On Fri, 14 Aug 2020 16:39:33 -0500
Babu Moger <babu.mo...@amd.com> wrote:
> Update the EPYC topology to use socket/dies/core/thread model. The EPYC
> model does not use the smp dies to build the topology. Instead, it uses
> numa nodes to build the topology. Internally both are similar concept
> which divides the cores on L3 boundary. Combining both into one terminology
> makes it simple to program.
>
> Add a new check to error out when smp dies are not provided when EPYC
> model is numa configured. Next task is to remove node_id, nr_nodes and
> nodes_per_pkg from EPYC topology which will be done in next patch.
>
> Signed-off-by: Babu Moger <babu.mo...@amd.com>
> ---
> hw/i386/x86.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/hw/i386/x86.c b/hw/i386/x86.c
> index 67bee1bcb8..e90c42d2fc 100644
> --- a/hw/i386/x86.c
> +++ b/hw/i386/x86.c
> @@ -138,6 +138,14 @@ void x86_cpus_init(X86MachineState *x86ms, int
> default_cpu_version)
>
> /* Check for apicid encoding */
> if (cpu_x86_use_epyc_apic_id_encoding(ms->cpu_type)) {
> + if ((ms->numa_state->num_nodes > 0) &&
> + ms->numa_state->num_nodes != (ms->smp.sockets *
> x86ms->smp_dies)) {
this case is gated by (ms->numa_state->num_nodes > 0) so it won't work in case
-smp dies=>1 but there is no -numa options at all
we need to error out and ask to provide numa nodes corresponding to
(ms->numa_state->num_nodes == 0) && (ms->smp.sockets * x86ms->smp_dies)
or better alternative would be to enable autonuma when EPYC cpu is enabled,
that will insure that this patch will work even if user hasn't specified -numa
option,
since it will create a single numa node automatically.
The later will take care of (-smp 1,dies=1) case, which is broken due to
lack of explicit -numa we end up with CPU_UNSET_NUMA_NODE_ID in
CPUID_Fn8000001E_ECX.
> + error_setg(&error_fatal, "Numa configuration here requires smp "
> + "'dies' parameter. Configure the cpu topology
> properly "
> + "with max_cpus = sockets * dies * cores * threads.
> Dies"
> + " is equivalent to number of numa nodes in a
> socket.");
> + return;
> + }
> x86_set_epyc_topo_handlers(ms);
> }
>
>
