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KVM: selftests: Extract guts of THP accessor to standalone sysfs helpers

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Extract the guts of thp_configured() and get_trans_hugepagesz() to
standalone helpers so that the core logic can be reused for other sysfs
files, e.g. to query numa_balancing.

Opportunistically assert that the initial fscanf() read at least one byte,
and add a comment explaining the second call to fscanf().

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: James Houghton <jthoughton@google.com>
Link: https://lore.kernel.org/r/20250508184649.2576210-2-jthoughton@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Sean Christopherson 2025-05-08 18:46:42 +00:00
parent 5e9ac644c4
commit d761c14d90
1 changed files with 27 additions and 14 deletions
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41
tools/testing/selftests/kvm/lib/test_util.c
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@ -132,35 +132,48 @@ void print_skip(const char *fmt, ...)
puts(", skipping test");
}
bool thp_configured(void)
static bool test_sysfs_path(const char *path)
{
int ret;
struct stat statbuf;
int ret;
ret = stat("/sys/kernel/mm/transparent_hugepage", &statbuf);
ret = stat(path, &statbuf);
TEST_ASSERT(ret == 0 || (ret == -1 && errno == ENOENT),
"Error in stating /sys/kernel/mm/transparent_hugepage");
"Error in stat()ing '%s'", path);
return ret == 0;
}
size_t get_trans_hugepagesz(void)
bool thp_configured(void)
{
return test_sysfs_path("/sys/kernel/mm/transparent_hugepage");
}
static size_t get_sysfs_val(const char *path)
{
size_t size;
FILE *f;
int ret;
f = fopen(path, "r");
TEST_ASSERT(f, "Error opening '%s'", path);
ret = fscanf(f, "%ld", &size);
TEST_ASSERT(ret > 0, "Error reading '%s'", path);
/* Re-scan the input stream to verify the entire file was read. */
ret = fscanf(f, "%ld", &size);
TEST_ASSERT(ret < 1, "Error reading '%s'", path);
fclose(f);
return size;
}
size_t get_trans_hugepagesz(void)
{
TEST_ASSERT(thp_configured(), "THP is not configured in host kernel");
f = fopen("/sys/kernel/mm/transparent_hugepage/hpage_pmd_size", "r");
TEST_ASSERT(f != NULL, "Error in opening transparent_hugepage/hpage_pmd_size");
ret = fscanf(f, "%ld", &size);
ret = fscanf(f, "%ld", &size);
TEST_ASSERT(ret < 1, "Error reading transparent_hugepage/hpage_pmd_size");
fclose(f);
return size;
return get_sysfs_val("/sys/kernel/mm/transparent_hugepage/hpage_pmd_size");
}
size_t get_def_hugetlb_pagesz(void)