[Qemu-devel] [PATCH] kvm: ppc: detect old headers

[Alexander Graf <agraf@suse.de>]

When compiling Qemu with older kernel headers, the PVR setting
mechanism isn't available yet. Unfortunately, back then I didn't add
a capability we could check against, so all we can do is add a configure
test to see if we support PVR setting. For BookE, we don't care yet.

While at it, also memset the sregs to zero, so we have sane state in
case we add fields later.

This fixes compilation errors with KVM enabled on older kernel headers
(like 2.6.32).

Signed-off-by: Alexander Graf <agraf@suse.de>
---
 configure        |   18 ++++++++++++++++++
 target-ppc/kvm.c |   24 +++++++++++++++++++++---
 2 files changed, 39 insertions(+), 3 deletions(-)

diff --git a/configure b/configure
index da2da04..7b90e1e 100755
--- a/configure
+++ b/configure
@@ -1772,6 +1772,21 @@ recent kvm-kmod from http://sourceforge.net/projects/kvm."
 fi
 
 ##########################################
+# test for ppc kvm pvr setting
+
+if test "$kvm" = "yes" && test "$cpu" = "ppc" -o "$cpu" = "ppc64"; then
+            cat > $TMPC <<EOF
+    #include <asm/kvm.h>
+    int main(void) { struct kvm_sregs s; s.pvr = 0; return 0; }
+EOF
+    if compile_prog "$kvm_cflags" "" ; then
+        kvm_ppc_pvr=yes
+    else
+        kvm_ppc_pvr=no
+    fi
+fi
+
+##########################################
 # test for vhost net
 
 if test "$vhost_net" != "no"; then
@@ -3241,6 +3256,9 @@ case "$target_arch2" in
       if test $vhost_net = "yes" ; then
         echo "CONFIG_VHOST_NET=y" >> $config_target_mak
       fi
+      if test $kvm_ppc_pvr = "yes" ; then
+        echo "CONFIG_KVM_PPC_PVR=y" >> $config_target_mak
+      fi
     fi
 esac
 if test "$target_bigendian" = "yes" ; then
diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c
index 2cfb24b..93d91df 100644
--- a/target-ppc/kvm.c
+++ b/target-ppc/kvm.c
@@ -80,10 +80,28 @@ int kvm_arch_init(KVMState *s)
 int kvm_arch_init_vcpu(CPUState *cenv)
 {
     int ret = 0;
-    struct kvm_sregs sregs;
 
-    sregs.pvr = cenv->spr[SPR_PVR];
-    ret = kvm_vcpu_ioctl(cenv, KVM_SET_SREGS, &sregs);
+    if ((cenv->mmu_model == POWERPC_MMU_BOOKE) ||
+        (cenv->mmu_model == POWERPC_MMU_BOOKE_FSL)) {
+        /* What we're really trying to say is "if we're on BookE, we use
+           the native PVR for now". This is the only sane way to check
+           it though, so we potentially confuse users that they can run
+           BookE guests on BookS. Let's hope nobody dares enough :) */
+    } else {
+#ifdef CONFIG_KVM_PPC_PVR
+        struct kvm_sregs sregs;
+
+        memset(&sregs, 0, sizeof(sregs));
+        sregs.pvr = cenv->spr[SPR_PVR];
+        ret = kvm_vcpu_ioctl(cenv, KVM_SET_SREGS, &sregs);
+#else
+        ret = -ENOSYS;
+#endif
+
+        if (ret) {
+            fprintf(stderr, "kvm error: missing PVR setting capability\n");
+        }
+    }
 
     idle_timer = qemu_new_timer_ns(vm_clock, kvm_kick_env, cenv);
 
-- 
1.6.0.2