From 51f909dcd178655b104d979a6870535268724498 Mon Sep 17 00:00:00 2001 From: Maciej Wieczor-Retman Date: Mon, 27 Jan 2025 16:31:56 +0100 Subject: [PATCH] selftests/lam: Skip test if LAM is disabled Until LASS is merged into the kernel: https://lore.kernel.org/all/20241028160917.1380714-1-alexander.shishkin@linux.intel.com/ LAM is left disabled in the config file. Running the LAM selftest with disabled LAM only results in unhelpful output. Use one of LAM syscalls() to determine whether the kernel was compiled with LAM support (CONFIG_ADDRESS_MASKING) or not. Skip running the tests in the latter case. Merge CPUID checking function with the one mentioned above to achieve a single function that shows LAM's availability from both CPU and the kernel. Signed-off-by: Maciej Wieczor-Retman Signed-off-by: Ingo Molnar Cc: Kirill A. Shutemov Cc: Dave Hansen Cc: Alexander Potapenko Cc: Peter Zijlstra Cc: Shuah Khan Link: https://lore.kernel.org/r/251d0f45f6a768030115e8d04bc85458910cb0dc.1737990375.git.maciej.wieczor-retman@intel.com --- tools/testing/selftests/x86/lam.c | 23 ++++++++++++++++++----- 1 file changed, 18 insertions(+), 5 deletions(-) diff --git a/tools/testing/selftests/x86/lam.c b/tools/testing/selftests/x86/lam.c index 60170a31aa696..df91a41a5babc 100644 --- a/tools/testing/selftests/x86/lam.c +++ b/tools/testing/selftests/x86/lam.c @@ -115,13 +115,28 @@ static void segv_handler(int sig) siglongjmp(segv_env, 1); } -static inline int cpu_has_lam(void) +static inline int lam_is_available(void) { unsigned int cpuinfo[4]; + unsigned long bits = 0; + int ret; __cpuid_count(0x7, 1, cpuinfo[0], cpuinfo[1], cpuinfo[2], cpuinfo[3]); - return (cpuinfo[0] & (1 << 26)); + /* Check if cpu supports LAM */ + if (!(cpuinfo[0] & (1 << 26))) { + ksft_print_msg("LAM is not supported!\n"); + return 0; + } + + /* Return 0 if CONFIG_ADDRESS_MASKING is not set */ + ret = syscall(SYS_arch_prctl, ARCH_GET_MAX_TAG_BITS, &bits); + if (ret) { + ksft_print_msg("LAM is disabled in the kernel!\n"); + return 0; + } + + return 1; } static inline int la57_enabled(void) @@ -1185,10 +1200,8 @@ int main(int argc, char **argv) tests_cnt = 0; - if (!cpu_has_lam()) { - ksft_print_msg("Unsupported LAM feature!\n"); + if (!lam_is_available()) return KSFT_SKIP; - } while ((c = getopt(argc, argv, "ht:")) != -1) { switch (c) { -- 2.50.1