Re: [PATCH 08/12] selftests: sev_migrate_tests: add tests for KVM_CAP_VM_COPY_ENC_CONTEXT_FROM

[Peter Gonda]

On Wed, Dec 1, 2021 at 11:09 AM Peter Gonda <pgonda@xxxxxxxxxx> wrote:
>
> On Mon, Nov 22, 2021 at 5:50 PM Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote:
> >
> > I am putting the tests in sev_migrate_tests because the failure conditions are
> > very similar and some of the setup code can be reused, too.
> >
> > The tests cover both successful creation of a mirror VM, and error
> > conditions.
> >
> > Cc: Peter Gonda <pgonda@xxxxxxxxxx>
> > Cc: Sean Christopherson <seanjc@xxxxxxxxxx>
> > Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> > ---
> >  .../selftests/kvm/x86_64/sev_migrate_tests.c  | 112 ++++++++++++++++--
> >  1 file changed, 105 insertions(+), 7 deletions(-)
> >
> > diff --git a/tools/testing/selftests/kvm/x86_64/sev_migrate_tests.c b/tools/testing/selftests/kvm/x86_64/sev_migrate_tests.c
> > index 0cd7e2eaa895..d265cea5de85 100644
> > --- a/tools/testing/selftests/kvm/x86_64/sev_migrate_tests.c
> > +++ b/tools/testing/selftests/kvm/x86_64/sev_migrate_tests.c
> > @@ -54,12 +54,15 @@ static struct kvm_vm *sev_vm_create(bool es)
> >         return vm;
> >  }
> >
> > -static struct kvm_vm *__vm_create(void)
> > +static struct kvm_vm *aux_vm_create(bool with_vcpus)
> >  {
> >         struct kvm_vm *vm;
> >         int i;
> >
> >         vm = vm_create(VM_MODE_DEFAULT, 0, O_RDWR);
> > +       if (!with_vcpus)
> > +               return vm;
> > +
> >         for (i = 0; i < NR_MIGRATE_TEST_VCPUS; ++i)
> >                 vm_vcpu_add(vm, i);
> >
> > @@ -93,7 +96,7 @@ static void test_sev_migrate_from(bool es)
> >
> >         src_vm = sev_vm_create(es);
> >         for (i = 0; i < NR_MIGRATE_TEST_VMS; ++i)
> > -               dst_vms[i] = __vm_create();
> > +               dst_vms[i] = aux_vm_create(true);
> >
> >         /* Initial migration from the src to the first dst. */
> >         sev_migrate_from(dst_vms[0]->fd, src_vm->fd);
> > @@ -162,7 +165,7 @@ static void test_sev_migrate_parameters(void)
> >         sev_vm = sev_vm_create(/* es= */ false);
> >         sev_es_vm = sev_vm_create(/* es= */ true);
> >         vm_no_vcpu = vm_create(VM_MODE_DEFAULT, 0, O_RDWR);
> > -       vm_no_sev = __vm_create();
> > +       vm_no_sev = aux_vm_create(true);
> >         sev_es_vm_no_vmsa = vm_create(VM_MODE_DEFAULT, 0, O_RDWR);
> >         sev_ioctl(sev_es_vm_no_vmsa->fd, KVM_SEV_ES_INIT, NULL);
> >         vm_vcpu_add(sev_es_vm_no_vmsa, 1);
> > @@ -203,11 +206,106 @@ static void test_sev_migrate_parameters(void)
> >         kvm_vm_free(vm_no_sev);
> >  }
> >
> > +static int __sev_mirror_create(int dst_fd, int src_fd)
> > +{
> > +       struct kvm_enable_cap cap = {
> > +               .cap = KVM_CAP_VM_COPY_ENC_CONTEXT_FROM,
> > +               .args = { src_fd }
> > +       };
> > +
> > +       return ioctl(dst_fd, KVM_ENABLE_CAP, &cap);
> > +}
> > +
> > +
> > +static void sev_mirror_create(int dst_fd, int src_fd)
> > +{
> > +       int ret;
> > +
> > +       ret = __sev_mirror_create(dst_fd, src_fd);
> > +       TEST_ASSERT(!ret, "Copying context failed, ret: %d, errno: %d\n", ret, errno);
> > +}
> > +
> > +static void test_sev_mirror(bool es)
> > +{
> > +       struct kvm_vm *src_vm, *dst_vm;
> > +       struct kvm_sev_launch_start start = {
> > +               .policy = es ? SEV_POLICY_ES : 0
> > +       };
> > +       int i;
> > +
> > +       src_vm = sev_vm_create(es);
> > +       dst_vm = aux_vm_create(false);
> > +
> > +       sev_mirror_create(dst_vm->fd, src_vm->fd);
> > +
> > +       /* Check that we can complete creation of the mirror VM.  */
> > +       for (i = 0; i < NR_MIGRATE_TEST_VCPUS; ++i)
> > +               vm_vcpu_add(dst_vm, i);
> > +       sev_ioctl(dst_vm->fd, KVM_SEV_LAUNCH_START, &start);
>
> I don't think this should be called on the mirror and I think it
> should be an error.
>
> In  is_cmd_allowed_from_mirror() KVM_SEV_LAUNCH_START should not be allowed:
>
> if (cmd_id == KVM_SEV_LAUNCH_UPDATE_VMSA ||
>    cmd_id == KVM_SEV_GUEST_STATUS || cmd_id == KVM_SEV_DBG_DECRYPT ||
>    cmd_id == KVM_SEV_DBG_ENCRYPT)
> return true;
>
> This overrides the mirrored values and sets up the VM as a new SEV
> context. I would have thought the sev_bind_asid() in
> sev_launch_start() would fail because the asid is already used by the
> source.

Since you already queue'd this I sent another patch to fix the issue
with sev_ioctl() and remove this call.

>
> > +       if (es)
> > +               sev_ioctl(dst_vm->fd, KVM_SEV_LAUNCH_UPDATE_VMSA, NULL);
> > +
> > +       kvm_vm_free(src_vm);
> > +       kvm_vm_free(dst_vm);
> > +}
> > +
> > +static void test_sev_mirror_parameters(void)
> > +{
> > +       struct kvm_vm *sev_vm, *sev_es_vm, *vm_no_vcpu, *vm_with_vcpu;
> > +       int ret;
> > +
> > +       sev_vm = sev_vm_create(/* es= */ false);
> > +       sev_es_vm = sev_vm_create(/* es= */ true);
> > +       vm_with_vcpu = aux_vm_create(true);
> > +       vm_no_vcpu = aux_vm_create(false);
> > +
> > +       ret = __sev_mirror_create(sev_vm->fd, sev_vm->fd);
> > +       TEST_ASSERT(
> > +               ret == -1 && errno == EINVAL,
> > +               "Should not be able copy context to self. ret: %d, errno: %d\n",
> > +               ret, errno);
> > +
> > +       ret = __sev_mirror_create(sev_vm->fd, sev_es_vm->fd);
> > +       TEST_ASSERT(
> > +               ret == -1 && errno == EINVAL,
> > +               "Should not be able copy context to SEV enabled VM. ret: %d, errno: %d\n",
> > +               ret, errno);
> > +
> > +       ret = __sev_mirror_create(sev_es_vm->fd, sev_vm->fd);
> > +       TEST_ASSERT(
> > +               ret == -1 && errno == EINVAL,
> > +               "Should not be able copy context to SEV-ES enabled VM. ret: %d, errno: %d\n",
> > +               ret, errno);
> > +
> > +       ret = __sev_mirror_create(vm_no_vcpu->fd, vm_with_vcpu->fd);
> > +       TEST_ASSERT(ret == -1 && errno == EINVAL,
> > +                   "Copy context requires SEV enabled. ret %d, errno: %d\n", ret,
> > +                   errno);
> > +
> > +       ret = __sev_mirror_create(vm_with_vcpu->fd, sev_vm->fd);
> > +       TEST_ASSERT(
> > +               ret == -1 && errno == EINVAL,
> > +               "SEV copy context requires no vCPUS on the destination. ret: %d, errno: %d\n",
> > +               ret, errno);
> > +
> > +       kvm_vm_free(sev_vm);
> > +       kvm_vm_free(sev_es_vm);
> > +       kvm_vm_free(vm_with_vcpu);
> > +       kvm_vm_free(vm_no_vcpu);
> > +}
> > +
> >  int main(int argc, char *argv[])
> >  {
> > -       test_sev_migrate_from(/* es= */ false);
> > -       test_sev_migrate_from(/* es= */ true);
> > -       test_sev_migrate_locking();
> > -       test_sev_migrate_parameters();
> > +       if (kvm_check_cap(KVM_CAP_VM_MOVE_ENC_CONTEXT_FROM)) {
> > +               test_sev_migrate_from(/* es= */ false);
> > +               test_sev_migrate_from(/* es= */ true);
> > +               test_sev_migrate_locking();
> > +               test_sev_migrate_parameters();
> > +       }
> > +       if (kvm_check_cap(KVM_CAP_VM_COPY_ENC_CONTEXT_FROM)) {
> > +               test_sev_mirror(/* es= */ false);
> > +               test_sev_mirror(/* es= */ true);
> > +               test_sev_mirror_parameters();
> > +       }
> >         return 0;
> >  }
> > --
> > 2.27.0
> >
> >