linux-kernel - Re: [PATCH v4 06/10] KVM: selftests: Add support for vcpu_args

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Message-ID: <3fd470e0-2929-c3fc-151a-ef2d682354d9@redhat.com>
Date:   Fri, 24 Jan 2020 10:44:24 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Andrew Jones <drjones@...hat.com>
Cc:     Ben Gardon <bgardon@...gle.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, linux-kselftest@...r.kernel.org,
        Cannon Matthews <cannonmatthews@...gle.com>,
        Peter Xu <peterx@...hat.com>, Peter Shier <pshier@...gle.com>,
        Oliver Upton <oupton@...gle.com>,
        Marc Zyngier <Marc.Zyngier@....com>,
        Cornelia Huck <cohuck@...hat.com>,
        Christian Borntraeger <borntraeger@...ibm.com>
Subject: Re: [PATCH v4 06/10] KVM: selftests: Add support for vcpu_args_set to
 aarch64 and s390x

On 24/01/20 10:35, Andrew Jones wrote:
> On Fri, Jan 24, 2020 at 10:03:08AM +0100, Paolo Bonzini wrote:
>> CCing Marc, Conny and Christian (plus Thomas and Drew who were already
>> in the list) for review.
>>
>> Thanks,
>>
>> Paolo
>>
>> On 23/01/20 19:04, Ben Gardon wrote:
>>> Currently vcpu_args_set is only implemented for x86. This makes writing
>>> tests with multiple vCPUs difficult as each guest vCPU must either a.)
>>> do the same thing or b.) derive some kind of unique token from it's
>>> registers or the architecture. To simplify the process of writing tests
>>> with multiple vCPUs for s390 and aarch64, add set args functions for
>>> those architectures.
> 
> It'd be nice to keep the separate architecture changes in separate
> patches. Otherwise I can't really give an r-b.

You can say:

For ARM parts:

Reviewed-by: ...

Paolo

>>>
>>> Signed-off-by: Ben Gardon <bgardon@...gle.com>
>>> ---
>>>  .../selftests/kvm/lib/aarch64/processor.c     | 33 +++++++++++++++++
>>>  .../selftests/kvm/lib/s390x/processor.c       | 35 +++++++++++++++++++
>>>  2 files changed, 68 insertions(+)
>>>
>>> diff --git a/tools/testing/selftests/kvm/lib/aarch64/processor.c b/tools/testing/selftests/kvm/lib/aarch64/processor.c
>>> index 86036a59a668e..a2ff90a75f326 100644
>>> --- a/tools/testing/selftests/kvm/lib/aarch64/processor.c
>>> +++ b/tools/testing/selftests/kvm/lib/aarch64/processor.c
>>> @@ -333,3 +333,36 @@ void vm_vcpu_add_default(struct kvm_vm *vm, uint32_t vcpuid, void *guest_code)
>>>  {
>>>  	aarch64_vcpu_add_default(vm, vcpuid, NULL, guest_code);
>>>  }
>>> +
>>> +/* VM VCPU Args Set
>>> + *
>>> + * Input Args:
>>> + *   vm - Virtual Machine
>>> + *   vcpuid - VCPU ID
>>> + *   num - number of arguments
>>> + *   ... - arguments, each of type uint64_t
>>> + *
>>> + * Output Args: None
>>> + *
>>> + * Return: None
>>> + *
>>> + * Sets the first num function input arguments to the values
>>> + * given as variable args.  Each of the variable args is expected to
>>> + * be of type uint64_t. The registers set by this function are r0-r7.
>>> + */
> 
> lib/aarch64/processor.c so far doesn't have big function headers like
> this. Also, since this function is common for all architectures [now],
> I feel like the documentation should be in common code - so in the header
> file.
> 
>>> +void vcpu_args_set(struct kvm_vm *vm, uint32_t vcpuid, unsigned int num, ...)
>>> +{
>>> +	va_list ap;
>>> +
>>> +	TEST_ASSERT(num >= 1 && num <= 8, "Unsupported number of args,\n"
>>> +		    "  num: %u\n",
>>> +		    num);
> 
> Weird line breaking. I see it came from the x86 implementation, but it's
> weird there too... Personally I'd just put it all on one line, because
> my vt100 died two decades ago.
> 
>>> +
>>> +	va_start(ap, num);
>>> +
>>> +	for (i = 0; i < num; i++)
>>> +		set_reg(vm, vcpuid, ARM64_CORE_REG(regs.regs[num]),
>                                                              ^^ should be 'i'
> 
>>> +			va_arg(ap, uint64_t));
> 
> nit: I'd use {} because of the line break. Or just not break the line and
> bust the 80 char "limit" (RIP vt100).
> 
> Thanks,
> drew
> 
>>> +
>>> +	va_end(ap);
>>> +}
>>> diff --git a/tools/testing/selftests/kvm/lib/s390x/processor.c b/tools/testing/selftests/kvm/lib/s390x/processor.c
>>> index 32a02360b1eb0..680f37be9dbc9 100644
>>> --- a/tools/testing/selftests/kvm/lib/s390x/processor.c
>>> +++ b/tools/testing/selftests/kvm/lib/s390x/processor.c
>>> @@ -269,6 +269,41 @@ void vm_vcpu_add_default(struct kvm_vm *vm, uint32_t vcpuid, void *guest_code)
>>>  	run->psw_addr = (uintptr_t)guest_code;
>>>  }
>>>  
>>> +/* VM VCPU Args Set
>>> + *
>>> + * Input Args:
>>> + *   vm - Virtual Machine
>>> + *   vcpuid - VCPU ID
>>> + *   num - number of arguments
>>> + *   ... - arguments, each of type uint64_t
>>> + *
>>> + * Output Args: None
>>> + *
>>> + * Return: None
>>> + *
>>> + * Sets the first num function input arguments to the values
>>> + * given as variable args.  Each of the variable args is expected to
>>> + * be of type uint64_t. The registers set by this function are r2-r6.
>>> + */
>>> +void vcpu_args_set(struct kvm_vm *vm, uint32_t vcpuid, unsigned int num, ...)
>>> +{
>>> +	va_list ap;
>>> +	struct kvm_regs regs;
>>> +
>>> +	TEST_ASSERT(num >= 1 && num <= 5, "Unsupported number of args,\n"
>>> +		    "  num: %u\n",
>>> +		    num);
>>> +
>>> +	va_start(ap, num);
>>> +	vcpu_regs_get(vm, vcpuid, &regs);
>>> +
>>> +	for (i = 0; i < num; i++)
>>> +		regs.gprs[i + 2] = va_arg(ap, uint64_t);
>>> +
>>> +	vcpu_regs_set(vm, vcpuid, &regs);
>>> +	va_end(ap);
>>> +}
>>> +
>>>  void vcpu_dump(FILE *stream, struct kvm_vm *vm, uint32_t vcpuid, uint8_t indent)
>>>  {
>>>  	struct vcpu *vcpu = vm->vcpu_head;
>>>
>>
>