Re: [PATCH v7 2/3] KVM: selftests: Carve out helper to create "default" VM without vCPUs

[Sean Christopherson <seanjc@google.com>]

On Tue, Feb 15, 2022, David Dunn wrote:
> Carve out portion of vm_create_default so that selftests can modify
> a "default" VM prior to creating vcpus.
> 
> Signed-off-by: David Dunn <daviddunn@google.com>
> ---
>  .../selftests/kvm/include/kvm_util_base.h     |  3 ++
>  tools/testing/selftests/kvm/lib/kvm_util.c    | 35 +++++++++++++++----
>  2 files changed, 32 insertions(+), 6 deletions(-)
> 
> diff --git a/tools/testing/selftests/kvm/include/kvm_util_base.h b/tools/testing/selftests/kvm/include/kvm_util_base.h
> index 4ed6aa049a91..f987cf7c0d2e 100644
> --- a/tools/testing/selftests/kvm/include/kvm_util_base.h
> +++ b/tools/testing/selftests/kvm/include/kvm_util_base.h
> @@ -336,6 +336,9 @@ struct kvm_vm *vm_create_with_vcpus(enum vm_guest_mode mode, uint32_t nr_vcpus,
>  				    uint32_t num_percpu_pages, void *guest_code,
>  				    uint32_t vcpuids[]);
>  
> +/* Create a default VM without any vcpus. */
> +struct kvm_vm *vm_create_without_vcpus(enum vm_guest_mode mode, uint64_t pages);
> +
>  /*
>   * Adds a vCPU with reasonable defaults (e.g. a stack)
>   *
> diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
> index d8cf851ab119..5aea7734cfe3 100644
> --- a/tools/testing/selftests/kvm/lib/kvm_util.c
> +++ b/tools/testing/selftests/kvm/lib/kvm_util.c
> @@ -362,6 +362,34 @@ struct kvm_vm *vm_create(enum vm_guest_mode mode, uint64_t phy_pages, int perm)
>  	return vm;
>  }
>  
> +/*
> + * Default VM creation without creating VCPUs
> + *
> + * Input Args:
> + *   mode - VM Mode (e.g. VM_MODE_P52V48_4K)
> + *   pages - pages of memory required for VM
> + *
> + * Output Args: None
> + *
> + * Return:
> + *   Pointer to opaque structure that describes the created VM.
> + *
> + * Creates a VM with the mode specified by mode (e.g. VM_MODE_P52V48_4K).
> + */

I vote to omit this function comment.  Most of the existing comments in kvm_util.c
are a waste of space, and (no offence) this is no different.  And I'm planning on
deleting most of the existing boilerplate comments that don't provide any insight :-)

> +struct kvm_vm *vm_create_without_vcpus(enum vm_guest_mode mode, uint64_t pages)
> +{
> +	struct kvm_vm *vm;
> +
> +	vm = vm_create(mode, pages, O_RDWR);
> +
> +	kvm_vm_elf_load(vm, program_invocation_name);
> +
> +#ifdef __x86_64__
> +	vm_create_irqchip(vm);
> +#endif
> +	return vm;
> +}
> +
>  /*
>   * VM Create with customized parameters
>   *
> @@ -412,13 +440,8 @@ struct kvm_vm *vm_create_with_vcpus(enum vm_guest_mode mode, uint32_t nr_vcpus,
>  		    nr_vcpus, kvm_check_cap(KVM_CAP_MAX_VCPUS));
>  
>  	pages = vm_adjust_num_guest_pages(mode, pages);
> -	vm = vm_create(mode, pages, O_RDWR);
> -
> -	kvm_vm_elf_load(vm, program_invocation_name);
>  
> -#ifdef __x86_64__
> -	vm_create_irqchip(vm);
> -#endif
> +	vm = vm_create_without_vcpus(mode, pages);
>  
>  	for (i = 0; i < nr_vcpus; ++i) {
>  		uint32_t vcpuid = vcpuids ? vcpuids[i] : i;
> -- 
> 2.35.1.265.g69c8d7142f-goog
>