[PATCH v3 0/2] selftests: kvm: Introduce the mem_slot_test test

[PATCH v3 0/2] selftests: kvm: Introduce the mem_slot_test test

[Wainer dos Santos Moschetta]

This series introduces a new KVM selftest (mem_slot_test) that goal
is to verify memory slots can be added up to the maximum allowed. An
extra slot is attempted which should occur on error.

The patch 01 is needed so that the VM fd can be accessed from the
test code (for the ioctl call attempting to add an extra slot).

I ran the test successfully on x86_64, aarch64, and s390x.  This
is why it is enabled to build on those arches.

- Changelog -

v2 -> v3:
 - Keep alphabetical order of .gitignore and Makefile [drjones]
 - Use memory region flags equals to zero [drjones]
 - Changed mmap() assert from 'mem != NULL' to 'mem != MAP_FAILED' [drjones]
 - kvm_region is declared along side other variables and malloc()'ed
   later [drjones]
 - Combined two asserts into a single 'ret == -1 && errno == EINVAL'
   [drjones]

v1 -> v2:
 - Rebased to queue
 - vm_get_fd() returns int instead of unsigned int (patch 01) [drjones]
 - Removed MEM_REG_FLAGS and GUEST_VM_MODE defines [drjones]
 - Replaced DEBUG() with pr_info() [drjones]
 - Calculate number of guest pages with vm_calc_num_guest_pages()
   [drjones]
 - Using memory region of 1 MB sized (matches mininum needed
   for s390x)
 - Removed the increment of guest_addr after the loop [drjones]
 - Added assert for the errno when adding a slot beyond-the-limit [drjones]
 - Prefer KVM_MEM_READONLY flag but on s390x it switch to KVM_MEM_LOG_DIRTY_PAGES,
   so ensure the coverage of both flags. Also somewhat tests the KVM_CAP_READONLY_MEM capability check [drjones]
 - Moved the test logic to test_add_max_slots(), this allows to more easily add new cases in the "suite".

v1: https://lore.kernel.org/kvm/20200330204310.21736-1-wainersm@redhat.com

Wainer dos Santos Moschetta (2):
  selftests: kvm: Add vm_get_fd() in kvm_util
  selftests: kvm: Add mem_slot_test test

 tools/testing/selftests/kvm/.gitignore        |  1 +
 tools/testing/selftests/kvm/Makefile          |  3 +
 .../testing/selftests/kvm/include/kvm_util.h  |  1 +
 tools/testing/selftests/kvm/lib/kvm_util.c    |  5 ++
 tools/testing/selftests/kvm/mem_slot_test.c   | 85 +++++++++++++++++++
 5 files changed, 95 insertions(+)
 create mode 100644 tools/testing/selftests/kvm/mem_slot_test.c

-- 
2.17.2

[PATCH v3 1/2] selftests: kvm: Add vm_get_fd() in kvm_util

[Wainer dos Santos Moschetta]

Introduces the vm_get_fd() function in kvm_util which returns
the VM file descriptor.

Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Wainer dos Santos Moschetta <wainersm@redhat.com>
---
 tools/testing/selftests/kvm/include/kvm_util.h | 1 +
 tools/testing/selftests/kvm/lib/kvm_util.c     | 5 +++++
 2 files changed, 6 insertions(+)

diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
index a99b875f50d2..4e122819ee24 100644
--- a/tools/testing/selftests/kvm/include/kvm_util.h
+++ b/tools/testing/selftests/kvm/include/kvm_util.h
@@ -254,6 +254,7 @@ bool vm_is_unrestricted_guest(struct kvm_vm *vm);
 unsigned int vm_get_page_size(struct kvm_vm *vm);
 unsigned int vm_get_page_shift(struct kvm_vm *vm);
 unsigned int vm_get_max_gfn(struct kvm_vm *vm);
+int vm_get_fd(struct kvm_vm *vm);
 
 unsigned int vm_calc_num_guest_pages(enum vm_guest_mode mode, size_t size);
 unsigned int vm_num_host_pages(enum vm_guest_mode mode, unsigned int num_guest_pages);
diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index 8a3523d4434f..3e36a1eb8771 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -1734,6 +1734,11 @@ unsigned int vm_get_max_gfn(struct kvm_vm *vm)
 	return vm->max_gfn;
 }
 
+int vm_get_fd(struct kvm_vm *vm)
+{
+        return vm->fd;
+}
+
 static unsigned int vm_calc_num_pages(unsigned int num_pages,
 				      unsigned int page_shift,
 				      unsigned int new_page_shift,
-- 
2.17.2

[PATCH v3 2/2] selftests: kvm: Add mem_slot_test test

[Wainer dos Santos Moschetta]

This patch introduces the mem_slot_test test which checks
an VM can have added memory slots up to the limit defined in
KVM_CAP_NR_MEMSLOTS. Then attempt to add one more slot to
verify it fails as expected.

Signed-off-by: Wainer dos Santos Moschetta <wainersm@redhat.com>
---
 tools/testing/selftests/kvm/.gitignore      |  1 +
 tools/testing/selftests/kvm/Makefile        |  3 +
 tools/testing/selftests/kvm/mem_slot_test.c | 85 +++++++++++++++++++++
 3 files changed, 89 insertions(+)
 create mode 100644 tools/testing/selftests/kvm/mem_slot_test.c

diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore
index 16877c3daabf..127d27188427 100644
--- a/tools/testing/selftests/kvm/.gitignore
+++ b/tools/testing/selftests/kvm/.gitignore
@@ -21,4 +21,5 @@
 /demand_paging_test
 /dirty_log_test
 /kvm_create_max_vcpus
+/mem_slot_test
 /steal_time
diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index 712a2ddd2a27..338b6cdce1a0 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -32,12 +32,14 @@ TEST_GEN_PROGS_x86_64 += clear_dirty_log_test
 TEST_GEN_PROGS_x86_64 += demand_paging_test
 TEST_GEN_PROGS_x86_64 += dirty_log_test
 TEST_GEN_PROGS_x86_64 += kvm_create_max_vcpus
+TEST_GEN_PROGS_x86_64 += mem_slot_test
 TEST_GEN_PROGS_x86_64 += steal_time
 
 TEST_GEN_PROGS_aarch64 += clear_dirty_log_test
 TEST_GEN_PROGS_aarch64 += demand_paging_test
 TEST_GEN_PROGS_aarch64 += dirty_log_test
 TEST_GEN_PROGS_aarch64 += kvm_create_max_vcpus
+TEST_GEN_PROGS_aarch64 += mem_slot_test
 TEST_GEN_PROGS_aarch64 += steal_time
 
 TEST_GEN_PROGS_s390x = s390x/memop
@@ -46,6 +48,7 @@ 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_create_max_vcpus
+TEST_GEN_PROGS_s390x += mem_slot_test
 
 TEST_GEN_PROGS += $(TEST_GEN_PROGS_$(UNAME_M))
 LIBKVM += $(LIBKVM_$(UNAME_M))
diff --git a/tools/testing/selftests/kvm/mem_slot_test.c b/tools/testing/selftests/kvm/mem_slot_test.c
new file mode 100644
index 000000000000..0588dc2e8e01
--- /dev/null
+++ b/tools/testing/selftests/kvm/mem_slot_test.c
@@ -0,0 +1,85 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * mem_slot_test
+ *
+ * Copyright (C) 2020, Red Hat, Inc.
+ *
+ * Test suite for memory region operations.
+ */
+#define _GNU_SOURCE /* for program_invocation_short_name */
+#include <linux/kvm.h>
+#include <sys/mman.h>
+
+#include "test_util.h"
+#include "kvm_util.h"
+
+/*
+ * Test it can be added memory slots up to KVM_CAP_NR_MEMSLOTS, then any
+ * tentative to add further slots should fail.
+ */
+static void test_add_max_slots(void)
+{
+	int ret;
+	struct kvm_userspace_memory_region *kvm_region;
+	struct kvm_vm *vm;
+	uint32_t max_mem_slots;
+	uint32_t mem_reg_flags;
+	uint32_t slot;
+	uint64_t guest_addr;
+	uint64_t mem_reg_npages;
+	uint64_t mem_reg_size;
+
+	max_mem_slots = kvm_check_cap(KVM_CAP_NR_MEMSLOTS);
+	TEST_ASSERT(max_mem_slots > 0,
+		    "KVM_CAP_NR_MEMSLOTS should be greater than 0");
+	pr_info("Allowed number of memory slots: %i\n", max_mem_slots);
+
+	vm = vm_create(VM_MODE_DEFAULT, 0, O_RDWR);
+
+	/*
+	 * Uses 1MB sized/aligned memory region since this is the minimal
+	 * required on s390x.
+	 */
+	mem_reg_size = 0x100000;
+	mem_reg_npages = vm_calc_num_guest_pages(VM_MODE_DEFAULT, mem_reg_size);
+	mem_reg_flags = 0;
+
+	guest_addr = 0x0;
+
+	/* Check it can be added memory slots up to the maximum allowed */
+	pr_info("Adding slots 0..%i, each memory region with %ldK size\n",
+		(max_mem_slots - 1), mem_reg_size >> 10);
+	for (slot = 0; slot < max_mem_slots; slot++) {
+		vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS,
+					    guest_addr, slot, mem_reg_npages,
+					    mem_reg_flags);
+		guest_addr += mem_reg_size;
+	}
+
+	/* Check it cannot be added memory slots beyond the limit */
+	void *mem = mmap(NULL, mem_reg_size, PROT_READ | PROT_WRITE,
+			 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	TEST_ASSERT(mem != MAP_FAILED, "Failed to mmap() host");
+
+	kvm_region = malloc(sizeof(struct kvm_userspace_memory_region));
+	TEST_ASSERT(kvm_region,
+		    "Failed to malloc() kvm_userspace_memory_region");
+	kvm_region->slot = slot;
+	kvm_region->flags = mem_reg_flags;
+	kvm_region->guest_phys_addr = guest_addr;
+	kvm_region->userspace_addr = (uint64_t) mem;
+
+	ret = ioctl(vm_get_fd(vm), KVM_SET_USER_MEMORY_REGION, kvm_region);
+	TEST_ASSERT(ret == -1 && errno == EINVAL,
+		    "Adding one more memory slot should fail with EINVAL");
+
+	munmap(mem, mem_reg_size);
+	free(kvm_region);
+	kvm_vm_free(vm);
+}
+
+int main(int argc, char *argv[])
+{
+	test_add_max_slots();
+	return 0;
+}
-- 
2.17.2

Re: [PATCH v3 2/2] selftests: kvm: Add mem_slot_test test

[Andrew Jones]

On Tue, Apr 07, 2020 at 12:37:31PM -0300, Wainer dos Santos Moschetta wrote:
> This patch introduces the mem_slot_test test which checks
> an VM can have added memory slots up to the limit defined in
> KVM_CAP_NR_MEMSLOTS. Then attempt to add one more slot to
> verify it fails as expected.
> 
> Signed-off-by: Wainer dos Santos Moschetta <wainersm@redhat.com>
> ---
>  tools/testing/selftests/kvm/.gitignore      |  1 +
>  tools/testing/selftests/kvm/Makefile        |  3 +
>  tools/testing/selftests/kvm/mem_slot_test.c | 85 +++++++++++++++++++++
>  3 files changed, 89 insertions(+)
>  create mode 100644 tools/testing/selftests/kvm/mem_slot_test.c
> 
> diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore
> index 16877c3daabf..127d27188427 100644
> --- a/tools/testing/selftests/kvm/.gitignore
> +++ b/tools/testing/selftests/kvm/.gitignore
> @@ -21,4 +21,5 @@
>  /demand_paging_test
>  /dirty_log_test
>  /kvm_create_max_vcpus
> +/mem_slot_test
>  /steal_time
> diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
> index 712a2ddd2a27..338b6cdce1a0 100644
> --- a/tools/testing/selftests/kvm/Makefile
> +++ b/tools/testing/selftests/kvm/Makefile
> @@ -32,12 +32,14 @@ TEST_GEN_PROGS_x86_64 += clear_dirty_log_test
>  TEST_GEN_PROGS_x86_64 += demand_paging_test
>  TEST_GEN_PROGS_x86_64 += dirty_log_test
>  TEST_GEN_PROGS_x86_64 += kvm_create_max_vcpus
> +TEST_GEN_PROGS_x86_64 += mem_slot_test
>  TEST_GEN_PROGS_x86_64 += steal_time
>  
>  TEST_GEN_PROGS_aarch64 += clear_dirty_log_test
>  TEST_GEN_PROGS_aarch64 += demand_paging_test
>  TEST_GEN_PROGS_aarch64 += dirty_log_test
>  TEST_GEN_PROGS_aarch64 += kvm_create_max_vcpus
> +TEST_GEN_PROGS_aarch64 += mem_slot_test
>  TEST_GEN_PROGS_aarch64 += steal_time
>  
>  TEST_GEN_PROGS_s390x = s390x/memop
> @@ -46,6 +48,7 @@ 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_create_max_vcpus
> +TEST_GEN_PROGS_s390x += mem_slot_test
>  
>  TEST_GEN_PROGS += $(TEST_GEN_PROGS_$(UNAME_M))
>  LIBKVM += $(LIBKVM_$(UNAME_M))
> diff --git a/tools/testing/selftests/kvm/mem_slot_test.c b/tools/testing/selftests/kvm/mem_slot_test.c
> new file mode 100644
> index 000000000000..0588dc2e8e01
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/mem_slot_test.c
> @@ -0,0 +1,85 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * mem_slot_test
> + *
> + * Copyright (C) 2020, Red Hat, Inc.
> + *
> + * Test suite for memory region operations.
> + */
> +#define _GNU_SOURCE /* for program_invocation_short_name */
> +#include <linux/kvm.h>
> +#include <sys/mman.h>
> +
> +#include "test_util.h"
> +#include "kvm_util.h"
> +
> +/*
> + * Test it can be added memory slots up to KVM_CAP_NR_MEMSLOTS, then any
> + * tentative to add further slots should fail.
> + */
> +static void test_add_max_slots(void)
> +{
> +	int ret;
> +	struct kvm_userspace_memory_region *kvm_region;

nit: this doesn't need to be a pointer, requiring the malloc.

> +	struct kvm_vm *vm;
> +	uint32_t max_mem_slots;
> +	uint32_t mem_reg_flags;
> +	uint32_t slot;
> +	uint64_t guest_addr;
> +	uint64_t mem_reg_npages;
> +	uint64_t mem_reg_size;
> +
> +	max_mem_slots = kvm_check_cap(KVM_CAP_NR_MEMSLOTS);
> +	TEST_ASSERT(max_mem_slots > 0,
> +		    "KVM_CAP_NR_MEMSLOTS should be greater than 0");
> +	pr_info("Allowed number of memory slots: %i\n", max_mem_slots);
> +
> +	vm = vm_create(VM_MODE_DEFAULT, 0, O_RDWR);
> +
> +	/*
> +	 * Uses 1MB sized/aligned memory region since this is the minimal
> +	 * required on s390x.
> +	 */
> +	mem_reg_size = 0x100000;
> +	mem_reg_npages = vm_calc_num_guest_pages(VM_MODE_DEFAULT, mem_reg_size);
> +	mem_reg_flags = 0;

nit: don't really need mem_reg_flags anymore.

> +
> +	guest_addr = 0x0;
> +
> +	/* Check it can be added memory slots up to the maximum allowed */
> +	pr_info("Adding slots 0..%i, each memory region with %ldK size\n",
> +		(max_mem_slots - 1), mem_reg_size >> 10);
> +	for (slot = 0; slot < max_mem_slots; slot++) {
> +		vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS,
> +					    guest_addr, slot, mem_reg_npages,
> +					    mem_reg_flags);
> +		guest_addr += mem_reg_size;
> +	}
> +
> +	/* Check it cannot be added memory slots beyond the limit */
> +	void *mem = mmap(NULL, mem_reg_size, PROT_READ | PROT_WRITE,
> +			 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);

nit: mem is another middle of block declaration that I didn't notice before

> +	TEST_ASSERT(mem != MAP_FAILED, "Failed to mmap() host");
> +
> +	kvm_region = malloc(sizeof(struct kvm_userspace_memory_region));
> +	TEST_ASSERT(kvm_region,
> +		    "Failed to malloc() kvm_userspace_memory_region");
> +	kvm_region->slot = slot;
> +	kvm_region->flags = mem_reg_flags;
> +	kvm_region->guest_phys_addr = guest_addr;
> +	kvm_region->userspace_addr = (uint64_t) mem;

You're missing memory_size here, and it's not even guaranteed to be zero,
since we malloc'ed and didn't zero initialize.

Actually, I'd probably just drop kvm_region and use a compound literal
in the ioctl.

> +
> +	ret = ioctl(vm_get_fd(vm), KVM_SET_USER_MEMORY_REGION, kvm_region);
> +	TEST_ASSERT(ret == -1 && errno == EINVAL,
> +		    "Adding one more memory slot should fail with EINVAL");
> +
> +	munmap(mem, mem_reg_size);
> +	free(kvm_region);
> +	kvm_vm_free(vm);
> +}
> +
> +int main(int argc, char *argv[])
> +{
> +	test_add_max_slots();
> +	return 0;
> +}
> -- 
> 2.17.2
>

Thanks,
drew