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[PATCH v8 00/29] 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 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 (29): 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: Introduce non-UNDEF FGT control 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: Add SME system registers to get-reg-list KVM: arm64: selftests: Add SME to set_id_regs test Documentation/virt/kvm/api.rst | 115 ++++++++--- arch/arm64/include/asm/fpsimd.h | 26 +++ arch/arm64/include/asm/kvm_emulate.h | 6 + arch/arm64/include/asm/kvm_host.h | 169 ++++++++++++--- 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 | 8 +- 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 | 175 ++++++++++++++-- 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 | 141 ++++++++++++- 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 | 27 ++- 31 files changed, 1327 insertions(+), 303 deletions(-) --- base-commit: 062b3e4a1f880f104a8d4b90b767788786aa7b78 change-id: 20230301-kvm-arm64-sme-06a1246d3636 Best regards, -- Mark Brown <broonie(a)kernel.org>

1 month, 2 weeks

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[PATCH 0/3] Fix a race with fput during eventq abort

by Jason Gunthorpe

Syzkaller found this, fput runs the release from a work queue so the refcount remains elevated during abort. This is tricky so move more handling of files into the core code. Add a WARN_ON to catch things like this more reliably without relying on kasn. Update the fail_nth test to succeed on 6.17 kernels. Jason Gunthorpe (3): iommufd: Fix race during abort for file descriptors iommufd: WARN if an object is aborted with an elevated refcount iommufd/selftest: Update the fail_nth limit drivers/iommu/iommufd/device.c | 3 +- drivers/iommu/iommufd/eventq.c | 9 +---- drivers/iommu/iommufd/iommufd_private.h | 3 +- drivers/iommu/iommufd/main.c | 39 +++++++++++++++++-- .../selftests/iommu/iommufd_fail_nth.c | 2 +- 5 files changed, 42 insertions(+), 14 deletions(-) base-commit: 1046d40b0e78d2cd63f6183629699b629b21f877 -- 2.43.0

1 month, 2 weeks

4
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[PATCH V2 0/8] Add selftests for mshare

by Yongting Lin

Mshare is a developing feature proposed by Anthony Yznaga and Khalid Aziz that enables sharing of PTEs across processes. The V3 patch set has been posted for review: https://lore.kernel.org/linux-mm/20250820010415.699353-1-anthony.yznaga@ora… This patch set adds selftests to exercise and demonstrate basic functionality of mshare. The initial tests use open, ioctl, and mmap syscalls to establish a shared memory mapping between two processes and verify the expected behavior. Additional tests are included to check interoperability with swap and Transparent Huge Pages. Future work will extend coverage to other use cases such as integration with KVM and more advanced scenarios. This series is intended to be applied on top of mshare V3, which is based on mm-new (2025-08-15). ----------------- V1->V2: - Based on mshare V3, which based on mm-new as of 2025-08-15 - (Fix) For test cases in basic.c, Change to use a small chunk of memory(4k/8K for normal pages, 2M/4M for hugetlb pages), as to ensure these tests can run on any server or device. - (Fix) For test cases of hugetlb, swap and THP, add a tips to configure corresponding settings. - (Fix) Add memory to .gitignore file once it exists - (fix) Correct the Changelog of THP test case that mshare support THP only when user configure shmem_enabled as always V1: https://lore.kernel.org/all/20250825145719.29455-1-linyongting@bytedance.co… Yongting Lin (8): mshare: Add selftests mshare: selftests: Adding config fragments mshare: selftests: Add some helper functions for mshare filesystem mshare: selftests: Add test case shared memory mshare: selftests: Add test case ioctl unmap mshare: selftests: Add some helper functions for configuring and retrieving cgroup mshare: selftests: Add test case to demostrate the swapping of mshare memory mshare: selftests: Add test case to demostrate that mshare partly supports THP tools/testing/selftests/mshare/.gitignore | 4 + tools/testing/selftests/mshare/Makefile | 7 + tools/testing/selftests/mshare/basic.c | 109 ++++++++++ tools/testing/selftests/mshare/config | 1 + tools/testing/selftests/mshare/memory.c | 89 ++++++++ tools/testing/selftests/mshare/util.c | 254 ++++++++++++++++++++++ 6 files changed, 464 insertions(+) create mode 100644 tools/testing/selftests/mshare/.gitignore create mode 100644 tools/testing/selftests/mshare/Makefile create mode 100644 tools/testing/selftests/mshare/basic.c create mode 100644 tools/testing/selftests/mshare/config create mode 100644 tools/testing/selftests/mshare/memory.c create mode 100644 tools/testing/selftests/mshare/util.c -- 2.20.1

1 month, 2 weeks

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[PATCH v2 00/33] ns: support file handles

by Christian Brauner

For a while now we have supported file handles for pidfds. This has proven to be very useful. Extend the concept to cover namespaces as well. After this patchset it is possible to encode and decode namespace file handles using the commong name_to_handle_at() and open_by_handle_at() apis. Namespaces file descriptors can already be derived from pidfds which means they aren't subject to overmount protection bugs. IOW, it's irrelevant if the caller would not have access to an appropriate /proc/<pid>/ns/ directory as they could always just derive the namespace based on a pidfd already. It has the same advantage as pidfds. It's possible to reliably and for the lifetime of the system refer to a namespace without pinning any resources and to compare them. Permission checking is kept simple. If the caller is located in the namespace the file handle refers to they are able to open it otherwise they must hold privilege over the owning namespace of the relevant namespace. Both the network namespace and the mount namespace already have an associated cookie that isn't recycled and is fully exposed to userspace. Move this into ns_common and use the same id space for all namespaces so they can trivially and reliably be compared. There's more coming based on the iterator infrastructure but the series is large enough and focuses on file handles. Extensive selftests included. Signed-off-by: Christian Brauner <brauner(a)kernel.org> --- Changes in v2: - Address various review comments. - Use a common NS_GET_ID ioctl() instead of individual ioctls. - Link to v1: https://lore.kernel.org/20250910-work-namespace-v1-0-4dd56e7359d8@kernel.org --- Christian Brauner (33): pidfs: validate extensible ioctls nsfs: drop tautological ioctl() check nsfs: validate extensible ioctls block: use extensible_ioctl_valid() ns: move to_ns_common() to ns_common.h nsfs: add nsfs.h header ns: uniformly initialize ns_common cgroup: use ns_common_init() ipc: use ns_common_init() mnt: use ns_common_init() net: use ns_common_init() pid: use ns_common_init() time: use ns_common_init() user: use ns_common_init() uts: use ns_common_init() ns: remove ns_alloc_inum() nstree: make iterator generic mnt: support ns lookup cgroup: support ns lookup ipc: support ns lookup net: support ns lookup pid: support ns lookup time: support ns lookup user: support ns lookup uts: support ns lookup ns: add to_<type>_ns() to respective headers nsfs: add current_in_namespace() nsfs: support file handles nsfs: support exhaustive file handles nsfs: add missing id retrieval support tools: update nsfs.h uapi header selftests/namespaces: add identifier selftests selftests/namespaces: add file handle selftests block/blk-integrity.c | 8 +- fs/fhandle.c | 6 + fs/internal.h | 1 + fs/mount.h | 10 +- fs/namespace.c | 156 +-- fs/nsfs.c | 201 ++- fs/pidfs.c | 2 +- include/linux/cgroup.h | 5 + include/linux/exportfs.h | 6 + include/linux/fs.h | 14 + include/linux/ipc_namespace.h | 5 + include/linux/ns_common.h | 29 + include/linux/nsfs.h | 40 + include/linux/nsproxy.h | 11 - include/linux/nstree.h | 89 ++ include/linux/pid_namespace.h | 5 + include/linux/proc_ns.h | 32 +- include/linux/time_namespace.h | 9 + include/linux/user_namespace.h | 5 + include/linux/utsname.h | 5 + include/net/net_namespace.h | 6 + include/uapi/linux/fcntl.h | 1 + include/uapi/linux/nsfs.h | 15 +- init/main.c | 2 + ipc/msgutil.c | 1 + ipc/namespace.c | 12 +- ipc/shm.c | 2 + kernel/Makefile | 2 +- kernel/cgroup/cgroup.c | 2 + kernel/cgroup/namespace.c | 24 +- kernel/nstree.c | 233 ++++ kernel/pid_namespace.c | 13 +- kernel/time/namespace.c | 23 +- kernel/user_namespace.c | 17 +- kernel/utsname.c | 28 +- net/core/net_namespace.c | 59 +- tools/include/uapi/linux/nsfs.h | 17 +- tools/testing/selftests/namespaces/.gitignore | 2 + tools/testing/selftests/namespaces/Makefile | 7 + tools/testing/selftests/namespaces/config | 7 + .../selftests/namespaces/file_handle_test.c | 1429 ++++++++++++++++++++ tools/testing/selftests/namespaces/nsid_test.c | 986 ++++++++++++++ 42 files changed, 3257 insertions(+), 270 deletions(-) --- base-commit: 8f5ae30d69d7543eee0d70083daf4de8fe15d585 change-id: 20250905-work-namespace-c68826dda0d4

1 month, 2 weeks

7
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[PATCH v21 0/8] fork: Support shadow stacks in clone3()

by Mark Brown

[ I think at this point everyone is OK with the ABI, and the x86 implementation has been tested so hopefully we are near to being able to get this merged? If there are any outstanding issues let me know and I can look at addressing them. The one possible issue I am aware of is that the RISC-V shadow stack support was briefly in -next but got dropped along with the general RISC-V issues during the last merge window, rebasing for that is still in progress. I guess ideally this could be applied on a branch and then pulled into the RISC-V tree? ] The kernel has recently added support for shadow stacks, currently x86 only using their CET feature but both arm64 and RISC-V have equivalent features (GCS and Zicfiss respectively), I am actively working on GCS[1]. With shadow stacks the hardware maintains an additional stack containing only the return addresses for branch instructions which is not generally writeable by userspace and ensures that any returns are to the recorded addresses. This provides some protection against ROP attacks and making it easier to collect call stacks. These shadow stacks are allocated in the address space of the userspace process. Our API for shadow stacks does not currently offer userspace any flexiblity for managing the allocation of shadow stacks for newly created threads, instead the kernel allocates a new shadow stack with the same size as the normal stack whenever a thread is created with the feature enabled. The stacks allocated in this way are freed by the kernel when the thread exits or shadow stacks are disabled for the thread. This lack of flexibility and control isn't ideal, in the vast majority of cases the shadow stack will be over allocated and the implicit allocation and deallocation is not consistent with other interfaces. As far as I can tell the interface is done in this manner mainly because the shadow stack patches were in development since before clone3() was implemented. Since clone3() is readily extensible let's add support for specifying a shadow stack when creating a new thread or process, keeping the current implicit allocation behaviour if one is not specified either with clone3() or through the use of clone(). The user must provide a shadow stack pointer, this must point to memory mapped for use as a shadow stackby map_shadow_stack() with an architecture specified shadow stack token at the top of the stack. Yuri Khrustalev has raised questions from the libc side regarding discoverability of extended clone3() structure sizes[2], this seems like a general issue with clone3(). There was a suggestion to add a hwcap on arm64 which isn't ideal but is doable there, though architecture specific mechanisms would also be needed for x86 (and RISC-V if it's support gets merged before this does). The idea has, however, had strong pushback from the architecture maintainers and it is possible to detect support for this in clone3() by attempting a call with a misaligned shadow stack pointer specified so no hwcap has been added. [1] https://lore.kernel.org/linux-arm-kernel/20241001-arm64-gcs-v13-0-222b78d87… [2] https://lore.kernel.org/r/aCs65ccRQtJBnZ_5@arm.com Signed-off-by: Mark Brown <broonie(a)kernel.org> --- Changes in v21: - Rebase onto https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git kernel-6.18.clone3 - Rename shadow_stack_token to shstk_token, since it's a simple rename I've kept the acks and reviews but I dropped the tested-bys just to be safe. - Link to v20: https://lore.kernel.org/r/20250902-clone3-shadow-stack-v20-0-4d9fff1c53e7@k… Changes in v20: - Comment fixes and clarifications in x86 arch_shstk_validate_clone() from Rick Edgecombe. - Spelling fix in documentation. - Link to v19: https://lore.kernel.org/r/20250819-clone3-shadow-stack-v19-0-bc957075479b@k… Changes in v19: - Rebase onto v6.17-rc1. - Link to v18: https://lore.kernel.org/r/20250702-clone3-shadow-stack-v18-0-7965d2b694db@k… Changes in v18: - Rebase onto v6.16-rc3. - Thanks to pointers from Yuri Khrustalev this version has been tested on x86 so I have removed the RFT tag. - Clarify clone3_shadow_stack_valid() comment about the Kconfig check. - Remove redundant GCSB DSYNCs in arm64 code. - Fix token validation on x86. - Link to v17: https://lore.kernel.org/r/20250609-clone3-shadow-stack-v17-0-8840ed97ff6f@k… Changes in v17: - Rebase onto v6.16-rc1. - Link to v16: https://lore.kernel.org/r/20250416-clone3-shadow-stack-v16-0-2ffc9ca3917b@k… Changes in v16: - Rebase onto v6.15-rc2. - Roll in fixes from x86 testing from Rick Edgecombe. - Rework so that the argument is shadow_stack_token. - Link to v15: https://lore.kernel.org/r/20250408-clone3-shadow-stack-v15-0-3fa245c6e3be@k… Changes in v15: - Rebase onto v6.15-rc1. - Link to v14: https://lore.kernel.org/r/20250206-clone3-shadow-stack-v14-0-805b53af73b9@k… Changes in v14: - Rebase onto v6.14-rc1. - Link to v13: https://lore.kernel.org/r/20241203-clone3-shadow-stack-v13-0-93b89a81a5ed@k… Changes in v13: - Rebase onto v6.13-rc1. - Link to v12: https://lore.kernel.org/r/20241031-clone3-shadow-stack-v12-0-7183eb8bee17@k… Changes in v12: - Add the regular prctl() to the userspace API document since arm64 support is queued in -next. - Link to v11: https://lore.kernel.org/r/20241005-clone3-shadow-stack-v11-0-2a6a2bd6d651@k… Changes in v11: - Rebase onto arm64 for-next/gcs, which is based on v6.12-rc1, and integrate arm64 support. - Rework the interface to specify a shadow stack pointer rather than a base and size like we do for the regular stack. - Link to v10: https://lore.kernel.org/r/20240821-clone3-shadow-stack-v10-0-06e8797b9445@k… Changes in v10: - Integrate fixes & improvements for the x86 implementation from Rick Edgecombe. - Require that the shadow stack be VM_WRITE. - Require that the shadow stack base and size be sizeof(void *) aligned. - Clean up trailing newline. - Link to v9: https://lore.kernel.org/r/20240819-clone3-shadow-stack-v9-0-962d74f99464@ke… Changes in v9: - Pull token validation earlier and report problems with an error return to parent rather than signal delivery to the child. - Verify that the top of the supplied shadow stack is VM_SHADOW_STACK. - Rework token validation to only do the page mapping once. - Drop no longer needed support for testing for signals in selftest. - Fix typo in comments. - Link to v8: https://lore.kernel.org/r/20240808-clone3-shadow-stack-v8-0-0acf37caf14c@ke… Changes in v8: - Fix token verification with user specified shadow stack. - Don't track user managed shadow stacks for child processes. - Link to v7: https://lore.kernel.org/r/20240731-clone3-shadow-stack-v7-0-a9532eebfb1d@ke… Changes in v7: - Rebase onto v6.11-rc1. - Typo fixes. - Link to v6: https://lore.kernel.org/r/20240623-clone3-shadow-stack-v6-0-9ee7783b1fb9@ke… Changes in v6: - Rebase onto v6.10-rc3. - Ensure we don't try to free the parent shadow stack in error paths of x86 arch code. - Spelling fixes in userspace API document. - Additional cleanups and improvements to the clone3() tests to support the shadow stack tests. - Link to v5: https://lore.kernel.org/r/20240203-clone3-shadow-stack-v5-0-322c69598e4b@ke… Changes in v5: - Rebase onto v6.8-rc2. - Rework ABI to have the user allocate the shadow stack memory with map_shadow_stack() and a token. - Force inlining of the x86 shadow stack enablement. - Move shadow stack enablement out into a shared header for reuse by other tests. - Link to v4: https://lore.kernel.org/r/20231128-clone3-shadow-stack-v4-0-8b28ffe4f676@ke… Changes in v4: - Formatting changes. - Use a define for minimum shadow stack size and move some basic validation to fork.c. - Link to v3: https://lore.kernel.org/r/20231120-clone3-shadow-stack-v3-0-a7b8ed3e2acc@ke… Changes in v3: - Rebase onto v6.7-rc2. - Remove stale shadow_stack in internal kargs. - If a shadow stack is specified unconditionally use it regardless of CLONE_ parameters. - Force enable shadow stacks in the selftest. - Update changelogs for RISC-V feature rename. - Link to v2: https://lore.kernel.org/r/20231114-clone3-shadow-stack-v2-0-b613f8681155@ke… Changes in v2: - Rebase onto v6.7-rc1. - Remove ability to provide preallocated shadow stack, just specify the desired size. - Link to v1: https://lore.kernel.org/r/20231023-clone3-shadow-stack-v1-0-d867d0b5d4d0@ke… --- Mark Brown (8): arm64/gcs: Return a success value from gcs_alloc_thread_stack() Documentation: userspace-api: Add shadow stack API documentation selftests: Provide helper header for shadow stack testing fork: Add shadow stack support to clone3() selftests/clone3: Remove redundant flushes of output streams selftests/clone3: Factor more of main loop into test_clone3() selftests/clone3: Allow tests to flag if -E2BIG is a valid error code selftests/clone3: Test shadow stack support Documentation/userspace-api/index.rst | 1 + Documentation/userspace-api/shadow_stack.rst | 44 +++++ arch/arm64/include/asm/gcs.h | 8 +- arch/arm64/kernel/process.c | 8 +- arch/arm64/mm/gcs.c | 55 +++++- arch/x86/include/asm/shstk.h | 11 +- arch/x86/kernel/process.c | 2 +- arch/x86/kernel/shstk.c | 53 ++++- include/asm-generic/cacheflush.h | 11 ++ include/linux/sched/task.h | 17 ++ include/uapi/linux/sched.h | 9 +- kernel/fork.c | 93 +++++++-- tools/testing/selftests/clone3/clone3.c | 226 ++++++++++++++++++---- tools/testing/selftests/clone3/clone3_selftests.h | 65 ++++++- tools/testing/selftests/ksft_shstk.h | 98 ++++++++++ 15 files changed, 620 insertions(+), 81 deletions(-) --- base-commit: 76cea30ad520238160bf8f5e2f2803fcd7a08d22 change-id: 20231019-clone3-shadow-stack-15d40d2bf536 Best regards, -- Mark Brown <broonie(a)kernel.org>

1 month, 2 weeks

4
14
0 0

[PATCH bpf-next 0/5] selftests/bpf: Extend sockmap_redir to test no-redir SK_DROP/SK_PASS

by Michal Luczaj

sockmap_redir was introduced to comprehensively test the BPF redirection. This series strives to increase the tested sockmap/sockhash code coverage; adds support for skipping the actual redirect part, allowing to simply SK_DROP or SK_PASS the packet. BPF_MAP_TYPE_SOCKMAP BPF_MAP_TYPE_SOCKHASH x sk_msg-to-egress sk_msg-to-ingress sk_skb-to-egress sk_skb-to-ingress x AF_INET, SOCK_STREAM AF_INET6, SOCK_STREAM AF_INET, SOCK_DGRAM AF_INET6, SOCK_DGRAM AF_UNIX, SOCK_STREAM AF_UNIX, SOCK_DGRAM AF_VSOCK, SOCK_STREAM AF_VSOCK, SOCK_SEQPACKET x SK_REDIRECT SK_DROP SK_PASS Patch 5 ("Support no-redirect SK_DROP/SK_PASS") implements the feature. Patches 3 ("Rename functions") and 4 ("Let test specify skel's redirect_type") make preparatory changes. I also took the opportunity to clean up (Patch 1, "Simplify try_recv()") and improve a bit (Patch 2, "Fix OOB handling"). $ cd tools/testing/selftests/bpf $ make $ sudo ./test_progs -t sockmap_redir ... Summary: 1/720 PASSED, 0 SKIPPED, 0 FAILED Signed-off-by: Michal Luczaj <mhal(a)rbox.co> --- Michal Luczaj (5): selftests/bpf: sockmap_redir: Simplify try_recv() selftests/bpf: sockmap_redir: Fix OOB handling selftests/bpf: sockmap_redir: Rename functions selftests/bpf: sockmap_redir: Let test specify skel's redirect_type selftests/bpf: sockmap_redir: Support no-redirect SK_DROP/SK_PASS .../selftests/bpf/prog_tests/sockmap_redir.c | 143 +++++++++++++++------ 1 file changed, 105 insertions(+), 38 deletions(-) --- base-commit: e8a6a9d3e8cc539d281e77b9df2439f223ec8153 change-id: 20250523-redir-test-pass-drop-2f2a5edca6e1 Best regards, -- Michal Luczaj <mhal(a)rbox.co>

1 month, 3 weeks

2
15
0 0

[PATCH v6 00/11] Direct Map Removal Support for guest_memfd

by Roy, Patrick

[ based on kvm/next ] Unmapping virtual machine guest memory from the host kernel's direct map is a successful mitigation against Spectre-style transient execution issues: If the kernel page tables do not contain entries pointing to guest memory, then any attempted speculative read through the direct map will necessarily be blocked by the MMU before any observable microarchitectural side-effects happen. This means that Spectre-gadgets and similar cannot be used to target virtual machine memory. Roughly 60% of speculative execution issues fall into this category [1, Table 1]. This patch series extends guest_memfd with the ability to remove its memory from the host kernel's direct map, to be able to attain the above protection for KVM guests running inside guest_memfd. Additionally, a Firecracker branch with support for these VMs can be found on GitHub [2]. For more details, please refer to the v5 cover letter [v5]. No substantial changes in design have taken place since. === Changes Since v5 === - Fix up error handling for set_direct_map_[in]valid_noflush() (Mike) - Fix capability check for KVM_GUEST_MEMFD_NO_DIRECT_MAP (Mike) - Make secretmem_aops static in mm/secretmem.c (Mike) - Fixup some more comments in gup.c that referred to secretmem specifically to instead point to AS_NO_DIRECT_MAP (Mike) - New patch (PATCH 4/11) to avoid ifdeffery in kvm_gmem_free_folio() (Mike) - vma_is_no_direct_map() -> vma_has_no_direct_map() rename (David) - Squash some patches (David) - Fix up const-ness of parameters to new functions in pagemap.h (Fuad) [1]: https://download.vusec.net/papers/quarantine_raid23.pdf [2]: https://github.com/firecracker-microvm/firecracker/tree/feature/secret-hidi… [RFCv1]: https://lore.kernel.org/kvm/20240709132041.3625501-1-roypat@amazon.co.uk/ [RFCv2]: https://lore.kernel.org/kvm/20240910163038.1298452-1-roypat@amazon.co.uk/ [RFCv3]: https://lore.kernel.org/kvm/20241030134912.515725-1-roypat@amazon.co.uk/ [v4]: https://lore.kernel.org/kvm/20250221160728.1584559-1-roypat@amazon.co.uk/ [v5]: https://lore.kernel.org/kvm/20250828093902.2719-1-roypat@amazon.co.uk/ Elliot Berman (1): filemap: Pass address_space mapping to ->free_folio() Patrick Roy (10): arch: export set_direct_map_valid_noflush to KVM module mm: introduce AS_NO_DIRECT_MAP KVM: guest_memfd: Add stub for kvm_arch_gmem_invalidate KVM: guest_memfd: Add flag to remove from direct map KVM: selftests: load elf via bounce buffer KVM: selftests: set KVM_MEM_GUEST_MEMFD in vm_mem_add() if guest_memfd != -1 KVM: selftests: Add guest_memfd based vm_mem_backing_src_types KVM: selftests: stuff vm_mem_backing_src_type into vm_shape KVM: selftests: cover GUEST_MEMFD_FLAG_NO_DIRECT_MAP in existing selftests KVM: selftests: Test guest execution from direct map removed gmem Documentation/filesystems/locking.rst | 2 +- Documentation/virt/kvm/api.rst | 5 ++ arch/arm64/include/asm/kvm_host.h | 12 ++++ arch/arm64/mm/pageattr.c | 1 + arch/loongarch/mm/pageattr.c | 1 + arch/riscv/mm/pageattr.c | 1 + arch/s390/mm/pageattr.c | 1 + arch/x86/mm/pat/set_memory.c | 1 + fs/nfs/dir.c | 11 ++-- fs/orangefs/inode.c | 3 +- include/linux/fs.h | 2 +- include/linux/kvm_host.h | 9 +++ include/linux/pagemap.h | 16 +++++ include/linux/secretmem.h | 18 ------ include/uapi/linux/kvm.h | 2 + lib/buildid.c | 4 +- mm/filemap.c | 9 +-- mm/gup.c | 19 ++---- mm/mlock.c | 2 +- mm/secretmem.c | 11 ++-- mm/vmscan.c | 4 +- .../testing/selftests/kvm/guest_memfd_test.c | 2 + .../testing/selftests/kvm/include/kvm_util.h | 37 ++++++++--- .../testing/selftests/kvm/include/test_util.h | 8 +++ tools/testing/selftests/kvm/lib/elf.c | 8 +-- tools/testing/selftests/kvm/lib/io.c | 23 +++++++ tools/testing/selftests/kvm/lib/kvm_util.c | 61 +++++++++++-------- tools/testing/selftests/kvm/lib/test_util.c | 8 +++ tools/testing/selftests/kvm/lib/x86/sev.c | 1 + .../selftests/kvm/pre_fault_memory_test.c | 1 + .../selftests/kvm/set_memory_region_test.c | 50 +++++++++++++-- .../kvm/x86/private_mem_conversions_test.c | 7 ++- virt/kvm/guest_memfd.c | 56 ++++++++++++++--- virt/kvm/kvm_main.c | 5 ++ 34 files changed, 288 insertions(+), 113 deletions(-) base-commit: a6ad54137af92535cfe32e19e5f3bc1bb7dbd383 -- 2.50.1

1 month, 3 weeks

6
20
0 0

[PATCH] selftests: riscv: Add README for RISC-V KSelfTest

by Bala-Vignesh-Reddy

Add a README file for RISC-V specific kernel selftests under tools/testing/selftests/riscv/. This mirrors the existing README for arm64, providing clear guidance on how the tests are architecture specific and skipped on non-riscv systems. It also includes standard make commands for building, running and installing the tests, along with a reference to general kselftest documentation. Signed-off-by: Bala-Vignesh-Reddy <reddybalavignesh9979(a)gmail.com> --- tools/testing/selftests/riscv/README | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) create mode 100644 tools/testing/selftests/riscv/README diff --git a/tools/testing/selftests/riscv/README b/tools/testing/selftests/riscv/README new file mode 100644 index 000000000000..443da395da68 --- /dev/null +++ b/tools/testing/selftests/riscv/README @@ -0,0 +1,24 @@ +KSelfTest RISC-V +================ + +- These tests are riscv specific and so not built or run but just skipped + completely when env-variable ARCH is found to be different than 'riscv'. + +- Holding true the above, RISC-V KSFT tests can be run within the + KSelfTest framework using standard Linux top-level-makefile targets: + + $ make TARGETS=riscv kselftest-clean + $ make TARGETS=riscv kselftest + + or + + $ make -C tools/testing/selftests TARGETS=riscv \ + INSTALL_PATH=<your-installation-path> install + + or, alternatively, only specific riscv/ subtargets can be picked: + + $ make -C tools/testing/selftests TARGETS=riscv RISCV_SUBTARGETS="mm vector" \ + INSTALL_PATH=<your-installation-path> install + + Further details on building and running KSFT can be found in: + Documentation/dev-tools/kselftest.rst -- 2.43.0

1 month, 3 weeks

3
2
0 0

[PATCH v2 0/7] vma count: fixes, test and improvements

by Kalesh Singh

Hi all, This is v2 to the VMA count patch I previously posted at: https://lore.kernel.org/r/20250903232437.1454293-1-kaleshsingh@google.com/ I've split it into multiple patches to address the feedback. The main changes in v2 are: - Use a capacity-based check for VMA count limit, per Lorenzo. - Rename map_count to vma_count, per David. - Add assertions for exceeding the limit, per Pedro. - Add tests for max_vma_count, per Liam. - Emit a trace event for failure due to insufficient capacity for observability Tested on x86_64 and arm64: - Build test: - allyesconfig for rename - Selftests: cd tools/testing/selftests/mm && \ make && \ ./run_vmtests.sh -t max_vma_count (With trace_max_vma_count_exceeded enabled) - vma tests: cd tools/testing/vma && \ make && \ ./vma Thanks, Kalesh Kalesh Singh (7): mm: fix off-by-one error in VMA count limit checks mm/selftests: add max_vma_count tests mm: introduce vma_count_remaining() mm: rename mm_struct::map_count to vma_count mm: harden vma_count against direct modification mm: add assertion for VMA count limit mm/tracing: introduce max_vma_count_exceeded trace event fs/binfmt_elf.c | 2 +- fs/coredump.c | 2 +- include/linux/mm.h | 35 +- include/linux/mm_types.h | 5 +- include/trace/events/vma.h | 32 + kernel/fork.c | 2 +- mm/debug.c | 2 +- mm/internal.h | 1 + mm/mmap.c | 28 +- mm/mremap.c | 13 +- mm/nommu.c | 8 +- mm/util.c | 1 - mm/vma.c | 88 ++- tools/testing/selftests/mm/Makefile | 1 + .../selftests/mm/max_vma_count_tests.c | 709 ++++++++++++++++++ tools/testing/selftests/mm/run_vmtests.sh | 5 + tools/testing/vma/vma.c | 32 +- tools/testing/vma/vma_internal.h | 44 +- 18 files changed, 949 insertions(+), 61 deletions(-) create mode 100644 include/trace/events/vma.h create mode 100644 tools/testing/selftests/mm/max_vma_count_tests.c base-commit: f83ec76bf285bea5727f478a68b894f5543ca76e -- 2.51.0.384.g4c02a37b29-goog

1 month, 3 weeks

8
64
0 0

[PATCH] selftests: always install UAPI headers to the correct directory

by Thomas Weißschuh

Currently the UAPI headers are always installed into the source directory. When building out-of-tree this doesn't work, as the include path will be wrong and it dirties the source tree, leading to complains by kbuild. Make sure the 'headers' target installs the UAPI headers in the correctly. The real target directory can come from multiple places. To handle them all extract the target directory from KHDR_INCLUDES. Reported-by: Jason Gunthorpe <jgg(a)nvidia.com> Closes: https://lore.kernel.org/lkml/20250917153209.GA2023406@nvidia.com/ Fixes: 1a59f5d31569 ("selftests: Add headers target") Signed-off-by: Thomas Weißschuh <thomas.weissschuh(a)linutronix.de> Reviewed-by: Jason Gunthorpe <jgg(a)nvidia.com> --- tools/testing/selftests/lib.mk | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/tools/testing/selftests/lib.mk b/tools/testing/selftests/lib.mk index 5303900339292e618dee4fd7ff8a7c2fa3209a68..a448fae57831d86098806adaff53f6f1a747febb 100644 --- a/tools/testing/selftests/lib.mk +++ b/tools/testing/selftests/lib.mk @@ -228,7 +228,10 @@ $(OUTPUT)/%:%.S $(LINK.S) $^ $(LDLIBS) -o $@ endif +# Extract the expected header directory +khdr_output := $(patsubst %/usr/include,%,$(filter %/usr/include,$(KHDR_INCLUDES))) + headers: - $(Q)$(MAKE) -C $(top_srcdir) headers + $(Q)$(MAKE) -f $(top_srcdir)/Makefile -C $(khdr_output) headers .PHONY: run_tests all clean install emit_tests gen_mods_dir clean_mods_dir headers --- base-commit: 8f5ae30d69d7543eee0d70083daf4de8fe15d585 change-id: 20250918-kselftest-uapi-out-of-tree-98d50f59040c Best regards, -- Thomas Weißschuh <thomas.weissschuh(a)linutronix.de>

1 month, 3 weeks

2
1
0 0

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