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selftests/lam: Skip test if LAM is disabled

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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 <maciej.wieczor-retman@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Link: https://lore.kernel.org/r/251d0f45f6a768030115e8d04bc85458910cb0dc.1737990375.git.maciej.wieczor-retman@intel.com
This commit is contained in:
Maciej Wieczor-Retman 2025-01-27 16:31:56 +01:00 committed by Ingo Molnar
parent ec8f5b4659
commit 51f909dcd1
1 changed files with 18 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

23
tools/testing/selftests/x86/lam.c
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@ -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) {