On 16/05/2020 00.20, Collin Walling wrote:
> The start of the CPU entry region in the Read SCP Info response data is
> denoted by the offset_cpu field. As such, QEMU needs to begin creating
> entries at this address. Note that the length of the Read SCP Info data
> (data_len) denotes the same value as the cpu offset.
>
> This is in preparation of when Read SCP Info inevitably introduces new
> bytes that push the start of the CPUEntry field further away.
>
> Read CPU Info is unlikely to ever change, so let's not bother
> accounting for the offset there.
>
> Signed-off-by: Collin Walling <walling@linux.ibm.com>
> ---
> hw/s390x/sclp.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/hw/s390x/sclp.c b/hw/s390x/sclp.c
> index 5d6e98ae64..755f5f3fab 100644
> --- a/hw/s390x/sclp.c
> +++ b/hw/s390x/sclp.c
> @@ -113,13 +113,14 @@ static void read_SCP_info(SCLPDevice *sclp, SCCB *sccb)
> int rnsize, rnmax;
> IplParameterBlock *ipib = s390_ipl_get_iplb();
> int data_len = get_read_scp_info_data_len();
> + CPUEntry *entries_start = (void *)sccb + data_len;
>
> if (!sccb_has_sufficient_len(sccb, machine->possible_cpus->len, data_len)) {
> return;
> }
>
> /* CPU information */
> - prepare_cpu_entries(machine, read_info->entries, &cpu_count);
> + prepare_cpu_entries(machine, entries_start, &cpu_count);
> read_info->entries_cpu = cpu_to_be16(cpu_count);
> read_info->offset_cpu = cpu_to_be16(data_len);
> read_info->highest_cpu = cpu_to_be16(machine->smp.max_cpus - 1);
>
Reviewed-by: Thomas Huth <thuth@redhat.com>