spapr: Add a new level of NUMA for GPUs

NUMA nodes corresponding to GPU memory currently have the same
affinity/distance as normal memory nodes. Add a third NUMA associativity
reference point enabling us to give GPU nodes more distance.

This is guest visible information, which shouldn't change under a
running guest across migration between different qemu versions, so make
the change effective only in new (pseries > 5.0) machine types.

Before, `numactl -H` output in a guest with 4 GPUs (nodes 2-5):

node distances:
node   0   1   2   3   4   5
  0:  10  40  40  40  40  40
  1:  40  10  40  40  40  40
  2:  40  40  10  40  40  40
  3:  40  40  40  10  40  40
  4:  40  40  40  40  10  40
  5:  40  40  40  40  40  10

After:

node distances:
node   0   1   2   3   4   5
  0:  10  40  80  80  80  80
  1:  40  10  80  80  80  80
  2:  80  80  10  80  80  80
  3:  80  80  80  10  80  80
  4:  80  80  80  80  10  80
  5:  80  80  80  80  80  10

These are the same distances as on the host, mirroring the change made
to host firmware in skiboot commit f845a648b8cb ("numa/associativity:
Add a new level of NUMA for GPU's").

Signed-off-by: Reza Arbab <arbab@linux.ibm.com>
Message-Id: <20200716225655.24289-1-arbab@linux.ibm.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

1 files changed, 19 insertions, 2 deletions

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 299908c..0ae293e 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -890,10 +890,16 @@ static int spapr_dt_rng(void *fdt)
 static void spapr_dt_rtas(SpaprMachineState *spapr, void *fdt)
 {
     MachineState *ms = MACHINE(spapr);
+    SpaprMachineClass *smc = SPAPR_MACHINE_GET_CLASS(ms);
     int rtas;
     GString *hypertas = g_string_sized_new(256);
     GString *qemu_hypertas = g_string_sized_new(256);
-    uint32_t refpoints[] = { cpu_to_be32(0x4), cpu_to_be32(0x4) };
+    uint32_t refpoints[] = {
+        cpu_to_be32(0x4),
+        cpu_to_be32(0x4),
+        cpu_to_be32(0x2),
+    };
+    uint32_t nr_refpoints = ARRAY_SIZE(refpoints);
     uint64_t max_device_addr = MACHINE(spapr)->device_memory->base +
         memory_region_size(&MACHINE(spapr)->device_memory->mr);
     uint32_t lrdr_capacity[] = {
@@ -945,8 +951,12 @@ static void spapr_dt_rtas(SpaprMachineState *spapr, void *fdt)
                      qemu_hypertas->str, qemu_hypertas->len));
     g_string_free(qemu_hypertas, TRUE);
 
+    if (smc->pre_5_1_assoc_refpoints) {
+        nr_refpoints = 2;
+    }
+
     _FDT(fdt_setprop(fdt, rtas, "ibm,associativity-reference-points",
-                     refpoints, sizeof(refpoints)));
+                     refpoints, nr_refpoints * sizeof(refpoints[0])));
 
     _FDT(fdt_setprop(fdt, rtas, "ibm,max-associativity-domains",
                      maxdomains, sizeof(maxdomains)));
@@ -4584,9 +4594,16 @@ DEFINE_SPAPR_MACHINE(5_1, "5.1", true);
  */
 static void spapr_machine_5_0_class_options(MachineClass *mc)
 {
+    SpaprMachineClass *smc = SPAPR_MACHINE_CLASS(mc);
+    static GlobalProperty compat[] = {
+        { TYPE_SPAPR_PCI_HOST_BRIDGE, "pre-5.1-associativity", "on" },
+    };
+
     spapr_machine_5_1_class_options(mc);
     compat_props_add(mc->compat_props, hw_compat_5_0, hw_compat_5_0_len);
+    compat_props_add(mc->compat_props, compat, G_N_ELEMENTS(compat));
     mc->numa_mem_supported = true;
+    smc->pre_5_1_assoc_refpoints = true;
 }
 
 DEFINE_SPAPR_MACHINE(5_0, "5.0", false);