Re: [PATCH v2 5/9] KVM: s390: pv: Add query dump information

[Claudio Imbrenda <imbrenda@linux.ibm.com>]

On Thu, 10 Mar 2022 10:31:08 +0000
Janosch Frank <frankja@linux.ibm.com> wrote:

> The dump API requires userspace to provide buffers into which we will
> store data. The dump information added in this patch tells userspace
> how big those buffers need to be.

it seems this has the same issue as the other patch.

if userspace gives a smaller buffer, as much data as possible should be
written into it

> 
> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
> ---
>  arch/s390/kvm/kvm-s390.c | 11 +++++++++++
>  include/uapi/linux/kvm.h | 12 +++++++++++-
>  2 files changed, 22 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index 67e1e445681f..c388d08b9626 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -2255,6 +2255,17 @@ static ssize_t kvm_s390_handle_pv_info(struct kvm_s390_pv_info *info)
>  
>  		return len;
>  	}
> +	case KVM_PV_INFO_DUMP: {
> +		len =  sizeof(info->header) + sizeof(info->dump);
> +
> +		if (info->header.len_max < len)
> +			return -EINVAL;
> +
> +		info->dump.dump_cpu_buffer_len = uv_info.guest_cpu_stor_len;
> +		info->dump.dump_config_mem_buffer_per_1m = uv_info.conf_dump_storage_state_len;
> +		info->dump.dump_config_finalize_len = uv_info.conf_dump_finalize_len;
> +		return len;
> +	}
>  	default:
>  		return -EINVAL;
>  	}
> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> index 21f19863c417..eed2ae8397ae 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -1645,6 +1645,13 @@ struct kvm_s390_pv_unp {
>  
>  enum pv_cmd_info_id {
>  	KVM_PV_INFO_VM,
> +	KVM_PV_INFO_DUMP,
> +};
> +
> +struct kvm_s390_pv_info_dump {
> +	__u64 dump_cpu_buffer_len;
> +	__u64 dump_config_mem_buffer_per_1m;
> +	__u64 dump_config_finalize_len;
>  };
>  
>  struct kvm_s390_pv_info_vm {
> @@ -1664,7 +1671,10 @@ struct kvm_s390_pv_info_header {
>  
>  struct kvm_s390_pv_info {
>  	struct kvm_s390_pv_info_header header;
> -	struct kvm_s390_pv_info_vm vm;
> +	union {
> +		struct kvm_s390_pv_info_dump dump;
> +		struct kvm_s390_pv_info_vm vm;
> +	};
>  };
>  
>  enum pv_cmd_id {