Re: [PATCH v4 18/21] kvm: x86: Add support for getting/setting expanded xstate buffer

[Sean Christopherson <seanjc@xxxxxxxxxx>]

On Wed, Dec 29, 2021, Yang Zhong wrote:
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index bdf89c28d2ce..76e1941db223 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -4296,6 +4296,11 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>  		else
>  			r = 0;
>  		break;
> +	case KVM_CAP_XSAVE2:
> +		r = kvm->vcpus[0]->arch.guest_fpu.uabi_size;

a) This does not compile against kvm/queue.

   arch/x86/kvm/x86.c: In function ‘kvm_vm_ioctl_check_extension’:
   arch/x86/kvm/x86.c:4317:24: error: ‘struct kvm’ has no member named ‘vcpus’
    4317 |                 r = kvm->vcpus[0]->arch.guest_fpu.uabi_size;

b) vcpu0 is not guaranteed to be non-NULL at this point.

> +		if (r < sizeof(struct kvm_xsave))
> +			r = sizeof(struct kvm_xsave);
> +		break;
>  	default:
>  		break;
>  	}