[PATCH 0/3] KVM: selftests: Small fixes for dirty_log_perf_test

[PATCH 0/3] KVM: selftests: Small fixes for dirty_log_perf_test

[David Matlack]

This series fixes 2 bugs in dirty_log_perf_test:
 - Incorrect interleaving of help messages for -s and -x (patch 2)
 - Buffer overflow when using multiple slots (patch 3)

Both bugs were introduced by commit 609e6202ea5f ("KVM: selftests:
Support multiple slots in dirty_log_perf_test").

Patch 1 is a small tangentially related cleanup to use a consistent
flag for the backing source across all selftests.

David Matlack (3):
  KVM: selftests: Change backing_src flag to -s in demand_paging_test
  KVM: selftests: Refactor help message for -s backing_src
  KVM: selftests: Fix dirty bitmap offset calculation

 .../selftests/kvm/access_tracking_perf_test.c |  6 ++---
 .../selftests/kvm/demand_paging_test.c        | 13 +++++------
 .../selftests/kvm/dirty_log_perf_test.c       | 23 +++++++++++++------
 .../testing/selftests/kvm/include/test_util.h |  5 +++-
 .../selftests/kvm/kvm_page_table_test.c       |  7 ++----
 tools/testing/selftests/kvm/lib/test_util.c   | 17 ++++++++++----
 6 files changed, 43 insertions(+), 28 deletions(-)

-- 
2.33.0.309.g3052b89438-goog

[PATCH 1/3] KVM: selftests: Change backing_src flag to -s in demand_paging_test

[David Matlack]

Every other KVM selftest uses -s for the backing_src, so switch
demand_paging_test to match.

Signed-off-by: David Matlack <dmatlack@google.com>
---
 tools/testing/selftests/kvm/demand_paging_test.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/tools/testing/selftests/kvm/demand_paging_test.c b/tools/testing/selftests/kvm/demand_paging_test.c
index e79c1b64977f..735c081e774e 100644
--- a/tools/testing/selftests/kvm/demand_paging_test.c
+++ b/tools/testing/selftests/kvm/demand_paging_test.c
@@ -416,7 +416,7 @@ static void help(char *name)
 {
 	puts("");
 	printf("usage: %s [-h] [-m vm_mode] [-u uffd_mode] [-d uffd_delay_usec]\n"
-	       "          [-b memory] [-t type] [-v vcpus] [-o]\n", name);
+	       "          [-b memory] [-s type] [-v vcpus] [-o]\n", name);
 	guest_modes_help();
 	printf(" -u: use userfaultfd to handle vCPU page faults. Mode is a\n"
 	       "     UFFD registration mode: 'MISSING' or 'MINOR'.\n");
@@ -426,7 +426,7 @@ static void help(char *name)
 	printf(" -b: specify the size of the memory region which should be\n"
 	       "     demand paged by each vCPU. e.g. 10M or 3G.\n"
 	       "     Default: 1G\n");
-	printf(" -t: The type of backing memory to use. Default: anonymous\n");
+	printf(" -s: The type of backing memory to use. Default: anonymous\n");
 	backing_src_help();
 	printf(" -v: specify the number of vCPUs to run.\n");
 	printf(" -o: Overlap guest memory accesses instead of partitioning\n"
@@ -446,7 +446,7 @@ int main(int argc, char *argv[])
 
 	guest_modes_append_default();
 
-	while ((opt = getopt(argc, argv, "hm:u:d:b:t:v:o")) != -1) {
+	while ((opt = getopt(argc, argv, "hm:u:d:b:s:v:o")) != -1) {
 		switch (opt) {
 		case 'm':
 			guest_modes_cmdline(optarg);
@@ -465,7 +465,7 @@ int main(int argc, char *argv[])
 		case 'b':
 			guest_percpu_mem_size = parse_size(optarg);
 			break;
-		case 't':
+		case 's':
 			p.src_type = parse_backing_src_type(optarg);
 			break;
 		case 'v':
@@ -485,7 +485,7 @@ int main(int argc, char *argv[])
 
 	if (p.uffd_mode == UFFDIO_REGISTER_MODE_MINOR &&
 	    !backing_src_is_shared(p.src_type)) {
-		TEST_FAIL("userfaultfd MINOR mode requires shared memory; pick a different -t");
+		TEST_FAIL("userfaultfd MINOR mode requires shared memory; pick a different -s");
 	}
 
 	for_each_guest_mode(run_test, &p);
-- 
2.33.0.309.g3052b89438-goog

[PATCH 2/3] KVM: selftests: Refactor help message for -s backing_src

[David Matlack]

All selftests that support the backing_src option were printing their
own description of the flag and then calling backing_src_help() to dump
the list of available backing sources. Consolidate the flag printing in
backing_src_help() to align indentation, reduce duplicated strings, and
improve consistency across tests.

Note: Passing "-s" to backing_src_help is unnecessary since every test
uses the same flag. However I decided to keep it for code readability
at the call sites.

While here this opportunistically fixes the incorrectly interleaved
printing -x help message and list of backing source types in
dirty_log_perf_test.

Fixes: 609e6202ea5f ("KVM: selftests: Support multiple slots in dirty_log_perf_test")
Signed-off-by: David Matlack <dmatlack@google.com>
---
 .../selftests/kvm/access_tracking_perf_test.c   |  6 ++----
 .../testing/selftests/kvm/demand_paging_test.c  |  5 ++---
 .../testing/selftests/kvm/dirty_log_perf_test.c |  8 +++-----
 tools/testing/selftests/kvm/include/test_util.h |  5 ++++-
 .../testing/selftests/kvm/kvm_page_table_test.c |  7 ++-----
 tools/testing/selftests/kvm/lib/test_util.c     | 17 +++++++++++++----
 6 files changed, 26 insertions(+), 22 deletions(-)

diff --git a/tools/testing/selftests/kvm/access_tracking_perf_test.c b/tools/testing/selftests/kvm/access_tracking_perf_test.c
index 71e277c7c3f3..5d95113c7b7c 100644
--- a/tools/testing/selftests/kvm/access_tracking_perf_test.c
+++ b/tools/testing/selftests/kvm/access_tracking_perf_test.c
@@ -371,9 +371,7 @@ static void help(char *name)
 	printf(" -v: specify the number of vCPUs to run.\n");
 	printf(" -o: Overlap guest memory accesses instead of partitioning\n"
 	       "     them into a separate region of memory for each vCPU.\n");
-	printf(" -s: specify the type of memory that should be used to\n"
-	       "     back the guest data region.\n\n");
-	backing_src_help();
+	backing_src_help("-s");
 	puts("");
 	exit(0);
 }
@@ -381,7 +379,7 @@ static void help(char *name)
 int main(int argc, char *argv[])
 {
 	struct test_params params = {
-		.backing_src = VM_MEM_SRC_ANONYMOUS,
+		.backing_src = DEFAULT_VM_MEM_SRC,
 		.vcpu_memory_bytes = DEFAULT_PER_VCPU_MEM_SIZE,
 		.vcpus = 1,
 	};
diff --git a/tools/testing/selftests/kvm/demand_paging_test.c b/tools/testing/selftests/kvm/demand_paging_test.c
index 735c081e774e..96cd3e0357f6 100644
--- a/tools/testing/selftests/kvm/demand_paging_test.c
+++ b/tools/testing/selftests/kvm/demand_paging_test.c
@@ -426,8 +426,7 @@ static void help(char *name)
 	printf(" -b: specify the size of the memory region which should be\n"
 	       "     demand paged by each vCPU. e.g. 10M or 3G.\n"
 	       "     Default: 1G\n");
-	printf(" -s: The type of backing memory to use. Default: anonymous\n");
-	backing_src_help();
+	backing_src_help("-s");
 	printf(" -v: specify the number of vCPUs to run.\n");
 	printf(" -o: Overlap guest memory accesses instead of partitioning\n"
 	       "     them into a separate region of memory for each vCPU.\n");
@@ -439,7 +438,7 @@ int main(int argc, char *argv[])
 {
 	int max_vcpus = kvm_check_cap(KVM_CAP_MAX_VCPUS);
 	struct test_params p = {
-		.src_type = VM_MEM_SRC_ANONYMOUS,
+		.src_type = DEFAULT_VM_MEM_SRC,
 		.partition_vcpu_memory_access = true,
 	};
 	int opt;
diff --git a/tools/testing/selftests/kvm/dirty_log_perf_test.c b/tools/testing/selftests/kvm/dirty_log_perf_test.c
index 3c30d0045d8d..5ad9f2bc7369 100644
--- a/tools/testing/selftests/kvm/dirty_log_perf_test.c
+++ b/tools/testing/selftests/kvm/dirty_log_perf_test.c
@@ -308,11 +308,9 @@ static void help(char *name)
 	printf(" -v: specify the number of vCPUs to run.\n");
 	printf(" -o: Overlap guest memory accesses instead of partitioning\n"
 	       "     them into a separate region of memory for each vCPU.\n");
-	printf(" -s: specify the type of memory that should be used to\n"
-	       "     back the guest data region.\n\n");
+	backing_src_help("-s");
 	printf(" -x: Split the memory region into this number of memslots.\n"
-	       "     (default: 1)");
-	backing_src_help();
+	       "     (default: 1)\n");
 	puts("");
 	exit(0);
 }
@@ -324,7 +322,7 @@ int main(int argc, char *argv[])
 		.iterations = TEST_HOST_LOOP_N,
 		.wr_fract = 1,
 		.partition_vcpu_memory_access = true,
-		.backing_src = VM_MEM_SRC_ANONYMOUS,
+		.backing_src = DEFAULT_VM_MEM_SRC,
 		.slots = 1,
 	};
 	int opt;
diff --git a/tools/testing/selftests/kvm/include/test_util.h b/tools/testing/selftests/kvm/include/test_util.h
index d79be15dd3d2..2f09f2994733 100644
--- a/tools/testing/selftests/kvm/include/test_util.h
+++ b/tools/testing/selftests/kvm/include/test_util.h
@@ -68,6 +68,7 @@ struct timespec timespec_sub(struct timespec ts1, struct timespec ts2);
 struct timespec timespec_elapsed(struct timespec start);
 struct timespec timespec_div(struct timespec ts, int divisor);
 
+
 enum vm_mem_backing_src_type {
 	VM_MEM_SRC_ANONYMOUS,
 	VM_MEM_SRC_ANONYMOUS_THP,
@@ -90,6 +91,8 @@ enum vm_mem_backing_src_type {
 	NUM_SRC_TYPES,
 };
 
+#define DEFAULT_VM_MEM_SRC VM_MEM_SRC_ANONYMOUS
+
 struct vm_mem_backing_src_alias {
 	const char *name;
 	uint32_t flag;
@@ -100,7 +103,7 @@ size_t get_trans_hugepagesz(void);
 size_t get_def_hugetlb_pagesz(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);
+void backing_src_help(const char *flag);
 enum vm_mem_backing_src_type parse_backing_src_type(const char *type_name);
 
 /*
diff --git a/tools/testing/selftests/kvm/kvm_page_table_test.c b/tools/testing/selftests/kvm/kvm_page_table_test.c
index 0d04a7db7f24..36407cb0ec85 100644
--- a/tools/testing/selftests/kvm/kvm_page_table_test.c
+++ b/tools/testing/selftests/kvm/kvm_page_table_test.c
@@ -456,10 +456,7 @@ static void help(char *name)
 	       "     (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();
+	backing_src_help("-s");
 	puts("");
 }
 
@@ -468,7 +465,7 @@ 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,
+		.src_type = DEFAULT_VM_MEM_SRC,
 	};
 	int opt;
 
diff --git a/tools/testing/selftests/kvm/lib/test_util.c b/tools/testing/selftests/kvm/lib/test_util.c
index af1031fed97f..ea23a86132ed 100644
--- a/tools/testing/selftests/kvm/lib/test_util.c
+++ b/tools/testing/selftests/kvm/lib/test_util.c
@@ -279,13 +279,22 @@ size_t get_backing_src_pagesz(uint32_t i)
 	}
 }
 
-void backing_src_help(void)
+void print_available_backing_src_types(const char *prefix)
 {
 	int i;
 
-	printf("Available backing src types:\n");
+	printf("%sAvailable backing src types:\n", prefix);
+
 	for (i = 0; i < NUM_SRC_TYPES; i++)
-		printf("\t%s\n", vm_mem_backing_src_alias(i)->name);
+		printf("%s    %s\n", prefix, vm_mem_backing_src_alias(i)->name);
+}
+
+void backing_src_help(const char *flag)
+{
+	printf(" %s: specify the type of memory that should be used to\n"
+	       "     back the guest data region. (default: %s)\n",
+	       flag, vm_mem_backing_src_alias(DEFAULT_VM_MEM_SRC)->name);
+	print_available_backing_src_types("     ");
 }
 
 enum vm_mem_backing_src_type parse_backing_src_type(const char *type_name)
@@ -296,7 +305,7 @@ enum vm_mem_backing_src_type parse_backing_src_type(const char *type_name)
 		if (!strcmp(type_name, vm_mem_backing_src_alias(i)->name))
 			return i;
 
-	backing_src_help();
+	print_available_backing_src_types("");
 	TEST_FAIL("Unknown backing src type: %s", type_name);
 	return -1;
 }
-- 
2.33.0.309.g3052b89438-goog

[PATCH 3/3] KVM: selftests: Fix dirty bitmap offset calculation

[David Matlack]

The calculation to get the per-slot dirty bitmap was incorrect leading
to a buffer overrun. Fix it by dividing the number of pages by
BITS_PER_LONG, since each element of the bitmap is a long and there is
one bit per page.

Fixes: 609e6202ea5f ("KVM: selftests: Support multiple slots in dirty_log_perf_test")
Signed-off-by: David Matlack <dmatlack@google.com>
---
 tools/testing/selftests/kvm/dirty_log_perf_test.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/kvm/dirty_log_perf_test.c b/tools/testing/selftests/kvm/dirty_log_perf_test.c
index 5ad9f2bc7369..0dd4626571e9 100644
--- a/tools/testing/selftests/kvm/dirty_log_perf_test.c
+++ b/tools/testing/selftests/kvm/dirty_log_perf_test.c
@@ -118,6 +118,12 @@ static inline void disable_dirty_logging(struct kvm_vm *vm, int slots)
 	toggle_dirty_logging(vm, slots, false);
 }
 
+static unsigned long *get_slot_bitmap(unsigned long *bitmap, uint64_t page_offset)
+{
+	/* Guaranteed to be evenly divisible by the TEST_ASSERT in run_test. */
+	return &bitmap[page_offset / BITS_PER_LONG];
+}
+
 static void get_dirty_log(struct kvm_vm *vm, int slots, unsigned long *bitmap,
 			  uint64_t nr_pages)
 {
@@ -126,7 +132,8 @@ static void get_dirty_log(struct kvm_vm *vm, int slots, unsigned long *bitmap,
 
 	for (i = 0; i < slots; i++) {
 		int slot = PERF_TEST_MEM_SLOT_INDEX + i;
-		unsigned long *slot_bitmap = bitmap + i * slot_pages;
+		uint64_t page_offset = slot_pages * i;
+		unsigned long *slot_bitmap = get_slot_bitmap(bitmap, page_offset);
 
 		kvm_vm_get_dirty_log(vm, slot, slot_bitmap);
 	}
@@ -140,7 +147,8 @@ static void clear_dirty_log(struct kvm_vm *vm, int slots, unsigned long *bitmap,
 
 	for (i = 0; i < slots; i++) {
 		int slot = PERF_TEST_MEM_SLOT_INDEX + i;
-		unsigned long *slot_bitmap = bitmap + i * slot_pages;
+		uint64_t page_offset = slot_pages * i;
+		unsigned long *slot_bitmap = get_slot_bitmap(bitmap, page_offset);
 
 		kvm_vm_clear_dirty_log(vm, slot, slot_bitmap, 0, slot_pages);
 	}
@@ -172,6 +180,9 @@ static void run_test(enum vm_guest_mode mode, void *arg)
 	guest_num_pages = vm_adjust_num_guest_pages(mode, guest_num_pages);
 	host_num_pages = vm_num_host_pages(mode, guest_num_pages);
 	bmap = bitmap_alloc(host_num_pages);
+	TEST_ASSERT((host_num_pages / p->slots) % BITS_PER_LONG == 0,
+		    "The number of pages per slot must be divisible by %d.",
+		    BITS_PER_LONG);
 
 	if (dirty_log_manual_caps) {
 		cap.cap = KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2;
-- 
2.33.0.309.g3052b89438-goog

Re: [PATCH 3/3] KVM: selftests: Fix dirty bitmap offset calculation

[Ben Gardon]

On Wed, Sep 15, 2021 at 2:30 PM David Matlack <dmatlack@google.com> wrote:
>
> The calculation to get the per-slot dirty bitmap was incorrect leading
> to a buffer overrun. Fix it by dividing the number of pages by
> BITS_PER_LONG, since each element of the bitmap is a long and there is
> one bit per page.
>
> Fixes: 609e6202ea5f ("KVM: selftests: Support multiple slots in dirty_log_perf_test")
> Signed-off-by: David Matlack <dmatlack@google.com>

I was a little confused initially because we're allocating only one
dirty bitmap in userspace even when we have multiple slots, but that's
not a problem.

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


>
> ---
>  tools/testing/selftests/kvm/dirty_log_perf_test.c | 15 +++++++++++++--
>  1 file changed, 13 insertions(+), 2 deletions(-)
>
> diff --git a/tools/testing/selftests/kvm/dirty_log_perf_test.c b/tools/testing/selftests/kvm/dirty_log_perf_test.c
> index 5ad9f2bc7369..0dd4626571e9 100644
> --- a/tools/testing/selftests/kvm/dirty_log_perf_test.c
> +++ b/tools/testing/selftests/kvm/dirty_log_perf_test.c
> @@ -118,6 +118,12 @@ static inline void disable_dirty_logging(struct kvm_vm *vm, int slots)
>         toggle_dirty_logging(vm, slots, false);
>  }
>
> +static unsigned long *get_slot_bitmap(unsigned long *bitmap, uint64_t page_offset)
> +{
> +       /* Guaranteed to be evenly divisible by the TEST_ASSERT in run_test. */
> +       return &bitmap[page_offset / BITS_PER_LONG];
> +}
> +
>  static void get_dirty_log(struct kvm_vm *vm, int slots, unsigned long *bitmap,
>                           uint64_t nr_pages)
>  {
> @@ -126,7 +132,8 @@ static void get_dirty_log(struct kvm_vm *vm, int slots, unsigned long *bitmap,
>
>         for (i = 0; i < slots; i++) {
>                 int slot = PERF_TEST_MEM_SLOT_INDEX + i;
> -               unsigned long *slot_bitmap = bitmap + i * slot_pages;
> +               uint64_t page_offset = slot_pages * i;
> +               unsigned long *slot_bitmap = get_slot_bitmap(bitmap, page_offset);
>
>                 kvm_vm_get_dirty_log(vm, slot, slot_bitmap);
>         }
> @@ -140,7 +147,8 @@ static void clear_dirty_log(struct kvm_vm *vm, int slots, unsigned long *bitmap,
>
>         for (i = 0; i < slots; i++) {
>                 int slot = PERF_TEST_MEM_SLOT_INDEX + i;
> -               unsigned long *slot_bitmap = bitmap + i * slot_pages;
> +               uint64_t page_offset = slot_pages * i;
> +               unsigned long *slot_bitmap = get_slot_bitmap(bitmap, page_offset);
>
>                 kvm_vm_clear_dirty_log(vm, slot, slot_bitmap, 0, slot_pages);
>         }
> @@ -172,6 +180,9 @@ static void run_test(enum vm_guest_mode mode, void *arg)
>         guest_num_pages = vm_adjust_num_guest_pages(mode, guest_num_pages);
>         host_num_pages = vm_num_host_pages(mode, guest_num_pages);
>         bmap = bitmap_alloc(host_num_pages);
> +       TEST_ASSERT((host_num_pages / p->slots) % BITS_PER_LONG == 0,
> +                   "The number of pages per slot must be divisible by %d.",
> +                   BITS_PER_LONG);
>
>         if (dirty_log_manual_caps) {
>                 cap.cap = KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2;
> --
> 2.33.0.309.g3052b89438-goog
>

Re: [PATCH 2/3] KVM: selftests: Refactor help message for -s backing_src

[Ben Gardon]

On Wed, Sep 15, 2021 at 2:30 PM David Matlack <dmatlack@google.com> wrote:
>
> All selftests that support the backing_src option were printing their
> own description of the flag and then calling backing_src_help() to dump
> the list of available backing sources. Consolidate the flag printing in
> backing_src_help() to align indentation, reduce duplicated strings, and
> improve consistency across tests.
>
> Note: Passing "-s" to backing_src_help is unnecessary since every test
> uses the same flag. However I decided to keep it for code readability
> at the call sites.
>
> While here this opportunistically fixes the incorrectly interleaved
> printing -x help message and list of backing source types in
> dirty_log_perf_test.
>
> Fixes: 609e6202ea5f ("KVM: selftests: Support multiple slots in dirty_log_perf_test")
> Signed-off-by: David Matlack <dmatlack@google.com>

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

> ---
>  .../selftests/kvm/access_tracking_perf_test.c   |  6 ++----
>  .../testing/selftests/kvm/demand_paging_test.c  |  5 ++---
>  .../testing/selftests/kvm/dirty_log_perf_test.c |  8 +++-----
>  tools/testing/selftests/kvm/include/test_util.h |  5 ++++-
>  .../testing/selftests/kvm/kvm_page_table_test.c |  7 ++-----
>  tools/testing/selftests/kvm/lib/test_util.c     | 17 +++++++++++++----
>  6 files changed, 26 insertions(+), 22 deletions(-)
>
> diff --git a/tools/testing/selftests/kvm/access_tracking_perf_test.c b/tools/testing/selftests/kvm/access_tracking_perf_test.c
> index 71e277c7c3f3..5d95113c7b7c 100644
> --- a/tools/testing/selftests/kvm/access_tracking_perf_test.c
> +++ b/tools/testing/selftests/kvm/access_tracking_perf_test.c
> @@ -371,9 +371,7 @@ static void help(char *name)
>         printf(" -v: specify the number of vCPUs to run.\n");
>         printf(" -o: Overlap guest memory accesses instead of partitioning\n"
>                "     them into a separate region of memory for each vCPU.\n");
> -       printf(" -s: specify the type of memory that should be used to\n"
> -              "     back the guest data region.\n\n");
> -       backing_src_help();
> +       backing_src_help("-s");
>         puts("");
>         exit(0);
>  }
> @@ -381,7 +379,7 @@ static void help(char *name)
>  int main(int argc, char *argv[])
>  {
>         struct test_params params = {
> -               .backing_src = VM_MEM_SRC_ANONYMOUS,
> +               .backing_src = DEFAULT_VM_MEM_SRC,
>                 .vcpu_memory_bytes = DEFAULT_PER_VCPU_MEM_SIZE,
>                 .vcpus = 1,
>         };
> diff --git a/tools/testing/selftests/kvm/demand_paging_test.c b/tools/testing/selftests/kvm/demand_paging_test.c
> index 735c081e774e..96cd3e0357f6 100644
> --- a/tools/testing/selftests/kvm/demand_paging_test.c
> +++ b/tools/testing/selftests/kvm/demand_paging_test.c
> @@ -426,8 +426,7 @@ static void help(char *name)
>         printf(" -b: specify the size of the memory region which should be\n"
>                "     demand paged by each vCPU. e.g. 10M or 3G.\n"
>                "     Default: 1G\n");
> -       printf(" -s: The type of backing memory to use. Default: anonymous\n");
> -       backing_src_help();
> +       backing_src_help("-s");
>         printf(" -v: specify the number of vCPUs to run.\n");
>         printf(" -o: Overlap guest memory accesses instead of partitioning\n"
>                "     them into a separate region of memory for each vCPU.\n");
> @@ -439,7 +438,7 @@ int main(int argc, char *argv[])
>  {
>         int max_vcpus = kvm_check_cap(KVM_CAP_MAX_VCPUS);
>         struct test_params p = {
> -               .src_type = VM_MEM_SRC_ANONYMOUS,
> +               .src_type = DEFAULT_VM_MEM_SRC,
>                 .partition_vcpu_memory_access = true,
>         };
>         int opt;
> diff --git a/tools/testing/selftests/kvm/dirty_log_perf_test.c b/tools/testing/selftests/kvm/dirty_log_perf_test.c
> index 3c30d0045d8d..5ad9f2bc7369 100644
> --- a/tools/testing/selftests/kvm/dirty_log_perf_test.c
> +++ b/tools/testing/selftests/kvm/dirty_log_perf_test.c
> @@ -308,11 +308,9 @@ static void help(char *name)
>         printf(" -v: specify the number of vCPUs to run.\n");
>         printf(" -o: Overlap guest memory accesses instead of partitioning\n"
>                "     them into a separate region of memory for each vCPU.\n");
> -       printf(" -s: specify the type of memory that should be used to\n"
> -              "     back the guest data region.\n\n");
> +       backing_src_help("-s");
>         printf(" -x: Split the memory region into this number of memslots.\n"
> -              "     (default: 1)");
> -       backing_src_help();
> +              "     (default: 1)\n");
>         puts("");
>         exit(0);
>  }
> @@ -324,7 +322,7 @@ int main(int argc, char *argv[])
>                 .iterations = TEST_HOST_LOOP_N,
>                 .wr_fract = 1,
>                 .partition_vcpu_memory_access = true,
> -               .backing_src = VM_MEM_SRC_ANONYMOUS,
> +               .backing_src = DEFAULT_VM_MEM_SRC,
>                 .slots = 1,
>         };
>         int opt;
> diff --git a/tools/testing/selftests/kvm/include/test_util.h b/tools/testing/selftests/kvm/include/test_util.h
> index d79be15dd3d2..2f09f2994733 100644
> --- a/tools/testing/selftests/kvm/include/test_util.h
> +++ b/tools/testing/selftests/kvm/include/test_util.h
> @@ -68,6 +68,7 @@ struct timespec timespec_sub(struct timespec ts1, struct timespec ts2);
>  struct timespec timespec_elapsed(struct timespec start);
>  struct timespec timespec_div(struct timespec ts, int divisor);
>
> +
>  enum vm_mem_backing_src_type {
>         VM_MEM_SRC_ANONYMOUS,
>         VM_MEM_SRC_ANONYMOUS_THP,
> @@ -90,6 +91,8 @@ enum vm_mem_backing_src_type {
>         NUM_SRC_TYPES,
>  };
>
> +#define DEFAULT_VM_MEM_SRC VM_MEM_SRC_ANONYMOUS
> +
>  struct vm_mem_backing_src_alias {
>         const char *name;
>         uint32_t flag;
> @@ -100,7 +103,7 @@ size_t get_trans_hugepagesz(void);
>  size_t get_def_hugetlb_pagesz(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);
> +void backing_src_help(const char *flag);
>  enum vm_mem_backing_src_type parse_backing_src_type(const char *type_name);
>
>  /*
> diff --git a/tools/testing/selftests/kvm/kvm_page_table_test.c b/tools/testing/selftests/kvm/kvm_page_table_test.c
> index 0d04a7db7f24..36407cb0ec85 100644
> --- a/tools/testing/selftests/kvm/kvm_page_table_test.c
> +++ b/tools/testing/selftests/kvm/kvm_page_table_test.c
> @@ -456,10 +456,7 @@ static void help(char *name)
>                "     (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();
> +       backing_src_help("-s");
>         puts("");
>  }
>
> @@ -468,7 +465,7 @@ 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,
> +               .src_type = DEFAULT_VM_MEM_SRC,
>         };
>         int opt;
>
> diff --git a/tools/testing/selftests/kvm/lib/test_util.c b/tools/testing/selftests/kvm/lib/test_util.c
> index af1031fed97f..ea23a86132ed 100644
> --- a/tools/testing/selftests/kvm/lib/test_util.c
> +++ b/tools/testing/selftests/kvm/lib/test_util.c
> @@ -279,13 +279,22 @@ size_t get_backing_src_pagesz(uint32_t i)
>         }
>  }
>
> -void backing_src_help(void)
> +void print_available_backing_src_types(const char *prefix)
>  {
>         int i;
>
> -       printf("Available backing src types:\n");
> +       printf("%sAvailable backing src types:\n", prefix);
> +
>         for (i = 0; i < NUM_SRC_TYPES; i++)
> -               printf("\t%s\n", vm_mem_backing_src_alias(i)->name);
> +               printf("%s    %s\n", prefix, vm_mem_backing_src_alias(i)->name);
> +}
> +
> +void backing_src_help(const char *flag)
> +{
> +       printf(" %s: specify the type of memory that should be used to\n"
> +              "     back the guest data region. (default: %s)\n",
> +              flag, vm_mem_backing_src_alias(DEFAULT_VM_MEM_SRC)->name);
> +       print_available_backing_src_types("     ");
>  }
>
>  enum vm_mem_backing_src_type parse_backing_src_type(const char *type_name)
> @@ -296,7 +305,7 @@ enum vm_mem_backing_src_type parse_backing_src_type(const char *type_name)
>                 if (!strcmp(type_name, vm_mem_backing_src_alias(i)->name))
>                         return i;
>
> -       backing_src_help();
> +       print_available_backing_src_types("");
>         TEST_FAIL("Unknown backing src type: %s", type_name);
>         return -1;
>  }
> --
> 2.33.0.309.g3052b89438-goog
>

Re: [PATCH 1/3] KVM: selftests: Change backing_src flag to -s in demand_paging_test

[Ben Gardon]

On Wed, Sep 15, 2021 at 2:30 PM David Matlack <dmatlack@google.com> wrote:
>
> Every other KVM selftest uses -s for the backing_src, so switch
> demand_paging_test to match.
>
> Signed-off-by: David Matlack <dmatlack@google.com>

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

> ---
>  tools/testing/selftests/kvm/demand_paging_test.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/tools/testing/selftests/kvm/demand_paging_test.c b/tools/testing/selftests/kvm/demand_paging_test.c
> index e79c1b64977f..735c081e774e 100644
> --- a/tools/testing/selftests/kvm/demand_paging_test.c
> +++ b/tools/testing/selftests/kvm/demand_paging_test.c
> @@ -416,7 +416,7 @@ static void help(char *name)
>  {
>         puts("");
>         printf("usage: %s [-h] [-m vm_mode] [-u uffd_mode] [-d uffd_delay_usec]\n"
> -              "          [-b memory] [-t type] [-v vcpus] [-o]\n", name);
> +              "          [-b memory] [-s type] [-v vcpus] [-o]\n", name);
>         guest_modes_help();
>         printf(" -u: use userfaultfd to handle vCPU page faults. Mode is a\n"
>                "     UFFD registration mode: 'MISSING' or 'MINOR'.\n");
> @@ -426,7 +426,7 @@ static void help(char *name)
>         printf(" -b: specify the size of the memory region which should be\n"
>                "     demand paged by each vCPU. e.g. 10M or 3G.\n"
>                "     Default: 1G\n");
> -       printf(" -t: The type of backing memory to use. Default: anonymous\n");
> +       printf(" -s: The type of backing memory to use. Default: anonymous\n");
>         backing_src_help();
>         printf(" -v: specify the number of vCPUs to run.\n");
>         printf(" -o: Overlap guest memory accesses instead of partitioning\n"
> @@ -446,7 +446,7 @@ int main(int argc, char *argv[])
>
>         guest_modes_append_default();
>
> -       while ((opt = getopt(argc, argv, "hm:u:d:b:t:v:o")) != -1) {
> +       while ((opt = getopt(argc, argv, "hm:u:d:b:s:v:o")) != -1) {
>                 switch (opt) {
>                 case 'm':
>                         guest_modes_cmdline(optarg);
> @@ -465,7 +465,7 @@ int main(int argc, char *argv[])
>                 case 'b':
>                         guest_percpu_mem_size = parse_size(optarg);
>                         break;
> -               case 't':
> +               case 's':
>                         p.src_type = parse_backing_src_type(optarg);
>                         break;
>                 case 'v':
> @@ -485,7 +485,7 @@ int main(int argc, char *argv[])
>
>         if (p.uffd_mode == UFFDIO_REGISTER_MODE_MINOR &&
>             !backing_src_is_shared(p.src_type)) {
> -               TEST_FAIL("userfaultfd MINOR mode requires shared memory; pick a different -t");
> +               TEST_FAIL("userfaultfd MINOR mode requires shared memory; pick a different -s");
>         }
>
>         for_each_guest_mode(run_test, &p);
> --
> 2.33.0.309.g3052b89438-goog
>

Re: [PATCH 1/3] KVM: selftests: Change backing_src flag to -s in demand_paging_test

[Andrew Jones]

On Wed, Sep 15, 2021 at 09:30:32PM +0000, David Matlack wrote:
> Every other KVM selftest uses -s for the backing_src, so switch
> demand_paging_test to match.
> 
> Signed-off-by: David Matlack <dmatlack@google.com>
> ---
>  tools/testing/selftests/kvm/demand_paging_test.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
>

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

Re: [PATCH 2/3] KVM: selftests: Refactor help message for -s backing_src

[Andrew Jones]

On Wed, Sep 15, 2021 at 09:30:33PM +0000, David Matlack wrote:
> All selftests that support the backing_src option were printing their
> own description of the flag and then calling backing_src_help() to dump
> the list of available backing sources. Consolidate the flag printing in
> backing_src_help() to align indentation, reduce duplicated strings, and
> improve consistency across tests.
> 
> Note: Passing "-s" to backing_src_help is unnecessary since every test
> uses the same flag. However I decided to keep it for code readability
> at the call sites.

I think I'd prefer not passing "-s", but I won't insist.

> 
> While here this opportunistically fixes the incorrectly interleaved
> printing -x help message and list of backing source types in
> dirty_log_perf_test.
> 
> Fixes: 609e6202ea5f ("KVM: selftests: Support multiple slots in dirty_log_perf_test")
> Signed-off-by: David Matlack <dmatlack@google.com>
> ---
>  .../selftests/kvm/access_tracking_perf_test.c   |  6 ++----
>  .../testing/selftests/kvm/demand_paging_test.c  |  5 ++---
>  .../testing/selftests/kvm/dirty_log_perf_test.c |  8 +++-----
>  tools/testing/selftests/kvm/include/test_util.h |  5 ++++-
>  .../testing/selftests/kvm/kvm_page_table_test.c |  7 ++-----
>  tools/testing/selftests/kvm/lib/test_util.c     | 17 +++++++++++++----
>  6 files changed, 26 insertions(+), 22 deletions(-)
> 
> diff --git a/tools/testing/selftests/kvm/access_tracking_perf_test.c b/tools/testing/selftests/kvm/access_tracking_perf_test.c
> index 71e277c7c3f3..5d95113c7b7c 100644
> --- a/tools/testing/selftests/kvm/access_tracking_perf_test.c
> +++ b/tools/testing/selftests/kvm/access_tracking_perf_test.c
> @@ -371,9 +371,7 @@ static void help(char *name)
>  	printf(" -v: specify the number of vCPUs to run.\n");
>  	printf(" -o: Overlap guest memory accesses instead of partitioning\n"
>  	       "     them into a separate region of memory for each vCPU.\n");
> -	printf(" -s: specify the type of memory that should be used to\n"
> -	       "     back the guest data region.\n\n");
> -	backing_src_help();
> +	backing_src_help("-s");
>  	puts("");
>  	exit(0);
>  }
> @@ -381,7 +379,7 @@ static void help(char *name)
>  int main(int argc, char *argv[])
>  {
>  	struct test_params params = {
> -		.backing_src = VM_MEM_SRC_ANONYMOUS,
> +		.backing_src = DEFAULT_VM_MEM_SRC,
>  		.vcpu_memory_bytes = DEFAULT_PER_VCPU_MEM_SIZE,
>  		.vcpus = 1,
>  	};
> diff --git a/tools/testing/selftests/kvm/demand_paging_test.c b/tools/testing/selftests/kvm/demand_paging_test.c
> index 735c081e774e..96cd3e0357f6 100644
> --- a/tools/testing/selftests/kvm/demand_paging_test.c
> +++ b/tools/testing/selftests/kvm/demand_paging_test.c
> @@ -426,8 +426,7 @@ static void help(char *name)
>  	printf(" -b: specify the size of the memory region which should be\n"
>  	       "     demand paged by each vCPU. e.g. 10M or 3G.\n"
>  	       "     Default: 1G\n");
> -	printf(" -s: The type of backing memory to use. Default: anonymous\n");
> -	backing_src_help();
> +	backing_src_help("-s");
>  	printf(" -v: specify the number of vCPUs to run.\n");
>  	printf(" -o: Overlap guest memory accesses instead of partitioning\n"
>  	       "     them into a separate region of memory for each vCPU.\n");
> @@ -439,7 +438,7 @@ int main(int argc, char *argv[])
>  {
>  	int max_vcpus = kvm_check_cap(KVM_CAP_MAX_VCPUS);
>  	struct test_params p = {
> -		.src_type = VM_MEM_SRC_ANONYMOUS,
> +		.src_type = DEFAULT_VM_MEM_SRC,
>  		.partition_vcpu_memory_access = true,
>  	};
>  	int opt;
> diff --git a/tools/testing/selftests/kvm/dirty_log_perf_test.c b/tools/testing/selftests/kvm/dirty_log_perf_test.c
> index 3c30d0045d8d..5ad9f2bc7369 100644
> --- a/tools/testing/selftests/kvm/dirty_log_perf_test.c
> +++ b/tools/testing/selftests/kvm/dirty_log_perf_test.c
> @@ -308,11 +308,9 @@ static void help(char *name)
>  	printf(" -v: specify the number of vCPUs to run.\n");
>  	printf(" -o: Overlap guest memory accesses instead of partitioning\n"
>  	       "     them into a separate region of memory for each vCPU.\n");
> -	printf(" -s: specify the type of memory that should be used to\n"
> -	       "     back the guest data region.\n\n");
> +	backing_src_help("-s");
>  	printf(" -x: Split the memory region into this number of memslots.\n"
> -	       "     (default: 1)");
> -	backing_src_help();
> +	       "     (default: 1)\n");
>  	puts("");
>  	exit(0);
>  }
> @@ -324,7 +322,7 @@ int main(int argc, char *argv[])
>  		.iterations = TEST_HOST_LOOP_N,
>  		.wr_fract = 1,
>  		.partition_vcpu_memory_access = true,
> -		.backing_src = VM_MEM_SRC_ANONYMOUS,
> +		.backing_src = DEFAULT_VM_MEM_SRC,
>  		.slots = 1,
>  	};
>  	int opt;
> diff --git a/tools/testing/selftests/kvm/include/test_util.h b/tools/testing/selftests/kvm/include/test_util.h
> index d79be15dd3d2..2f09f2994733 100644
> --- a/tools/testing/selftests/kvm/include/test_util.h
> +++ b/tools/testing/selftests/kvm/include/test_util.h
> @@ -68,6 +68,7 @@ struct timespec timespec_sub(struct timespec ts1, struct timespec ts2);
>  struct timespec timespec_elapsed(struct timespec start);
>  struct timespec timespec_div(struct timespec ts, int divisor);
>  
> +

New extra blank line. Added on purpose?

>  enum vm_mem_backing_src_type {
>  	VM_MEM_SRC_ANONYMOUS,
>  	VM_MEM_SRC_ANONYMOUS_THP,
> @@ -90,6 +91,8 @@ enum vm_mem_backing_src_type {
>  	NUM_SRC_TYPES,
>  };
>  
> +#define DEFAULT_VM_MEM_SRC VM_MEM_SRC_ANONYMOUS
> +
>  struct vm_mem_backing_src_alias {
>  	const char *name;
>  	uint32_t flag;
> @@ -100,7 +103,7 @@ size_t get_trans_hugepagesz(void);
>  size_t get_def_hugetlb_pagesz(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);
> +void backing_src_help(const char *flag);
>  enum vm_mem_backing_src_type parse_backing_src_type(const char *type_name);
>  
>  /*
> diff --git a/tools/testing/selftests/kvm/kvm_page_table_test.c b/tools/testing/selftests/kvm/kvm_page_table_test.c
> index 0d04a7db7f24..36407cb0ec85 100644
> --- a/tools/testing/selftests/kvm/kvm_page_table_test.c
> +++ b/tools/testing/selftests/kvm/kvm_page_table_test.c
> @@ -456,10 +456,7 @@ static void help(char *name)
>  	       "     (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();
> +	backing_src_help("-s");
>  	puts("");
>  }
>  
> @@ -468,7 +465,7 @@ 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,
> +		.src_type = DEFAULT_VM_MEM_SRC,
>  	};
>  	int opt;
>  
> diff --git a/tools/testing/selftests/kvm/lib/test_util.c b/tools/testing/selftests/kvm/lib/test_util.c
> index af1031fed97f..ea23a86132ed 100644
> --- a/tools/testing/selftests/kvm/lib/test_util.c
> +++ b/tools/testing/selftests/kvm/lib/test_util.c
> @@ -279,13 +279,22 @@ size_t get_backing_src_pagesz(uint32_t i)
>  	}
>  }
>  
> -void backing_src_help(void)
> +void print_available_backing_src_types(const char *prefix)

This can probably be static.

>  {
>  	int i;
>  
> -	printf("Available backing src types:\n");
> +	printf("%sAvailable backing src types:\n", prefix);
> +
>  	for (i = 0; i < NUM_SRC_TYPES; i++)
> -		printf("\t%s\n", vm_mem_backing_src_alias(i)->name);
> +		printf("%s    %s\n", prefix, vm_mem_backing_src_alias(i)->name);
> +}
> +
> +void backing_src_help(const char *flag)
> +{
> +	printf(" %s: specify the type of memory that should be used to\n"
> +	       "     back the guest data region. (default: %s)\n",
> +	       flag, vm_mem_backing_src_alias(DEFAULT_VM_MEM_SRC)->name);
> +	print_available_backing_src_types("     ");
>  }
>  
>  enum vm_mem_backing_src_type parse_backing_src_type(const char *type_name)
> @@ -296,7 +305,7 @@ enum vm_mem_backing_src_type parse_backing_src_type(const char *type_name)
>  		if (!strcmp(type_name, vm_mem_backing_src_alias(i)->name))
>  			return i;
>  
> -	backing_src_help();
> +	print_available_backing_src_types("");
>  	TEST_FAIL("Unknown backing src type: %s", type_name);
>  	return -1;
>  }
> -- 
> 2.33.0.309.g3052b89438-goog
>


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

Thanks,
drew

Re: [PATCH 3/3] KVM: selftests: Fix dirty bitmap offset calculation

[Andrew Jones]

On Wed, Sep 15, 2021 at 02:55:03PM -0700, Ben Gardon wrote:
> On Wed, Sep 15, 2021 at 2:30 PM David Matlack <dmatlack@google.com> wrote:
> >
> > The calculation to get the per-slot dirty bitmap was incorrect leading
> > to a buffer overrun. Fix it by dividing the number of pages by
> > BITS_PER_LONG, since each element of the bitmap is a long and there is
> > one bit per page.
> >
> > Fixes: 609e6202ea5f ("KVM: selftests: Support multiple slots in dirty_log_perf_test")
> > Signed-off-by: David Matlack <dmatlack@google.com>
> 
> I was a little confused initially because we're allocating only one
> dirty bitmap in userspace even when we have multiple slots, but that's
> not a problem.

It's also confusing to me. Wouldn't it be better to create a bitmap per
slot? I think the new constraint that host mem must be a multiple of 64
is unfortunate.

Thanks,
drew

Re: [PATCH 2/3] KVM: selftests: Refactor help message for -s backing_src

[David Matlack]

On Thu, Sep 16, 2021 at 1:41 AM Andrew Jones <drjones@redhat.com> wrote:
>
> On Wed, Sep 15, 2021 at 09:30:33PM +0000, David Matlack wrote:
> > All selftests that support the backing_src option were printing their
> > own description of the flag and then calling backing_src_help() to dump
> > the list of available backing sources. Consolidate the flag printing in
> > backing_src_help() to align indentation, reduce duplicated strings, and
> > improve consistency across tests.
> >
> > Note: Passing "-s" to backing_src_help is unnecessary since every test
> > uses the same flag. However I decided to keep it for code readability
> > at the call sites.
>
> I think I'd prefer not passing "-s", but I won't insist.
>
> >
> > While here this opportunistically fixes the incorrectly interleaved
> > printing -x help message and list of backing source types in
> > dirty_log_perf_test.
> >
> > Fixes: 609e6202ea5f ("KVM: selftests: Support multiple slots in dirty_log_perf_test")
> > Signed-off-by: David Matlack <dmatlack@google.com>
> > ---
> >  .../selftests/kvm/access_tracking_perf_test.c   |  6 ++----
> >  .../testing/selftests/kvm/demand_paging_test.c  |  5 ++---
> >  .../testing/selftests/kvm/dirty_log_perf_test.c |  8 +++-----
> >  tools/testing/selftests/kvm/include/test_util.h |  5 ++++-
> >  .../testing/selftests/kvm/kvm_page_table_test.c |  7 ++-----
> >  tools/testing/selftests/kvm/lib/test_util.c     | 17 +++++++++++++----
> >  6 files changed, 26 insertions(+), 22 deletions(-)
> >
> > diff --git a/tools/testing/selftests/kvm/access_tracking_perf_test.c b/tools/testing/selftests/kvm/access_tracking_perf_test.c
> > index 71e277c7c3f3..5d95113c7b7c 100644
> > --- a/tools/testing/selftests/kvm/access_tracking_perf_test.c
> > +++ b/tools/testing/selftests/kvm/access_tracking_perf_test.c
> > @@ -371,9 +371,7 @@ static void help(char *name)
> >       printf(" -v: specify the number of vCPUs to run.\n");
> >       printf(" -o: Overlap guest memory accesses instead of partitioning\n"
> >              "     them into a separate region of memory for each vCPU.\n");
> > -     printf(" -s: specify the type of memory that should be used to\n"
> > -            "     back the guest data region.\n\n");
> > -     backing_src_help();
> > +     backing_src_help("-s");
> >       puts("");
> >       exit(0);
> >  }
> > @@ -381,7 +379,7 @@ static void help(char *name)
> >  int main(int argc, char *argv[])
> >  {
> >       struct test_params params = {
> > -             .backing_src = VM_MEM_SRC_ANONYMOUS,
> > +             .backing_src = DEFAULT_VM_MEM_SRC,
> >               .vcpu_memory_bytes = DEFAULT_PER_VCPU_MEM_SIZE,
> >               .vcpus = 1,
> >       };
> > diff --git a/tools/testing/selftests/kvm/demand_paging_test.c b/tools/testing/selftests/kvm/demand_paging_test.c
> > index 735c081e774e..96cd3e0357f6 100644
> > --- a/tools/testing/selftests/kvm/demand_paging_test.c
> > +++ b/tools/testing/selftests/kvm/demand_paging_test.c
> > @@ -426,8 +426,7 @@ static void help(char *name)
> >       printf(" -b: specify the size of the memory region which should be\n"
> >              "     demand paged by each vCPU. e.g. 10M or 3G.\n"
> >              "     Default: 1G\n");
> > -     printf(" -s: The type of backing memory to use. Default: anonymous\n");
> > -     backing_src_help();
> > +     backing_src_help("-s");
> >       printf(" -v: specify the number of vCPUs to run.\n");
> >       printf(" -o: Overlap guest memory accesses instead of partitioning\n"
> >              "     them into a separate region of memory for each vCPU.\n");
> > @@ -439,7 +438,7 @@ int main(int argc, char *argv[])
> >  {
> >       int max_vcpus = kvm_check_cap(KVM_CAP_MAX_VCPUS);
> >       struct test_params p = {
> > -             .src_type = VM_MEM_SRC_ANONYMOUS,
> > +             .src_type = DEFAULT_VM_MEM_SRC,
> >               .partition_vcpu_memory_access = true,
> >       };
> >       int opt;
> > diff --git a/tools/testing/selftests/kvm/dirty_log_perf_test.c b/tools/testing/selftests/kvm/dirty_log_perf_test.c
> > index 3c30d0045d8d..5ad9f2bc7369 100644
> > --- a/tools/testing/selftests/kvm/dirty_log_perf_test.c
> > +++ b/tools/testing/selftests/kvm/dirty_log_perf_test.c
> > @@ -308,11 +308,9 @@ static void help(char *name)
> >       printf(" -v: specify the number of vCPUs to run.\n");
> >       printf(" -o: Overlap guest memory accesses instead of partitioning\n"
> >              "     them into a separate region of memory for each vCPU.\n");
> > -     printf(" -s: specify the type of memory that should be used to\n"
> > -            "     back the guest data region.\n\n");
> > +     backing_src_help("-s");
> >       printf(" -x: Split the memory region into this number of memslots.\n"
> > -            "     (default: 1)");
> > -     backing_src_help();
> > +            "     (default: 1)\n");
> >       puts("");
> >       exit(0);
> >  }
> > @@ -324,7 +322,7 @@ int main(int argc, char *argv[])
> >               .iterations = TEST_HOST_LOOP_N,
> >               .wr_fract = 1,
> >               .partition_vcpu_memory_access = true,
> > -             .backing_src = VM_MEM_SRC_ANONYMOUS,
> > +             .backing_src = DEFAULT_VM_MEM_SRC,
> >               .slots = 1,
> >       };
> >       int opt;
> > diff --git a/tools/testing/selftests/kvm/include/test_util.h b/tools/testing/selftests/kvm/include/test_util.h
> > index d79be15dd3d2..2f09f2994733 100644
> > --- a/tools/testing/selftests/kvm/include/test_util.h
> > +++ b/tools/testing/selftests/kvm/include/test_util.h
> > @@ -68,6 +68,7 @@ struct timespec timespec_sub(struct timespec ts1, struct timespec ts2);
> >  struct timespec timespec_elapsed(struct timespec start);
> >  struct timespec timespec_div(struct timespec ts, int divisor);
> >
> > +
>
> New extra blank line. Added on purpose?

No that's a mistake. Will fix in v2.

>
> >  enum vm_mem_backing_src_type {
> >       VM_MEM_SRC_ANONYMOUS,
> >       VM_MEM_SRC_ANONYMOUS_THP,
> > @@ -90,6 +91,8 @@ enum vm_mem_backing_src_type {
> >       NUM_SRC_TYPES,
> >  };
> >
> > +#define DEFAULT_VM_MEM_SRC VM_MEM_SRC_ANONYMOUS
> > +
> >  struct vm_mem_backing_src_alias {
> >       const char *name;
> >       uint32_t flag;
> > @@ -100,7 +103,7 @@ size_t get_trans_hugepagesz(void);
> >  size_t get_def_hugetlb_pagesz(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);
> > +void backing_src_help(const char *flag);
> >  enum vm_mem_backing_src_type parse_backing_src_type(const char *type_name);
> >
> >  /*
> > diff --git a/tools/testing/selftests/kvm/kvm_page_table_test.c b/tools/testing/selftests/kvm/kvm_page_table_test.c
> > index 0d04a7db7f24..36407cb0ec85 100644
> > --- a/tools/testing/selftests/kvm/kvm_page_table_test.c
> > +++ b/tools/testing/selftests/kvm/kvm_page_table_test.c
> > @@ -456,10 +456,7 @@ static void help(char *name)
> >              "     (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();
> > +     backing_src_help("-s");
> >       puts("");
> >  }
> >
> > @@ -468,7 +465,7 @@ 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,
> > +             .src_type = DEFAULT_VM_MEM_SRC,
> >       };
> >       int opt;
> >
> > diff --git a/tools/testing/selftests/kvm/lib/test_util.c b/tools/testing/selftests/kvm/lib/test_util.c
> > index af1031fed97f..ea23a86132ed 100644
> > --- a/tools/testing/selftests/kvm/lib/test_util.c
> > +++ b/tools/testing/selftests/kvm/lib/test_util.c
> > @@ -279,13 +279,22 @@ size_t get_backing_src_pagesz(uint32_t i)
> >       }
> >  }
> >
> > -void backing_src_help(void)
> > +void print_available_backing_src_types(const char *prefix)
>
> This can probably be static.

Ack. Will fix in v2.


>
> >  {
> >       int i;
> >
> > -     printf("Available backing src types:\n");
> > +     printf("%sAvailable backing src types:\n", prefix);
> > +
> >       for (i = 0; i < NUM_SRC_TYPES; i++)
> > -             printf("\t%s\n", vm_mem_backing_src_alias(i)->name);
> > +             printf("%s    %s\n", prefix, vm_mem_backing_src_alias(i)->name);
> > +}
> > +
> > +void backing_src_help(const char *flag)
> > +{
> > +     printf(" %s: specify the type of memory that should be used to\n"
> > +            "     back the guest data region. (default: %s)\n",
> > +            flag, vm_mem_backing_src_alias(DEFAULT_VM_MEM_SRC)->name);
> > +     print_available_backing_src_types("     ");
> >  }
> >
> >  enum vm_mem_backing_src_type parse_backing_src_type(const char *type_name)
> > @@ -296,7 +305,7 @@ enum vm_mem_backing_src_type parse_backing_src_type(const char *type_name)
> >               if (!strcmp(type_name, vm_mem_backing_src_alias(i)->name))
> >                       return i;
> >
> > -     backing_src_help();
> > +     print_available_backing_src_types("");
> >       TEST_FAIL("Unknown backing src type: %s", type_name);
> >       return -1;
> >  }
> > --
> > 2.33.0.309.g3052b89438-goog
> >
>
>
> Reviewed-by: Andrew Jones <drjones@redhat.com>
>
> Thanks,
> drew
>

Re: [PATCH 3/3] KVM: selftests: Fix dirty bitmap offset calculation

[David Matlack]

On Thu, Sep 16, 2021 at 1:49 AM Andrew Jones <drjones@redhat.com> wrote:
>
> On Wed, Sep 15, 2021 at 02:55:03PM -0700, Ben Gardon wrote:
> > On Wed, Sep 15, 2021 at 2:30 PM David Matlack <dmatlack@google.com> wrote:
> > >
> > > The calculation to get the per-slot dirty bitmap was incorrect leading
> > > to a buffer overrun. Fix it by dividing the number of pages by
> > > BITS_PER_LONG, since each element of the bitmap is a long and there is
> > > one bit per page.
> > >
> > > Fixes: 609e6202ea5f ("KVM: selftests: Support multiple slots in dirty_log_perf_test")
> > > Signed-off-by: David Matlack <dmatlack@google.com>
> >
> > I was a little confused initially because we're allocating only one
> > dirty bitmap in userspace even when we have multiple slots, but that's
> > not a problem.
>
> It's also confusing to me. Wouldn't it be better to create a bitmap per
> slot? I think the new constraint that host mem must be a multiple of 64
> is unfortunate.

I don't think think the multiple-of-64 (256K) constraint will matter
much in practice. But it wouldn't be very complicated to switch to a
bitmap per slot, and would prevent further confusion.

I'll switch it over in v2.

>
> Thanks,
> drew
>

Re: [PATCH 3/3] KVM: selftests: Fix dirty bitmap offset calculation

[Paolo Bonzini]

On 16/09/21 10:49, Andrew Jones wrote:
>> I was a little confused initially because we're allocating only one
>> dirty bitmap in userspace even when we have multiple slots, but that's
>> not a problem.
> It's also confusing to me. Wouldn't it be better to create a bitmap per
> slot? I think the new constraint that host mem must be a multiple of 64
> is unfortunate.

Yeah, I wouldn't mind if someone took a look at that.  Also because 
anyway this patch doesn't apply to master right now, I've queued 1-2 only.

Paolo

Re: [PATCH 3/3] KVM: selftests: Fix dirty bitmap offset calculation

[Andrew Jones]

On Wed, Sep 22, 2021 at 01:09:57PM +0200, Paolo Bonzini wrote:
> On 16/09/21 10:49, Andrew Jones wrote:
> > > I was a little confused initially because we're allocating only one
> > > dirty bitmap in userspace even when we have multiple slots, but that's
> > > not a problem.
> > It's also confusing to me. Wouldn't it be better to create a bitmap per
> > slot? I think the new constraint that host mem must be a multiple of 64
> > is unfortunate.
> 
> Yeah, I wouldn't mind if someone took a look at that.  Also because anyway
> this patch doesn't apply to master right now, I've queued 1-2 only.

David posted a v2 on Sept. 17 with the bitmap split up per slot for patch
3/3. I think the other patches got some tweaks too.

Thanks
drew