target/ppc: Fix host PVR matching for KVM

ppc_cpu_compare_class_pvr_mask() should match the best CPU class in the
family, because it is used by the KVM subsystem to find the host CPU
class. Since commit 03ae4133ab8 ("target-ppc: Add pvr_match()
callback"), it matches any class in the family (the first one in the
comparison list).

Since commit f30c843ced5 ("ppc/pnv: Introduce PowerNV machines with
fixed CPU models"), pnv has relied on pnv_match having these new
semantics to check machine compatibility with a CPU family.

Resolve this by adding a parameter to the pvr_match function to select
the best or any match, and restore the old behaviour for the KVM case.

Prior to this fix, e.g., a POWER9 DD2.3 KVM host matches to the
power9_v1.0 class (because that happens to be the first POWER9 family
CPU compared). After the patch, it matches the power9_v2.0 class.

This approach requires pnv_match contain knowledge of the CPU classes
implemented in the same family, which feels ugly. But pushing the 'best'
match down to the class would still require they know about one another
which is not obviously much better. For now this gets things working.

Fixes: 03ae4133ab8 ("target-ppc: Add pvr_match() callback")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Message-Id: <20220731013358.170187-1-npiggin@gmail.com>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>

hw/ppc/pnv.c

@@ -714,7 +714,7 @@ static bool pnv_match_cpu(const char *default_type, const char *cpu_type)
     PowerPCCPUClass *ppc =
         POWERPC_CPU_CLASS(object_class_by_name(cpu_type));
 
-    return ppc_default->pvr_match(ppc_default, ppc->pvr);
+    return ppc_default->pvr_match(ppc_default, ppc->pvr, false);
 }
 
 static void pnv_ipmi_bt_init(ISABus *bus, IPMIBmc *bmc, uint32_t irq)

target/ppc/cpu-qom.h

@@ -158,7 +158,11 @@ struct PowerPCCPUClass {
     void (*parent_parse_features)(const char *type, char *str, Error **errp);
 
     uint32_t pvr;
-    bool (*pvr_match)(struct PowerPCCPUClass *pcc, uint32_t pvr);
+    /*
+     * If @best is false, match if pcc is in the family of pvr
+     * Else match only if pcc is the best match for pvr in this family.
+     */
+    bool (*pvr_match)(struct PowerPCCPUClass *pcc, uint32_t pvr, bool best);
     uint64_t pcr_mask;          /* Available bits in PCR register */
     uint64_t pcr_supported;     /* Bits for supported PowerISA versions */
     uint32_t svr;

target/ppc/cpu_init.c

@@ -5912,15 +5912,25 @@ static void init_proc_POWER7(CPUPPCState *env)
     ppcPOWER7_irq_init(env_archcpu(env));
 }
 
-static bool ppc_pvr_match_power7(PowerPCCPUClass *pcc, uint32_t pvr)
+static bool ppc_pvr_match_power7(PowerPCCPUClass *pcc, uint32_t pvr, bool best)
 {
-    if ((pvr & CPU_POWERPC_POWER_SERVER_MASK) == CPU_POWERPC_POWER7P_BASE) {
-        return true;
+    uint32_t base = pvr & CPU_POWERPC_POWER_SERVER_MASK;
+    uint32_t pcc_base = pcc->pvr & CPU_POWERPC_POWER_SERVER_MASK;
+
+    if (!best) {
+        if (base == CPU_POWERPC_POWER7_BASE) {
+            return true;
+        }
+        if (base == CPU_POWERPC_POWER7P_BASE) {
+            return true;
+        }
     }
-    if ((pvr & CPU_POWERPC_POWER_SERVER_MASK) == CPU_POWERPC_POWER7_BASE) {
-        return true;
+
+    if (base != pcc_base) {
+        return false;
     }
-    return false;
+
+    return true;
 }
 
 static bool cpu_has_work_POWER7(CPUState *cs)
@@ -6073,18 +6083,27 @@ static void init_proc_POWER8(CPUPPCState *env)
     ppcPOWER7_irq_init(env_archcpu(env));
 }
 
-static bool ppc_pvr_match_power8(PowerPCCPUClass *pcc, uint32_t pvr)
+static bool ppc_pvr_match_power8(PowerPCCPUClass *pcc, uint32_t pvr, bool best)
 {
-    if ((pvr & CPU_POWERPC_POWER_SERVER_MASK) == CPU_POWERPC_POWER8NVL_BASE) {
-        return true;
-    }
-    if ((pvr & CPU_POWERPC_POWER_SERVER_MASK) == CPU_POWERPC_POWER8E_BASE) {
-        return true;
+    uint32_t base = pvr & CPU_POWERPC_POWER_SERVER_MASK;
+    uint32_t pcc_base = pcc->pvr & CPU_POWERPC_POWER_SERVER_MASK;
+
+    if (!best) {
+        if (base == CPU_POWERPC_POWER8_BASE) {
+            return true;
+        }
+        if (base == CPU_POWERPC_POWER8E_BASE) {
+            return true;
+        }
+        if (base == CPU_POWERPC_POWER8NVL_BASE) {
+            return true;
+        }
     }
-    if ((pvr & CPU_POWERPC_POWER_SERVER_MASK) == CPU_POWERPC_POWER8_BASE) {
-        return true;
+    if (base != pcc_base) {
+        return false;
     }
-    return false;
+
+    return true;
 }
 
 static bool cpu_has_work_POWER8(CPUState *cs)
@@ -6282,11 +6301,26 @@ static void init_proc_POWER9(CPUPPCState *env)
     ppcPOWER9_irq_init(env_archcpu(env));
 }
 
-static bool ppc_pvr_match_power9(PowerPCCPUClass *pcc, uint32_t pvr)
+static bool ppc_pvr_match_power9(PowerPCCPUClass *pcc, uint32_t pvr, bool best)
 {
-    if ((pvr & CPU_POWERPC_POWER_SERVER_MASK) == CPU_POWERPC_POWER9_BASE) {
+    uint32_t base = pvr & CPU_POWERPC_POWER_SERVER_MASK;
+    uint32_t pcc_base = pcc->pvr & CPU_POWERPC_POWER_SERVER_MASK;
+
+    if (!best) {
+        if (base == CPU_POWERPC_POWER9_BASE) {
+            return true;
+        }
+    }
+
+    if (base != pcc_base) {
+        return false;
+    }
+
+    if ((pvr & 0x0f00) == (pcc->pvr & 0x0f00)) {
+        /* Major DD version matches to power9_v1.0 and power9_v2.0 */
         return true;
     }
+
     return false;
 }
 
@@ -6499,11 +6533,26 @@ static void init_proc_POWER10(CPUPPCState *env)
     ppcPOWER9_irq_init(env_archcpu(env));
 }
 
-static bool ppc_pvr_match_power10(PowerPCCPUClass *pcc, uint32_t pvr)
+static bool ppc_pvr_match_power10(PowerPCCPUClass *pcc, uint32_t pvr, bool best)
 {
-    if ((pvr & CPU_POWERPC_POWER_SERVER_MASK) == CPU_POWERPC_POWER10_BASE) {
+    uint32_t base = pvr & CPU_POWERPC_POWER_SERVER_MASK;
+    uint32_t pcc_base = pcc->pvr & CPU_POWERPC_POWER_SERVER_MASK;
+
+    if (!best) {
+        if (base == CPU_POWERPC_POWER10_BASE) {
+            return true;
+        }
+    }
+
+    if (base != pcc_base) {
+        return false;
+    }
+
+    if ((pvr & 0x0f00) == (pcc->pvr & 0x0f00)) {
+        /* Major DD version matches to power10_v1.0 and power10_v2.0 */
         return true;
     }
+
     return false;
 }
 
@@ -6910,7 +6959,7 @@ static gint ppc_cpu_compare_class_pvr_mask(gconstpointer a, gconstpointer b)
         return -1;
     }
 
-    if (pcc->pvr_match(pcc, pvr)) {
+    if (pcc->pvr_match(pcc, pvr, true)) {
         return 0;
     }
 
@@ -7308,7 +7357,7 @@ static void ppc_cpu_instance_finalize(Object *obj)
     ppc_hash64_finalize(cpu);
 }
 
-static bool ppc_pvr_match_default(PowerPCCPUClass *pcc, uint32_t pvr)
+static bool ppc_pvr_match_default(PowerPCCPUClass *pcc, uint32_t pvr, bool best)
 {
     return pcc->pvr == pvr;
 }

target/ppc/machine.c

@@ -234,7 +234,7 @@ static bool pvr_match(PowerPCCPU *cpu, uint32_t pvr)
     if (pvr == pcc->pvr) {
         return true;
     }
-    return pcc->pvr_match(pcc, pvr);
+    return pcc->pvr_match(pcc, pvr, true);
 }
 
 static int cpu_post_load(void *opaque, int version_id)