Re: [PATCH v4 1/2] selftests: kvm: Add vm_get_fd() in kvm_util

From: Krish Sadhukhan
Date: Thu Apr 09 2020 - 13:57:34 EST



On 4/8/20 7:45 PM, Wainer dos Santos Moschetta wrote:

On 4/8/20 10:25 PM, Krish Sadhukhan wrote:

On 4/8/20 3:08 PM, Wainer dos Santos Moschetta wrote:
Introduces the vm_get_fd() function in kvm_util which returns
the VM file descriptor.

Reviewed-by: Andrew Jones <drjones@xxxxxxxxxx>
Signed-off-by: Wainer dos Santos Moschetta <wainersm@xxxxxxxxxx>
---
 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)
ÂÂÂÂÂ return vm->max_gfn;
 }
 +int vm_get_fd(struct kvm_vm *vm)
+{
+ÂÂÂÂÂÂÂ return vm->fd;
+}
+


I am just trying to understand why we need a separate function when the 'vm' variable is all local within the same file. There are a number of places in kvm_util.c where it is used directly.


The problem is to access of kvm_vm attributes outside of kvm_utils.c. For example, if I try to vm->fd in my test I get the compiler error:

mem_slot_test.c: In function âtest_add_max_slotsâ:
mem_slot_test.c:62:16: error: dereferencing pointer to incomplete type âstruct kvm_vmâ
 ret = ioctl(vm->fd, KVM_SET_USER_MEMORY_REGION,
ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ ^~


My bad ! I missed the fact that the structure is defined in kvm_util_internal.h and not in kvm_util.h.


Reviewed-by: Krish Sadhukhan <krish.sadhukhan@xxxxxxxxxx>




 static unsigned int vm_calc_num_pages(unsigned int num_pages,
ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ unsigned int page_shift,
ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ unsigned int new_page_shift,