Commit a95ecac5 authored by Naveen N. Rao's avatar Naveen N. Rao Committed by Michael Ellerman
Browse files

selftests/powerpc: Relax L1d miss targets for rfi_flush test 



When running the rfi_flush test, if the system is loaded, we see two
issues:
1. The L1d misses when rfi_flush is disabled increase significantly due
to other workloads interfering with the cache.
2. The L1d misses when rfi_flush is enabled sometimes goes slightly
below the expected number of misses.

To address these, let's relax the expected number of L1d misses:
1. When rfi_flush is disabled, we allow upto half the expected number of
the misses for when rfi_flush is enabled.
2. When rfi_flush is enabled, we allow ~1% lower number of cache misses.

Reported-by: default avatarJoel Stanley <joel@jms.id.au>
Signed-off-by: default avatarNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Tested-by: default avatarJoel Stanley <joel@jms.id.au>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 3b9672ff

tools/testing/selftests/powerpc/security/rfi_flush.c

+13 −5
Original line number Diff line number Diff line
@@ -49,6 +49,7 @@ int rfi_flush_test(void) 
	struct perf_event_read v;

	__u64 l1d_misses_total = 0;

	unsigned long iterations = 100000, zero_size = 24 * 1024;

	unsigned long l1d_misses_expected;

	int rfi_flush_org, rfi_flush;



	SKIP_IF(geteuid() != 0);
@@ -71,6 +72,12 @@ int rfi_flush_test(void) 


	iter = repetitions;



	/*

	 * We expect to see l1d miss for each cacheline access when rfi_flush

	 * is set. Allow a small variation on this.

	 */

	l1d_misses_expected = iterations * (zero_size / CACHELINE_SIZE - 2);



again:

	FAIL_IF(perf_event_reset(fd));
@@ -78,10 +85,9 @@ again: 


	FAIL_IF(read(fd, &v, sizeof(v)) != sizeof(v));



	/* Expect at least zero_size/CACHELINE_SIZE misses per iteration */

	if (v.l1d_misses >= (iterations * zero_size / CACHELINE_SIZE) && rfi_flush)

	if (rfi_flush && v.l1d_misses >= l1d_misses_expected)

		passes++;

	else if (v.l1d_misses < iterations && !rfi_flush)

	else if (!rfi_flush && v.l1d_misses < (l1d_misses_expected / 2))

		passes++;



	l1d_misses_total += v.l1d_misses;
@@ -92,13 +98,15 @@ again: 
	if (passes < repetitions) {

		printf("FAIL (L1D misses with rfi_flush=%d: %llu %c %lu) [%d/%d failures]\n",

		       rfi_flush, l1d_misses_total, rfi_flush ? '<' : '>',

		       rfi_flush ? (repetitions * iterations * zero_size / CACHELINE_SIZE) : iterations,

		       rfi_flush ? repetitions * l1d_misses_expected :

		       repetitions * l1d_misses_expected / 2,

		       repetitions - passes, repetitions);

		rc = 1;

	} else

		printf("PASS (L1D misses with rfi_flush=%d: %llu %c %lu) [%d/%d pass]\n",

		       rfi_flush, l1d_misses_total, rfi_flush ? '>' : '<',

		       rfi_flush ? (repetitions * iterations * zero_size / CACHELINE_SIZE) : iterations,

		       rfi_flush ? repetitions * l1d_misses_expected :

		       repetitions * l1d_misses_expected / 2,

		       passes, repetitions);



	if (rfi_flush == rfi_flush_org) {

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