[Qemu-devel] [PATCH] kvm: ppc: warn user on PAGE_SIZE mismatch

[Qemu-devel] [PATCH] kvm: ppc: warn user on PAGE_SIZE mismatch

[Alexander Graf]

On PPC, the default PAGE_SIZE is 64kb. Unfortunately, the hardware
alignments don't match here: There are RAM and MMIO regions within
a single page when it's 64kb in size.

So the only way out for now is to tell the user that he should use 4k
PAGE_SIZE.

This patch gives the user a hint on that, telling him that failing to
register a prefix slot is most likely to be caused by mismatching PAGE_SIZE.

This way it's also more future-proof, as bigger PAGE_SIZE can easily be
supported by other machines then, as long as they stick to 64kb granularities.

Signed-off-by: Alexander Graf <agraf@suse.de>
---
 kvm-all.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/kvm-all.c b/kvm-all.c
index 1d7e8ea..ff30858 100644
--- a/kvm-all.c
+++ b/kvm-all.c
@@ -577,6 +577,11 @@ static void kvm_set_phys_mem(target_phys_addr_t start_addr, ram_addr_t size,
             if (err) {
                 fprintf(stderr, "%s: error registering prefix slot: %s\n",
                         __func__, strerror(-err));
+#ifdef TARGET_PPC
+                fprintf(stderr, "%s: This is probably because your kernel's " \
+                                "PAGE_SIZE is too big. Please try to use 4k " \
+                                "PAGE_SIZE!\n", __func__);
+#endif
                 abort();
             }
         }
-- 
1.6.0.2

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

[Alexander Graf]

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.

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 |   16 +++++++++++++++-
 2 files changed, 33 insertions(+), 1 deletions(-)

diff --git a/configure b/configure
index fbf5d5f..adfbb40 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 "$vhost_net" != "no"; then
@@ -3257,6 +3272,9 @@ case "$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 5a1b6cb..ccf4668 100644
--- a/target-ppc/kvm.c
+++ b/target-ppc/kvm.c
@@ -94,19 +94,33 @@ static int kvm_arch_sync_sregs(CPUState *cenv)
     int ret;
 
     if (cenv->excp_model == POWERPC_EXCP_BOOKE) {
+        /* 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 :) */
         return 0;
     } else {
         if (!cap_segstate) {
-            return 0;
+            fprintf(stderr, "kvm error: missing PVR setting capability\n");
+            return -ENOSYS;
         }
     }
 
+#if !defined(CONFIG_KVM_PPC_PVR)
+    if (1) {
+        fprintf(stderr, "kvm error: missing PVR setting capability\n");
+        return -ENOSYS;
+    }
+#endif
+
     ret = kvm_vcpu_ioctl(cenv, KVM_GET_SREGS, &sregs);
     if (ret) {
         return ret;
     }
 
+#ifdef CONFIG_KVM_PPC_PVR
     sregs.pvr = cenv->spr[SPR_PVR];
+#endif
     return kvm_vcpu_ioctl(cenv, KVM_SET_SREGS, &sregs);
 }
 
-- 
1.6.0.2

[Qemu-devel] [PATCH] kvm: ppc: warn user on PAGE_SIZE mismatch

[Alexander Graf]

On PPC, the default PAGE_SIZE is 64kb. Unfortunately, the hardware
alignments don't match here: There are RAM and MMIO regions within
a single page when it's 64kb in size.

So the only way out for now is to tell the user that he should use 4k
PAGE_SIZE.

This patch gives the user a hint on that, telling him that failing to
register a prefix slot is most likely to be caused by mismatching PAGE_SIZE.

This way it's also more future-proof, as bigger PAGE_SIZE can easily be
supported by other machines then, as long as they stick to 64kb granularities.

Signed-off-by: Alexander Graf <agraf@suse.de>
---
 kvm-all.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/kvm-all.c b/kvm-all.c
index d92c20e..a30865e 100644
--- a/kvm-all.c
+++ b/kvm-all.c
@@ -590,6 +590,11 @@ static void kvm_set_phys_mem(target_phys_addr_t start_addr, ram_addr_t size,
             if (err) {
                 fprintf(stderr, "%s: error registering prefix slot: %s\n",
                         __func__, strerror(-err));
+#ifdef TARGET_PPC
+                fprintf(stderr, "%s: This is probably because your kernel's " \
+                                "PAGE_SIZE is too big. Please try to use 4k " \
+                                "PAGE_SIZE!\n", __func__);
+#endif
                 abort();
             }
         }
-- 
1.6.0.2