ppc/kvm: Mark 64kB page size support as disabled if not available

QEMU currently refuses to start with KVM-PR and only prints out

	qemu: fatal: Unknown MMU model 851972

when being started there. This is because commit 4322e8ce
("ppc: Fix 64K pages support in full emulation") introduced a new
POWERPC_MMU_64K bit to indicate support for this page size, but
it never gets cleared on KVM-PR if the host kernel does not support
this. Thus we've got to turn off this bit in the mmu_model for KVM-PR.
Signed-off-by: NThomas Huth <thuth@redhat.com>
Signed-off-by: NDavid Gibson <david@gibson.dropbear.id.au>
(cherry picked from commit 0d594f55)
Signed-off-by: NMichael Roth <mdroth@linux.vnet.ibm.com>

target-ppc/kvm.c

@@ -429,6 +429,7 @@ static void kvm_fixup_page_sizes(PowerPCCPU *cpu)
     CPUPPCState *env = &cpu->env;
     long rampagesize;
     int iq, ik, jq, jk;
+    bool has_64k_pages = false;
 
     /* We only handle page sizes for 64-bit server guests for now */
     if (!(env->mmu_model & POWERPC_MMU_64)) {
@@ -472,6 +473,9 @@ static void kvm_fixup_page_sizes(PowerPCCPU *cpu)
                                      ksps->enc[jk].page_shift)) {
                 continue;
             }
+            if (ksps->enc[jk].page_shift == 16) {
+                has_64k_pages = true;
+            }
             qsps->enc[jq].page_shift = ksps->enc[jk].page_shift;
             qsps->enc[jq].pte_enc = ksps->enc[jk].pte_enc;
             if (++jq >= PPC_PAGE_SIZES_MAX_SZ) {
@@ -486,6 +490,9 @@ static void kvm_fixup_page_sizes(PowerPCCPU *cpu)
     if (!(smmu_info.flags & KVM_PPC_1T_SEGMENTS)) {
         env->mmu_model &= ~POWERPC_MMU_1TSEG;
     }
+    if (!has_64k_pages) {
+        env->mmu_model &= ~POWERPC_MMU_64K;
+    }
 }
 #else /* defined (TARGET_PPC64) */