spapr_numa.c: FORM2 NUMA affinity support

The main feature of FORM2 affinity support is the separation of NUMA
distances from ibm,associativity information. This allows for a more
flexible and straightforward NUMA distance assignment without relying on
complex associations between several levels of NUMA via
ibm,associativity matches. Another feature is its extensibility. This base
support contains the facilities for NUMA distance assignment, but in the
future more facilities will be added for latency, performance, bandwidth
and so on.

This patch implements the base FORM2 affinity support as follows:

- the use of FORM2 associativity is indicated by using bit 2 of byte 5
of ibm,architecture-vec-5. A FORM2 aware guest can choose to use FORM1
or FORM2 affinity. Setting both forms will default to FORM2. We're not
advertising FORM2 for pseries-6.1 and older machine versions to prevent
guest visible changes in those;

- ibm,associativity-reference-points has a new semantic. Instead of
being used to calculate distances via NUMA levels, it's now used to
indicate the primary domain index in the ibm,associativity domain of
each resource. In our case it's set to {0x4}, matching the position
where we already place logical_domain_id;

- two new RTAS DT artifacts are introduced: ibm,numa-lookup-index-table
and ibm,numa-distance-table. The index table is used to list all the
NUMA logical domains of the platform, in ascending order, and allows for
spartial NUMA configurations (although QEMU ATM doesn't support that).
ibm,numa-distance-table is an array that contains all the distances from
the first NUMA node to all other nodes, then the second NUMA node
distances to all other nodes and so on;

- get_max_dist_ref_points(), get_numa_assoc_size() and get_associativity()
now checks for OV5_FORM2_AFFINITY and returns FORM2 values if the guest
selected FORM2 affinity during CAS.

Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Message-Id: <20210920174947.556324-7-danielhb413@gmail.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

2 files changed, 154 insertions, 0 deletions

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 524951d..b7bee5f 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -2753,6 +2753,11 @@ static void spapr_machine_init(MachineState *machine)
 
     spapr_ovec_set(spapr->ov5, OV5_FORM1_AFFINITY);
 
+    /* Do not advertise FORM2 NUMA support for pseries-6.1 and older */
+    if (!smc->pre_6_2_numa_affinity) {
+        spapr_ovec_set(spapr->ov5, OV5_FORM2_AFFINITY);
+    }
+
     /* advertise support for dedicated HP event source to guests */
     if (spapr->use_hotplug_event_source) {
         spapr_ovec_set(spapr->ov5, OV5_HP_EVT);
@@ -4675,8 +4680,11 @@ DEFINE_SPAPR_MACHINE(6_2, "6.2", true);
  */
 static void spapr_machine_6_1_class_options(MachineClass *mc)
 {
+    SpaprMachineClass *smc = SPAPR_MACHINE_CLASS(mc);
+
     spapr_machine_6_2_class_options(mc);
     compat_props_add(mc->compat_props, hw_compat_6_1, hw_compat_6_1_len);
+    smc->pre_6_2_numa_affinity = true;
 }
 
 DEFINE_SPAPR_MACHINE(6_1, "6.1", false);
diff --git a/hw/ppc/spapr_numa.c b/hw/ppc/spapr_numa.c
index 6718c0f..13db321 100644
--- a/hw/ppc/spapr_numa.c
+++ b/hw/ppc/spapr_numa.c
@@ -24,6 +24,10 @@
  */
 static int get_max_dist_ref_points(SpaprMachineState *spapr)
 {
+    if (spapr_ovec_test(spapr->ov5_cas, OV5_FORM2_AFFINITY)) {
+        return FORM2_DIST_REF_POINTS;
+    }
+
     return FORM1_DIST_REF_POINTS;
 }
 
@@ -32,6 +36,10 @@ static int get_max_dist_ref_points(SpaprMachineState *spapr)
  */
 static int get_numa_assoc_size(SpaprMachineState *spapr)
 {
+    if (spapr_ovec_test(spapr->ov5_cas, OV5_FORM2_AFFINITY)) {
+        return FORM2_NUMA_ASSOC_SIZE;
+    }
+
     return FORM1_NUMA_ASSOC_SIZE;
 }
 
@@ -52,6 +60,9 @@ static int get_vcpu_assoc_size(SpaprMachineState *spapr)
  */
 static const uint32_t *get_associativity(SpaprMachineState *spapr, int node_id)
 {
+    if (spapr_ovec_test(spapr->ov5_cas, OV5_FORM2_AFFINITY)) {
+        return spapr->FORM2_assoc_array[node_id];
+    }
     return spapr->FORM1_assoc_array[node_id];
 }
 
@@ -295,14 +306,50 @@ static void spapr_numa_FORM1_affinity_init(SpaprMachineState *spapr,
     spapr_numa_define_FORM1_domains(spapr);
 }
 
+/*
+ * Init NUMA FORM2 machine state data
+ */
+static void spapr_numa_FORM2_affinity_init(SpaprMachineState *spapr)
+{
+    int i;
+
+    /*
+     * For all resources but CPUs, FORM2 associativity arrays will
+     * be a size 2 array with the following format:
+     *
+     * ibm,associativity = {1, numa_id}
+     *
+     * CPUs will write an additional 'vcpu_id' on top of the arrays
+     * being initialized here. 'numa_id' is represented by the
+     * index 'i' of the loop.
+     *
+     * Given that this initialization is also valid for GPU associativity
+     * arrays, handle everything in one single step by populating the
+     * arrays up to NUMA_NODES_MAX_NUM.
+     */
+    for (i = 0; i < NUMA_NODES_MAX_NUM; i++) {
+        spapr->FORM2_assoc_array[i][0] = cpu_to_be32(1);
+        spapr->FORM2_assoc_array[i][1] = cpu_to_be32(i);
+    }
+}
+
 void spapr_numa_associativity_init(SpaprMachineState *spapr,
                                    MachineState *machine)
 {
     spapr_numa_FORM1_affinity_init(spapr, machine);
+    spapr_numa_FORM2_affinity_init(spapr);
 }
 
 void spapr_numa_associativity_check(SpaprMachineState *spapr)
 {
+    /*
+     * FORM2 does not have any restrictions we need to handle
+     * at CAS time, for now.
+     */
+    if (spapr_ovec_test(spapr->ov5_cas, OV5_FORM2_AFFINITY)) {
+        return;
+    }
+
     spapr_numa_FORM1_affinity_check(MACHINE(spapr));
 }
 
@@ -447,6 +494,100 @@ static void spapr_numa_FORM1_write_rtas_dt(SpaprMachineState *spapr,
                      maxdomains, sizeof(maxdomains)));
 }
 
+static void spapr_numa_FORM2_write_rtas_tables(SpaprMachineState *spapr,
+                                               void *fdt, int rtas)
+{
+    MachineState *ms = MACHINE(spapr);
+    NodeInfo *numa_info = ms->numa_state->nodes;
+    int nb_numa_nodes = ms->numa_state->num_nodes;
+    int distance_table_entries = nb_numa_nodes * nb_numa_nodes;
+    g_autofree uint32_t *lookup_index_table = NULL;
+    g_autofree uint32_t *distance_table = NULL;
+    int src, dst, i, distance_table_size;
+    uint8_t *node_distances;
+
+    /*
+     * ibm,numa-lookup-index-table: array with length and a
+     * list of NUMA ids present in the guest.
+     */
+    lookup_index_table = g_new0(uint32_t, nb_numa_nodes + 1);
+    lookup_index_table[0] = cpu_to_be32(nb_numa_nodes);
+
+    for (i = 0; i < nb_numa_nodes; i++) {
+        lookup_index_table[i + 1] = cpu_to_be32(i);
+    }
+
+    _FDT(fdt_setprop(fdt, rtas, "ibm,numa-lookup-index-table",
+                     lookup_index_table,
+                     (nb_numa_nodes + 1) * sizeof(uint32_t)));
+
+    /*
+     * ibm,numa-distance-table: contains all node distances. First
+     * element is the size of the table as uint32, followed up
+     * by all the uint8 distances from the first NUMA node, then all
+     * distances from the second NUMA node and so on.
+     *
+     * ibm,numa-lookup-index-table is used by guest to navigate this
+     * array because NUMA ids can be sparse (node 0 is the first,
+     * node 8 is the second ...).
+     */
+    distance_table = g_new0(uint32_t, distance_table_entries + 1);
+    distance_table[0] = cpu_to_be32(distance_table_entries);
+
+    node_distances = (uint8_t *)&distance_table[1];
+    i = 0;
+
+    for (src = 0; src < nb_numa_nodes; src++) {
+        for (dst = 0; dst < nb_numa_nodes; dst++) {
+            node_distances[i++] = numa_info[src].distance[dst];
+        }
+    }
+
+    distance_table_size = distance_table_entries * sizeof(uint8_t) +
+                          sizeof(uint32_t);
+    _FDT(fdt_setprop(fdt, rtas, "ibm,numa-distance-table",
+                     distance_table, distance_table_size));
+}
+
+/*
+ * This helper could be compressed in a single function with
+ * FORM1 logic since we're setting the same DT values, with the
+ * difference being a call to spapr_numa_FORM2_write_rtas_tables()
+ * in the end. The separation was made to avoid clogging FORM1 code
+ * which already has to deal with compat modes from previous
+ * QEMU machine types.
+ */
+static void spapr_numa_FORM2_write_rtas_dt(SpaprMachineState *spapr,
+                                           void *fdt, int rtas)
+{
+    MachineState *ms = MACHINE(spapr);
+    uint32_t number_nvgpus_nodes = spapr->gpu_numa_id -
+                                   spapr_numa_initial_nvgpu_numa_id(ms);
+
+    /*
+     * In FORM2, ibm,associativity-reference-points will point to
+     * the element in the ibm,associativity array that contains the
+     * primary domain index (for FORM2, the first element).
+     *
+     * This value (in our case, the numa-id) is then used as an index
+     * to retrieve all other attributes of the node (distance,
+     * bandwidth, latency) via ibm,numa-lookup-index-table and other
+     * ibm,numa-*-table properties.
+     */
+    uint32_t refpoints[] = { cpu_to_be32(1) };
+
+    uint32_t maxdomain = ms->numa_state->num_nodes + number_nvgpus_nodes;
+    uint32_t maxdomains[] = { cpu_to_be32(1), cpu_to_be32(maxdomain) };
+
+    _FDT(fdt_setprop(fdt, rtas, "ibm,associativity-reference-points",
+                     refpoints, sizeof(refpoints)));
+
+    _FDT(fdt_setprop(fdt, rtas, "ibm,max-associativity-domains",
+                     maxdomains, sizeof(maxdomains)));
+
+    spapr_numa_FORM2_write_rtas_tables(spapr, fdt, rtas);
+}
+
 /*
  * Helper that writes ibm,associativity-reference-points and
  * max-associativity-domains in the RTAS pointed by @rtas
@@ -454,6 +595,11 @@ static void spapr_numa_FORM1_write_rtas_dt(SpaprMachineState *spapr,
  */
 void spapr_numa_write_rtas_dt(SpaprMachineState *spapr, void *fdt, int rtas)
 {
+    if (spapr_ovec_test(spapr->ov5_cas, OV5_FORM2_AFFINITY)) {
+        spapr_numa_FORM2_write_rtas_dt(spapr, fdt, rtas);
+        return;
+    }
+
     spapr_numa_FORM1_write_rtas_dt(spapr, fdt, rtas);
 }