Re: [PATCH v2 3/8] KVM: selftests: Delete dead ucall code

[Sean Christopherson <seanjc@xxxxxxxxxx>]

On Tue, Oct 18, 2022, David Matlack wrote:
> Delete a bunch of code related to ucall handling from
> smaller_maxphyaddr_emulation_test. The only thing
> smaller_maxphyaddr_emulation_test needs to check is that the vCPU exits
> with UCALL_DONE after the second vcpu_run().
> 
> Signed-off-by: David Matlack <dmatlack@xxxxxxxxxx>
> ---
>  .../smaller_maxphyaddr_emulation_test.c       | 54 +------------------
>  1 file changed, 2 insertions(+), 52 deletions(-)
> 
> diff --git a/tools/testing/selftests/kvm/x86_64/smaller_maxphyaddr_emulation_test.c b/tools/testing/selftests/kvm/x86_64/smaller_maxphyaddr_emulation_test.c
> index c5353ad0e06d..d6e71549ca08 100644
> --- a/tools/testing/selftests/kvm/x86_64/smaller_maxphyaddr_emulation_test.c
> +++ b/tools/testing/selftests/kvm/x86_64/smaller_maxphyaddr_emulation_test.c
> @@ -90,64 +90,15 @@ static void process_exit_on_emulation_error(struct kvm_vcpu *vcpu)
>  	vcpu_regs_set(vcpu, &regs);
>  }
>  
> -static void do_guest_assert(struct ucall *uc)
> -{
> -	REPORT_GUEST_ASSERT(*uc);
> -}
> -
> -static void check_for_guest_assert(struct kvm_vcpu *vcpu)
> +static void assert_ucall_done(struct kvm_vcpu *vcpu)

I vote to delete this helper too, it's used exactly once and doesn't exactly make
the code more readable.

>  	TEST_ASSERT(get_ucall(vcpu, &uc) == UCALL_DONE,
>  		    "Unexpected ucall command: %lu, expected UCALL_DONE (%d)",
>  		    uc.cmd, UCALL_DONE);

I believe the warning is due to gcc resolving the VA args inputs to test_assert()
before the call to get_ucall().  One thought:

  uint64_t cmd = get_ucall(vcpu, NULL);

  TEST_ASSERT(cmd == UCALL_DONE, ...)

In file included from x86_64/smaller_maxphyaddr_emulation_test.c:11:
include/test_util.h: In function ‘assert_ucall_done’:
include/test_util.h:54:9: warning: ‘uc.cmd’ is used uninitialized [-Wuninitialized]
   54 |         test_assert((e), #e, __FILE__, __LINE__, fmt, ##__VA_ARGS__)
      |         ^~~~~~~~~~~
x86_64/smaller_maxphyaddr_emulation_test.c:69:22: note: ‘uc’ declared here
   69 |         struct ucall uc;
      |                      ^~