[RFC PATCH v2 0/7] Some improvement and a new test for kvm page table

[RFC PATCH v2 0/7] Some improvement and a new test for kvm page table

[Yanan Wang]

Hi,
This v2 series can mainly include two parts.
Based on kvm queue branch: https://git.kernel.org/pub/scm/virt/kvm/kvm.git/log/?h=queue
Links of v1: https://lore.kernel.org/lkml/20210208090841.333724-1-wangyanan55@huawei.com/

In the first part, all the known hugetlb backing src types specified
with different hugepage sizes are listed, so that we can specify use
of hugetlb source of the exact granularity that we want, instead of
the system default ones. And as all the known hugetlb page sizes are
listed, it's appropriate for all architectures. Besides, a helper that
can get granularity of different backing src types(anonumous/thp/hugetlb)
is added, so that we can use the accurate backing src granularity for
kinds of alignment or guest memory accessing of vcpus.

In the second part, a new test is added:
This test is added to serve as a performance tester and a bug reproducer
for kvm page table code (GPA->HPA mappings), it gives guidance for the
people trying to make some improvement for kvm. And the following explains
what we can exactly do through this test.

The function guest_code() can cover the conditions where a single vcpu or
multiple vcpus access guest pages within the same memory region, in three
VM stages(before dirty logging, during dirty logging, after dirty logging).
Besides, the backing src memory type(ANONYMOUS/THP/HUGETLB) of the tested
memory region can be specified by users, which means normal page mappings
or block mappings can be chosen by users to be created in the test.

If ANONYMOUS memory is specified, kvm will create normal page mappings
for the tested memory region before dirty logging, and update attributes
of the page mappings from RO to RW during dirty logging. If THP/HUGETLB
memory is specified, kvm will create block mappings for the tested memory
region before dirty logging, and split the blcok mappings into normal page
mappings during dirty logging, and coalesce the page mappings back into
block mappings after dirty logging is stopped.

So in summary, as a performance tester, this test can present the
performance of kvm creating/updating normal page mappings, or the
performance of kvm creating/splitting/recovering block mappings,
through execution time.

When we need to coalesce the page mappings back to block mappings after
dirty logging is stopped, we have to firstly invalidate *all* the TLB
entries for the page mappings right before installation of the block entry,
because a TLB conflict abort error could occur if we can't invalidate the
TLB entries fully. We have hit this TLB conflict twice on aarch64 software
implementation and fixed it. As this test can imulate process from dirty
logging enabled to dirty logging stopped of a VM with block mappings,
so it can also reproduce this TLB conflict abort due to inadequate TLB
invalidation when coalescing tables.

Links about the TLB conflict abort:
https://lore.kernel.org/lkml/20201201201034.116760-3-wangyanan55@huawei.com/

Yanan Wang (7):
  tools include: sync head files of mmap flag encodings about hugetlb
  KVM: selftests: Use flag CLOCK_MONOTONIC_RAW for timing
  KVM: selftests: Make a generic helper to get vm guest mode strings
  KVM: selftests: Add a helper to get system configured THP page size
  KVM: selftests: List all hugetlb src types specified with page sizes
  KVM: selftests: Adapt vm_userspace_mem_region_add to new helpers
  KVM: selftests: Add a test for kvm page table code

 tools/include/asm-generic/hugetlb_encode.h    |   3 +
 tools/testing/selftests/kvm/Makefile          |   3 +
 .../selftests/kvm/demand_paging_test.c        |   8 +-
 .../selftests/kvm/dirty_log_perf_test.c       |  14 +-
 .../testing/selftests/kvm/include/kvm_util.h  |   4 +-
 .../testing/selftests/kvm/include/test_util.h |  21 +-
 .../selftests/kvm/kvm_page_table_test.c       | 476 ++++++++++++++++++
 tools/testing/selftests/kvm/lib/kvm_util.c    |  58 +--
 tools/testing/selftests/kvm/lib/test_util.c   |  92 +++-
 tools/testing/selftests/kvm/steal_time.c      |   4 +-
 10 files changed, 623 insertions(+), 60 deletions(-)
 create mode 100644 tools/testing/selftests/kvm/kvm_page_table_test.c

-- 
2.19.1

[RFC PATCH v2 1/7] tools include: sync head files of mmap flag encodings about hugetlb

[Yanan Wang]

This patch syncs contents of tools/include/asm-generic/hugetlb_encode.h
and include/uapi/asm-generic/hugetlb_encode.h. Arch powerpc supports 16KB
hugepages and ARM64 supports 32MB/512MB hugepages. The corresponding mmap
flags have already been added in include/uapi/asm-generic/hugetlb_encode.h,
but not tools/include/asm-generic/hugetlb_encode.h.

Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
---
 tools/include/asm-generic/hugetlb_encode.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/tools/include/asm-generic/hugetlb_encode.h b/tools/include/asm-generic/hugetlb_encode.h
index e4732d3c2998..4f3d5aaa11f5 100644
--- a/tools/include/asm-generic/hugetlb_encode.h
+++ b/tools/include/asm-generic/hugetlb_encode.h
@@ -20,13 +20,16 @@
 #define HUGETLB_FLAG_ENCODE_SHIFT	26
 #define HUGETLB_FLAG_ENCODE_MASK	0x3f
 
+#define HUGETLB_FLAG_ENCODE_16KB	(14 << HUGETLB_FLAG_ENCODE_SHIFT)
 #define HUGETLB_FLAG_ENCODE_64KB	(16 << HUGETLB_FLAG_ENCODE_SHIFT)
 #define HUGETLB_FLAG_ENCODE_512KB	(19 << HUGETLB_FLAG_ENCODE_SHIFT)
 #define HUGETLB_FLAG_ENCODE_1MB		(20 << HUGETLB_FLAG_ENCODE_SHIFT)
 #define HUGETLB_FLAG_ENCODE_2MB		(21 << HUGETLB_FLAG_ENCODE_SHIFT)
 #define HUGETLB_FLAG_ENCODE_8MB		(23 << HUGETLB_FLAG_ENCODE_SHIFT)
 #define HUGETLB_FLAG_ENCODE_16MB	(24 << HUGETLB_FLAG_ENCODE_SHIFT)
+#define HUGETLB_FLAG_ENCODE_32MB	(25 << HUGETLB_FLAG_ENCODE_SHIFT)
 #define HUGETLB_FLAG_ENCODE_256MB	(28 << HUGETLB_FLAG_ENCODE_SHIFT)
+#define HUGETLB_FLAG_ENCODE_512MB	(29 << HUGETLB_FLAG_ENCODE_SHIFT)
 #define HUGETLB_FLAG_ENCODE_1GB		(30 << HUGETLB_FLAG_ENCODE_SHIFT)
 #define HUGETLB_FLAG_ENCODE_2GB		(31 << HUGETLB_FLAG_ENCODE_SHIFT)
 #define HUGETLB_FLAG_ENCODE_16GB	(34 << HUGETLB_FLAG_ENCODE_SHIFT)
-- 
2.19.1

[RFC PATCH v2 2/7] KVM: selftests: Use flag CLOCK_MONOTONIC_RAW for timing

[Yanan Wang]

In addition to function of CLOCK_MONOTONIC, flag CLOCK_MONOTONIC_RAW can
also shield possiable impact of NTP, which can provide more robustness.

Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
---
 tools/testing/selftests/kvm/demand_paging_test.c  |  8 ++++----
 tools/testing/selftests/kvm/dirty_log_perf_test.c | 14 +++++++-------
 tools/testing/selftests/kvm/lib/test_util.c       |  2 +-
 tools/testing/selftests/kvm/steal_time.c          |  4 ++--
 4 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/tools/testing/selftests/kvm/demand_paging_test.c b/tools/testing/selftests/kvm/demand_paging_test.c
index 5f7a229c3af1..efbf0c1e9130 100644
--- a/tools/testing/selftests/kvm/demand_paging_test.c
+++ b/tools/testing/selftests/kvm/demand_paging_test.c
@@ -53,7 +53,7 @@ static void *vcpu_worker(void *data)
 	vcpu_args_set(vm, vcpu_id, 1, vcpu_id);
 	run = vcpu_state(vm, vcpu_id);
 
-	clock_gettime(CLOCK_MONOTONIC, &start);
+	clock_gettime(CLOCK_MONOTONIC_RAW, &start);
 
 	/* Let the guest access its memory */
 	ret = _vcpu_run(vm, vcpu_id);
@@ -86,7 +86,7 @@ static int handle_uffd_page_request(int uffd, uint64_t addr)
 	copy.len = perf_test_args.host_page_size;
 	copy.mode = 0;
 
-	clock_gettime(CLOCK_MONOTONIC, &start);
+	clock_gettime(CLOCK_MONOTONIC_RAW, &start);
 
 	r = ioctl(uffd, UFFDIO_COPY, &copy);
 	if (r == -1) {
@@ -123,7 +123,7 @@ static void *uffd_handler_thread_fn(void *arg)
 	struct timespec start;
 	struct timespec ts_diff;
 
-	clock_gettime(CLOCK_MONOTONIC, &start);
+	clock_gettime(CLOCK_MONOTONIC_RAW, &start);
 	while (!quit_uffd_thread) {
 		struct uffd_msg msg;
 		struct pollfd pollfd[2];
@@ -336,7 +336,7 @@ static void run_test(enum vm_guest_mode mode, void *arg)
 
 	pr_info("Finished creating vCPUs and starting uffd threads\n");
 
-	clock_gettime(CLOCK_MONOTONIC, &start);
+	clock_gettime(CLOCK_MONOTONIC_RAW, &start);
 
 	for (vcpu_id = 0; vcpu_id < nr_vcpus; vcpu_id++) {
 		pthread_create(&vcpu_threads[vcpu_id], NULL, vcpu_worker,
diff --git a/tools/testing/selftests/kvm/dirty_log_perf_test.c b/tools/testing/selftests/kvm/dirty_log_perf_test.c
index 04a2641261be..6cff4ccf9525 100644
--- a/tools/testing/selftests/kvm/dirty_log_perf_test.c
+++ b/tools/testing/selftests/kvm/dirty_log_perf_test.c
@@ -50,7 +50,7 @@ static void *vcpu_worker(void *data)
 	while (!READ_ONCE(host_quit)) {
 		int current_iteration = READ_ONCE(iteration);
 
-		clock_gettime(CLOCK_MONOTONIC, &start);
+		clock_gettime(CLOCK_MONOTONIC_RAW, &start);
 		ret = _vcpu_run(vm, vcpu_id);
 		ts_diff = timespec_elapsed(start);
 
@@ -141,7 +141,7 @@ static void run_test(enum vm_guest_mode mode, void *arg)
 	iteration = 0;
 	host_quit = false;
 
-	clock_gettime(CLOCK_MONOTONIC, &start);
+	clock_gettime(CLOCK_MONOTONIC_RAW, &start);
 	for (vcpu_id = 0; vcpu_id < nr_vcpus; vcpu_id++) {
 		vcpu_last_completed_iteration[vcpu_id] = -1;
 
@@ -162,7 +162,7 @@ static void run_test(enum vm_guest_mode mode, void *arg)
 		ts_diff.tv_sec, ts_diff.tv_nsec);
 
 	/* Enable dirty logging */
-	clock_gettime(CLOCK_MONOTONIC, &start);
+	clock_gettime(CLOCK_MONOTONIC_RAW, &start);
 	vm_mem_region_set_flags(vm, PERF_TEST_MEM_SLOT_INDEX,
 				KVM_MEM_LOG_DIRTY_PAGES);
 	ts_diff = timespec_elapsed(start);
@@ -174,7 +174,7 @@ static void run_test(enum vm_guest_mode mode, void *arg)
 		 * Incrementing the iteration number will start the vCPUs
 		 * dirtying memory again.
 		 */
-		clock_gettime(CLOCK_MONOTONIC, &start);
+		clock_gettime(CLOCK_MONOTONIC_RAW, &start);
 		iteration++;
 
 		pr_debug("Starting iteration %d\n", iteration);
@@ -189,7 +189,7 @@ static void run_test(enum vm_guest_mode mode, void *arg)
 		pr_info("Iteration %d dirty memory time: %ld.%.9lds\n",
 			iteration, ts_diff.tv_sec, ts_diff.tv_nsec);
 
-		clock_gettime(CLOCK_MONOTONIC, &start);
+		clock_gettime(CLOCK_MONOTONIC_RAW, &start);
 		kvm_vm_get_dirty_log(vm, PERF_TEST_MEM_SLOT_INDEX, bmap);
 
 		ts_diff = timespec_elapsed(start);
@@ -199,7 +199,7 @@ static void run_test(enum vm_guest_mode mode, void *arg)
 			iteration, ts_diff.tv_sec, ts_diff.tv_nsec);
 
 		if (dirty_log_manual_caps) {
-			clock_gettime(CLOCK_MONOTONIC, &start);
+			clock_gettime(CLOCK_MONOTONIC_RAW, &start);
 			kvm_vm_clear_dirty_log(vm, PERF_TEST_MEM_SLOT_INDEX, bmap, 0,
 					       host_num_pages);
 
@@ -212,7 +212,7 @@ static void run_test(enum vm_guest_mode mode, void *arg)
 	}
 
 	/* Disable dirty logging */
-	clock_gettime(CLOCK_MONOTONIC, &start);
+	clock_gettime(CLOCK_MONOTONIC_RAW, &start);
 	vm_mem_region_set_flags(vm, PERF_TEST_MEM_SLOT_INDEX, 0);
 	ts_diff = timespec_elapsed(start);
 	pr_info("Disabling dirty logging time: %ld.%.9lds\n",
diff --git a/tools/testing/selftests/kvm/lib/test_util.c b/tools/testing/selftests/kvm/lib/test_util.c
index 906c955384e2..c7c0627c6842 100644
--- a/tools/testing/selftests/kvm/lib/test_util.c
+++ b/tools/testing/selftests/kvm/lib/test_util.c
@@ -89,7 +89,7 @@ struct timespec timespec_elapsed(struct timespec start)
 {
 	struct timespec end;
 
-	clock_gettime(CLOCK_MONOTONIC, &end);
+	clock_gettime(CLOCK_MONOTONIC_RAW, &end);
 	return timespec_sub(end, start);
 }
 
diff --git a/tools/testing/selftests/kvm/steal_time.c b/tools/testing/selftests/kvm/steal_time.c
index fcc840088c91..5bc582d3f2a2 100644
--- a/tools/testing/selftests/kvm/steal_time.c
+++ b/tools/testing/selftests/kvm/steal_time.c
@@ -237,11 +237,11 @@ static void *do_steal_time(void *arg)
 {
 	struct timespec ts, stop;
 
-	clock_gettime(CLOCK_MONOTONIC, &ts);
+	clock_gettime(CLOCK_MONOTONIC_RAW, &ts);
 	stop = timespec_add_ns(ts, MIN_RUN_DELAY_NS);
 
 	while (1) {
-		clock_gettime(CLOCK_MONOTONIC, &ts);
+		clock_gettime(CLOCK_MONOTONIC_RAW, &ts);
 		if (timespec_to_ns(timespec_sub(ts, stop)) >= 0)
 			break;
 	}
-- 
2.19.1

[RFC PATCH v2 3/7] KVM: selftests: Make a generic helper to get vm guest mode strings

[Yanan Wang]

For generality and conciseness, make an API which can be used in all
kvm libs and selftests to get vm guest mode strings. And the index i
is checked in the API in case of possiable faults.

Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
---
 .../testing/selftests/kvm/include/kvm_util.h  |  4 +--
 tools/testing/selftests/kvm/lib/kvm_util.c    | 29 ++++++++++++-------
 2 files changed, 19 insertions(+), 14 deletions(-)

diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
index 2d7eb6989e83..f52a7492f47f 100644
--- a/tools/testing/selftests/kvm/include/kvm_util.h
+++ b/tools/testing/selftests/kvm/include/kvm_util.h
@@ -68,9 +68,6 @@ enum vm_guest_mode {
 #define MIN_PAGE_SIZE		(1U << MIN_PAGE_SHIFT)
 #define PTES_PER_MIN_PAGE	ptes_per_page(MIN_PAGE_SIZE)
 
-#define vm_guest_mode_string(m) vm_guest_mode_string[m]
-extern const char * const vm_guest_mode_string[];
-
 struct vm_guest_mode_params {
 	unsigned int pa_bits;
 	unsigned int va_bits;
@@ -84,6 +81,7 @@ int vm_enable_cap(struct kvm_vm *vm, struct kvm_enable_cap *cap);
 int vcpu_enable_cap(struct kvm_vm *vm, uint32_t vcpu_id,
 		    struct kvm_enable_cap *cap);
 void vm_enable_dirty_ring(struct kvm_vm *vm, uint32_t ring_size);
+const char *vm_guest_mode_string(uint32_t i);
 
 struct kvm_vm *vm_create(enum vm_guest_mode mode, uint64_t phy_pages, int perm);
 void kvm_vm_free(struct kvm_vm *vmp);
diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index d787cb802b4a..cc22c4ab7d67 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -141,17 +141,24 @@ static void vm_open(struct kvm_vm *vm, int perm)
 		"rc: %i errno: %i", vm->fd, errno);
 }
 
-const char * const vm_guest_mode_string[] = {
-	"PA-bits:52,  VA-bits:48,  4K pages",
-	"PA-bits:52,  VA-bits:48, 64K pages",
-	"PA-bits:48,  VA-bits:48,  4K pages",
-	"PA-bits:48,  VA-bits:48, 64K pages",
-	"PA-bits:40,  VA-bits:48,  4K pages",
-	"PA-bits:40,  VA-bits:48, 64K pages",
-	"PA-bits:ANY, VA-bits:48,  4K pages",
-};
-_Static_assert(sizeof(vm_guest_mode_string)/sizeof(char *) == NUM_VM_MODES,
-	       "Missing new mode strings?");
+const char *vm_guest_mode_string(uint32_t i)
+{
+	static const char * const strings[] = {
+		[VM_MODE_P52V48_4K]	= "PA-bits:52,  VA-bits:48,  4K pages",
+		[VM_MODE_P52V48_64K]	= "PA-bits:52,  VA-bits:48, 64K pages",
+		[VM_MODE_P48V48_4K]	= "PA-bits:48,  VA-bits:48,  4K pages",
+		[VM_MODE_P48V48_64K]	= "PA-bits:48,  VA-bits:48, 64K pages",
+		[VM_MODE_P40V48_4K]	= "PA-bits:40,  VA-bits:48,  4K pages",
+		[VM_MODE_P40V48_64K]	= "PA-bits:40,  VA-bits:48, 64K pages",
+		[VM_MODE_PXXV48_4K]	= "PA-bits:ANY, VA-bits:48,  4K pages",
+	};
+	_Static_assert(sizeof(strings)/sizeof(char *) == NUM_VM_MODES,
+		       "Missing new mode strings?");
+
+	TEST_ASSERT(i < NUM_VM_MODES, "Guest mode ID %d too big", i);
+
+	return strings[i];
+}
 
 const struct vm_guest_mode_params vm_guest_mode_params[] = {
 	{ 52, 48,  0x1000, 12 },
-- 
2.19.1

[RFC PATCH v2 4/7] KVM: selftests: Add a helper to get system configured THP page size

[Yanan Wang]

If we want to have some tests about transparent hugepages, the system
configured THP hugepage size should better be known by the tests, which
can be used for kinds of alignment or guest memory accessing of vcpus...
So it makes sense to add a helper to get the transparent hugepage size.

With VM_MEM_SRC_ANONYMOUS_THP specified in vm_userspace_mem_region_add(),
we now stat /sys/kernel/mm/transparent_hugepage to check whether THP is
configured in the host kernel before madvise(). Based on this, we can also
read file /sys/kernel/mm/transparent_hugepage/hpage_pmd_size to get THP
hugepage size.

Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
---
 .../testing/selftests/kvm/include/test_util.h |  2 ++
 tools/testing/selftests/kvm/lib/test_util.c   | 36 +++++++++++++++++++
 2 files changed, 38 insertions(+)

diff --git a/tools/testing/selftests/kvm/include/test_util.h b/tools/testing/selftests/kvm/include/test_util.h
index b7f41399f22c..ef24c76ba89a 100644
--- a/tools/testing/selftests/kvm/include/test_util.h
+++ b/tools/testing/selftests/kvm/include/test_util.h
@@ -78,6 +78,8 @@ struct vm_mem_backing_src_alias {
 	enum vm_mem_backing_src_type type;
 };
 
+bool thp_configured(void);
+size_t get_trans_hugepagesz(void);
 void backing_src_help(void);
 enum vm_mem_backing_src_type parse_backing_src_type(const char *type_name);
 
diff --git a/tools/testing/selftests/kvm/lib/test_util.c b/tools/testing/selftests/kvm/lib/test_util.c
index c7c0627c6842..f2d133f76c67 100644
--- a/tools/testing/selftests/kvm/lib/test_util.c
+++ b/tools/testing/selftests/kvm/lib/test_util.c
@@ -10,6 +10,7 @@
 #include <limits.h>
 #include <stdlib.h>
 #include <time.h>
+#include <sys/stat.h>
 #include "linux/kernel.h"
 
 #include "test_util.h"
@@ -117,6 +118,41 @@ const struct vm_mem_backing_src_alias backing_src_aliases[] = {
 	{"anonymous_hugetlb", VM_MEM_SRC_ANONYMOUS_HUGETLB,},
 };
 
+bool thp_configured(void)
+{
+	int ret;
+	struct stat statbuf;
+
+	ret = stat("/sys/kernel/mm/transparent_hugepage", &statbuf);
+	TEST_ASSERT(ret == 0 || (ret == -1 && errno == ENOENT),
+		    "Error in stating /sys/kernel/mm/transparent_hugepage: %d",
+		    errno);
+
+	return ret == 0;
+}
+
+size_t get_trans_hugepagesz(void)
+{
+	size_t size;
+	char buf[16];
+	FILE *f;
+
+	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: %d",
+		    errno);
+
+	if (fread(buf, sizeof(char), sizeof(buf), f) == 0) {
+		fclose(f);
+		TEST_FAIL("Unable to read transparent_hugepage/hpage_pmd_size");
+	}
+
+	size = strtoull(buf, NULL, 10);
+	return size;
+}
+
 void backing_src_help(void)
 {
 	int i;
-- 
2.19.1

[RFC PATCH v2 5/7] KVM: selftests: List all hugetlb src types specified with page sizes

[Yanan Wang]

With VM_MEM_SRC_ANONYMOUS_HUGETLB, we currently can only use system
default hugetlb pages to back the testing guest memory. In order to
add flexibility, now list all the known hugetlb backing src types with
different page sizes, so that we can specify use of hugetlb pages of the
exact granularity that we want. And as all the known hugetlb page sizes
are listed, it's appropriate for all architectures.

Besides, the helper get_backing_src_pagesz() is added to get the
granularity of different backing src types(anonumous, thp, hugetlb).

Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
---
 .../testing/selftests/kvm/include/test_util.h | 19 ++++++-
 tools/testing/selftests/kvm/lib/kvm_util.c    |  2 +-
 tools/testing/selftests/kvm/lib/test_util.c   | 56 +++++++++++++++----
 3 files changed, 63 insertions(+), 14 deletions(-)

diff --git a/tools/testing/selftests/kvm/include/test_util.h b/tools/testing/selftests/kvm/include/test_util.h
index ef24c76ba89a..be5d08bcdca7 100644
--- a/tools/testing/selftests/kvm/include/test_util.h
+++ b/tools/testing/selftests/kvm/include/test_util.h
@@ -70,16 +70,31 @@ struct timespec timespec_div(struct timespec ts, int divisor);
 enum vm_mem_backing_src_type {
 	VM_MEM_SRC_ANONYMOUS,
 	VM_MEM_SRC_ANONYMOUS_THP,
-	VM_MEM_SRC_ANONYMOUS_HUGETLB,
+	VM_MEM_SRC_ANONYMOUS_HUGETLB_16KB,
+	VM_MEM_SRC_ANONYMOUS_HUGETLB_64KB,
+	VM_MEM_SRC_ANONYMOUS_HUGETLB_512KB,
+	VM_MEM_SRC_ANONYMOUS_HUGETLB_1MB,
+	VM_MEM_SRC_ANONYMOUS_HUGETLB_2MB,
+	VM_MEM_SRC_ANONYMOUS_HUGETLB_8MB,
+	VM_MEM_SRC_ANONYMOUS_HUGETLB_16MB,
+	VM_MEM_SRC_ANONYMOUS_HUGETLB_32MB,
+	VM_MEM_SRC_ANONYMOUS_HUGETLB_256MB,
+	VM_MEM_SRC_ANONYMOUS_HUGETLB_512MB,
+	VM_MEM_SRC_ANONYMOUS_HUGETLB_1GB,
+	VM_MEM_SRC_ANONYMOUS_HUGETLB_2GB,
+	VM_MEM_SRC_ANONYMOUS_HUGETLB_16GB,
+	NUM_SRC_TYPES,
 };
 
 struct vm_mem_backing_src_alias {
 	const char *name;
-	enum vm_mem_backing_src_type type;
+	uint32_t flag;
 };
 
 bool thp_configured(void);
 size_t get_trans_hugepagesz(void);
+const struct vm_mem_backing_src_alias *vm_mem_backing_src_alias(uint32_t i);
+size_t get_backing_src_pagesz(uint32_t i);
 void backing_src_help(void);
 enum vm_mem_backing_src_type parse_backing_src_type(const char *type_name);
 
diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index cc22c4ab7d67..b91c8e3a7ee1 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -757,7 +757,7 @@ void vm_userspace_mem_region_add(struct kvm_vm *vm,
 	region->mmap_start = mmap(NULL, region->mmap_size,
 				  PROT_READ | PROT_WRITE,
 				  MAP_PRIVATE | MAP_ANONYMOUS
-				  | (src_type == VM_MEM_SRC_ANONYMOUS_HUGETLB ? MAP_HUGETLB : 0),
+				  | vm_mem_backing_src_alias(src_type)->flag,
 				  -1, 0);
 	TEST_ASSERT(region->mmap_start != MAP_FAILED,
 		    "test_malloc failed, mmap_start: %p errno: %i",
diff --git a/tools/testing/selftests/kvm/lib/test_util.c b/tools/testing/selftests/kvm/lib/test_util.c
index f2d133f76c67..6780aa058f35 100644
--- a/tools/testing/selftests/kvm/lib/test_util.c
+++ b/tools/testing/selftests/kvm/lib/test_util.c
@@ -11,6 +11,7 @@
 #include <stdlib.h>
 #include <time.h>
 #include <sys/stat.h>
+#include <linux/mman.h>
 #include "linux/kernel.h"
 
 #include "test_util.h"
@@ -112,12 +113,6 @@ void print_skip(const char *fmt, ...)
 	puts(", skipping test");
 }
 
-const struct vm_mem_backing_src_alias backing_src_aliases[] = {
-	{"anonymous", VM_MEM_SRC_ANONYMOUS,},
-	{"anonymous_thp", VM_MEM_SRC_ANONYMOUS_THP,},
-	{"anonymous_hugetlb", VM_MEM_SRC_ANONYMOUS_HUGETLB,},
-};
-
 bool thp_configured(void)
 {
 	int ret;
@@ -153,22 +148,61 @@ size_t get_trans_hugepagesz(void)
 	return size;
 }
 
+const struct vm_mem_backing_src_alias *vm_mem_backing_src_alias(uint32_t i)
+{
+	static const struct vm_mem_backing_src_alias aliases[] = {
+		{ "anonymous",               0                            },
+		{ "anonymous_thp",           0                            },
+		{ "anonymous_hugetlb_16kb",  MAP_HUGETLB | MAP_HUGE_16KB  },
+		{ "anonymous_hugetlb_64kb",  MAP_HUGETLB | MAP_HUGE_64KB  },
+		{ "anonymous_hugetlb_512kb", MAP_HUGETLB | MAP_HUGE_512KB },
+		{ "anonymous_hugetlb_1mb",   MAP_HUGETLB | MAP_HUGE_1MB   },
+		{ "anonymous_hugetlb_2mb",   MAP_HUGETLB | MAP_HUGE_2MB   },
+		{ "anonymous_hugetlb_8mb",   MAP_HUGETLB | MAP_HUGE_8MB   },
+		{ "anonymous_hugetlb_16mb",  MAP_HUGETLB | MAP_HUGE_16MB  },
+		{ "anonymous_hugetlb_32mb",  MAP_HUGETLB | MAP_HUGE_32MB  },
+		{ "anonymous_hugetlb_256mb", MAP_HUGETLB | MAP_HUGE_256MB },
+		{ "anonymous_hugetlb_512mb", MAP_HUGETLB | MAP_HUGE_512MB },
+		{ "anonymous_hugetlb_1gb",   MAP_HUGETLB | MAP_HUGE_1GB   },
+		{ "anonymous_hugetlb_2gb",   MAP_HUGETLB | MAP_HUGE_2GB   },
+		{ "anonymous_hugetlb_16gb",  MAP_HUGETLB | MAP_HUGE_16GB  },
+	};
+	_Static_assert(ARRAY_SIZE(aliases) == NUM_SRC_TYPES,
+		       "Missing new backing src types?");
+
+	TEST_ASSERT(i < NUM_SRC_TYPES, "Backing src type ID %d too big", i);
+
+	return aliases + i;
+}
+
+size_t get_backing_src_pagesz(uint32_t i)
+{
+	uint32_t flag = vm_mem_backing_src_alias(i)->flag;
+
+	if (i == VM_MEM_SRC_ANONYMOUS)
+		return getpagesize();
+	if (i == VM_MEM_SRC_ANONYMOUS_THP)
+		return get_trans_hugepagesz();
+
+	return 1ULL << (flag >> HUGETLB_FLAG_ENCODE_SHIFT);
+}
+
 void backing_src_help(void)
 {
 	int i;
 
 	printf("Available backing src types:\n");
-	for (i = 0; i < ARRAY_SIZE(backing_src_aliases); i++)
-		printf("\t%s\n", backing_src_aliases[i].name);
+	for (i = 0; i < NUM_SRC_TYPES; i++)
+		printf("\t%s\n", vm_mem_backing_src_alias(i)->name);
 }
 
 enum vm_mem_backing_src_type parse_backing_src_type(const char *type_name)
 {
 	int i;
 
-	for (i = 0; i < ARRAY_SIZE(backing_src_aliases); i++)
-		if (!strcmp(type_name, backing_src_aliases[i].name))
-			return backing_src_aliases[i].type;
+	for (i = 0; i < NUM_SRC_TYPES; i++)
+		if (!strcmp(type_name, vm_mem_backing_src_alias(i)->name))
+			return i;
 
 	backing_src_help();
 	TEST_FAIL("Unknown backing src type: %s", type_name);
-- 
2.19.1

[RFC PATCH v2 6/7] KVM: selftests: Adapt vm_userspace_mem_region_add to new helpers

[Yanan Wang]

With VM_MEM_SRC_ANONYMOUS_THP specified in vm_userspace_mem_region_add(),
we have to get the transparent hugepage size for HVA alignment. With the
new helpers, we can use get_backing_src_pagesz() to check whether THP is
configured and then get the exact configured hugepage size.

As different architectures may have different THP page sizes configured,
this can get the accurate THP page sizes on any platform.

Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
---
 tools/testing/selftests/kvm/lib/kvm_util.c | 27 +++++++---------------
 1 file changed, 8 insertions(+), 19 deletions(-)

diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index b91c8e3a7ee1..0105fbfed036 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -18,7 +18,6 @@
 #include <unistd.h>
 #include <linux/kernel.h>
 
-#define KVM_UTIL_PGS_PER_HUGEPG 512
 #define KVM_UTIL_MIN_PFN	2
 
 /* Aligns x up to the next multiple of size. Size must be a power of 2. */
@@ -686,7 +685,7 @@ void vm_userspace_mem_region_add(struct kvm_vm *vm,
 {
 	int ret;
 	struct userspace_mem_region *region;
-	size_t huge_page_size = KVM_UTIL_PGS_PER_HUGEPG * vm->page_size;
+	size_t backing_src_pagesz = get_backing_src_pagesz(src_type);
 	size_t alignment;
 
 	TEST_ASSERT(vm_adjust_num_guest_pages(vm->mode, npages) == npages,
@@ -748,7 +747,7 @@ void vm_userspace_mem_region_add(struct kvm_vm *vm,
 #endif
 
 	if (src_type == VM_MEM_SRC_ANONYMOUS_THP)
-		alignment = max(huge_page_size, alignment);
+		alignment = max(backing_src_pagesz, alignment);
 
 	/* Add enough memory to align up if necessary */
 	if (alignment > 1)
@@ -767,22 +766,12 @@ void vm_userspace_mem_region_add(struct kvm_vm *vm,
 	region->host_mem = align(region->mmap_start, alignment);
 
 	/* As needed perform madvise */
-	if (src_type == VM_MEM_SRC_ANONYMOUS || src_type == VM_MEM_SRC_ANONYMOUS_THP) {
-		struct stat statbuf;
-
-		ret = stat("/sys/kernel/mm/transparent_hugepage", &statbuf);
-		TEST_ASSERT(ret == 0 || (ret == -1 && errno == ENOENT),
-			    "stat /sys/kernel/mm/transparent_hugepage");
-
-		TEST_ASSERT(ret == 0 || src_type != VM_MEM_SRC_ANONYMOUS_THP,
-			    "VM_MEM_SRC_ANONYMOUS_THP requires THP to be configured in the host kernel");
-
-		if (ret == 0) {
-			ret = madvise(region->host_mem, npages * vm->page_size,
-				      src_type == VM_MEM_SRC_ANONYMOUS ? MADV_NOHUGEPAGE : MADV_HUGEPAGE);
-			TEST_ASSERT(ret == 0, "madvise failed, addr: %p length: 0x%lx src_type: %x",
-				    region->host_mem, npages * vm->page_size, src_type);
-		}
+	if (src_type <= VM_MEM_SRC_ANONYMOUS_THP && thp_configured()) {
+		ret = madvise(region->host_mem, npages * vm->page_size,
+			      src_type == VM_MEM_SRC_ANONYMOUS ? MADV_NOHUGEPAGE : MADV_HUGEPAGE);
+		TEST_ASSERT(ret == 0, "madvise failed, addr: %p length: 0x%lx src_type: %s",
+			    region->host_mem, npages * vm->page_size,
+			    vm_mem_backing_src_alias(src_type)->name);
 	}
 
 	region->unused_phy_pages = sparsebit_alloc();
-- 
2.19.1

[RFC PATCH v2 7/7] KVM: selftests: Add a test for kvm page table code

[Yanan Wang]

This test serves as a performance tester and a bug reproducer for
kvm page table code (GPA->HPA mappings), so it gives guidance for
people trying to make some improvement for kvm.

The function guest_code() can cover the conditions where a single vcpu or
multiple vcpus access guest pages within the same memory region, in three
VM stages(before dirty logging, during dirty logging, after dirty logging).
Besides, the backing src memory type(ANONYMOUS/THP/HUGETLB) of the tested
memory region can be specified by users, which means normal page mappings
or block mappings can be chosen by users to be created in the test.

If ANONYMOUS memory is specified, kvm will create normal page mappings
for the tested memory region before dirty logging, and update attributes
of the page mappings from RO to RW during dirty logging. If THP/HUGETLB
memory is specified, kvm will create block mappings for the tested memory
region before dirty logging, and split the blcok mappings into normal page
mappings during dirty logging, and coalesce the page mappings back into
block mappings after dirty logging is stopped.

So in summary, as a performance tester, this test can present the
performance of kvm creating/updating normal page mappings, or the
performance of kvm creating/splitting/recovering block mappings,
through execution time.

When we need to coalesce the page mappings back to block mappings after
dirty logging is stopped, we have to firstly invalidate *all* the TLB
entries for the page mappings right before installation of the block entry,
because a TLB conflict abort error could occur if we can't invalidate the
TLB entries fully. We have hit this TLB conflict twice on aarch64 software
implementation and fixed it. As this test can imulate process from dirty
logging enabled to dirty logging stopped of a VM with block mappings,
so it can also reproduce this TLB conflict abort due to inadequate TLB
invalidation when coalescing tables.

Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
---
 tools/testing/selftests/kvm/Makefile          |   3 +
 .../selftests/kvm/kvm_page_table_test.c       | 476 ++++++++++++++++++
 2 files changed, 479 insertions(+)
 create mode 100644 tools/testing/selftests/kvm/kvm_page_table_test.c

diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index a6d61f451f88..bac81924166d 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -67,6 +67,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/xen_vmcall_test
 TEST_GEN_PROGS_x86_64 += demand_paging_test
 TEST_GEN_PROGS_x86_64 += dirty_log_test
 TEST_GEN_PROGS_x86_64 += dirty_log_perf_test
+TEST_GEN_PROGS_x86_64 += kvm_page_table_test
 TEST_GEN_PROGS_x86_64 += hardware_disable_test
 TEST_GEN_PROGS_x86_64 += kvm_create_max_vcpus
 TEST_GEN_PROGS_x86_64 += memslot_modification_stress_test
@@ -78,6 +79,7 @@ TEST_GEN_PROGS_aarch64 += aarch64/get-reg-list-sve
 TEST_GEN_PROGS_aarch64 += demand_paging_test
 TEST_GEN_PROGS_aarch64 += dirty_log_test
 TEST_GEN_PROGS_aarch64 += dirty_log_perf_test
+TEST_GEN_PROGS_aarch64 += kvm_page_table_test
 TEST_GEN_PROGS_aarch64 += kvm_create_max_vcpus
 TEST_GEN_PROGS_aarch64 += set_memory_region_test
 TEST_GEN_PROGS_aarch64 += steal_time
@@ -87,6 +89,7 @@ TEST_GEN_PROGS_s390x += s390x/resets
 TEST_GEN_PROGS_s390x += s390x/sync_regs_test
 TEST_GEN_PROGS_s390x += demand_paging_test
 TEST_GEN_PROGS_s390x += dirty_log_test
+TEST_GEN_PROGS_s390x += kvm_page_table_test
 TEST_GEN_PROGS_s390x += kvm_create_max_vcpus
 TEST_GEN_PROGS_s390x += set_memory_region_test
 
diff --git a/tools/testing/selftests/kvm/kvm_page_table_test.c b/tools/testing/selftests/kvm/kvm_page_table_test.c
new file mode 100644
index 000000000000..032b49d1483b
--- /dev/null
+++ b/tools/testing/selftests/kvm/kvm_page_table_test.c
@@ -0,0 +1,476 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * KVM page table test
+ *
+ * Copyright (C) 2021, Huawei, Inc.
+ *
+ * Make sure that THP has been enabled or enough HUGETLB pages with specific
+ * page size have been pre-allocated on your system, if you are planning to
+ * use hugepages to back the guest memory for testing.
+ */
+
+#define _GNU_SOURCE /* for program_invocation_name */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <pthread.h>
+
+#include "test_util.h"
+#include "kvm_util.h"
+#include "processor.h"
+#include "guest_modes.h"
+
+#define TEST_MEM_SLOT_INDEX             1
+
+/* Default size(1GB) of the memory for testing */
+#define DEFAULT_TEST_MEM_SIZE		(1 << 30)
+
+/* Default guest test virtual memory offset */
+#define DEFAULT_GUEST_TEST_MEM		0xc0000000
+
+/* Number of guest memory accessing types(read/write) */
+#define NUM_ACCESS_TYPES		2
+
+/* Different guest memory accessing stages */
+enum test_stage {
+	KVM_BEFORE_MAPPINGS,
+	KVM_CREATE_MAPPINGS,
+	KVM_UPDATE_MAPPINGS,
+	KVM_ADJUST_MAPPINGS,
+	NUM_TEST_STAGES,
+};
+
+static const char * const test_stage_string[] = {
+	"KVM_BEFORE_MAPPINGS",
+	"KVM_CREATE_MAPPINGS",
+	"KVM_UPDATE_MAPPINGS",
+	"KVM_ADJUST_MAPPINGS",
+};
+
+struct perf_test_vcpu_args {
+	int vcpu_id;
+	bool vcpu_write;
+};
+
+struct perf_test_args {
+	struct kvm_vm *vm;
+	uint64_t guest_test_virt_mem;
+	uint64_t host_page_size;
+	uint64_t host_num_pages;
+	uint64_t large_page_size;
+	uint64_t large_num_pages;
+	uint64_t host_pages_per_lpage;
+	enum vm_mem_backing_src_type src_type;
+	struct perf_test_vcpu_args vcpu_args[KVM_MAX_VCPUS];
+};
+
+/*
+ * Guest variables. Use addr_gva2hva() if these variables need
+ * to be changed in host.
+ */
+static enum test_stage guest_test_stage;
+
+/* Host variables */
+static uint32_t nr_vcpus = 1;
+static struct perf_test_args perf_test_args;
+static enum test_stage *current_stage;
+static enum test_stage vcpu_last_completed_stage[KVM_MAX_VCPUS];
+static bool host_quit;
+
+/*
+ * Guest physical memory offset of the testing memory slot.
+ * This will be set to the topmost valid physical address minus
+ * the test memory size.
+ */
+static uint64_t guest_test_phys_mem;
+
+/*
+ * Guest virtual memory offset of the testing memory slot.
+ * Must not conflict with identity mapped test code.
+ */
+static uint64_t guest_test_virt_mem = DEFAULT_GUEST_TEST_MEM;
+
+static void guest_code(int vcpu_id)
+{
+	struct perf_test_vcpu_args *vcpu_args = &perf_test_args.vcpu_args[vcpu_id];
+	enum vm_mem_backing_src_type src_type = perf_test_args.src_type;
+	uint64_t host_page_size = perf_test_args.host_page_size;
+	uint64_t host_num_pages = perf_test_args.host_num_pages;
+	uint64_t large_page_size = perf_test_args.large_page_size;
+	uint64_t large_num_pages = perf_test_args.large_num_pages;
+	uint64_t host_pages_per_lpage = perf_test_args.host_pages_per_lpage;
+	uint64_t half = host_pages_per_lpage / 2;
+	bool vcpu_write;
+	enum test_stage stage;
+	uint64_t addr;
+	int i, j;
+
+	/* Make sure vCPU args data structure is not corrupt */
+	GUEST_ASSERT(vcpu_args->vcpu_id == vcpu_id);
+	vcpu_write = vcpu_args->vcpu_write;
+
+	while (true) {
+		stage = READ_ONCE(guest_test_stage);
+		addr = perf_test_args.guest_test_virt_mem;
+
+		switch (stage) {
+		/*
+		 * Before dirty logging, vCPUs concurrently access the first
+		 * 8 bytes of each page (host page/large page) within the same
+		 * memory region with different accessing types (read/write).
+		 * Then KVM will create normal page mappings or huge block
+		 * mappings for them.
+		 */
+		case KVM_CREATE_MAPPINGS:
+			for (i = 0; i < large_num_pages; i++) {
+				if (vcpu_write)
+					*(uint64_t *)addr = 0x0123456789ABCDEF;
+				else
+					READ_ONCE(*(uint64_t *)addr);
+
+				addr += large_page_size;
+			}
+			break;
+
+		/*
+		 * During dirty logging, KVM will only update attributes of the
+		 * normal page mappings from RO to RW if memory backing src type
+		 * is anonymous. In other cases, KVM will split the huge block
+		 * mappings into normal page mappings if memory backing src type
+		 * is THP or HUGETLB.
+		 */
+		case KVM_UPDATE_MAPPINGS:
+			if (src_type == VM_MEM_SRC_ANONYMOUS) {
+				for (i = 0; i < host_num_pages; i++) {
+					*(uint64_t *)addr = 0x0123456789ABCDEF;
+					addr += host_page_size;
+				}
+				break;
+			}
+
+			for (i = 0; i < large_num_pages; i++) {
+				/*
+				 * Write to the first host page in each large
+				 * page region, and triger break of large pages.
+				 */
+				*(uint64_t *)addr = 0x0123456789ABCDEF;
+
+				/*
+				 * Access the middle host pages in each large
+				 * page region. Since dirty logging is enabled,
+				 * this will create new mappings at the smallest
+				 * granularity.
+				 */
+				addr += host_page_size * half;
+				for (j = half; j < host_pages_per_lpage; j++) {
+					READ_ONCE(*(uint64_t *)addr);
+					addr += host_page_size;
+				}
+			}
+			break;
+
+		/*
+		 * After dirty logging is stopped, vCPUs concurrently read
+		 * from every single host page. Then KVM will coalesce the
+		 * split page mappings back to block mappings. And a TLB
+		 * conflict abort could occur here if TLB entries of the
+		 * page mappings are not fully invalidated.
+		 */
+		case KVM_ADJUST_MAPPINGS:
+			for (i = 0; i < host_num_pages; i++) {
+				READ_ONCE(*(uint64_t *)addr);
+				addr += host_page_size;
+			}
+			break;
+
+		default:
+			break;
+		}
+
+		GUEST_SYNC(1);
+	}
+}
+
+static void *vcpu_worker(void *data)
+{
+	int ret;
+	struct perf_test_vcpu_args *vcpu_args = data;
+	struct kvm_vm *vm = perf_test_args.vm;
+	int vcpu_id = vcpu_args->vcpu_id;
+	struct kvm_run *run;
+	struct timespec start;
+	struct timespec ts_diff;
+	enum test_stage stage;
+
+	vcpu_args_set(vm, vcpu_id, 1, vcpu_id);
+	run = vcpu_state(vm, vcpu_id);
+
+	while (!READ_ONCE(host_quit)) {
+		clock_gettime(CLOCK_MONOTONIC_RAW, &start);
+		ret = _vcpu_run(vm, vcpu_id);
+		ts_diff = timespec_elapsed(start);
+
+		TEST_ASSERT(ret == 0, "vcpu_run failed: %d\n", ret);
+
+		TEST_ASSERT(get_ucall(vm, vcpu_id, NULL) == UCALL_SYNC,
+			    "Invalid guest sync status: exit_reason=%s\n",
+			    exit_reason_str(run->exit_reason));
+
+		pr_debug("Got sync event from vCPU %d\n", vcpu_id);
+		stage = READ_ONCE(*current_stage);
+		vcpu_last_completed_stage[vcpu_id] = stage;
+		pr_debug("vCPU %d has completed stage %s\n"
+			 "execution time is: %ld.%.9lds\n\n",
+			 vcpu_id, test_stage_string[stage],
+			 ts_diff.tv_sec, ts_diff.tv_nsec);
+
+		while (stage == READ_ONCE(*current_stage) &&
+		       !READ_ONCE(host_quit)) {}
+	}
+
+	return NULL;
+}
+
+struct test_params {
+	uint64_t phys_offset;
+	uint64_t test_mem_size;
+	enum vm_mem_backing_src_type src_type;
+};
+
+static struct kvm_vm *pre_init_before_test(enum vm_guest_mode mode, void *arg)
+{
+	struct test_params *p = arg;
+	struct perf_test_vcpu_args *vcpu_args;
+	enum vm_mem_backing_src_type src_type = p->src_type;
+	uint64_t large_page_size = get_backing_src_pagesz(src_type);
+	uint64_t test_mem_size = p->test_mem_size, guest_num_pages;
+	uint64_t guest_page_size = vm_guest_mode_params[mode].page_size;
+	uint64_t host_page_size = getpagesize();
+	uint64_t alignment;
+	void *host_test_mem;
+	struct kvm_vm *vm;
+	int vcpu_id;
+
+	/* Align up the test memory size */
+	alignment = max(large_page_size, guest_page_size);
+	test_mem_size = (test_mem_size + alignment - 1) & ~(alignment - 1);
+
+	/* Create a VM with enough guest pages */
+	guest_num_pages = test_mem_size / guest_page_size;
+	vm = vm_create_with_vcpus(mode, nr_vcpus,
+				  guest_num_pages, 0, guest_code, NULL);
+
+	/* Align down GPA of the testing memslot */
+	if (!p->phys_offset)
+		guest_test_phys_mem = (vm_get_max_gfn(vm) - guest_num_pages) *
+				       guest_page_size;
+	else
+		guest_test_phys_mem = p->phys_offset;
+#ifdef __s390x__
+	alignment = max(0x100000, alignment);
+#endif
+	guest_test_phys_mem &= ~(alignment - 1);
+
+	/* Set up the shared data structure perf_test_args */
+	perf_test_args.vm = vm;
+	perf_test_args.guest_test_virt_mem = guest_test_virt_mem;
+	perf_test_args.host_page_size = host_page_size;
+	perf_test_args.host_num_pages = test_mem_size / host_page_size;
+	perf_test_args.large_page_size = large_page_size;
+	perf_test_args.large_num_pages = test_mem_size / large_page_size;
+	perf_test_args.host_pages_per_lpage = large_page_size / host_page_size;
+	perf_test_args.src_type = src_type;
+
+	for (vcpu_id = 0; vcpu_id < KVM_MAX_VCPUS; vcpu_id++) {
+		vcpu_args = &perf_test_args.vcpu_args[vcpu_id];
+		vcpu_args->vcpu_id = vcpu_id;
+		vcpu_args->vcpu_write = !(vcpu_id % NUM_ACCESS_TYPES);
+
+		vcpu_last_completed_stage[vcpu_id] = NUM_TEST_STAGES;
+	}
+
+	/* Add an extra memory slot with specified backing src type */
+	vm_userspace_mem_region_add(vm, src_type, guest_test_phys_mem,
+				    TEST_MEM_SLOT_INDEX, guest_num_pages, 0);
+
+	/* Do mapping(GVA->GPA) for the testing memory slot */
+	virt_map(vm, guest_test_virt_mem, guest_test_phys_mem, guest_num_pages, 0);
+
+	/* Cache the HVA pointer of the region */
+	host_test_mem = addr_gpa2hva(vm, (vm_paddr_t)guest_test_phys_mem);
+
+	/* Export shared structure perf_test_args to guest */
+	ucall_init(vm, NULL);
+	sync_global_to_guest(vm, perf_test_args);
+
+	current_stage = addr_gva2hva(vm, (vm_vaddr_t)(&guest_test_stage));
+	*current_stage = NUM_TEST_STAGES;
+
+	pr_info("Testing guest mode: %s\n", vm_guest_mode_string(mode));
+	pr_info("Testing memory backing src type: %s\n",
+		vm_mem_backing_src_alias(src_type)->name);
+	pr_info("Testing memory backing src granularity: 0x%lx\n",
+		large_page_size);
+	pr_info("Testing memory size(aligned): 0x%lx\n", test_mem_size);
+	pr_info("Guest physical test memory offset: 0x%lx\n",
+		guest_test_phys_mem);
+	pr_info("Host  virtual  test memory offset: 0x%lx\n",
+		(uint64_t)host_test_mem);
+	pr_info("Number of testing vCPUs: %d\n", nr_vcpus);
+
+	return vm;
+}
+
+static void run_test(enum vm_guest_mode mode, void *arg)
+{
+	pthread_t *vcpu_threads;
+	struct kvm_vm *vm;
+	int vcpu_id;
+	enum test_stage stage;
+	struct timespec start;
+	struct timespec ts_diff;
+
+	/* Create VM with vCPUs and make some pre-initialization */
+	vm = pre_init_before_test(mode, arg);
+
+	vcpu_threads = malloc(nr_vcpus * sizeof(*vcpu_threads));
+	TEST_ASSERT(vcpu_threads, "Memory allocation failed");
+
+	host_quit = false;
+	stage = KVM_BEFORE_MAPPINGS;
+	*current_stage = stage;
+
+	for (vcpu_id = 0; vcpu_id < nr_vcpus; vcpu_id++) {
+		pthread_create(&vcpu_threads[vcpu_id], NULL, vcpu_worker,
+			       &perf_test_args.vcpu_args[vcpu_id]);
+	}
+	for (vcpu_id = 0; vcpu_id < nr_vcpus; vcpu_id++) {
+		while (READ_ONCE(vcpu_last_completed_stage[vcpu_id]) != stage)
+			pr_debug("Waiting for vCPU %d to complete stage %s\n",
+				 vcpu_id, test_stage_string[stage]);
+	}
+	pr_info("Started all vCPUs successfully\n");
+
+	/* Test the stage of KVM creating mappings */
+	clock_gettime(CLOCK_MONOTONIC_RAW, &start);
+	stage = KVM_CREATE_MAPPINGS;
+	*current_stage = stage;
+
+	for (vcpu_id = 0; vcpu_id < nr_vcpus; vcpu_id++) {
+		while (READ_ONCE(vcpu_last_completed_stage[vcpu_id]) != stage)
+			pr_debug("Waiting for vCPU %d to complete stage %s\n",
+				 vcpu_id, test_stage_string[stage]);
+	}
+
+	ts_diff = timespec_elapsed(start);
+	pr_info("KVM_CREATE_MAPPINGS: total execution time: %ld.%.9lds\n\n",
+		ts_diff.tv_sec, ts_diff.tv_nsec);
+
+	/* Test the stage of KVM updating mappings */
+	vm_mem_region_set_flags(vm, TEST_MEM_SLOT_INDEX,
+				KVM_MEM_LOG_DIRTY_PAGES);
+
+	clock_gettime(CLOCK_MONOTONIC_RAW, &start);
+	stage = KVM_UPDATE_MAPPINGS;
+	*current_stage = stage;
+
+	for (vcpu_id = 0; vcpu_id < nr_vcpus; vcpu_id++) {
+		while (READ_ONCE(vcpu_last_completed_stage[vcpu_id]) != stage)
+			pr_debug("Waiting for vCPU %d to complete stage %s\n",
+				 vcpu_id, test_stage_string[stage]);
+	}
+
+	ts_diff = timespec_elapsed(start);
+	pr_info("KVM_UPDATE_MAPPINGS: total execution time: %ld.%.9lds\n\n",
+		ts_diff.tv_sec, ts_diff.tv_nsec);
+
+	/* Test the stage of KVM adjusting mappings */
+	vm_mem_region_set_flags(vm, TEST_MEM_SLOT_INDEX, 0);
+
+	clock_gettime(CLOCK_MONOTONIC_RAW, &start);
+	stage = KVM_ADJUST_MAPPINGS;
+	*current_stage = stage;
+
+	for (vcpu_id = 0; vcpu_id < nr_vcpus; vcpu_id++) {
+		while (READ_ONCE(vcpu_last_completed_stage[vcpu_id]) != stage)
+			pr_debug("Waiting for vCPU %d to complete stage %s\n",
+				 vcpu_id, test_stage_string[stage]);
+	}
+
+	ts_diff = timespec_elapsed(start);
+	pr_info("KVM_ADJUST_MAPPINGS: total execution time: %ld.%.9lds\n\n",
+		ts_diff.tv_sec, ts_diff.tv_nsec);
+
+	/* Tell the vcpu thread to quit */
+	host_quit = true;
+	for (vcpu_id = 0; vcpu_id < nr_vcpus; vcpu_id++)
+		pthread_join(vcpu_threads[vcpu_id], NULL);
+
+	free(vcpu_threads);
+	ucall_uninit(vm);
+	kvm_vm_free(vm);
+}
+
+static void help(char *name)
+{
+	puts("");
+	printf("usage: %s [-h] [-p offset] [-m mode] "
+	       "[-b mem size] [-v vcpus] [-s mem type]\n", name);
+	puts("");
+	printf(" -p: specify guest physical test memory offset\n"
+	       "     Warning: a low offset can conflict with the loaded test code.\n");
+	guest_modes_help();
+	printf(" -b: specify size of the memory region for testing. e.g. 10M or 3G.\n"
+	       "     (default: 1G)\n");
+	printf(" -v: specify the number of vCPUs to run\n"
+	       "     (default: 1)\n");
+	printf(" -s: specify the type of memory that should be used to\n"
+	       "     back the guest data region.\n"
+	       "     (default: anonymous)\n\n");
+	backing_src_help();
+	puts("");
+	exit(0);
+}
+
+int main(int argc, char *argv[])
+{
+	int max_vcpus = kvm_check_cap(KVM_CAP_MAX_VCPUS);
+	struct test_params p = {
+		.test_mem_size = DEFAULT_TEST_MEM_SIZE,
+		.src_type = VM_MEM_SRC_ANONYMOUS,
+	};
+	int opt;
+
+	guest_modes_append_default();
+
+	while ((opt = getopt(argc, argv, "hp:m:b:v:s:")) != -1) {
+		switch (opt) {
+		case 'p':
+			p.phys_offset = strtoull(optarg, NULL, 0);
+			break;
+		case 'm':
+			guest_modes_cmdline(optarg);
+			break;
+		case 'b':
+			p.test_mem_size = parse_size(optarg);
+			break;
+		case 'v':
+			nr_vcpus = atoi(optarg);
+			TEST_ASSERT(nr_vcpus > 0 && nr_vcpus <= max_vcpus,
+				    "Invalid number of vcpus, must be between 1 and %d", max_vcpus);
+			break;
+		case 's':
+			p.src_type = parse_backing_src_type(optarg);
+			break;
+		case 'h':
+		default:
+			help(argv[0]);
+			break;
+		}
+	}
+
+	for_each_guest_mode(run_test, &p);
+
+	return 0;
+}
-- 
2.19.1

Re: [RFC PATCH v2 2/7] KVM: selftests: Use flag CLOCK_MONOTONIC_RAW for timing

[Andrew Jones]

On Thu, Feb 25, 2021 at 01:59:35PM +0800, Yanan Wang wrote:
> In addition to function of CLOCK_MONOTONIC, flag CLOCK_MONOTONIC_RAW can
> also shield possiable impact of NTP, which can provide more robustness.

IIRC, this should include

Suggested-by: Vitaly Kuznetsov <vkuznets@redhat.com>

> 
> Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
> ---
>  tools/testing/selftests/kvm/demand_paging_test.c  |  8 ++++----
>  tools/testing/selftests/kvm/dirty_log_perf_test.c | 14 +++++++-------
>  tools/testing/selftests/kvm/lib/test_util.c       |  2 +-
>  tools/testing/selftests/kvm/steal_time.c          |  4 ++--
>  4 files changed, 14 insertions(+), 14 deletions(-)
> 
> diff --git a/tools/testing/selftests/kvm/demand_paging_test.c b/tools/testing/selftests/kvm/demand_paging_test.c
> index 5f7a229c3af1..efbf0c1e9130 100644
> --- a/tools/testing/selftests/kvm/demand_paging_test.c
> +++ b/tools/testing/selftests/kvm/demand_paging_test.c
> @@ -53,7 +53,7 @@ static void *vcpu_worker(void *data)
>  	vcpu_args_set(vm, vcpu_id, 1, vcpu_id);
>  	run = vcpu_state(vm, vcpu_id);
>  
> -	clock_gettime(CLOCK_MONOTONIC, &start);
> +	clock_gettime(CLOCK_MONOTONIC_RAW, &start);
>  
>  	/* Let the guest access its memory */
>  	ret = _vcpu_run(vm, vcpu_id);
> @@ -86,7 +86,7 @@ static int handle_uffd_page_request(int uffd, uint64_t addr)
>  	copy.len = perf_test_args.host_page_size;
>  	copy.mode = 0;
>  
> -	clock_gettime(CLOCK_MONOTONIC, &start);
> +	clock_gettime(CLOCK_MONOTONIC_RAW, &start);
>  
>  	r = ioctl(uffd, UFFDIO_COPY, &copy);
>  	if (r == -1) {
> @@ -123,7 +123,7 @@ static void *uffd_handler_thread_fn(void *arg)
>  	struct timespec start;
>  	struct timespec ts_diff;
>  
> -	clock_gettime(CLOCK_MONOTONIC, &start);
> +	clock_gettime(CLOCK_MONOTONIC_RAW, &start);
>  	while (!quit_uffd_thread) {
>  		struct uffd_msg msg;
>  		struct pollfd pollfd[2];
> @@ -336,7 +336,7 @@ static void run_test(enum vm_guest_mode mode, void *arg)
>  
>  	pr_info("Finished creating vCPUs and starting uffd threads\n");
>  
> -	clock_gettime(CLOCK_MONOTONIC, &start);
> +	clock_gettime(CLOCK_MONOTONIC_RAW, &start);
>  
>  	for (vcpu_id = 0; vcpu_id < nr_vcpus; vcpu_id++) {
>  		pthread_create(&vcpu_threads[vcpu_id], NULL, vcpu_worker,
> diff --git a/tools/testing/selftests/kvm/dirty_log_perf_test.c b/tools/testing/selftests/kvm/dirty_log_perf_test.c
> index 04a2641261be..6cff4ccf9525 100644
> --- a/tools/testing/selftests/kvm/dirty_log_perf_test.c
> +++ b/tools/testing/selftests/kvm/dirty_log_perf_test.c
> @@ -50,7 +50,7 @@ static void *vcpu_worker(void *data)
>  	while (!READ_ONCE(host_quit)) {
>  		int current_iteration = READ_ONCE(iteration);
>  
> -		clock_gettime(CLOCK_MONOTONIC, &start);
> +		clock_gettime(CLOCK_MONOTONIC_RAW, &start);
>  		ret = _vcpu_run(vm, vcpu_id);
>  		ts_diff = timespec_elapsed(start);
>  
> @@ -141,7 +141,7 @@ static void run_test(enum vm_guest_mode mode, void *arg)
>  	iteration = 0;
>  	host_quit = false;
>  
> -	clock_gettime(CLOCK_MONOTONIC, &start);
> +	clock_gettime(CLOCK_MONOTONIC_RAW, &start);
>  	for (vcpu_id = 0; vcpu_id < nr_vcpus; vcpu_id++) {
>  		vcpu_last_completed_iteration[vcpu_id] = -1;
>  
> @@ -162,7 +162,7 @@ static void run_test(enum vm_guest_mode mode, void *arg)
>  		ts_diff.tv_sec, ts_diff.tv_nsec);
>  
>  	/* Enable dirty logging */
> -	clock_gettime(CLOCK_MONOTONIC, &start);
> +	clock_gettime(CLOCK_MONOTONIC_RAW, &start);
>  	vm_mem_region_set_flags(vm, PERF_TEST_MEM_SLOT_INDEX,
>  				KVM_MEM_LOG_DIRTY_PAGES);
>  	ts_diff = timespec_elapsed(start);
> @@ -174,7 +174,7 @@ static void run_test(enum vm_guest_mode mode, void *arg)
>  		 * Incrementing the iteration number will start the vCPUs
>  		 * dirtying memory again.
>  		 */
> -		clock_gettime(CLOCK_MONOTONIC, &start);
> +		clock_gettime(CLOCK_MONOTONIC_RAW, &start);
>  		iteration++;
>  
>  		pr_debug("Starting iteration %d\n", iteration);
> @@ -189,7 +189,7 @@ static void run_test(enum vm_guest_mode mode, void *arg)
>  		pr_info("Iteration %d dirty memory time: %ld.%.9lds\n",
>  			iteration, ts_diff.tv_sec, ts_diff.tv_nsec);
>  
> -		clock_gettime(CLOCK_MONOTONIC, &start);
> +		clock_gettime(CLOCK_MONOTONIC_RAW, &start);
>  		kvm_vm_get_dirty_log(vm, PERF_TEST_MEM_SLOT_INDEX, bmap);
>  
>  		ts_diff = timespec_elapsed(start);
> @@ -199,7 +199,7 @@ static void run_test(enum vm_guest_mode mode, void *arg)
>  			iteration, ts_diff.tv_sec, ts_diff.tv_nsec);
>  
>  		if (dirty_log_manual_caps) {
> -			clock_gettime(CLOCK_MONOTONIC, &start);
> +			clock_gettime(CLOCK_MONOTONIC_RAW, &start);
>  			kvm_vm_clear_dirty_log(vm, PERF_TEST_MEM_SLOT_INDEX, bmap, 0,
>  					       host_num_pages);
>  
> @@ -212,7 +212,7 @@ static void run_test(enum vm_guest_mode mode, void *arg)
>  	}
>  
>  	/* Disable dirty logging */
> -	clock_gettime(CLOCK_MONOTONIC, &start);
> +	clock_gettime(CLOCK_MONOTONIC_RAW, &start);
>  	vm_mem_region_set_flags(vm, PERF_TEST_MEM_SLOT_INDEX, 0);
>  	ts_diff = timespec_elapsed(start);
>  	pr_info("Disabling dirty logging time: %ld.%.9lds\n",
> diff --git a/tools/testing/selftests/kvm/lib/test_util.c b/tools/testing/selftests/kvm/lib/test_util.c
> index 906c955384e2..c7c0627c6842 100644
> --- a/tools/testing/selftests/kvm/lib/test_util.c
> +++ b/tools/testing/selftests/kvm/lib/test_util.c
> @@ -89,7 +89,7 @@ struct timespec timespec_elapsed(struct timespec start)
>  {
>  	struct timespec end;
>  
> -	clock_gettime(CLOCK_MONOTONIC, &end);
> +	clock_gettime(CLOCK_MONOTONIC_RAW, &end);
>  	return timespec_sub(end, start);
>  }
>  
> diff --git a/tools/testing/selftests/kvm/steal_time.c b/tools/testing/selftests/kvm/steal_time.c
> index fcc840088c91..5bc582d3f2a2 100644
> --- a/tools/testing/selftests/kvm/steal_time.c
> +++ b/tools/testing/selftests/kvm/steal_time.c
> @@ -237,11 +237,11 @@ static void *do_steal_time(void *arg)
>  {
>  	struct timespec ts, stop;
>  
> -	clock_gettime(CLOCK_MONOTONIC, &ts);
> +	clock_gettime(CLOCK_MONOTONIC_RAW, &ts);
>  	stop = timespec_add_ns(ts, MIN_RUN_DELAY_NS);
>  
>  	while (1) {
> -		clock_gettime(CLOCK_MONOTONIC, &ts);
> +		clock_gettime(CLOCK_MONOTONIC_RAW, &ts);
>  		if (timespec_to_ns(timespec_sub(ts, stop)) >= 0)
>  			break;
>  	}
> -- 
> 2.19.1
> 

Re: [RFC PATCH v2 3/7] KVM: selftests: Make a generic helper to get vm guest mode strings

[Andrew Jones]

On Thu, Feb 25, 2021 at 01:59:36PM +0800, Yanan Wang wrote:
> For generality and conciseness, make an API which can be used in all
> kvm libs and selftests to get vm guest mode strings. And the index i
> is checked in the API in case of possiable faults.
> 
> Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
> ---
>  .../testing/selftests/kvm/include/kvm_util.h  |  4 +--
>  tools/testing/selftests/kvm/lib/kvm_util.c    | 29 ++++++++++++-------
>  2 files changed, 19 insertions(+), 14 deletions(-)
> 
> diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
> index 2d7eb6989e83..f52a7492f47f 100644
> --- a/tools/testing/selftests/kvm/include/kvm_util.h
> +++ b/tools/testing/selftests/kvm/include/kvm_util.h
> @@ -68,9 +68,6 @@ enum vm_guest_mode {
>  #define MIN_PAGE_SIZE		(1U << MIN_PAGE_SHIFT)
>  #define PTES_PER_MIN_PAGE	ptes_per_page(MIN_PAGE_SIZE)
>  
> -#define vm_guest_mode_string(m) vm_guest_mode_string[m]
> -extern const char * const vm_guest_mode_string[];
> -
>  struct vm_guest_mode_params {
>  	unsigned int pa_bits;
>  	unsigned int va_bits;
> @@ -84,6 +81,7 @@ int vm_enable_cap(struct kvm_vm *vm, struct kvm_enable_cap *cap);
>  int vcpu_enable_cap(struct kvm_vm *vm, uint32_t vcpu_id,
>  		    struct kvm_enable_cap *cap);
>  void vm_enable_dirty_ring(struct kvm_vm *vm, uint32_t ring_size);
> +const char *vm_guest_mode_string(uint32_t i);
>  
>  struct kvm_vm *vm_create(enum vm_guest_mode mode, uint64_t phy_pages, int perm);
>  void kvm_vm_free(struct kvm_vm *vmp);
> diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
> index d787cb802b4a..cc22c4ab7d67 100644
> --- a/tools/testing/selftests/kvm/lib/kvm_util.c
> +++ b/tools/testing/selftests/kvm/lib/kvm_util.c
> @@ -141,17 +141,24 @@ static void vm_open(struct kvm_vm *vm, int perm)
>  		"rc: %i errno: %i", vm->fd, errno);
>  }
>  
> -const char * const vm_guest_mode_string[] = {
> -	"PA-bits:52,  VA-bits:48,  4K pages",
> -	"PA-bits:52,  VA-bits:48, 64K pages",
> -	"PA-bits:48,  VA-bits:48,  4K pages",
> -	"PA-bits:48,  VA-bits:48, 64K pages",
> -	"PA-bits:40,  VA-bits:48,  4K pages",
> -	"PA-bits:40,  VA-bits:48, 64K pages",
> -	"PA-bits:ANY, VA-bits:48,  4K pages",
> -};
> -_Static_assert(sizeof(vm_guest_mode_string)/sizeof(char *) == NUM_VM_MODES,
> -	       "Missing new mode strings?");
> +const char *vm_guest_mode_string(uint32_t i)
> +{
> +	static const char * const strings[] = {
> +		[VM_MODE_P52V48_4K]	= "PA-bits:52,  VA-bits:48,  4K pages",
> +		[VM_MODE_P52V48_64K]	= "PA-bits:52,  VA-bits:48, 64K pages",
> +		[VM_MODE_P48V48_4K]	= "PA-bits:48,  VA-bits:48,  4K pages",
> +		[VM_MODE_P48V48_64K]	= "PA-bits:48,  VA-bits:48, 64K pages",
> +		[VM_MODE_P40V48_4K]	= "PA-bits:40,  VA-bits:48,  4K pages",
> +		[VM_MODE_P40V48_64K]	= "PA-bits:40,  VA-bits:48, 64K pages",
> +		[VM_MODE_PXXV48_4K]	= "PA-bits:ANY, VA-bits:48,  4K pages",
> +	};
> +	_Static_assert(sizeof(strings)/sizeof(char *) == NUM_VM_MODES,
> +		       "Missing new mode strings?");
> +
> +	TEST_ASSERT(i < NUM_VM_MODES, "Guest mode ID %d too big", i);
> +
> +	return strings[i];
> +}
>  
>  const struct vm_guest_mode_params vm_guest_mode_params[] = {
>  	{ 52, 48,  0x1000, 12 },
> -- 
> 2.19.1
>

Reviewed-by: Andrew Jones <drjones@redhat.com>

Re: [RFC PATCH v2 4/7] KVM: selftests: Add a helper to get system configured THP page size

[Ben Gardon]

On Wed, Feb 24, 2021 at 10:00 PM Yanan Wang <wangyanan55@huawei.com> wrote:
>
> If we want to have some tests about transparent hugepages, the system
> configured THP hugepage size should better be known by the tests, which
> can be used for kinds of alignment or guest memory accessing of vcpus...
> So it makes sense to add a helper to get the transparent hugepage size.
>
> With VM_MEM_SRC_ANONYMOUS_THP specified in vm_userspace_mem_region_add(),
> we now stat /sys/kernel/mm/transparent_hugepage to check whether THP is
> configured in the host kernel before madvise(). Based on this, we can also
> read file /sys/kernel/mm/transparent_hugepage/hpage_pmd_size to get THP
> hugepage size.
>
> Signed-off-by: Yanan Wang <wangyanan55@huawei.com>

Reviewed-by: Ben Gardon <bgardon@google.com>

> ---
>  .../testing/selftests/kvm/include/test_util.h |  2 ++
>  tools/testing/selftests/kvm/lib/test_util.c   | 36 +++++++++++++++++++
>  2 files changed, 38 insertions(+)
>
> diff --git a/tools/testing/selftests/kvm/include/test_util.h b/tools/testing/selftests/kvm/include/test_util.h
> index b7f41399f22c..ef24c76ba89a 100644
> --- a/tools/testing/selftests/kvm/include/test_util.h
> +++ b/tools/testing/selftests/kvm/include/test_util.h
> @@ -78,6 +78,8 @@ struct vm_mem_backing_src_alias {
>         enum vm_mem_backing_src_type type;
>  };
>
> +bool thp_configured(void);
> +size_t get_trans_hugepagesz(void);
>  void backing_src_help(void);
>  enum vm_mem_backing_src_type parse_backing_src_type(const char *type_name);
>
> diff --git a/tools/testing/selftests/kvm/lib/test_util.c b/tools/testing/selftests/kvm/lib/test_util.c
> index c7c0627c6842..f2d133f76c67 100644
> --- a/tools/testing/selftests/kvm/lib/test_util.c
> +++ b/tools/testing/selftests/kvm/lib/test_util.c
> @@ -10,6 +10,7 @@
>  #include <limits.h>
>  #include <stdlib.h>
>  #include <time.h>
> +#include <sys/stat.h>
>  #include "linux/kernel.h"
>
>  #include "test_util.h"
> @@ -117,6 +118,41 @@ const struct vm_mem_backing_src_alias backing_src_aliases[] = {
>         {"anonymous_hugetlb", VM_MEM_SRC_ANONYMOUS_HUGETLB,},
>  };
>
> +bool thp_configured(void)
> +{
> +       int ret;
> +       struct stat statbuf;
> +
> +       ret = stat("/sys/kernel/mm/transparent_hugepage", &statbuf);
> +       TEST_ASSERT(ret == 0 || (ret == -1 && errno == ENOENT),
> +                   "Error in stating /sys/kernel/mm/transparent_hugepage: %d",
> +                   errno);
> +
> +       return ret == 0;
> +}
> +
> +size_t get_trans_hugepagesz(void)
> +{
> +       size_t size;
> +       char buf[16];
> +       FILE *f;
> +
> +       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: %d",
> +                   errno);
> +
> +       if (fread(buf, sizeof(char), sizeof(buf), f) == 0) {
> +               fclose(f);
> +               TEST_FAIL("Unable to read transparent_hugepage/hpage_pmd_size");
> +       }
> +
> +       size = strtoull(buf, NULL, 10);
> +       return size;
> +}
> +
>  void backing_src_help(void)
>  {
>         int i;
> --
> 2.19.1
>

Re: [RFC PATCH v2 5/7] KVM: selftests: List all hugetlb src types specified with page sizes

[Ben Gardon]

On Wed, Feb 24, 2021 at 10:03 PM Yanan Wang <wangyanan55@huawei.com> wrote:
>
> With VM_MEM_SRC_ANONYMOUS_HUGETLB, we currently can only use system
> default hugetlb pages to back the testing guest memory. In order to
> add flexibility, now list all the known hugetlb backing src types with
> different page sizes, so that we can specify use of hugetlb pages of the
> exact granularity that we want. And as all the known hugetlb page sizes
> are listed, it's appropriate for all architectures.
>
> Besides, the helper get_backing_src_pagesz() is added to get the
> granularity of different backing src types(anonumous, thp, hugetlb).
>
> Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
> ---
>  .../testing/selftests/kvm/include/test_util.h | 19 ++++++-
>  tools/testing/selftests/kvm/lib/kvm_util.c    |  2 +-
>  tools/testing/selftests/kvm/lib/test_util.c   | 56 +++++++++++++++----
>  3 files changed, 63 insertions(+), 14 deletions(-)
>
> diff --git a/tools/testing/selftests/kvm/include/test_util.h b/tools/testing/selftests/kvm/include/test_util.h
> index ef24c76ba89a..be5d08bcdca7 100644
> --- a/tools/testing/selftests/kvm/include/test_util.h
> +++ b/tools/testing/selftests/kvm/include/test_util.h
> @@ -70,16 +70,31 @@ struct timespec timespec_div(struct timespec ts, int divisor);
>  enum vm_mem_backing_src_type {
>         VM_MEM_SRC_ANONYMOUS,
>         VM_MEM_SRC_ANONYMOUS_THP,
> -       VM_MEM_SRC_ANONYMOUS_HUGETLB,
> +       VM_MEM_SRC_ANONYMOUS_HUGETLB_16KB,
> +       VM_MEM_SRC_ANONYMOUS_HUGETLB_64KB,
> +       VM_MEM_SRC_ANONYMOUS_HUGETLB_512KB,
> +       VM_MEM_SRC_ANONYMOUS_HUGETLB_1MB,
> +       VM_MEM_SRC_ANONYMOUS_HUGETLB_2MB,
> +       VM_MEM_SRC_ANONYMOUS_HUGETLB_8MB,
> +       VM_MEM_SRC_ANONYMOUS_HUGETLB_16MB,
> +       VM_MEM_SRC_ANONYMOUS_HUGETLB_32MB,
> +       VM_MEM_SRC_ANONYMOUS_HUGETLB_256MB,
> +       VM_MEM_SRC_ANONYMOUS_HUGETLB_512MB,
> +       VM_MEM_SRC_ANONYMOUS_HUGETLB_1GB,
> +       VM_MEM_SRC_ANONYMOUS_HUGETLB_2GB,
> +       VM_MEM_SRC_ANONYMOUS_HUGETLB_16GB,
> +       NUM_SRC_TYPES,
>  };
>
>  struct vm_mem_backing_src_alias {
>         const char *name;
> -       enum vm_mem_backing_src_type type;
> +       uint32_t flag;
>  };
>
>  bool thp_configured(void);
>  size_t get_trans_hugepagesz(void);
> +const struct vm_mem_backing_src_alias *vm_mem_backing_src_alias(uint32_t i);
> +size_t get_backing_src_pagesz(uint32_t i);
>  void backing_src_help(void);
>  enum vm_mem_backing_src_type parse_backing_src_type(const char *type_name);
>
> diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
> index cc22c4ab7d67..b91c8e3a7ee1 100644
> --- a/tools/testing/selftests/kvm/lib/kvm_util.c
> +++ b/tools/testing/selftests/kvm/lib/kvm_util.c
> @@ -757,7 +757,7 @@ void vm_userspace_mem_region_add(struct kvm_vm *vm,
>         region->mmap_start = mmap(NULL, region->mmap_size,
>                                   PROT_READ | PROT_WRITE,
>                                   MAP_PRIVATE | MAP_ANONYMOUS
> -                                 | (src_type == VM_MEM_SRC_ANONYMOUS_HUGETLB ? MAP_HUGETLB : 0),
> +                                 | vm_mem_backing_src_alias(src_type)->flag,
>                                   -1, 0);
>         TEST_ASSERT(region->mmap_start != MAP_FAILED,
>                     "test_malloc failed, mmap_start: %p errno: %i",
> diff --git a/tools/testing/selftests/kvm/lib/test_util.c b/tools/testing/selftests/kvm/lib/test_util.c
> index f2d133f76c67..6780aa058f35 100644
> --- a/tools/testing/selftests/kvm/lib/test_util.c
> +++ b/tools/testing/selftests/kvm/lib/test_util.c
> @@ -11,6 +11,7 @@
>  #include <stdlib.h>
>  #include <time.h>
>  #include <sys/stat.h>
> +#include <linux/mman.h>
>  #include "linux/kernel.h"
>
>  #include "test_util.h"
> @@ -112,12 +113,6 @@ void print_skip(const char *fmt, ...)
>         puts(", skipping test");
>  }
>
> -const struct vm_mem_backing_src_alias backing_src_aliases[] = {
> -       {"anonymous", VM_MEM_SRC_ANONYMOUS,},
> -       {"anonymous_thp", VM_MEM_SRC_ANONYMOUS_THP,},
> -       {"anonymous_hugetlb", VM_MEM_SRC_ANONYMOUS_HUGETLB,},
> -};
> -
>  bool thp_configured(void)
>  {
>         int ret;
> @@ -153,22 +148,61 @@ size_t get_trans_hugepagesz(void)
>         return size;
>  }
>
> +const struct vm_mem_backing_src_alias *vm_mem_backing_src_alias(uint32_t i)
> +{
> +       static const struct vm_mem_backing_src_alias aliases[] = {
> +               { "anonymous",               0                            },
> +               { "anonymous_thp",           0                            },
> +               { "anonymous_hugetlb_16kb",  MAP_HUGETLB | MAP_HUGE_16KB  },
> +               { "anonymous_hugetlb_64kb",  MAP_HUGETLB | MAP_HUGE_64KB  },
> +               { "anonymous_hugetlb_512kb", MAP_HUGETLB | MAP_HUGE_512KB },
> +               { "anonymous_hugetlb_1mb",   MAP_HUGETLB | MAP_HUGE_1MB   },
> +               { "anonymous_hugetlb_2mb",   MAP_HUGETLB | MAP_HUGE_2MB   },
> +               { "anonymous_hugetlb_8mb",   MAP_HUGETLB | MAP_HUGE_8MB   },
> +               { "anonymous_hugetlb_16mb",  MAP_HUGETLB | MAP_HUGE_16MB  },
> +               { "anonymous_hugetlb_32mb",  MAP_HUGETLB | MAP_HUGE_32MB  },
> +               { "anonymous_hugetlb_256mb", MAP_HUGETLB | MAP_HUGE_256MB },
> +               { "anonymous_hugetlb_512mb", MAP_HUGETLB | MAP_HUGE_512MB },
> +               { "anonymous_hugetlb_1gb",   MAP_HUGETLB | MAP_HUGE_1GB   },
> +               { "anonymous_hugetlb_2gb",   MAP_HUGETLB | MAP_HUGE_2GB   },
> +               { "anonymous_hugetlb_16gb",  MAP_HUGETLB | MAP_HUGE_16GB  },
> +       };
> +       _Static_assert(ARRAY_SIZE(aliases) == NUM_SRC_TYPES,
> +                      "Missing new backing src types?");
> +
> +       TEST_ASSERT(i < NUM_SRC_TYPES, "Backing src type ID %d too big", i);
> +
> +       return aliases + i;

NIT: This would be easier for me to read as return &aliases[i];


> +}
> +
> +size_t get_backing_src_pagesz(uint32_t i)
> +{
> +       uint32_t flag = vm_mem_backing_src_alias(i)->flag;
> +
> +       if (i == VM_MEM_SRC_ANONYMOUS)
> +               return getpagesize();
> +       if (i == VM_MEM_SRC_ANONYMOUS_THP)
> +               return get_trans_hugepagesz();
> +
> +       return 1ULL << (flag >> HUGETLB_FLAG_ENCODE_SHIFT);

It might also be nice to add a macro where MAP_HUGE_1GB and company
are defined to get the size for a given hugeTLB type. I think you're
mixing macros here too (which works because they're defined off one
another) but it's a little confusing.
MAP_HUGE_1GB and company are defined in
tools/include/uapi/linux/mman.h as equal to the values
HUGETLB_FLAG_ENCODE_1GB and friends in
tools/include/asm-generic/hugetlb_encode.h, but it seems like it would
be good to use MAP_HUGE_SHIFT to match in that case. I think this all
also relies on MAP_HUGETLB being in the bits less than MAP_HUGE_SHIFT
which isn't stated here. All up, I would add a macro to
tools/include/uapi/linux/mman.h:

#define MAP_HUGE_PAGE_SIZE(x) (1ULL << ((x >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK))

Or something similar, and use that here.

> +}
> +
>  void backing_src_help(void)
>  {
>         int i;
>
>         printf("Available backing src types:\n");
> -       for (i = 0; i < ARRAY_SIZE(backing_src_aliases); i++)
> -               printf("\t%s\n", backing_src_aliases[i].name);
> +       for (i = 0; i < NUM_SRC_TYPES; i++)
> +               printf("\t%s\n", vm_mem_backing_src_alias(i)->name);
>  }
>
>  enum vm_mem_backing_src_type parse_backing_src_type(const char *type_name)
>  {
>         int i;
>
> -       for (i = 0; i < ARRAY_SIZE(backing_src_aliases); i++)
> -               if (!strcmp(type_name, backing_src_aliases[i].name))
> -                       return backing_src_aliases[i].type;
> +       for (i = 0; i < NUM_SRC_TYPES; i++)
> +               if (!strcmp(type_name, vm_mem_backing_src_alias(i)->name))
> +                       return i;
>
>         backing_src_help();
>         TEST_FAIL("Unknown backing src type: %s", type_name);
> --
> 2.19.1
>

Re: [RFC PATCH v2 6/7] KVM: selftests: Adapt vm_userspace_mem_region_add to new helpers

[Ben Gardon]

On Wed, Feb 24, 2021 at 10:03 PM Yanan Wang <wangyanan55@huawei.com> wrote:
>
> With VM_MEM_SRC_ANONYMOUS_THP specified in vm_userspace_mem_region_add(),
> we have to get the transparent hugepage size for HVA alignment. With the
> new helpers, we can use get_backing_src_pagesz() to check whether THP is
> configured and then get the exact configured hugepage size.
>
> As different architectures may have different THP page sizes configured,
> this can get the accurate THP page sizes on any platform.
>
> Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
> ---
>  tools/testing/selftests/kvm/lib/kvm_util.c | 27 +++++++---------------
>  1 file changed, 8 insertions(+), 19 deletions(-)
>
> diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
> index b91c8e3a7ee1..0105fbfed036 100644
> --- a/tools/testing/selftests/kvm/lib/kvm_util.c
> +++ b/tools/testing/selftests/kvm/lib/kvm_util.c
> @@ -18,7 +18,6 @@
>  #include <unistd.h>
>  #include <linux/kernel.h>
>
> -#define KVM_UTIL_PGS_PER_HUGEPG 512
>  #define KVM_UTIL_MIN_PFN       2
>
>  /* Aligns x up to the next multiple of size. Size must be a power of 2. */
> @@ -686,7 +685,7 @@ void vm_userspace_mem_region_add(struct kvm_vm *vm,
>  {
>         int ret;
>         struct userspace_mem_region *region;
> -       size_t huge_page_size = KVM_UTIL_PGS_PER_HUGEPG * vm->page_size;
> +       size_t backing_src_pagesz = get_backing_src_pagesz(src_type);
>         size_t alignment;
>
>         TEST_ASSERT(vm_adjust_num_guest_pages(vm->mode, npages) == npages,
> @@ -748,7 +747,7 @@ void vm_userspace_mem_region_add(struct kvm_vm *vm,
>  #endif
>
>         if (src_type == VM_MEM_SRC_ANONYMOUS_THP)
> -               alignment = max(huge_page_size, alignment);
> +               alignment = max(backing_src_pagesz, alignment);
>
>         /* Add enough memory to align up if necessary */
>         if (alignment > 1)
> @@ -767,22 +766,12 @@ void vm_userspace_mem_region_add(struct kvm_vm *vm,
>         region->host_mem = align(region->mmap_start, alignment);
>
>         /* As needed perform madvise */
> -       if (src_type == VM_MEM_SRC_ANONYMOUS || src_type == VM_MEM_SRC_ANONYMOUS_THP) {
> -               struct stat statbuf;
> -
> -               ret = stat("/sys/kernel/mm/transparent_hugepage", &statbuf);
> -               TEST_ASSERT(ret == 0 || (ret == -1 && errno == ENOENT),
> -                           "stat /sys/kernel/mm/transparent_hugepage");
> -
> -               TEST_ASSERT(ret == 0 || src_type != VM_MEM_SRC_ANONYMOUS_THP,
> -                           "VM_MEM_SRC_ANONYMOUS_THP requires THP to be configured in the host kernel");
> -
> -               if (ret == 0) {
> -                       ret = madvise(region->host_mem, npages * vm->page_size,
> -                                     src_type == VM_MEM_SRC_ANONYMOUS ? MADV_NOHUGEPAGE : MADV_HUGEPAGE);
> -                       TEST_ASSERT(ret == 0, "madvise failed, addr: %p length: 0x%lx src_type: %x",
> -                                   region->host_mem, npages * vm->page_size, src_type);
> -               }
> +       if (src_type <= VM_MEM_SRC_ANONYMOUS_THP && thp_configured()) {

This check relies on an unstated property of the backing src type
enums where VM_MEM_SRC_ANONYMOUS and VM_MEM_SRC_ANONYMOUS_THP are
declared first.
It would probably be more readable for folks if the check was explicit:
if ((src_type == VM_MEM_SRC_ANONYMOUS || src_type ==
VM_MEM_SRC_ANONYMOUS_THP) && thp_configured()) {


> +               ret = madvise(region->host_mem, npages * vm->page_size,
> +                             src_type == VM_MEM_SRC_ANONYMOUS ? MADV_NOHUGEPAGE : MADV_HUGEPAGE);
> +               TEST_ASSERT(ret == 0, "madvise failed, addr: %p length: 0x%lx src_type: %s",
> +                           region->host_mem, npages * vm->page_size,
> +                           vm_mem_backing_src_alias(src_type)->name);
>         }
>
>         region->unused_phy_pages = sparsebit_alloc();
> --
> 2.19.1
>

Re: [RFC PATCH v2 0/7] Some improvement and a new test for kvm page table

[Ben Gardon]

On Wed, Feb 24, 2021 at 9:59 PM Yanan Wang <wangyanan55@huawei.com> wrote:
>
> Hi,
> This v2 series can mainly include two parts.
> Based on kvm queue branch: https://git.kernel.org/pub/scm/virt/kvm/kvm.git/log/?h=queue
> Links of v1: https://lore.kernel.org/lkml/20210208090841.333724-1-wangyanan55@huawei.com/
>
> In the first part, all the known hugetlb backing src types specified
> with different hugepage sizes are listed, so that we can specify use
> of hugetlb source of the exact granularity that we want, instead of
> the system default ones. And as all the known hugetlb page sizes are
> listed, it's appropriate for all architectures. Besides, a helper that
> can get granularity of different backing src types(anonumous/thp/hugetlb)
> is added, so that we can use the accurate backing src granularity for
> kinds of alignment or guest memory accessing of vcpus.
>
> In the second part, a new test is added:
> This test is added to serve as a performance tester and a bug reproducer
> for kvm page table code (GPA->HPA mappings), it gives guidance for the
> people trying to make some improvement for kvm. And the following explains
> what we can exactly do through this test.
>
> The function guest_code() can cover the conditions where a single vcpu or
> multiple vcpus access guest pages within the same memory region, in three
> VM stages(before dirty logging, during dirty logging, after dirty logging).
> Besides, the backing src memory type(ANONYMOUS/THP/HUGETLB) of the tested
> memory region can be specified by users, which means normal page mappings
> or block mappings can be chosen by users to be created in the test.
>
> If ANONYMOUS memory is specified, kvm will create normal page mappings
> for the tested memory region before dirty logging, and update attributes
> of the page mappings from RO to RW during dirty logging. If THP/HUGETLB
> memory is specified, kvm will create block mappings for the tested memory
> region before dirty logging, and split the blcok mappings into normal page
> mappings during dirty logging, and coalesce the page mappings back into
> block mappings after dirty logging is stopped.
>
> So in summary, as a performance tester, this test can present the
> performance of kvm creating/updating normal page mappings, or the
> performance of kvm creating/splitting/recovering block mappings,
> through execution time.
>
> When we need to coalesce the page mappings back to block mappings after
> dirty logging is stopped, we have to firstly invalidate *all* the TLB
> entries for the page mappings right before installation of the block entry,
> because a TLB conflict abort error could occur if we can't invalidate the
> TLB entries fully. We have hit this TLB conflict twice on aarch64 software
> implementation and fixed it. As this test can imulate process from dirty
> logging enabled to dirty logging stopped of a VM with block mappings,
> so it can also reproduce this TLB conflict abort due to inadequate TLB
> invalidation when coalescing tables.
>
> Links about the TLB conflict abort:
> https://lore.kernel.org/lkml/20201201201034.116760-3-wangyanan55@huawei.com/

Besides a few style / readability comments, this series looks good to
me. Thanks for generalizing the way these selftests handle different
hugeTLB sizes!


>
> Yanan Wang (7):
>   tools include: sync head files of mmap flag encodings about hugetlb
>   KVM: selftests: Use flag CLOCK_MONOTONIC_RAW for timing
>   KVM: selftests: Make a generic helper to get vm guest mode strings
>   KVM: selftests: Add a helper to get system configured THP page size
>   KVM: selftests: List all hugetlb src types specified with page sizes
>   KVM: selftests: Adapt vm_userspace_mem_region_add to new helpers
>   KVM: selftests: Add a test for kvm page table code
>
>  tools/include/asm-generic/hugetlb_encode.h    |   3 +
>  tools/testing/selftests/kvm/Makefile          |   3 +
>  .../selftests/kvm/demand_paging_test.c        |   8 +-
>  .../selftests/kvm/dirty_log_perf_test.c       |  14 +-
>  .../testing/selftests/kvm/include/kvm_util.h  |   4 +-
>  .../testing/selftests/kvm/include/test_util.h |  21 +-
>  .../selftests/kvm/kvm_page_table_test.c       | 476 ++++++++++++++++++
>  tools/testing/selftests/kvm/lib/kvm_util.c    |  58 +--
>  tools/testing/selftests/kvm/lib/test_util.c   |  92 +++-
>  tools/testing/selftests/kvm/steal_time.c      |   4 +-
>  10 files changed, 623 insertions(+), 60 deletions(-)
>  create mode 100644 tools/testing/selftests/kvm/kvm_page_table_test.c
>
> --
> 2.19.1
>

Re: [RFC PATCH v2 2/7] KVM: selftests: Use flag CLOCK_MONOTONIC_RAW for timing

[wangyanan (Y)]

On 2021/2/26 2:54, Andrew Jones wrote:
> On Thu, Feb 25, 2021 at 01:59:35PM +0800, Yanan Wang wrote:
>> In addition to function of CLOCK_MONOTONIC, flag CLOCK_MONOTONIC_RAW can
>> also shield possiable impact of NTP, which can provide more robustness.
> IIRC, this should include
>
> Suggested-by: Vitaly Kuznetsov <vkuznets@redhat.com>

Oh, sorry for my rashness. I will include it in v3.

Thanks,

Yanan

>> Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
>> ---
>>   tools/testing/selftests/kvm/demand_paging_test.c  |  8 ++++----
>>   tools/testing/selftests/kvm/dirty_log_perf_test.c | 14 +++++++-------
>>   tools/testing/selftests/kvm/lib/test_util.c       |  2 +-
>>   tools/testing/selftests/kvm/steal_time.c          |  4 ++--
>>   4 files changed, 14 insertions(+), 14 deletions(-)
>>
>> diff --git a/tools/testing/selftests/kvm/demand_paging_test.c b/tools/testing/selftests/kvm/demand_paging_test.c
>> index 5f7a229c3af1..efbf0c1e9130 100644
>> --- a/tools/testing/selftests/kvm/demand_paging_test.c
>> +++ b/tools/testing/selftests/kvm/demand_paging_test.c
>> @@ -53,7 +53,7 @@ static void *vcpu_worker(void *data)
>>   	vcpu_args_set(vm, vcpu_id, 1, vcpu_id);
>>   	run = vcpu_state(vm, vcpu_id);
>>   
>> -	clock_gettime(CLOCK_MONOTONIC, &start);
>> +	clock_gettime(CLOCK_MONOTONIC_RAW, &start);
>>   
>>   	/* Let the guest access its memory */
>>   	ret = _vcpu_run(vm, vcpu_id);
>> @@ -86,7 +86,7 @@ static int handle_uffd_page_request(int uffd, uint64_t addr)
>>   	copy.len = perf_test_args.host_page_size;
>>   	copy.mode = 0;
>>   
>> -	clock_gettime(CLOCK_MONOTONIC, &start);
>> +	clock_gettime(CLOCK_MONOTONIC_RAW, &start);
>>   
>>   	r = ioctl(uffd, UFFDIO_COPY, &copy);
>>   	if (r == -1) {
>> @@ -123,7 +123,7 @@ static void *uffd_handler_thread_fn(void *arg)
>>   	struct timespec start;
>>   	struct timespec ts_diff;
>>   
>> -	clock_gettime(CLOCK_MONOTONIC, &start);
>> +	clock_gettime(CLOCK_MONOTONIC_RAW, &start);
>>   	while (!quit_uffd_thread) {
>>   		struct uffd_msg msg;
>>   		struct pollfd pollfd[2];
>> @@ -336,7 +336,7 @@ static void run_test(enum vm_guest_mode mode, void *arg)
>>   
>>   	pr_info("Finished creating vCPUs and starting uffd threads\n");
>>   
>> -	clock_gettime(CLOCK_MONOTONIC, &start);
>> +	clock_gettime(CLOCK_MONOTONIC_RAW, &start);
>>   
>>   	for (vcpu_id = 0; vcpu_id < nr_vcpus; vcpu_id++) {
>>   		pthread_create(&vcpu_threads[vcpu_id], NULL, vcpu_worker,
>> diff --git a/tools/testing/selftests/kvm/dirty_log_perf_test.c b/tools/testing/selftests/kvm/dirty_log_perf_test.c
>> index 04a2641261be..6cff4ccf9525 100644
>> --- a/tools/testing/selftests/kvm/dirty_log_perf_test.c
>> +++ b/tools/testing/selftests/kvm/dirty_log_perf_test.c
>> @@ -50,7 +50,7 @@ static void *vcpu_worker(void *data)
>>   	while (!READ_ONCE(host_quit)) {
>>   		int current_iteration = READ_ONCE(iteration);
>>   
>> -		clock_gettime(CLOCK_MONOTONIC, &start);
>> +		clock_gettime(CLOCK_MONOTONIC_RAW, &start);
>>   		ret = _vcpu_run(vm, vcpu_id);
>>   		ts_diff = timespec_elapsed(start);
>>   
>> @@ -141,7 +141,7 @@ static void run_test(enum vm_guest_mode mode, void *arg)
>>   	iteration = 0;
>>   	host_quit = false;
>>   
>> -	clock_gettime(CLOCK_MONOTONIC, &start);
>> +	clock_gettime(CLOCK_MONOTONIC_RAW, &start);
>>   	for (vcpu_id = 0; vcpu_id < nr_vcpus; vcpu_id++) {
>>   		vcpu_last_completed_iteration[vcpu_id] = -1;
>>   
>> @@ -162,7 +162,7 @@ static void run_test(enum vm_guest_mode mode, void *arg)
>>   		ts_diff.tv_sec, ts_diff.tv_nsec);
>>   
>>   	/* Enable dirty logging */
>> -	clock_gettime(CLOCK_MONOTONIC, &start);
>> +	clock_gettime(CLOCK_MONOTONIC_RAW, &start);
>>   	vm_mem_region_set_flags(vm, PERF_TEST_MEM_SLOT_INDEX,
>>   				KVM_MEM_LOG_DIRTY_PAGES);
>>   	ts_diff = timespec_elapsed(start);
>> @@ -174,7 +174,7 @@ static void run_test(enum vm_guest_mode mode, void *arg)
>>   		 * Incrementing the iteration number will start the vCPUs
>>   		 * dirtying memory again.
>>   		 */
>> -		clock_gettime(CLOCK_MONOTONIC, &start);
>> +		clock_gettime(CLOCK_MONOTONIC_RAW, &start);
>>   		iteration++;
>>   
>>   		pr_debug("Starting iteration %d\n", iteration);
>> @@ -189,7 +189,7 @@ static void run_test(enum vm_guest_mode mode, void *arg)
>>   		pr_info("Iteration %d dirty memory time: %ld.%.9lds\n",
>>   			iteration, ts_diff.tv_sec, ts_diff.tv_nsec);
>>   
>> -		clock_gettime(CLOCK_MONOTONIC, &start);
>> +		clock_gettime(CLOCK_MONOTONIC_RAW, &start);
>>   		kvm_vm_get_dirty_log(vm, PERF_TEST_MEM_SLOT_INDEX, bmap);
>>   
>>   		ts_diff = timespec_elapsed(start);
>> @@ -199,7 +199,7 @@ static void run_test(enum vm_guest_mode mode, void *arg)
>>   			iteration, ts_diff.tv_sec, ts_diff.tv_nsec);
>>   
>>   		if (dirty_log_manual_caps) {
>> -			clock_gettime(CLOCK_MONOTONIC, &start);
>> +			clock_gettime(CLOCK_MONOTONIC_RAW, &start);
>>   			kvm_vm_clear_dirty_log(vm, PERF_TEST_MEM_SLOT_INDEX, bmap, 0,
>>   					       host_num_pages);
>>   
>> @@ -212,7 +212,7 @@ static void run_test(enum vm_guest_mode mode, void *arg)
>>   	}
>>   
>>   	/* Disable dirty logging */
>> -	clock_gettime(CLOCK_MONOTONIC, &start);
>> +	clock_gettime(CLOCK_MONOTONIC_RAW, &start);
>>   	vm_mem_region_set_flags(vm, PERF_TEST_MEM_SLOT_INDEX, 0);
>>   	ts_diff = timespec_elapsed(start);
>>   	pr_info("Disabling dirty logging time: %ld.%.9lds\n",
>> diff --git a/tools/testing/selftests/kvm/lib/test_util.c b/tools/testing/selftests/kvm/lib/test_util.c
>> index 906c955384e2..c7c0627c6842 100644
>> --- a/tools/testing/selftests/kvm/lib/test_util.c
>> +++ b/tools/testing/selftests/kvm/lib/test_util.c
>> @@ -89,7 +89,7 @@ struct timespec timespec_elapsed(struct timespec start)
>>   {
>>   	struct timespec end;
>>   
>> -	clock_gettime(CLOCK_MONOTONIC, &end);
>> +	clock_gettime(CLOCK_MONOTONIC_RAW, &end);
>>   	return timespec_sub(end, start);
>>   }
>>   
>> diff --git a/tools/testing/selftests/kvm/steal_time.c b/tools/testing/selftests/kvm/steal_time.c
>> index fcc840088c91..5bc582d3f2a2 100644
>> --- a/tools/testing/selftests/kvm/steal_time.c
>> +++ b/tools/testing/selftests/kvm/steal_time.c
>> @@ -237,11 +237,11 @@ static void *do_steal_time(void *arg)
>>   {
>>   	struct timespec ts, stop;
>>   
>> -	clock_gettime(CLOCK_MONOTONIC, &ts);
>> +	clock_gettime(CLOCK_MONOTONIC_RAW, &ts);
>>   	stop = timespec_add_ns(ts, MIN_RUN_DELAY_NS);
>>   
>>   	while (1) {
>> -		clock_gettime(CLOCK_MONOTONIC, &ts);
>> +		clock_gettime(CLOCK_MONOTONIC_RAW, &ts);
>>   		if (timespec_to_ns(timespec_sub(ts, stop)) >= 0)
>>   			break;
>>   	}
>> -- 
>> 2.19.1
>>
> .

Re: [RFC PATCH v2 5/7] KVM: selftests: List all hugetlb src types specified with page sizes

[wangyanan (Y)]

On 2021/2/26 7:42, Ben Gardon wrote:
> On Wed, Feb 24, 2021 at 10:03 PM Yanan Wang <wangyanan55@huawei.com> wrote:
>> With VM_MEM_SRC_ANONYMOUS_HUGETLB, we currently can only use system
>> default hugetlb pages to back the testing guest memory. In order to
>> add flexibility, now list all the known hugetlb backing src types with
>> different page sizes, so that we can specify use of hugetlb pages of the
>> exact granularity that we want. And as all the known hugetlb page sizes
>> are listed, it's appropriate for all architectures.
>>
>> Besides, the helper get_backing_src_pagesz() is added to get the
>> granularity of different backing src types(anonumous, thp, hugetlb).
>>
>> Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
>> ---
>>   .../testing/selftests/kvm/include/test_util.h | 19 ++++++-
>>   tools/testing/selftests/kvm/lib/kvm_util.c    |  2 +-
>>   tools/testing/selftests/kvm/lib/test_util.c   | 56 +++++++++++++++----
>>   3 files changed, 63 insertions(+), 14 deletions(-)
>>
>> diff --git a/tools/testing/selftests/kvm/include/test_util.h b/tools/testing/selftests/kvm/include/test_util.h
>> index ef24c76ba89a..be5d08bcdca7 100644
>> --- a/tools/testing/selftests/kvm/include/test_util.h
>> +++ b/tools/testing/selftests/kvm/include/test_util.h
>> @@ -70,16 +70,31 @@ struct timespec timespec_div(struct timespec ts, int divisor);
>>   enum vm_mem_backing_src_type {
>>          VM_MEM_SRC_ANONYMOUS,
>>          VM_MEM_SRC_ANONYMOUS_THP,
>> -       VM_MEM_SRC_ANONYMOUS_HUGETLB,
>> +       VM_MEM_SRC_ANONYMOUS_HUGETLB_16KB,
>> +       VM_MEM_SRC_ANONYMOUS_HUGETLB_64KB,
>> +       VM_MEM_SRC_ANONYMOUS_HUGETLB_512KB,
>> +       VM_MEM_SRC_ANONYMOUS_HUGETLB_1MB,
>> +       VM_MEM_SRC_ANONYMOUS_HUGETLB_2MB,
>> +       VM_MEM_SRC_ANONYMOUS_HUGETLB_8MB,
>> +       VM_MEM_SRC_ANONYMOUS_HUGETLB_16MB,
>> +       VM_MEM_SRC_ANONYMOUS_HUGETLB_32MB,
>> +       VM_MEM_SRC_ANONYMOUS_HUGETLB_256MB,
>> +       VM_MEM_SRC_ANONYMOUS_HUGETLB_512MB,
>> +       VM_MEM_SRC_ANONYMOUS_HUGETLB_1GB,
>> +       VM_MEM_SRC_ANONYMOUS_HUGETLB_2GB,
>> +       VM_MEM_SRC_ANONYMOUS_HUGETLB_16GB,
>> +       NUM_SRC_TYPES,
>>   };
>>
>>   struct vm_mem_backing_src_alias {
>>          const char *name;
>> -       enum vm_mem_backing_src_type type;
>> +       uint32_t flag;
>>   };
>>
>>   bool thp_configured(void);
>>   size_t get_trans_hugepagesz(void);
>> +const struct vm_mem_backing_src_alias *vm_mem_backing_src_alias(uint32_t i);
>> +size_t get_backing_src_pagesz(uint32_t i);
>>   void backing_src_help(void);
>>   enum vm_mem_backing_src_type parse_backing_src_type(const char *type_name);
>>
>> diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
>> index cc22c4ab7d67..b91c8e3a7ee1 100644
>> --- a/tools/testing/selftests/kvm/lib/kvm_util.c
>> +++ b/tools/testing/selftests/kvm/lib/kvm_util.c
>> @@ -757,7 +757,7 @@ void vm_userspace_mem_region_add(struct kvm_vm *vm,
>>          region->mmap_start = mmap(NULL, region->mmap_size,
>>                                    PROT_READ | PROT_WRITE,
>>                                    MAP_PRIVATE | MAP_ANONYMOUS
>> -                                 | (src_type == VM_MEM_SRC_ANONYMOUS_HUGETLB ? MAP_HUGETLB : 0),
>> +                                 | vm_mem_backing_src_alias(src_type)->flag,
>>                                    -1, 0);
>>          TEST_ASSERT(region->mmap_start != MAP_FAILED,
>>                      "test_malloc failed, mmap_start: %p errno: %i",
>> diff --git a/tools/testing/selftests/kvm/lib/test_util.c b/tools/testing/selftests/kvm/lib/test_util.c
>> index f2d133f76c67..6780aa058f35 100644
>> --- a/tools/testing/selftests/kvm/lib/test_util.c
>> +++ b/tools/testing/selftests/kvm/lib/test_util.c
>> @@ -11,6 +11,7 @@
>>   #include <stdlib.h>
>>   #include <time.h>
>>   #include <sys/stat.h>
>> +#include <linux/mman.h>
>>   #include "linux/kernel.h"
>>
>>   #include "test_util.h"
>> @@ -112,12 +113,6 @@ void print_skip(const char *fmt, ...)
>>          puts(", skipping test");
>>   }
>>
>> -const struct vm_mem_backing_src_alias backing_src_aliases[] = {
>> -       {"anonymous", VM_MEM_SRC_ANONYMOUS,},
>> -       {"anonymous_thp", VM_MEM_SRC_ANONYMOUS_THP,},
>> -       {"anonymous_hugetlb", VM_MEM_SRC_ANONYMOUS_HUGETLB,},
>> -};
>> -
>>   bool thp_configured(void)
>>   {
>>          int ret;
>> @@ -153,22 +148,61 @@ size_t get_trans_hugepagesz(void)
>>          return size;
>>   }
>>
>> +const struct vm_mem_backing_src_alias *vm_mem_backing_src_alias(uint32_t i)
>> +{
>> +       static const struct vm_mem_backing_src_alias aliases[] = {
>> +               { "anonymous",               0                            },
>> +               { "anonymous_thp",           0                            },
>> +               { "anonymous_hugetlb_16kb",  MAP_HUGETLB | MAP_HUGE_16KB  },
>> +               { "anonymous_hugetlb_64kb",  MAP_HUGETLB | MAP_HUGE_64KB  },
>> +               { "anonymous_hugetlb_512kb", MAP_HUGETLB | MAP_HUGE_512KB },
>> +               { "anonymous_hugetlb_1mb",   MAP_HUGETLB | MAP_HUGE_1MB   },
>> +               { "anonymous_hugetlb_2mb",   MAP_HUGETLB | MAP_HUGE_2MB   },
>> +               { "anonymous_hugetlb_8mb",   MAP_HUGETLB | MAP_HUGE_8MB   },
>> +               { "anonymous_hugetlb_16mb",  MAP_HUGETLB | MAP_HUGE_16MB  },
>> +               { "anonymous_hugetlb_32mb",  MAP_HUGETLB | MAP_HUGE_32MB  },
>> +               { "anonymous_hugetlb_256mb", MAP_HUGETLB | MAP_HUGE_256MB },
>> +               { "anonymous_hugetlb_512mb", MAP_HUGETLB | MAP_HUGE_512MB },
>> +               { "anonymous_hugetlb_1gb",   MAP_HUGETLB | MAP_HUGE_1GB   },
>> +               { "anonymous_hugetlb_2gb",   MAP_HUGETLB | MAP_HUGE_2GB   },
>> +               { "anonymous_hugetlb_16gb",  MAP_HUGETLB | MAP_HUGE_16GB  },
>> +       };
>> +       _Static_assert(ARRAY_SIZE(aliases) == NUM_SRC_TYPES,
>> +                      "Missing new backing src types?");
>> +
>> +       TEST_ASSERT(i < NUM_SRC_TYPES, "Backing src type ID %d too big", i);
>> +
>> +       return aliases + i;
> NIT: This would be easier for me to read as return &aliases[i];
Ok, will change it.
>
>> +}
>> +
>> +size_t get_backing_src_pagesz(uint32_t i)
>> +{
>> +       uint32_t flag = vm_mem_backing_src_alias(i)->flag;
>> +
>> +       if (i == VM_MEM_SRC_ANONYMOUS)
>> +               return getpagesize();
>> +       if (i == VM_MEM_SRC_ANONYMOUS_THP)
>> +               return get_trans_hugepagesz();
>> +
>> +       return 1ULL << (flag >> HUGETLB_FLAG_ENCODE_SHIFT);
> It might also be nice to add a macro where MAP_HUGE_1GB and company
> are defined to get the size for a given hugeTLB type. I think you're
> mixing macros here too (which works because they're defined off one
> another) but it's a little confusing.
> MAP_HUGE_1GB and company are defined in
> tools/include/uapi/linux/mman.h as equal to the values
> HUGETLB_FLAG_ENCODE_1GB and friends in
> tools/include/asm-generic/hugetlb_encode.h, but it seems like it would
> be good to use MAP_HUGE_SHIFT to match in that case. I think this all
> also relies on MAP_HUGETLB being in the bits less than MAP_HUGE_SHIFT
> which isn't stated here. All up, I would add a macro to
> tools/include/uapi/linux/mman.h:
>
> #define MAP_HUGE_PAGE_SIZE(x) (1ULL << ((x >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK))
Good idea. This will be more stable and easier to read. Thanks.
>
> Or something similar, and use that here.
>
>> +}
>> +
>>   void backing_src_help(void)
>>   {
>>          int i;
>>
>>          printf("Available backing src types:\n");
>> -       for (i = 0; i < ARRAY_SIZE(backing_src_aliases); i++)
>> -               printf("\t%s\n", backing_src_aliases[i].name);
>> +       for (i = 0; i < NUM_SRC_TYPES; i++)
>> +               printf("\t%s\n", vm_mem_backing_src_alias(i)->name);
>>   }
>>
>>   enum vm_mem_backing_src_type parse_backing_src_type(const char *type_name)
>>   {
>>          int i;
>>
>> -       for (i = 0; i < ARRAY_SIZE(backing_src_aliases); i++)
>> -               if (!strcmp(type_name, backing_src_aliases[i].name))
>> -                       return backing_src_aliases[i].type;
>> +       for (i = 0; i < NUM_SRC_TYPES; i++)
>> +               if (!strcmp(type_name, vm_mem_backing_src_alias(i)->name))
>> +                       return i;
>>
>>          backing_src_help();
>>          TEST_FAIL("Unknown backing src type: %s", type_name);
>> --
>> 2.19.1
>>
> .

Re: [RFC PATCH v2 6/7] KVM: selftests: Adapt vm_userspace_mem_region_add to new helpers

[wangyanan (Y)]

On 2021/2/26 7:44, Ben Gardon wrote:
> On Wed, Feb 24, 2021 at 10:03 PM Yanan Wang <wangyanan55@huawei.com> wrote:
>> With VM_MEM_SRC_ANONYMOUS_THP specified in vm_userspace_mem_region_add(),
>> we have to get the transparent hugepage size for HVA alignment. With the
>> new helpers, we can use get_backing_src_pagesz() to check whether THP is
>> configured and then get the exact configured hugepage size.
>>
>> As different architectures may have different THP page sizes configured,
>> this can get the accurate THP page sizes on any platform.
>>
>> Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
>> ---
>>   tools/testing/selftests/kvm/lib/kvm_util.c | 27 +++++++---------------
>>   1 file changed, 8 insertions(+), 19 deletions(-)
>>
>> diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
>> index b91c8e3a7ee1..0105fbfed036 100644
>> --- a/tools/testing/selftests/kvm/lib/kvm_util.c
>> +++ b/tools/testing/selftests/kvm/lib/kvm_util.c
>> @@ -18,7 +18,6 @@
>>   #include <unistd.h>
>>   #include <linux/kernel.h>
>>
>> -#define KVM_UTIL_PGS_PER_HUGEPG 512
>>   #define KVM_UTIL_MIN_PFN       2
>>
>>   /* Aligns x up to the next multiple of size. Size must be a power of 2. */
>> @@ -686,7 +685,7 @@ void vm_userspace_mem_region_add(struct kvm_vm *vm,
>>   {
>>          int ret;
>>          struct userspace_mem_region *region;
>> -       size_t huge_page_size = KVM_UTIL_PGS_PER_HUGEPG * vm->page_size;
>> +       size_t backing_src_pagesz = get_backing_src_pagesz(src_type);
>>          size_t alignment;
>>
>>          TEST_ASSERT(vm_adjust_num_guest_pages(vm->mode, npages) == npages,
>> @@ -748,7 +747,7 @@ void vm_userspace_mem_region_add(struct kvm_vm *vm,
>>   #endif
>>
>>          if (src_type == VM_MEM_SRC_ANONYMOUS_THP)
>> -               alignment = max(huge_page_size, alignment);
>> +               alignment = max(backing_src_pagesz, alignment);
>>
>>          /* Add enough memory to align up if necessary */
>>          if (alignment > 1)
>> @@ -767,22 +766,12 @@ void vm_userspace_mem_region_add(struct kvm_vm *vm,
>>          region->host_mem = align(region->mmap_start, alignment);
>>
>>          /* As needed perform madvise */
>> -       if (src_type == VM_MEM_SRC_ANONYMOUS || src_type == VM_MEM_SRC_ANONYMOUS_THP) {
>> -               struct stat statbuf;
>> -
>> -               ret = stat("/sys/kernel/mm/transparent_hugepage", &statbuf);
>> -               TEST_ASSERT(ret == 0 || (ret == -1 && errno == ENOENT),
>> -                           "stat /sys/kernel/mm/transparent_hugepage");
>> -
>> -               TEST_ASSERT(ret == 0 || src_type != VM_MEM_SRC_ANONYMOUS_THP,
>> -                           "VM_MEM_SRC_ANONYMOUS_THP requires THP to be configured in the host kernel");
>> -
>> -               if (ret == 0) {
>> -                       ret = madvise(region->host_mem, npages * vm->page_size,
>> -                                     src_type == VM_MEM_SRC_ANONYMOUS ? MADV_NOHUGEPAGE : MADV_HUGEPAGE);
>> -                       TEST_ASSERT(ret == 0, "madvise failed, addr: %p length: 0x%lx src_type: %x",
>> -                                   region->host_mem, npages * vm->page_size, src_type);
>> -               }
>> +       if (src_type <= VM_MEM_SRC_ANONYMOUS_THP && thp_configured()) {
> This check relies on an unstated property of the backing src type
> enums where VM_MEM_SRC_ANONYMOUS and VM_MEM_SRC_ANONYMOUS_THP are
> declared first.
> It would probably be more readable for folks if the check was explicit:
> if ((src_type == VM_MEM_SRC_ANONYMOUS || src_type ==
> VM_MEM_SRC_ANONYMOUS_THP) && thp_configured()) {
>
Yes, this makes sense, I will fix it.

Thanks,

Yanan

>> +               ret = madvise(region->host_mem, npages * vm->page_size,
>> +                             src_type == VM_MEM_SRC_ANONYMOUS ? MADV_NOHUGEPAGE : MADV_HUGEPAGE);
>> +               TEST_ASSERT(ret == 0, "madvise failed, addr: %p length: 0x%lx src_type: %s",
>> +                           region->host_mem, npages * vm->page_size,
>> +                           vm_mem_backing_src_alias(src_type)->name);
>>          }
>>
>>          region->unused_phy_pages = sparsebit_alloc();
>> --
>> 2.19.1
>>
> .

Re: [RFC PATCH v2 3/7] KVM: selftests: Make a generic helper to get vm guest mode strings

[wangyanan (Y)]

On 2021/2/25 13:59, Yanan Wang wrote:
> For generality and conciseness, make an API which can be used in all
> kvm libs and selftests to get vm guest mode strings. And the index i
> is checked in the API in case of possiable faults.
>
> Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
And here too, will include Suggested-by: Sean Christopherson 
<seanjc@google.com>.
> ---
>   .../testing/selftests/kvm/include/kvm_util.h  |  4 +--
>   tools/testing/selftests/kvm/lib/kvm_util.c    | 29 ++++++++++++-------
>   2 files changed, 19 insertions(+), 14 deletions(-)
>
> diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
> index 2d7eb6989e83..f52a7492f47f 100644
> --- a/tools/testing/selftests/kvm/include/kvm_util.h
> +++ b/tools/testing/selftests/kvm/include/kvm_util.h
> @@ -68,9 +68,6 @@ enum vm_guest_mode {
>   #define MIN_PAGE_SIZE		(1U << MIN_PAGE_SHIFT)
>   #define PTES_PER_MIN_PAGE	ptes_per_page(MIN_PAGE_SIZE)
>   
> -#define vm_guest_mode_string(m) vm_guest_mode_string[m]
> -extern const char * const vm_guest_mode_string[];
> -
>   struct vm_guest_mode_params {
>   	unsigned int pa_bits;
>   	unsigned int va_bits;
> @@ -84,6 +81,7 @@ int vm_enable_cap(struct kvm_vm *vm, struct kvm_enable_cap *cap);
>   int vcpu_enable_cap(struct kvm_vm *vm, uint32_t vcpu_id,
>   		    struct kvm_enable_cap *cap);
>   void vm_enable_dirty_ring(struct kvm_vm *vm, uint32_t ring_size);
> +const char *vm_guest_mode_string(uint32_t i);
>   
>   struct kvm_vm *vm_create(enum vm_guest_mode mode, uint64_t phy_pages, int perm);
>   void kvm_vm_free(struct kvm_vm *vmp);
> diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
> index d787cb802b4a..cc22c4ab7d67 100644
> --- a/tools/testing/selftests/kvm/lib/kvm_util.c
> +++ b/tools/testing/selftests/kvm/lib/kvm_util.c
> @@ -141,17 +141,24 @@ static void vm_open(struct kvm_vm *vm, int perm)
>   		"rc: %i errno: %i", vm->fd, errno);
>   }
>   
> -const char * const vm_guest_mode_string[] = {
> -	"PA-bits:52,  VA-bits:48,  4K pages",
> -	"PA-bits:52,  VA-bits:48, 64K pages",
> -	"PA-bits:48,  VA-bits:48,  4K pages",
> -	"PA-bits:48,  VA-bits:48, 64K pages",
> -	"PA-bits:40,  VA-bits:48,  4K pages",
> -	"PA-bits:40,  VA-bits:48, 64K pages",
> -	"PA-bits:ANY, VA-bits:48,  4K pages",
> -};
> -_Static_assert(sizeof(vm_guest_mode_string)/sizeof(char *) == NUM_VM_MODES,
> -	       "Missing new mode strings?");
> +const char *vm_guest_mode_string(uint32_t i)
> +{
> +	static const char * const strings[] = {
> +		[VM_MODE_P52V48_4K]	= "PA-bits:52,  VA-bits:48,  4K pages",
> +		[VM_MODE_P52V48_64K]	= "PA-bits:52,  VA-bits:48, 64K pages",
> +		[VM_MODE_P48V48_4K]	= "PA-bits:48,  VA-bits:48,  4K pages",
> +		[VM_MODE_P48V48_64K]	= "PA-bits:48,  VA-bits:48, 64K pages",
> +		[VM_MODE_P40V48_4K]	= "PA-bits:40,  VA-bits:48,  4K pages",
> +		[VM_MODE_P40V48_64K]	= "PA-bits:40,  VA-bits:48, 64K pages",
> +		[VM_MODE_PXXV48_4K]	= "PA-bits:ANY, VA-bits:48,  4K pages",
> +	};
> +	_Static_assert(sizeof(strings)/sizeof(char *) == NUM_VM_MODES,
> +		       "Missing new mode strings?");
> +
> +	TEST_ASSERT(i < NUM_VM_MODES, "Guest mode ID %d too big", i);
> +
> +	return strings[i];
> +}
>   
>   const struct vm_guest_mode_params vm_guest_mode_params[] = {
>   	{ 52, 48,  0x1000, 12 },