ppc: Rewrite ppc_get_compat_smt_threads()

To continue consolidation of compatibility mode information, this rewrites
the ppc_get_compat_smt_threads() function using the table of compatiblity
modes in target-ppc/compat.c.

It's not a direct replacement, the new ppc_compat_max_threads() function
has simpler semantics - it just returns the number of threads the cpu
model has, taking into account any compatiblity mode it is in.

This no longer takes into account kvmppc_smt_threads() as the previous
version did.  That check wasn't useful because we check in
ppc_cpu_realizefn() that CPUs aren't instantiated with more threads
than kvm allows (or if we didn't things will already be broken and
this won't make it any worse).

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>

1 files changed, 18 insertions, 0 deletions

diff --git a/target/ppc/compat.c b/target/ppc/compat.c
index f3fd9c695c..66529a6b83 100644
--- a/target/ppc/compat.c
+++ b/target/ppc/compat.c
@@ -28,6 +28,7 @@
 typedef struct {
     uint32_t pvr;
     uint64_t pcr;
+    int max_threads;
 } CompatInfo;
 
 static const CompatInfo compat_table[] = {
@@ -35,18 +36,22 @@ static const CompatInfo compat_table[] = {
         .pvr = CPU_POWERPC_LOGICAL_2_05,
         .pcr = PCR_COMPAT_2_07 | PCR_COMPAT_2_06 | PCR_COMPAT_2_05
                | PCR_TM_DIS | PCR_VSX_DIS,
+        .max_threads = 2,
     },
     { /* POWER7, ISA2.06 */
         .pvr = CPU_POWERPC_LOGICAL_2_06,
         .pcr = PCR_COMPAT_2_07 | PCR_COMPAT_2_06 | PCR_TM_DIS,
+        .max_threads = 4,
     },
     {
         .pvr = CPU_POWERPC_LOGICAL_2_06_PLUS,
         .pcr = PCR_COMPAT_2_07 | PCR_COMPAT_2_06 | PCR_TM_DIS,
+        .max_threads = 4,
     },
     { /* POWER8, ISA2.07 */
         .pvr = CPU_POWERPC_LOGICAL_2_07,
         .pcr = PCR_COMPAT_2_07,
+        .max_threads = 8,
     },
 };
 
@@ -89,3 +94,16 @@ void ppc_set_compat(PowerPCCPU *cpu, uint32_t compat_pvr, Error **errp)
         }
     }
 }
+
+int ppc_compat_max_threads(PowerPCCPU *cpu)
+{
+    const CompatInfo *compat = compat_by_pvr(cpu->compat_pvr);
+    int n_threads = CPU(cpu)->nr_threads;
+
+    if (cpu->compat_pvr) {
+        g_assert(compat);
+        n_threads = MIN(n_threads, compat->max_threads);
+    }
+
+    return n_threads;
+}