linux-ext4 - [PATCH v2 11/11] tools: add hmm gup test for long term pinned device pages

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Message-ID: <20211206185251.20646-12-alex.sierra@amd.com>
Date:   Mon, 6 Dec 2021 12:52:51 -0600
From:   Alex Sierra <alex.sierra@....com>
To:     <akpm@...ux-foundation.org>, <Felix.Kuehling@....com>,
        <linux-mm@...ck.org>, <rcampbell@...dia.com>,
        <linux-ext4@...r.kernel.org>, <linux-xfs@...r.kernel.org>
CC:     <amd-gfx@...ts.freedesktop.org>, <dri-devel@...ts.freedesktop.org>,
        <hch@....de>, <jgg@...dia.com>, <jglisse@...hat.com>,
        <apopple@...dia.com>, <willy@...radead.org>
Subject: [PATCH v2 11/11] tools: add hmm gup test for long term pinned device pages

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@....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