups and test fixes following on from the rebase. - Flush register state on VMM PSTATE.{SM,ZA}. - Link to v3: https://lore.kernel.org/r/20241220-kvm-arm64-sme-v3-0-05b018c1ffeb@kernel.o… Changes in v3: - Rebase onto v6.12-rc2. - Link to v2: https://lore.kernel.org/r/20231222-kvm-arm64-sme-v2-0-da226cb180bb@kernel.o… Changes in v2: - Rebase onto v6.7-rc3. - Configure subfeatures based on host system only. - Complete nVHE support. - There was some snafu with sending v1 out, it didn't make it to the lists but in case it hit people's inboxes I'm sending as v2. --- Mark Brown (30): arm64/sysreg: Update SMIDR_EL1 to DDI0601 2025-06 arm64/fpsimd: Update FA64 and ZT0 enables when loading SME state arm64/fpsimd: Decide to save ZT0 and streaming mode FFR at bind time arm64/fpsimd: Check enable bit for FA64 when saving EFI state arm64/fpsimd: Determine maximum virtualisable SME vector length KVM: arm64: Pay attention to FFR parameter in SVE save and load KVM: arm64: Pull ctxt_has_ helpers to start of sysreg-sr.h KVM: arm64: Move SVE state access macros after feature test macros KVM: arm64: Rename SVE finalization constants to be more general KVM: arm64: Document the KVM ABI for SME KVM: arm64: Define internal features for SME KVM: arm64: Rename sve_state_reg_region KVM: arm64: Store vector lengths in an array KVM: arm64: Implement SME vector length configuration KVM: arm64: Support SME control registers KVM: arm64: Support TPIDR2_EL0 KVM: arm64: Support SME identification registers for guests KVM: arm64: Support SME priority registers KVM: arm64: Provide assembly for SME register access KVM: arm64: Support userspace access to streaming mode Z and P registers KVM: arm64: Flush register state on writes to SVCR.SM and SVCR.ZA KVM: arm64: Expose SME specific state to userspace KVM: arm64: Context switch SME state for guests KVM: arm64: Handle SME exceptions KVM: arm64: Expose SME to nested guests KVM: arm64: Provide interface for configuring and enabling SME for guests KVM: arm64: selftests: Remove spurious check for single bit safe values KVM: arm64: selftests: Skip impossible invalid value tests KVM: arm64: selftests: Add SME system registers to get-reg-list KVM: arm64: selftests: Add SME to set_id_regs test Documentation/virt/kvm/api.rst | 120 ++++++++--- arch/arm64/include/asm/fpsimd.h | 26 +++ arch/arm64/include/asm/kvm_emulate.h | 6 + arch/arm64/include/asm/kvm_host.h | 163 ++++++++++++--- arch/arm64/include/asm/kvm_hyp.h | 5 +- arch/arm64/include/asm/kvm_pkvm.h | 2 +- arch/arm64/include/asm/vncr_mapping.h | 2 + arch/arm64/include/uapi/asm/kvm.h | 33 +++ arch/arm64/kernel/cpufeature.c | 2 - arch/arm64/kernel/fpsimd.c | 89 ++++---- arch/arm64/kvm/arm.c | 10 + arch/arm64/kvm/config.c | 11 +- arch/arm64/kvm/fpsimd.c | 28 ++- arch/arm64/kvm/guest.c | 252 ++++++++++++++++++++--- arch/arm64/kvm/handle_exit.c | 14 ++ arch/arm64/kvm/hyp/fpsimd.S | 28 ++- arch/arm64/kvm/hyp/include/hyp/switch.h | 168 +++++++++++++-- arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h | 110 ++++++---- arch/arm64/kvm/hyp/nvhe/hyp-main.c | 86 ++++++-- arch/arm64/kvm/hyp/nvhe/pkvm.c | 85 ++++++-- arch/arm64/kvm/hyp/nvhe/switch.c | 4 +- arch/arm64/kvm/hyp/nvhe/sys_regs.c | 6 + arch/arm64/kvm/hyp/vhe/switch.c | 17 +- arch/arm64/kvm/hyp/vhe/sysreg-sr.c | 7 + arch/arm64/kvm/nested.c | 3 +- arch/arm64/kvm/reset.c | 156 ++++++++++---- arch/arm64/kvm/sys_regs.c | 140 ++++++++++++- arch/arm64/tools/sysreg | 8 +- include/uapi/linux/kvm.h | 1 + tools/testing/selftests/kvm/arm64/get-reg-list.c | 15 +- tools/testing/selftests/kvm/arm64/set_id_regs.c | 84 ++++++-- 31 files changed, 1367 insertions(+), 314 deletions(-) --- base-commit: 3e7f562e20ee87a25e104ef4fce557d39d62fa85 change-id: 20230301-kvm-arm64-sme-06a1246d3636 Best regards, -- Mark Brown <broonie(a)kernel.org>

4 hours, 16 minutes

[PATCH v2] KVM: selftests: Fix sign extension bug in get_desc64_base()

by MJ Pooladkhay

The function get_desc64_base() performs a series of bitwise left shifts on fields of various sizes. More specifically, when performing '<< 24' on 'desc->base2' (which is a u8), 'base2' is promoted to a signed integer before shifting. In a scenario where base2 >= 0x80, the shift places a 1 into bit 31, causing the 32-bit intermediate value to become negative. When this result is cast to uint64_t or ORed into the return value, sign extension occurs, corrupting the upper 32 bits of the address (base3). Example: Given: base0 = 0x5000 base1 = 0xd6 base2 = 0xf8 base3 = 0xfffffe7c Expected return: 0xfffffe7cf8d65000 Actual return: 0xfffffffff8d65000 Fix this by explicitly casting the fields to 'uint64_t' before shifting to prevent sign extension. Signed-off-by: MJ Pooladkhay <mj(a)pooladkhay.com> --- v2: - Remove the intermediate 'low' variable and use a single return statement as suggested by Sean Christopherson. v1: https://lore.kernel.org/kvm/20251220021050.88490-1-mj@pooladkhay.com/ While using get_desc64_base() to set the HOST_TR_BASE value for a custom educational hypervisor, I observed system freezes, either immediately or after migrating the guest to a new core. I eventually realized that KVM uses get_cpu_entry_area() for the TR base. Switching to that fixed my freezes (which were triple faults on one core followed by soft lockups on others, waiting on smp_call_function_many_cond) and helped me identify the sign-extension bug in this helper function that was corrupting the HOST_TR_BASE value. Thanks, MJ Pooladkhay tools/testing/selftests/kvm/include/x86/processor.h | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/tools/testing/selftests/kvm/include/x86/processor.h b/tools/testing/selftests/kvm/include/x86/processor.h index 57d62a425..26a91bb73 100644 --- a/tools/testing/selftests/kvm/include/x86/processor.h +++ b/tools/testing/selftests/kvm/include/x86/processor.h @@ -436,8 +436,10 @@ struct kvm_x86_state { static inline uint64_t get_desc64_base(const struct desc64 *desc) { - return ((uint64_t)desc->base3 << 32) | - (desc->base0 | ((desc->base1) << 16) | ((desc->base2) << 24)); + return (uint64_t)desc->base3 << 32 | + (uint64_t)desc->base2 << 24 | + (uint64_t)desc->base1 << 16 | + (uint64_t)desc->base0; } static inline uint64_t rdtsc(void) -- 2.52.0

5 hours, 46 minutes

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