Commit d761c14d authored by Sean Christopherson's avatar Sean Christopherson
Browse files

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



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: default avatarMaxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: default avatarJames Houghton <jthoughton@google.com>
Link: https://lore.kernel.org/r/20250508184649.2576210-2-jthoughton@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent 5e9ac644

tools/testing/selftests/kvm/lib/test_util.c

+24 −11
Original line number Diff line number Diff line
@@ -132,37 +132,50 @@ 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;



	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");

	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 transparent_hugepage/hpage_pmd_size");

	fclose(f);

	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");



	return get_sysfs_val("/sys/kernel/mm/transparent_hugepage/hpage_pmd_size");

}



size_t get_def_hugetlb_pagesz(void)

{

	char buf[64];