[Xen-changelog] [qemu-xen master] target/ppc: Clean up probing of VMX, VSX and DFP availability on KVM

[patchbot@xxxxxxx]

commit 7c578cbc37bb4fdb54408dc565895b23020341ee
Author:     David Gibson <david@xxxxxxxxxxxxxxxxxxxxx>
AuthorDate: Mon Dec 11 17:41:34 2017 +1100
Commit:     Michael Roth <mdroth@xxxxxxxxxxxxxxxxxx>
CommitDate: Mon Feb 5 18:53:42 2018 -0600

    target/ppc: Clean up probing of VMX, VSX and DFP availability on KVM
    
    When constructing the "host" cpu class we modify whether the VMX and VSX
    vector extensions and DFP (Decimal Floating Point) are available
    based on whether KVM can support those instructions.  This can depend on
    policy in the host kernel as well as on the actual host cpu capabilities.
    
    However, the way we probe for this is not very nice: we explicitly check
    the host's device tree.  That works in practice, but it's not really
    correct, since the device tree is a property of the host kernel's platform
    which we don't really know about.  We get away with it because the only
    modern POWER platforms happen to encode VMX, VSX and DFP availability in
    the device tree in the same way.
    
    Arguably we should have an explicit KVM capability for this, but we haven't
    needed one so far.  Barring specific KVM policies which don't yet exist,
    each of these instruction classes will be available in the guest if and
    only if they're available in the qemu userspace process.  We can determine
    that from the ELF AUX vector we're supplied with.
    
    Once reworked like this, there are no more callers for kvmppc_get_vmx() and
    kvmppc_get_dfp() so remove them.
    
    Signed-off-by: David Gibson <david@xxxxxxxxxxxxxxxxxxxxx>
    Reviewed-by: Greg Kurz <groug@xxxxxxxx>
    (cherry picked from commit 3f2ca480eb872b4946baf77f756236b637a5b15a)
    Signed-off-by: Michael Roth <mdroth@xxxxxxxxxxxxxxxxxx>
---
 target/ppc/kvm.c     | 27 ++++++---------------------
 target/ppc/kvm_ppc.h |  2 --
 2 files changed, 6 insertions(+), 23 deletions(-)

diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c
index 9d57deb..81d9bd5 100644
--- a/target/ppc/kvm.c
+++ b/target/ppc/kvm.c
@@ -2014,16 +2014,6 @@ uint64_t kvmppc_get_clockfreq(void)
     return kvmppc_read_int_cpu_dt("clock-frequency");
 }
 
-uint32_t kvmppc_get_vmx(void)
-{
-    return kvmppc_read_int_cpu_dt("ibm,vmx");
-}
-
-uint32_t kvmppc_get_dfp(void)
-{
-    return kvmppc_read_int_cpu_dt("ibm,dfp");
-}
-
 static int kvmppc_get_pvinfo(CPUPPCState *env, struct kvm_ppc_pvinfo *pvinfo)
  {
      PowerPCCPU *cpu = ppc_env_get_cpu(env);
@@ -2407,23 +2397,18 @@ static void alter_insns(uint64_t *word, uint64_t flags, 
bool on)
 static void kvmppc_host_cpu_class_init(ObjectClass *oc, void *data)
 {
     PowerPCCPUClass *pcc = POWERPC_CPU_CLASS(oc);
-    uint32_t vmx = kvmppc_get_vmx();
-    uint32_t dfp = kvmppc_get_dfp();
     uint32_t dcache_size = kvmppc_read_int_cpu_dt("d-cache-size");
     uint32_t icache_size = kvmppc_read_int_cpu_dt("i-cache-size");
 
     /* Now fix up the class with information we can query from the host */
     pcc->pvr = mfpvr();
 
-    if (vmx != -1) {
-        /* Only override when we know what the host supports */
-        alter_insns(&pcc->insns_flags, PPC_ALTIVEC, vmx > 0);
-        alter_insns(&pcc->insns_flags2, PPC2_VSX, vmx > 1);
-    }
-    if (dfp != -1) {
-        /* Only override when we know what the host supports */
-        alter_insns(&pcc->insns_flags2, PPC2_DFP, dfp);
-    }
+    alter_insns(&pcc->insns_flags, PPC_ALTIVEC,
+                qemu_getauxval(AT_HWCAP) & PPC_FEATURE_HAS_ALTIVEC);
+    alter_insns(&pcc->insns_flags2, PPC2_VSX,
+                qemu_getauxval(AT_HWCAP) & PPC_FEATURE_HAS_VSX);
+    alter_insns(&pcc->insns_flags2, PPC2_DFP,
+                qemu_getauxval(AT_HWCAP) & PPC_FEATURE_HAS_DFP);
 
     if (dcache_size != -1) {
         pcc->l1_dcache_size = dcache_size;
diff --git a/target/ppc/kvm_ppc.h b/target/ppc/kvm_ppc.h
index d6be38e..ecb5549 100644
--- a/target/ppc/kvm_ppc.h
+++ b/target/ppc/kvm_ppc.h
@@ -15,8 +15,6 @@
 
 uint32_t kvmppc_get_tbfreq(void);
 uint64_t kvmppc_get_clockfreq(void);
-uint32_t kvmppc_get_vmx(void);
-uint32_t kvmppc_get_dfp(void);
 bool kvmppc_get_host_model(char **buf);
 bool kvmppc_get_host_serial(char **buf);
 int kvmppc_get_hasidle(CPUPPCState *env);
--
generated by git-patchbot for /home/xen/git/qemu-xen.git#master

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