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

On Mon, Mar 30, 2020 at 05:43:10PM -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 | 92 +++++++++++++++++++++ 3 files changed, 96 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 30072c3f52fb..b1b94d50f6a2 100644 --- a/tools/testing/selftests/kvm/.gitignore +++ b/tools/testing/selftests/kvm/.gitignore @@ -17,3 +17,4 @@ /clear_dirty_log_test /dirty_log_test /kvm_create_max_vcpus +/mem_slot_test diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile index d91c53b726e6..070133349403 100644 --- a/tools/testing/selftests/kvm/Makefile +++ b/tools/testing/selftests/kvm/Makefile @@ -30,16 +30,19 @@ TEST_GEN_PROGS_x86_64 += x86_64/svm_vmcall_test TEST_GEN_PROGS_x86_64 += clear_dirty_log_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_aarch64 += clear_dirty_log_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_s390x = s390x/memop TEST_GEN_PROGS_s390x += s390x/sync_regs_test TEST_GEN_PROGS_s390x += s390x/resets 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..75d2bbd71642 --- /dev/null +++ b/tools/testing/selftests/kvm/mem_slot_test.c @@ -0,0 +1,92 @@ +// SPDX-License-Identifier: GPL-2.0-only +/*

• • mem_slot_test
• • Copyright (C) 2020, Red Hat, Inc.
• • Test it can be added memory slots up to KVM_CAP_NR_MEMSLOTS, then any
• • tentative to add further slots should fail.
• */

+#define _GNU_SOURCE /* for program_invocation_short_name */ +#include <linux/kvm.h> +#include <sys/mman.h> +#include <unistd.h>

+#include "test_util.h" +#include "kvm_util.h"

+/* Memory region flags */ +#define MEM_REG_FLAGS KVM_MEM_LOG_DIRTY_PAGES

+/* Guest VM mode */ +#define GUEST_VM_MODE VM_MODE_DEFAULT

I'm not sure what the value of the two defines above are. I'd prefer we avoid unnecessary renaming. Also, do we need KVM_MEM_LOG_DIRTY_PAGES for this test?

+int main(int argc, char *argv[]) +{

• struct kvm_vm *vm;
• /* Maximum allowed number of memory slots */
• uint32_t max_mem_slots;
• /* Slot number */
• uint32_t slot;
• /* Number of pages in a memory region */
• uint64_t mem_reg_npages;
• /* Memory region size */
• uint64_t mem_reg_size;
• /* Guest physical memory guest_address */
• uint64_t guest_addr;
• /* VM page size */
• uint64_t vm_page_size;

nit: IMO, the variable names above are descriptive enough to drop the comments.

• 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");
  

• DEBUG("Allowed number of memory slots: %i\n", max_mem_slots);

DEBUG() no longer exists in kvm/queue. This should now be pr_debug().

• vm = vm_create(GUEST_VM_MODE, 0, O_RDWR);
• /* Determine the minimal number of pages as possible per region. */
• vm_page_size = vm_get_page_size(vm);

+#ifdef __s390x__

• mem_reg_size = 0x100000;

+#else

• uint64_t host_page_size = sysconf(_SC_PAGESIZE);
• mem_reg_size = (host_page_size > vm_page_size) ? host_page_size :

• 					 vm_page_size;
  

+#endif

• mem_reg_npages = mem_reg_size / vm_page_size;

On kvm/queue the above 11 lines can now all be done with

mem_reg_size = SOME_ARBITRARY_MEM_REG_SIZE; mem_reg_npages = vm_calc_num_guest_pages(VM_MODE_DEFAULT, mem_reg_size);

• guest_addr = 0x0;
• /* Check it can be added memory slots up to the maximum allowed */
• DEBUG("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 */
• guest_addr += mem_reg_size;

nit: shouldn't be necessary. We already incremented guest_addr on the last loop.

• 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");

Shouldn't we also check that we get the correct errno?

• munmap(mem, mem_reg_size);
• kvm_vm_free(vm);
• return 0;

+}

2.17.2

Thanks, drew