Re: [PATCH v2 2/5] KVM: selftests: Introduce UCALL_UNHANDLED for unhandled vector reporting

[Auger Eric <eric.auger@redhat.com>]

Hi Ricardo,

On 5/3/21 1:09 PM, Andrew Jones wrote:
> On Fri, Apr 30, 2021 at 04:24:04PM -0700, Ricardo Koller wrote:
>> x86, the only arch implementing exception handling, reports unhandled
>> vectors using port IO at a specific port number. This replicates what
>> ucall already does.
>>
>> Introduce a new ucall type, UCALL_UNHANDLED, for guests to report
>> unhandled exceptions. Then replace the x86 unhandled vector exception
>> reporting to use it instead of port IO.  This new ucall type will be
>> used in the next commits by arm64 to report unhandled vectors as well.
>>
>> Tested: Forcing a page fault in the ./x86_64/xapic_ipi_test
>> 	halter_guest_code() shows this:
>>
>> 	$ ./x86_64/xapic_ipi_test
>> 	...
>> 	  Unexpected vectored event in guest (vector:0xe)
>>
>> Signed-off-by: Ricardo Koller <ricarkol@google.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>

Eric

>> ---
>>  tools/testing/selftests/kvm/include/kvm_util.h    |  1 +
>>  .../selftests/kvm/include/x86_64/processor.h      |  2 --
>>  .../testing/selftests/kvm/lib/x86_64/processor.c  | 15 ++++++---------
>>  3 files changed, 7 insertions(+), 11 deletions(-)
>>
>> diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
>> index bea4644d645d..7880929ea548 100644
>> --- a/tools/testing/selftests/kvm/include/kvm_util.h
>> +++ b/tools/testing/selftests/kvm/include/kvm_util.h
>> @@ -347,6 +347,7 @@ enum {
>>  	UCALL_SYNC,
>>  	UCALL_ABORT,
>>  	UCALL_DONE,
>> +	UCALL_UNHANDLED,
>>  };
>>  
>>  #define UCALL_MAX_ARGS 6
>> diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h b/tools/testing/selftests/kvm/include/x86_64/processor.h
>> index 12889d3e8948..ff4da2f95b13 100644
>> --- a/tools/testing/selftests/kvm/include/x86_64/processor.h
>> +++ b/tools/testing/selftests/kvm/include/x86_64/processor.h
>> @@ -53,8 +53,6 @@
>>  #define CPUID_PKU		(1ul << 3)
>>  #define CPUID_LA57		(1ul << 16)
>>  
>> -#define UNEXPECTED_VECTOR_PORT 0xfff0u
>> -
>>  /* General Registers in 64-Bit Mode */
>>  struct gpr64_regs {
>>  	u64 rax;
>> diff --git a/tools/testing/selftests/kvm/lib/x86_64/processor.c b/tools/testing/selftests/kvm/lib/x86_64/processor.c
>> index e156061263a6..96e2bd9d66eb 100644
>> --- a/tools/testing/selftests/kvm/lib/x86_64/processor.c
>> +++ b/tools/testing/selftests/kvm/lib/x86_64/processor.c
>> @@ -1207,7 +1207,7 @@ static void set_idt_entry(struct kvm_vm *vm, int vector, unsigned long addr,
>>  
>>  void kvm_exit_unexpected_vector(uint32_t value)
>>  {
>> -	outl(UNEXPECTED_VECTOR_PORT, value);
>> +	ucall(UCALL_UNHANDLED, 1, value);
>>  }
>>  
>>  void route_exception(struct ex_regs *regs)
>> @@ -1260,16 +1260,13 @@ void vm_install_vector_handler(struct kvm_vm *vm, int vector,
>>  
>>  void assert_on_unhandled_exception(struct kvm_vm *vm, uint32_t vcpuid)
>>  {
>> -	if (vcpu_state(vm, vcpuid)->exit_reason == KVM_EXIT_IO
>> -		&& vcpu_state(vm, vcpuid)->io.port == UNEXPECTED_VECTOR_PORT
>> -		&& vcpu_state(vm, vcpuid)->io.size == 4) {
>> -		/* Grab pointer to io data */
>> -		uint32_t *data = (void *)vcpu_state(vm, vcpuid)
>> -			+ vcpu_state(vm, vcpuid)->io.data_offset;
>> +	struct ucall uc;
>>  
>> +	if (get_ucall(vm, vcpuid, &uc) == UCALL_UNHANDLED) {
>> +		uint64_t vector = uc.args[0];
>>  		TEST_ASSERT(false,
>> -			    "Unexpected vectored event in guest (vector:0x%x)",
>> -			    *data);
>> +			    "Unexpected vectored event in guest (vector:0x%lx)",
>> +			    vector);
> 
> nit: Could have changed this TEST_ASSERT(false, ...) to TEST_FAIL while
> touching it.
> 
>>  	}
>>  }
>>  
>> -- 
>> 2.31.1.527.g47e6f16901-goog
>>
> 
> Reviewed-by: Andrew Jones <drjones@redhat.com>
> 
> Thanks,
> drew
>