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

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Date:   Mon, 27 Jan 2020 10:01:43 +0100
From:   Thomas Huth <thuth@...hat.com>
To:     Ben Gardon <bgardon@...gle.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, linux-kselftest@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Cannon Matthews <cannonmatthews@...gle.com>,
        Peter Xu <peterx@...hat.com>,
        Andrew Jones <drjones@...hat.com>,
        Peter Shier <pshier@...gle.com>,
        Oliver Upton <oupton@...gle.com>
Subject: Re: [PATCH v4 06/10] KVM: selftests: Add support for vcpu_args_set to
 aarch64 and s390x

On 23/01/2020 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.
> 
> 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/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;

You need an "int i;" here to make it compile.

> +	TEST_ASSERT(num >= 1 && num <= 5, "Unsupported number of args,\n"

why the "\n" right in the middle of the string? Could you please make it
one-line only?

> +		    "  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);
> +}

... but apart from the nits, this looks basically sane to me.

 Thomas