[PATCH v5 3/3] spapr_numa: use spapr_numa_get_vcpu_assoc() in home_node hcall

[Daniel Henrique Barboza <danielhb413@gmail.com>]

The current implementation of h_home_node_associativity hard codes
the values of associativity domains of the vcpus. Let's make
it consider the values already initialized in spapr->numa_assoc_array,
via the spapr_numa_get_vcpu_assoc() helper.

We want to set it and forget it, and for that we also need to
assert that we don't overflow the registers of the hypercall.
From R4 to R9 we can squeeze in 12 associativity domains for
vcpus, so let's assert that VCPU_ASSOC_SIZE -1 isn't greater
than that.

Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
---
 hw/ppc/spapr_numa.c | 41 +++++++++++++++++++++++++++++++++--------
 1 file changed, 33 insertions(+), 8 deletions(-)

diff --git a/hw/ppc/spapr_numa.c b/hw/ppc/spapr_numa.c
index 674d2ee86d..07eb921737 100644
--- a/hw/ppc/spapr_numa.c
+++ b/hw/ppc/spapr_numa.c
@@ -178,10 +178,11 @@ static target_ulong h_home_node_associativity(PowerPCCPU *cpu,
                                               target_ulong opcode,
                                               target_ulong *args)
 {
+    g_autofree uint32_t *vcpu_assoc = NULL;
     target_ulong flags = args[0];
     target_ulong procno = args[1];
     PowerPCCPU *tcpu;
-    int idx;
+    int idx, assoc_idx;
 
     /* only support procno from H_REGISTER_VPA */
     if (flags != 0x1) {
@@ -193,16 +194,40 @@ static target_ulong h_home_node_associativity(PowerPCCPU *cpu,
         return H_P2;
     }
 
-    /* sequence is the same as in the "ibm,associativity" property */
+    /*
+     * Given that we want to be flexible with the sizes and indexes,
+     * we must consider that there is a hard limit of how many
+     * associativities domain we can fit in R4 up to R9, which would be
+     * 12 associativity domains for vcpus. Assert and bail if that's
+     * not the case.
+     */
+    G_STATIC_ASSERT((VCPU_ASSOC_SIZE - 1) <= 12);
+
+    vcpu_assoc = spapr_numa_get_vcpu_assoc(spapr, tcpu);
+    /* assoc_idx starts at 1 to skip associativity size */
+    assoc_idx = 1;
 
-    idx = 0;
 #define ASSOCIATIVITY(a, b) (((uint64_t)(a) << 32) | \
                              ((uint64_t)(b) & 0xffffffff))
-    args[idx++] = ASSOCIATIVITY(0, 0);
-    args[idx++] = ASSOCIATIVITY(0, tcpu->node_id);
-    args[idx++] = ASSOCIATIVITY(procno, -1);
-    for ( ; idx < 6; idx++) {
-        args[idx] = -1;
+
+    for (idx = 0; idx < 6; idx++) {
+        int32_t a, b;
+
+        /*
+         * vcpu_assoc[] will contain the associativity domains for tcpu,
+         * including tcpu->node_id and procno, meaning that we don't
+         * need to use these variables here.
+         *
+         * We'll read 2 values at a time to fill up the ASSOCIATIVITY()
+         * macro. The ternary will fill the remaining registers with -1
+         * after we went through vcpu_assoc[].
+         */
+        a = assoc_idx < VCPU_ASSOC_SIZE ?
+            be32_to_cpu(vcpu_assoc[assoc_idx++]) : -1;
+        b = assoc_idx < VCPU_ASSOC_SIZE ?
+            be32_to_cpu(vcpu_assoc[assoc_idx++]) : -1;
+
+        args[idx] = ASSOCIATIVITY(a, b);
     }
 #undef ASSOCIATIVITY
 
-- 
2.26.2