[PATCH v2 0/2] selftests: kvm: Introduce the mem_slot_test test

[PATCH v2 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.

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

Changes 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".

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 v2 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.

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 v2 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..232f24d6931a 100644
--- a/tools/testing/selftests/kvm/.gitignore
+++ b/tools/testing/selftests/kvm/.gitignore
@@ -22,3 +22,4 @@
 /dirty_log_test
 /kvm_create_max_vcpus
 /steal_time
+/mem_slot_test
diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index 712a2ddd2a27..69b44178f48b 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -33,12 +33,14 @@ 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 += steal_time
+TEST_GEN_PROGS_x86_64 += mem_slot_test
 
 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 += steal_time
+TEST_GEN_PROGS_aarch64 += mem_slot_test
 
 TEST_GEN_PROGS_s390x = s390x/memop
 TEST_GEN_PROGS_s390x += s390x/resets
@@ -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..eef6f506f41d
--- /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)
+{
+	struct kvm_vm *vm;
+	uint32_t max_mem_slots;
+	uint32_t slot;
+	uint64_t mem_reg_npages;
+	uint64_t mem_reg_size;
+	uint32_t mem_reg_flags;
+	uint64_t guest_addr;
+	int ret;
+
+	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 = kvm_check_cap(KVM_CAP_READONLY_MEM) ? KVM_MEM_READONLY :
+		KVM_MEM_LOG_DIRTY_PAGES;
+
+	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 != NULL, "Failed to mmap() host");
+
+	struct kvm_userspace_memory_region kvm_region = {
+		.slot = slot,
+		.flags = mem_reg_flags,
+		.guest_phys_addr = guest_addr,
+		.memory_size = mem_reg_size,
+		.userspace_addr = (uint64_t) mem,
+	};
+
+	ret = ioctl(vm_get_fd(vm), KVM_SET_USER_MEMORY_REGION, &kvm_region);
+	TEST_ASSERT(ret == -1, "Adding one more memory slot should fail");
+	TEST_ASSERT(errno == EINVAL, "Should return EINVAL errno");
+
+	munmap(mem, mem_reg_size);
+	kvm_vm_free(vm);
+}
+
+int main(int argc, char *argv[])
+{
+	test_add_max_slots();
+	return 0;
+}
-- 
2.17.2

Re: [PATCH v2 1/2] selftests: kvm: Add vm_get_fd() in kvm_util

[Andrew Jones]

On Fri, Apr 03, 2020 at 02:24:27PM -0300, Wainer dos Santos Moschetta wrote:
> Introduces the vm_get_fd() function in kvm_util which returns
> the VM file descriptor.
> 
> 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
>

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

Re: [PATCH v2 2/2] selftests: kvm: Add mem_slot_test test

[Andrew Jones]

On Fri, Apr 03, 2020 at 02:24:28PM -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..232f24d6931a 100644
> --- a/tools/testing/selftests/kvm/.gitignore
> +++ b/tools/testing/selftests/kvm/.gitignore
> @@ -22,3 +22,4 @@
>  /dirty_log_test
>  /kvm_create_max_vcpus
>  /steal_time
> +/mem_slot_test
> diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
> index 712a2ddd2a27..69b44178f48b 100644
> --- a/tools/testing/selftests/kvm/Makefile
> +++ b/tools/testing/selftests/kvm/Makefile
> @@ -33,12 +33,14 @@ 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 += steal_time
> +TEST_GEN_PROGS_x86_64 += mem_slot_test
>  
>  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 += steal_time
> +TEST_GEN_PROGS_aarch64 += mem_slot_test
>  

kvm selftests has a bad case of OCD when it comes to lists of tests. In
the .gitignore and the Makefile we keep our tests in alphabetical order.
Maybe we should stop, because it's a bit annoying to maintain, but my
personal OCD won't allow it to be on my watch. Please fix the above
three lists.

>  TEST_GEN_PROGS_s390x = s390x/memop
>  TEST_GEN_PROGS_s390x += s390x/resets
> @@ -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..eef6f506f41d
> --- /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)
> +{
> +	struct kvm_vm *vm;
> +	uint32_t max_mem_slots;
> +	uint32_t slot;
> +	uint64_t mem_reg_npages;
> +	uint64_t mem_reg_size;
> +	uint32_t mem_reg_flags;
> +	uint64_t guest_addr;
> +	int ret;
> +
> +	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 = kvm_check_cap(KVM_CAP_READONLY_MEM) ? KVM_MEM_READONLY :
> +		KVM_MEM_LOG_DIRTY_PAGES;

I still don't see why we're setting a flag at all, and now we're setting
different flags depending on what's available, so the test isn't the
same for every environment. I would just have mem->flags = 0 for this
test.

> +
> +	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 != NULL, "Failed to mmap() host");

This should be testing mem != MAP_FAILED

> +
> +	struct kvm_userspace_memory_region kvm_region = {
> +		.slot = slot,
> +		.flags = mem_reg_flags,
> +		.guest_phys_addr = guest_addr,
> +		.memory_size = mem_reg_size,
> +		.userspace_addr = (uint64_t) mem,
> +	};

Declaring kvm_region in the middle of the block. I don't really care
myself, but it's inconsistent with all the other variables which are
declared at the top.

> +
> +	ret = ioctl(vm_get_fd(vm), KVM_SET_USER_MEMORY_REGION, &kvm_region);
> +	TEST_ASSERT(ret == -1, "Adding one more memory slot should fail");
> +	TEST_ASSERT(errno == EINVAL, "Should return EINVAL errno");

Please make the second assert message more specific. Or better would be
to combine the asserts

  TEST_ASSERT(ret == -1 && errno == EINVAL, "Adding one more memory slot should fail with EINVAL");

> +
> +	munmap(mem, mem_reg_size);
> +	kvm_vm_free(vm);
> +}
> +
> +int main(int argc, char *argv[])
> +{
> +	test_add_max_slots();
> +	return 0;
> +}
> -- 
> 2.17.2
>

Thanks,
drew

Re: [PATCH v2 2/2] selftests: kvm: Add mem_slot_test test

[Wainer dos Santos Moschetta]

On 4/4/20 4:32 AM, Andrew Jones wrote:
> On Fri, Apr 03, 2020 at 02:24:28PM -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..232f24d6931a 100644
>> --- a/tools/testing/selftests/kvm/.gitignore
>> +++ b/tools/testing/selftests/kvm/.gitignore
>> @@ -22,3 +22,4 @@
>>   /dirty_log_test
>>   /kvm_create_max_vcpus
>>   /steal_time
>> +/mem_slot_test
>> diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
>> index 712a2ddd2a27..69b44178f48b 100644
>> --- a/tools/testing/selftests/kvm/Makefile
>> +++ b/tools/testing/selftests/kvm/Makefile
>> @@ -33,12 +33,14 @@ 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 += steal_time
>> +TEST_GEN_PROGS_x86_64 += mem_slot_test
>>   
>>   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 += steal_time
>> +TEST_GEN_PROGS_aarch64 += mem_slot_test
>>   
> kvm selftests has a bad case of OCD when it comes to lists of tests. In
> the .gitignore and the Makefile we keep our tests in alphabetical order.
> Maybe we should stop, because it's a bit annoying to maintain, but my
> personal OCD won't allow it to be on my watch. Please fix the above
> three lists.

I will fix it on v3.

Kind of related... has ever been discussed a naming convention for kvm 
selftests? It would allow the use of regex on both .gitignore and 
Makefile...and bye-bye those sorted lists.


>
>>   TEST_GEN_PROGS_s390x = s390x/memop
>>   TEST_GEN_PROGS_s390x += s390x/resets
>> @@ -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..eef6f506f41d
>> --- /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)
>> +{
>> +	struct kvm_vm *vm;
>> +	uint32_t max_mem_slots;
>> +	uint32_t slot;
>> +	uint64_t mem_reg_npages;
>> +	uint64_t mem_reg_size;
>> +	uint32_t mem_reg_flags;
>> +	uint64_t guest_addr;
>> +	int ret;
>> +
>> +	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 = kvm_check_cap(KVM_CAP_READONLY_MEM) ? KVM_MEM_READONLY :
>> +		KVM_MEM_LOG_DIRTY_PAGES;
> I still don't see why we're setting a flag at all, and now we're setting
> different flags depending on what's available, so the test isn't the
> same for every environment. I would just have mem->flags = 0 for this
> test.
I thought I had to set a memory flag always. If mem->flags = 0 works 
across the arches, then I change this on v3.
>
>> +
>> +	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 != NULL, "Failed to mmap() host");
> This should be testing mem != MAP_FAILED

Ok.

>
>> +
>> +	struct kvm_userspace_memory_region kvm_region = {
>> +		.slot = slot,
>> +		.flags = mem_reg_flags,
>> +		.guest_phys_addr = guest_addr,
>> +		.memory_size = mem_reg_size,
>> +		.userspace_addr = (uint64_t) mem,
>> +	};
> Declaring kvm_region in the middle of the block. I don't really care
> myself, but it's inconsistent with all the other variables which are
> declared at the top.

Makes sense.

>
>> +
>> +	ret = ioctl(vm_get_fd(vm), KVM_SET_USER_MEMORY_REGION, &kvm_region);
>> +	TEST_ASSERT(ret == -1, "Adding one more memory slot should fail");
>> +	TEST_ASSERT(errno == EINVAL, "Should return EINVAL errno");
> Please make the second assert message more specific. Or better would be
> to combine the asserts
>
>    TEST_ASSERT(ret == -1 && errno == EINVAL, "Adding one more memory slot should fail with EINVAL");

Yeah, I was unsure about and'ing the checks. I will change it on v3.

Thanks!

Wainer

>
>> +
>> +	munmap(mem, mem_reg_size);
>> +	kvm_vm_free(vm);
>> +}
>> +
>> +int main(int argc, char *argv[])
>> +{
>> +	test_add_max_slots();
>> +	return 0;
>> +}
>> -- 
>> 2.17.2
>>
> Thanks,
> drew

Re: [PATCH v2 2/2] selftests: kvm: Add mem_slot_test test

[Andrew Jones]

On Mon, Apr 06, 2020 at 02:10:53PM -0300, Wainer dos Santos Moschetta wrote:
> 
> On 4/4/20 4:32 AM, Andrew Jones wrote:
> > On Fri, Apr 03, 2020 at 02:24:28PM -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..232f24d6931a 100644
> > > --- a/tools/testing/selftests/kvm/.gitignore
> > > +++ b/tools/testing/selftests/kvm/.gitignore
> > > @@ -22,3 +22,4 @@
> > >   /dirty_log_test
> > >   /kvm_create_max_vcpus
> > >   /steal_time
> > > +/mem_slot_test
> > > diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
> > > index 712a2ddd2a27..69b44178f48b 100644
> > > --- a/tools/testing/selftests/kvm/Makefile
> > > +++ b/tools/testing/selftests/kvm/Makefile
> > > @@ -33,12 +33,14 @@ 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 += steal_time
> > > +TEST_GEN_PROGS_x86_64 += mem_slot_test
> > >   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 += steal_time
> > > +TEST_GEN_PROGS_aarch64 += mem_slot_test
> > kvm selftests has a bad case of OCD when it comes to lists of tests. In
> > the .gitignore and the Makefile we keep our tests in alphabetical order.
> > Maybe we should stop, because it's a bit annoying to maintain, but my
> > personal OCD won't allow it to be on my watch. Please fix the above
> > three lists.
> 
> I will fix it on v3.
> 
> Kind of related... has ever been discussed a naming convention for kvm
> selftests? It would allow the use of regex on both .gitignore and
> Makefile...and bye-bye those sorted lists.

It's never been discussed that I know of. Feel free to send an RFC if
you'd like to kick off the discussion :-)

Thanks,
drew