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[PATCH 0/7] KVM: x86: Improve the handling of debug exceptions during instruction emulation

by Hou Wenlong

During my testing, I found that guest debugging with 'DR6.BD' does not work in instruction emulation, as the current code only considers the guest's DR7. Upon reviewing the code, I also observed that the checks for the userspace guest debugging feature and the guest's own debugging feature are repeated in different places during instruction emulation, but the overall logic is the same. If guest debugging is enabled, it needs to exit to userspace; otherwise, a #DB exception needs to be injected into the guest. Therefore, as suggested by Jiangshan Lai, some cleanup has been done for #DB handling in instruction emulation in this patchset. A new function named 'kvm_inject_emulated_db()' is introduced to consolidate all the checking logic. Moreover, I hope we can make the #DB interception path use the same function as well. Additionally, when I looked into the single-step #DB handling in instruction emulation, I noticed that the interrupt shadow is toggled, but it is not considered in the single-step #DB injection. This oversight causes VM entry to fail on VMX (due to pending debug exceptions checking) or breaks the 'MOV SS' suppressed #DB. For the latter, I have kept the behavior for now in my patchset, as I need some suggestions. Hou Wenlong (7): KVM: x86: Set guest DR6 by kvm_queue_exception_p() in instruction emulation KVM: x86: Check guest debug in DR access instruction emulation KVM: x86: Only check effective code breakpoint in emulation KVM: x86: Consolidate KVM_GUESTDBG_SINGLESTEP check into the kvm_inject_emulated_db() KVM: VMX: Set 'BS' bit in pending debug exceptions during instruction emulation KVM: selftests: Verify guest debug DR7.GD checking during instruction emulation KVM: selftests: Verify 'BS' bit checking in pending debug exception during VM entry arch/x86/include/asm/kvm-x86-ops.h | 1 + arch/x86/include/asm/kvm_host.h | 1 + arch/x86/kvm/emulate.c | 14 +-- arch/x86/kvm/kvm_emulate.h | 7 +- arch/x86/kvm/vmx/main.c | 9 ++ arch/x86/kvm/vmx/vmx.c | 14 ++- arch/x86/kvm/vmx/x86_ops.h | 1 + arch/x86/kvm/x86.c | 109 +++++++++++------- arch/x86/kvm/x86.h | 7 ++ .../selftests/kvm/include/x86/processor.h | 3 +- tools/testing/selftests/kvm/x86/debug_regs.c | 64 +++++++++- 11 files changed, 167 insertions(+), 63 deletions(-) base-commit: ecbcc2461839e848970468b44db32282e5059925 -- 2.31.1

6 days, 15 hours

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[PATCH v3 0/7] seccomp: support nested listeners

by Alexander Mikhalitsyn

Dear friends, this patch series adds support for nested seccomp listeners. It allows container runtimes and other sandboxing software to install seccomp listeners on top of existing ones, which is useful for nested LXC containers and other similar use-cases. Expecting potential discussions around this patch series, I'm going to present a talk at LPC 2025 about the design and implementation details of this feature [1]. Git tree (based on for-next/seccomp): v3: https://github.com/mihalicyn/linux/commits/seccomp.mult.listeners.v3 current: https://github.com/mihalicyn/linux/commits/seccomp.mult.listeners Changelog for version 3: - almost completely rewritten (no static array on the stack, no nesting limit) - more testcases Changelog for version 2: - add some explanatory comments - add RWB tags from Tycho Andersen (thanks, Tycho! ;) ) - CC-ed Aleksa as he might be interested in this stuff too Links to previous versions: v2: https://lore.kernel.org/all/20251202115200.110646-1-aleksandr.mikhalitsyn@c… tree: https://github.com/mihalicyn/linux/commits/seccomp.mult.listeners.v2 v1: https://lore.kernel.org/all/20251201122406.105045-1-aleksandr.mikhalitsyn@c… tree: https://github.com/mihalicyn/linux/commits/seccomp.mult.listeners.v1 Link: https://lpc.events/event/19/contributions/2241/ [1] Cc: linux-doc(a)vger.kernel.org Cc: linux-kernel(a)vger.kernel.org Cc: linux-kselftest(a)vger.kernel.org Cc: bpf(a)vger.kernel.org Cc: Kees Cook <kees(a)kernel.org> Cc: Andy Lutomirski <luto(a)amacapital.net> Cc: Will Drewry <wad(a)chromium.org> Cc: Jonathan Corbet <corbet(a)lwn.net> Cc: Shuah Khan <shuah(a)kernel.org> Cc: Aleksa Sarai <cyphar(a)cyphar.com> Cc: Tycho Andersen <tycho(a)tycho.pizza> Cc: Andrei Vagin <avagin(a)gmail.com> Cc: Christian Brauner <brauner(a)kernel.org> Cc: Stéphane Graber <stgraber(a)stgraber.org> Alexander Mikhalitsyn (7): seccomp: remove unused argument from seccomp_do_user_notification seccomp: use bitfields for boolean flags on seccomp_filter struct seccomp: keep track of seccomp filters with closed listeners seccomp: mark first listener in the tree seccomp: handle multiple listeners case seccomp: allow nested listeners tools/testing/selftests/seccomp: test nested listeners .../userspace-api/seccomp_filter.rst | 6 + include/linux/seccomp.h | 3 +- include/uapi/linux/seccomp.h | 13 +- kernel/seccomp.c | 129 +++++++- tools/include/uapi/linux/seccomp.h | 13 +- tools/testing/selftests/seccomp/seccomp_bpf.c | 303 ++++++++++++++++++ 6 files changed, 438 insertions(+), 29 deletions(-) -- 2.43.0

6 days, 16 hours

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[PATCH RESEND] selftests: gpio: correctly check the type of /dev/gpiochipX

by Guixin Liu

/dev/gpiochipX is a character device, not a directory, so we should use "test -c" instead of "test -d" to check for its existence; otherwise, the current check will not work correctly when /dev/gpiochipX is left over (e.g., as a stale device node). Signed-off-by: Guixin Liu <kanie(a)linux.alibaba.com> --- tools/testing/selftests/gpio/gpio-aggregator.sh | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/tools/testing/selftests/gpio/gpio-aggregator.sh b/tools/testing/selftests/gpio/gpio-aggregator.sh index 9b6f80ad9f8a..13d8e1607571 100755 --- a/tools/testing/selftests/gpio/gpio-aggregator.sh +++ b/tools/testing/selftests/gpio/gpio-aggregator.sh @@ -351,7 +351,7 @@ test "$(agg_get_chip_num_lines _sysfs.0)" = "1" || fail "number of lines is not test "$(agg_get_line_name _sysfs.0 0)" = "" || fail "line name is unset" echo "$(agg_configfs_dev_name _sysfs.0)" > "$SYSFS_AGG_DIR/delete_device" test -d $CONFIGFS_AGG_DIR/_sysfs.0 && fail "_sysfs.0 unexpectedly remains" -test -d /dev/${CHIPNAME} && fail "/dev/${CHIPNAME} unexpectedly remains" +test -c /dev/${CHIPNAME} && fail "/dev/${CHIPNAME} unexpectedly remains" echo "1.2.2. Complex creation/deletion" echo "chip0bank0_0 chip1_bank1 10-11" > "$SYSFS_AGG_DIR/new_device" @@ -365,7 +365,7 @@ test "$(agg_get_line_name _sysfs.0 1)" = "" || fail "line name is unset" test "$(agg_get_line_name _sysfs.0 2)" = "" || fail "line name is unset" echo "$(agg_configfs_dev_name _sysfs.0)" > "$SYSFS_AGG_DIR/delete_device" test -d $CONFIGFS_AGG_DIR/_sysfs.0 && fail "_sysfs.0 unexpectedly remains" -test -d /dev/${CHIPNAME} && fail "/dev/${CHIPNAME} unexpectedly remains" +test -c /dev/${CHIPNAME} && fail "/dev/${CHIPNAME} unexpectedly remains" echo "1.2.3. Asynchronous creation with deferred probe" sim_disable_chip chip0 @@ -382,7 +382,7 @@ test "$(agg_get_chip_num_lines _sysfs.0)" = "1" || fail "number of lines is not test "$(agg_get_line_name _sysfs.0 0)" = "" || fail "line name unexpectedly set" echo "$(agg_configfs_dev_name _sysfs.0)" > "$SYSFS_AGG_DIR/delete_device" test -d $CONFIGFS_AGG_DIR/_sysfs.0 && fail "_sysfs.0 unexpectedly remains" -test -d /dev/${CHIPNAME} && fail "/dev/${CHIPNAME} unexpectedly remains" +test -c /dev/${CHIPNAME} && fail "/dev/${CHIPNAME} unexpectedly remains" echo "1.2.4. Can't instantiate a chip with invalid configuration" echo "xyz 0" > "$SYSFS_AGG_DIR/new_device" -- 2.43.0

1 week

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[PATCH v2 00/13] selftests: Fix build warnings and errors

by Guenter Roeck

This series fixes build warnings and errors observed when trying to build selftests. v2: Emphasize that the patch series fixes build warnings and errors which are seen even if -Werror is not provided. Fix usage of cc-option. For "ignoring return value" warnings, use perror() to display an error message if the affected function returns an error. ---------------------------------------------------------------- Guenter Roeck (13): clone3: clone3_cap_checkpoint_restore: Fix build warnings selftests: ntsync: Fix build warnings selftests/filesystems: fclog: Fix build warnings and errors selftests/filesystems: file_stressor: Fix build warning selftests/filesystems: anon_inode_test: Fix build warning selftest: af_unix: Support compilers without flex-array-member-not-at-end support selftest/futex: Comment out test_futex_mpol selftests: net: netlink-dumps: Avoid uninitialized variable warning selftests/seccomp: Fix build warning selftests: net: Fix build warnings selftests/fs/mount-notify: Fix build warning selftests/fs/mount-notify-ns: Fix build warning selftests: net: tfo: Fix build warning tools/testing/selftests/clone3/clone3_cap_checkpoint_restore.c | 4 ---- tools/testing/selftests/drivers/ntsync/ntsync.c | 4 ++-- tools/testing/selftests/filesystems/anon_inode_test.c | 1 + tools/testing/selftests/filesystems/fclog.c | 1 + tools/testing/selftests/filesystems/file_stressor.c | 2 -- .../testing/selftests/filesystems/mount-notify/mount-notify_test.c | 3 ++- .../selftests/filesystems/mount-notify/mount-notify_test_ns.c | 3 ++- tools/testing/selftests/futex/functional/futex_numa_mpol.c | 2 ++ tools/testing/selftests/net/af_unix/Makefile | 7 ++++++- tools/testing/selftests/net/lib/ksft.h | 6 ++++-- tools/testing/selftests/net/netlink-dumps.c | 2 +- tools/testing/selftests/net/tfo.c | 3 ++- tools/testing/selftests/seccomp/seccomp_bpf.c | 3 ++- 13 files changed, 25 insertions(+), 16 deletions(-)

1 week

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[PATCH bpf v5 0/2] bpf: fix bpf_d_path() helper prototype

by Shuran Liu

Hi, This series fixes a verifier issue with bpf_d_path() and adds a regression test to cover its use within a hook function. Patch 1 updates the bpf_d_path() helper prototype so that the second argument is marked as MEM_WRITE. This makes it explicit to the verifier that the helper writes into the provided buffer. Patch 2 extends the existing d_path selftest to cover incorrect verifier assumptions caused by an incorrect function prototype. The test program calls bpf_d_path() and checks if the first character of the path can be read. It ensures the verifier does not assume the buffer remains unwritten. Changelog ========= v5: - Moved the temporary file for the fallocate test from /tmp to /dev/shm Since bpf CI's 9P filesystem under /tmp does not support fallocate. v4: - Use the fallocate hook instead of an LSM hook to simplify the selftest, as suggested by Matt and Alexei. - Add a utility function in test_d_path.c to load the BPF program, improving code reuse. v3: - Switch the pathname prefix loop to use bpf_for() instead of #pragma unroll, as suggested by Matt. - Remove /tmp/bpf_d_path_test in the test cleanup path. - Add the missing Reviewed-by tags. v2: - Merge the new test into the existing d_path selftest rather than creating new files. - Add PID filtering in the LSM program to avoid nondeterministic failures due to unrelated processes triggering bprm_check_security. - Synchronize child execution using a pipe to ensure deterministic updates to the PID. Thanks for your time and reviews. Shuran Liu (2): bpf: mark bpf_d_path() buffer as writeable selftests/bpf: add regression test for bpf_d_path() kernel/trace/bpf_trace.c | 2 +- .../testing/selftests/bpf/prog_tests/d_path.c | 91 +++++++++++++++---- .../testing/selftests/bpf/progs/test_d_path.c | 23 +++++ 3 files changed, 97 insertions(+), 19 deletions(-) -- 2.52.0

1 week

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[PATCH net-next v2] selftests: tls: fix warning of uninitialized variable

by Ankit Khushwaha

In 'poll_partial_rec_async' a uninitialized char variable 'token' with is used for write/read instruction to synchronize between threads via a pipe. tls.c:2833:26: warning: variable 'token' is uninitialized when passed as a const pointer argument Initialize 'token' to '\0' to silence compiler warning. Signed-off-by: Ankit Khushwaha <ankitkhushwaha.linux(a)gmail.com> --- compiler used: clang version 21.1.5 (Fedora 21.1.5-1.fc43). changelog: v2: - update patch name and msg v1: https://lore.kernel.org/all/20251129063726.31210-1-ankitkhushwaha.linux@gma… --- tools/testing/selftests/net/tls.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/testing/selftests/net/tls.c b/tools/testing/selftests/net/tls.c index a3ef4b57eb5f..a4d16a460fbe 100644 --- a/tools/testing/selftests/net/tls.c +++ b/tools/testing/selftests/net/tls.c @@ -2786,10 +2786,10 @@ TEST_F(tls_err, epoll_partial_rec) TEST_F(tls_err, poll_partial_rec_async) { struct pollfd pfd = { }; + char token = '\0'; ssize_t rec_len; char rec[256]; char buf[128]; - char token; int p[2]; int ret; -- 2.52.0

1 week

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[PATCH] kunit: Drop unused parameter from kunit_device_register_internal

by Uwe Kleine-König

The passed driver isn't used, so just drop this parameter. Signed-off-by: Uwe Kleine-König <u.kleine-koenig(a)baylibre.com> --- lib/kunit/device.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/lib/kunit/device.c b/lib/kunit/device.c index 520c1fccee8a..f201aaacd4cf 100644 --- a/lib/kunit/device.c +++ b/lib/kunit/device.c @@ -106,8 +106,7 @@ EXPORT_SYMBOL_GPL(kunit_driver_create); /* Helper which creates a kunit_device, attaches it to the kunit_bus*/ static struct kunit_device *kunit_device_register_internal(struct kunit *test, - const char *name, - const struct device_driver *drv) + const char *name) { struct kunit_device *kunit_dev; int err = -ENOMEM; @@ -150,7 +149,7 @@ struct device *kunit_device_register_with_driver(struct kunit *test, const char *name, const struct device_driver *drv) { - struct kunit_device *kunit_dev = kunit_device_register_internal(test, name, drv); + struct kunit_device *kunit_dev = kunit_device_register_internal(test, name); if (IS_ERR_OR_NULL(kunit_dev)) return ERR_CAST(kunit_dev); @@ -172,7 +171,7 @@ struct device *kunit_device_register(struct kunit *test, const char *name) if (IS_ERR(drv)) return ERR_CAST(drv); - dev = kunit_device_register_internal(test, name, drv); + dev = kunit_device_register_internal(test, name); if (IS_ERR(dev)) { kunit_release_action(test, driver_unregister_wrapper, (void *)drv); return ERR_CAST(dev); base-commit: 7d0a66e4bb9081d75c82ec4957c50034cb0ea449 -- 2.47.3

1 week

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[PATCH] kunit: make FAULT_TEST default to n when PANIC_ON_OOPS

by Brendan Jackman

As describe in the help string, the user might want to disable these tests if they don't like to see stacktraces/BUG etc in their kernel log. However, if they enable PANIC_ON_OOPS, these tests also crash the machine, which it's safe to assume _almost_ nobody wants. One might argue that _absolutely_ nobody ever wants their kernel to crash so this should just be a hard dependency instead of a default. However, since this is rather special code that's anyway concerned with deliberately doing "bad" things, the normal rules don't seem to apply, hence prefer flexibility and allow users to set up a crashing Kconfig if they so choose. Signed-off-by: Brendan Jackman <jackmanb(a)google.com> --- lib/kunit/Kconfig | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/lib/kunit/Kconfig b/lib/kunit/Kconfig index 50ecf55d2b9c8a82f2aff7a0b4156bd6179b0a2f..498cc51e493dc9a819e012b8082fb765f25512b9 100644 --- a/lib/kunit/Kconfig +++ b/lib/kunit/Kconfig @@ -28,7 +28,7 @@ config KUNIT_FAULT_TEST bool "Enable KUnit tests which print BUG stacktraces" depends on KUNIT_TEST depends on !UML - default y + default !PANIC_ON_OOPS help Enables fault handling tests for the KUnit framework. These tests may trigger a kernel BUG(), and the associated stack trace, even when they --- base-commit: 7bc16e72ddb993d706f698c2f6cee694e485f557 change-id: 20251207-kunit-fault-no-panic-e9bdce848031 Best regards, -- Brendan Jackman <jackmanb(a)google.com>

1 week

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[PATCH bpf-next v2 0/2] bpf: cpumap: improve error propagation in cpu_map_update_elem()

by Kohei Enju

This series improves error propagation in cpumap and adds selftests that cover the failure cases. Currently, failures returned from __cpu_map_entry_alloc() are ignored and always converted to -ENOMEM by cpu_map_update_elem(). This series ensures the correct error propagation and adds selftests. Changes: v2: - send to bpf-next, not to bpf - drop Fixes: tag v1: https://lore.kernel.org/bpf/20251128160504.57844-1-enjuk@amazon.com/ Kohei Enju (2): bpf: cpumap: propagate underlying error in cpu_map_update_elem() selftests/bpf: add tests for attaching invalid fd kernel/bpf/cpumap.c | 21 ++++++++++++------- .../bpf/prog_tests/xdp_cpumap_attach.c | 19 +++++++++++++++-- 2 files changed, 30 insertions(+), 10 deletions(-) -- 2.51.0

1 week

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[PATCH bpf 1/2] bpf: Fix truncated dmabuf iterator reads

by T.J. Mercier

If there is a large number (hundreds) of dmabufs allocated, the text output generated from dmabuf_iter_seq_show can exceed common user buffer sizes (e.g. PAGE_SIZE) necessitating multiple start/stop cycles to iterate through all dmabufs. However the dmabuf iterator currently returns NULL in dmabuf_iter_seq_start for all non-zero pos values, which results in the truncation of the output before all dmabufs are handled. After dma_buf_iter_begin / dma_buf_iter_next, the refcount of the buffer is elevated so that the BPF iterator program can run without holding any locks. When a stop occurs, instead of immediately dropping the reference on the buffer, stash a pointer to the buffer in seq->priv until either start is called or the iterator is released. This also enables the resumption of iteration without first walking through the list of dmabufs based on the pos value. Fixes: 76ea95534995 ("bpf: Add dmabuf iterator") Signed-off-by: T.J. Mercier <tjmercier(a)google.com> --- kernel/bpf/dmabuf_iter.c | 56 +++++++++++++++++++++++++++++++++++----- 1 file changed, 49 insertions(+), 7 deletions(-) diff --git a/kernel/bpf/dmabuf_iter.c b/kernel/bpf/dmabuf_iter.c index 4dd7ef7c145c..cd500248abd9 100644 --- a/kernel/bpf/dmabuf_iter.c +++ b/kernel/bpf/dmabuf_iter.c @@ -6,10 +6,33 @@ #include <linux/kernel.h> #include <linux/seq_file.h> +struct dmabuf_iter_priv { + /* + * If this pointer is non-NULL, the buffer's refcount is elevated to + * prevent destruction between stop/start. If reading is not resumed and + * start is never called again, then dmabuf_iter_seq_fini drops the + * reference when the iterator is released. + */ + struct dma_buf *dmabuf; +}; + static void *dmabuf_iter_seq_start(struct seq_file *seq, loff_t *pos) { - if (*pos) - return NULL; + struct dmabuf_iter_priv *p = seq->private; + + if (*pos) { + struct dma_buf *dmabuf = p->dmabuf; + + if (!dmabuf) + return NULL; + + /* + * Always resume from where we stopped, regardless of the value + * of pos. + */ + p->dmabuf = NULL; + return dmabuf; + } return dma_buf_iter_begin(); } @@ -54,8 +77,11 @@ static void dmabuf_iter_seq_stop(struct seq_file *seq, void *v) { struct dma_buf *dmabuf = v; - if (dmabuf) - dma_buf_put(dmabuf); + if (dmabuf) { + struct dmabuf_iter_priv *p = seq->private; + + p->dmabuf = dmabuf; + } } static const struct seq_operations dmabuf_iter_seq_ops = { @@ -71,11 +97,27 @@ static void bpf_iter_dmabuf_show_fdinfo(const struct bpf_iter_aux_info *aux, seq_puts(seq, "dmabuf iter\n"); } +static int dmabuf_iter_seq_init(void *priv, struct bpf_iter_aux_info *aux) +{ + struct dmabuf_iter_priv *p = (struct dmabuf_iter_priv *)priv; + + p->dmabuf = NULL; + return 0; +} + +static void dmabuf_iter_seq_fini(void *priv) +{ + struct dmabuf_iter_priv *p = (struct dmabuf_iter_priv *)priv; + + if (p->dmabuf) + dma_buf_put(p->dmabuf); +} + static const struct bpf_iter_seq_info dmabuf_iter_seq_info = { .seq_ops = &dmabuf_iter_seq_ops, - .init_seq_private = NULL, - .fini_seq_private = NULL, - .seq_priv_size = 0, + .init_seq_private = dmabuf_iter_seq_init, + .fini_seq_private = dmabuf_iter_seq_fini, + .seq_priv_size = sizeof(struct dmabuf_iter_priv), }; static struct bpf_iter_reg bpf_dmabuf_reg_info = { base-commit: 30f09200cc4aefbd8385b01e41bde2e4565a6f0e -- 2.52.0.177.g9f829587af-goog

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