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References: <20211208191642.3792819-1-pgonda@google.com> <20211208191642.3792819-4-pgonda@google.com>
In-Reply-To: <20211208191642.3792819-4-pgonda@google.com>
From:   Marc Orr <marcorr@google.com>
Date:   Wed, 8 Dec 2021 21:53:25 -0800
Message-ID: <CAA03e5H6TxcL6WVYcBs5aX5zHLB=sCYcrBLggAtmLZADn_BHyA@mail.gmail.com>
Subject: Re: [PATCH 3/3] selftests: sev_migrate_tests: Add mirror command tests
To:     Peter Gonda <pgonda@google.com>
Cc:     linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
        Paolo Bonzini <pbonzini@redhat.com>,
        Sean Christopherson <seanjc@google.com>
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On Wed, Dec 8, 2021 at 11:16 AM Peter Gonda <pgonda@google.com> wrote:
>
> Add tests to confirm mirror vms can only run correct subset of commands.
>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Sean Christopherson <seanjc@google.com>
> Cc: Marc Orr <marcorr@google.com>
> Signed-off-by: Peter Gonda <pgonda@google.com>
> ---
>  .../selftests/kvm/x86_64/sev_migrate_tests.c  | 55 +++++++++++++++++--
>  1 file changed, 51 insertions(+), 4 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 4bb960ca6486..80056bbbb003 100644
> --- a/tools/testing/selftests/kvm/x86_64/sev_migrate_tests.c
> +++ b/tools/testing/selftests/kvm/x86_64/sev_migrate_tests.c
> @@ -21,7 +21,7 @@
>  #define NR_LOCK_TESTING_THREADS 3
>  #define NR_LOCK_TESTING_ITERATIONS 10000
>
> -static void sev_ioctl(int vm_fd, int cmd_id, void *data)
> +static int __sev_ioctl(int vm_fd, int cmd_id, void *data, __u32 *fw_error)
>  {
>         struct kvm_sev_cmd cmd = {
>                 .id = cmd_id,
> @@ -30,11 +30,20 @@ static void sev_ioctl(int vm_fd, int cmd_id, void *data)
>         };
>         int ret;
>
> -
>         ret = ioctl(vm_fd, KVM_MEMORY_ENCRYPT_OP, &cmd);
> -       TEST_ASSERT(ret == 0 && cmd.error == SEV_RET_SUCCESS,
> +       *fw_error = cmd.error;
> +       return ret;
> +}
> +
> +static void sev_ioctl(int vm_fd, int cmd_id, void *data)
> +{
> +       int ret;
> +       __u32 fw_error;
> +
> +       ret = __sev_ioctl(vm_fd, cmd_id, data, &fw_error);
> +       TEST_ASSERT(ret == 0 && fw_error == SEV_RET_SUCCESS,
>                     "%d failed: return code: %d, errno: %d, fw error: %d",
> -                   cmd_id, ret, errno, cmd.error);
> +                   cmd_id, ret, errno, fw_error);
>  }
>
>  static struct kvm_vm *sev_vm_create(bool es)
> @@ -226,6 +235,42 @@ static void sev_mirror_create(int dst_fd, int src_fd)
>         TEST_ASSERT(!ret, "Copying context failed, ret: %d, errno: %d\n", ret, errno);
>  }
>
> +static void verify_mirror_allowed_cmds(int vm_fd)
> +{
> +       struct kvm_sev_guest_status status;
> +
> +       for (int cmd_id = KVM_SEV_INIT; cmd_id < KVM_SEV_NR_MAX; ++cmd_id) {
> +               int ret;
> +               __u32 fw_error;
> +
> +               /*
> +                * These commands are allowed for mirror VMs, all others are
> +                * not.
> +                */
> +               switch (cmd_id) {
> +               case KVM_SEV_LAUNCH_UPDATE_VMSA:
> +               case KVM_SEV_GUEST_STATUS:
> +               case KVM_SEV_DBG_DECRYPT:
> +               case KVM_SEV_DBG_ENCRYPT:
> +                       continue;
> +               default:
> +                       break;
> +               }
> +
> +               /*
> +                * These commands should be disallowed before the data
> +                * parameter is examined so NULL is OK here.
> +                */
> +               ret = __sev_ioctl(vm_fd, cmd_id, NULL, &fw_error);
> +               TEST_ASSERT(
> +                       ret == -1 && errno == EINVAL,
> +                       "Should not be able call command: %d. ret: %d, errno: %d\n",
> +                       cmd_id, ret, errno);
> +       }
> +
> +       sev_ioctl(vm_fd, KVM_SEV_GUEST_STATUS, &status);

Why is this here? I'd either delete it or maybe alternatively move it
into the `case KVM_SEV_GUEST_STATUS` with a corresponding TEST_ASSERT
to check that the command succeeded. Something like:

...
               switch (cmd_id) {
               case KVM_SEV_GUEST_STATUS:
                    sev_ioctl(vm_fd, KVM_SEV_GUEST_STATUS, &status);
                    TEST_ASSERT(ret == 0 && fw_error == SEV_RET_SUCCESS, ...);
                    continue;
               case KVM_SEV_LAUNCH_UPDATE_VMSA:
               case KVM_SEV_DBG_DECRYPT:
               case KVM_SEV_DBG_ENCRYPT:
                       continue;
               default:
                       break;
               }

> +}
> +
>  static void test_sev_mirror(bool es)
>  {
>         struct kvm_vm *src_vm, *dst_vm;
> @@ -243,6 +288,8 @@ static void test_sev_mirror(bool es)
>         if (es)
>                 sev_ioctl(dst_vm->fd, KVM_SEV_LAUNCH_UPDATE_VMSA, NULL);
>
> +       verify_mirror_allowed_cmds(dst_vm->fd);
> +
>         kvm_vm_free(src_vm);
>         kvm_vm_free(dst_vm);
>  }
> --
> 2.34.1.400.ga245620fadb-goog
>