[PATCH v2 11/11] tools: add hmm gup test for long term pinned device pages

Alex Sierra
2021-12-06T18:53:19Z

The intention is to test device coherent type pages that have been
called through get user pages with PIN_LONGTERM flag set.

Signed-off-by: Alex Sierra <alex.sierra@amd.com>
---
tools/testing/selftests/vm/Makefile | 2 +-
tools/testing/selftests/vm/hmm-tests.c | 81 ++++++++++++++++++++++++++
2 files changed, 82 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/vm/Makefile b/tools/testing/selftests/vm/Makefile
index d9605bd10f2d..527a7bfd80bd 100644
--- a/tools/testing/selftests/vm/Makefile
+++ b/tools/testing/selftests/vm/Makefile
@@ -141,7 +141,7 @@ $(OUTPUT)/mlock-random-test $(OUTPUT)/memfd_secret: LDLIBS += -lcap

$(OUTPUT)/gup_test: ../../../../mm/gup_test.h

-$(OUTPUT)/hmm-tests: local_config.h
+$(OUTPUT)/hmm-tests: local_config.h ../../../../mm/gup_test.h

# HMM_EXTRA_LIBS may get set in local_config.mk, or it may be left empty.
$(OUTPUT)/hmm-tests: LDLIBS += $(HMM_EXTRA_LIBS)
diff --git a/tools/testing/selftests/vm/hmm-tests.c b/tools/testing/selftests/vm/hmm-tests.c
index 8eb81dfba4b3..9a0b7e44a674 100644
--- a/tools/testing/selftests/vm/hmm-tests.c
+++ b/tools/testing/selftests/vm/hmm-tests.c
@@ -36,6 +36,7 @@
* in the usual include/uapi/... directory.
*/
#include "../../../../lib/test_hmm_uapi.h"
+#include "../../../../mm/gup_test.h"

struct hmm_buffer {
void *ptr;
@@ -60,6 +61,8 @@ enum {
#define NTIMES 10

#define ALIGN(x, a) (((x) + (a - 1)) & (~((a) - 1)))
+/* Just the flags we need, copied from mm.h: */
+#define FOLL_WRITE 0x01 /* check pte is writable */

FIXTURE(hmm)
{
@@ -1723,4 +1726,82 @@ TEST_F(hmm, exclusive_cow)
hmm_buffer_free(buffer);
}

+/*
+ * Test get user device pages through gup_test. Setting PIN_LONGTERM flag.
+ * This should trigger a migration back to system memory for both, private
+ * and coherent type pages.
+ * This test makes use of gup_test module. Make sure GUP_TEST_CONFIG is added
+ * to your configuration before you run it.
+ */
+TEST_F(hmm, hmm_gup_test)
+{
+ struct hmm_buffer *buffer;
+ struct gup_test gup;
+ int gup_fd;
+ unsigned long npages;
+ unsigned long size;
+ unsigned long i;
+ int *ptr;
+ int ret;
+ unsigned char *m;
+
+ gup_fd = open("/sys/kernel/debug/gup_test", O_RDWR);
+ if (gup_fd == -1)
+ SKIP(return, "Skipping test, could not find gup_test driver");
+
+ npages = 4;
+ ASSERT_NE(npages, 0);
+ size = npages << self->page_shift;
+
+ buffer = malloc(sizeof(*buffer));
+ ASSERT_NE(buffer, NULL);
+
+ buffer->fd = -1;
+ buffer->size = size;
+ buffer->mirror = malloc(size);
+ ASSERT_NE(buffer->mirror, NULL);
+
+ buffer->ptr = mmap(NULL, size,
+ PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANONYMOUS,
+ buffer->fd, 0);
+ ASSERT_NE(buffer->ptr, MAP_FAILED);
+
+ /* Initialize buffer in system memory. */
+ for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+ ptr[i] = i;
+
+ /* Migrate memory to device. */
+ ret = hmm_migrate_sys_to_dev(self->fd, buffer, npages);
+ ASSERT_EQ(ret, 0);
+ ASSERT_EQ(buffer->cpages, npages);
+ /* Check what the device read. */
+ for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i)
+ ASSERT_EQ(ptr[i], i);
+
+ gup.nr_pages_per_call = npages;
+ gup.addr = (unsigned long)buffer->ptr;
+ gup.gup_flags = FOLL_WRITE;
+ gup.size = size;
+ /*
+ * Calling gup_test ioctl. It will try to PIN_LONGTERM these device pages
+ * causing a migration back to system memory for both, private and coherent
+ * type pages.
+ */
+ if (ioctl(gup_fd, PIN_LONGTERM_BENCHMARK, &gup)) {
+ perror("ioctl on PIN_LONGTERM_BENCHMARK\n");
+ goto out_test;
+ }
+
+ /* Take snapshot to make sure pages have been migrated to sys memory */
+ ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_SNAPSHOT, buffer, npages);
+ ASSERT_EQ(ret, 0);
+ ASSERT_EQ(buffer->cpages, npages);
+ m = buffer->mirror;
+ for (i = 0; i < npages; i++)
+ ASSERT_EQ(m[i], HMM_DMIRROR_PROT_WRITE);
+out_test:
+ close(gup_fd);
+ hmm_buffer_free(buffer);
+}
TEST_HARNESS_MAIN
--
2.32.0