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

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

On Tue, 10 May 2022 14:36:14 +0200
Janosch Frank <frankja@linux.ibm.com> wrote:

> On 5/9/22 17:28, Claudio Imbrenda wrote:
> > On Thu, 28 Apr 2022 13:00:58 +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.
> >>
> >> 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 23352d45a386..e327a5b8ef78 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_min;
> >>   	}
> >> +	case KVM_PV_INFO_DUMP: {
> >> +		len_min =  sizeof(info->header) + sizeof(info->dump);  
> > 
> > so the output will have some zero-padded stuff at the end?  
> 
> In which situation?

for example when I don't read the patch correctly (oops)

> 
> >   
> >> +
> >> +		if (info->header.len_max < len_min)
> >> +			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_min;
> >> +	}
> >>   	default:
> >>   		return -EINVAL;
> >>   	}
> >> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> >> index 59e4fb6c7a34..2eba89d7ec29 100644
> >> --- a/include/uapi/linux/kvm.h
> >> +++ b/include/uapi/linux/kvm.h
> >> @@ -1647,6 +1647,13 @@ 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 {
> >> @@ -1666,7 +1673,10 @@ 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 {  
> >   
>