[Qemu-devel] [PATCH] ppc/kvm: Mark 64kB page size support as disabled if not available

[Thomas Huth <thuth@redhat.com>]

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 4322e8ced5aaac719
("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: Thomas Huth <thuth@redhat.com>
---
 target-ppc/kvm.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c
index dcb68b9..6bdc804 100644
--- a/target-ppc/kvm.c
+++ b/target-ppc/kvm.c
@@ -427,6 +427,7 @@ 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)) {
@@ -470,6 +471,9 @@ 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) {
@@ -484,6 +488,9 @@ 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) */
 
-- 
1.8.3.1