[Xen-changelog] [xen-4.0-testing] x86/hvm: Don't expose CPUID time leaf when not using PVRDTSCP

[Xen patchbot-4.0-testing <patchbot@xxxxxxx>]

# HG changeset patch
# User Paul Durrant <paul.durrant@xxxxxxxxxx>
# Date 1310112123 -3600
# Node ID a353b8304f7a630fd3160fd88e31133fa0fc7bd2
# Parent  a9c73a1e746adb4ace5628083f2b5ab5338c3570
x86/hvm: Don't expose CPUID time leaf when not using PVRDTSCP

Some versions of Oracle's Solaris PV drivers make a check that the
maximal Xen hypervisor CPUID leaf is <= base leaf + 2 and refuse to
work if this is not the case.  The addition of the time leaf makes the
maximal leaf == base leaf + 3 so this patch introduces a workaround
that obscures the time leaf unless PVRDTSCP is in operation.

Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
xen-unstable changeset:   23661:8fe6f4be18aa
xen-unstable date:        Fri Jul 08 08:31:10 2011 +0100
---


diff -r a9c73a1e746a -r a353b8304f7a xen/arch/x86/traps.c
--- a/xen/arch/x86/traps.c      Fri Jul 08 09:01:08 2011 +0100
+++ b/xen/arch/x86/traps.c      Fri Jul 08 09:02:03 2011 +0100
@@ -686,15 +686,23 @@
     struct domain *d = current->domain;
     /* Optionally shift out of the way of Viridian architectural leaves. */
     uint32_t base = is_viridian_domain(d) ? 0x40000100 : 0x40000000;
+    uint32_t limit;
 
     idx -= base;
-    if ( idx > 3 ) 
+
+    /*
+     * Some Solaris PV drivers fail if max > base + 2. Help them out by
+     * hiding the PVRDTSCP leaf if PVRDTSCP is disabled.
+     */
+    limit = (d->arch.tsc_mode < TSC_MODE_PVRDTSCP) ? 2 : 3;
+
+    if ( idx > limit ) 
         return 0;
 
     switch ( idx )
     {
     case 0:
-        *eax = base + 3; /* Largest leaf */
+        *eax = base + limit; /* Largest leaf */
         *ebx = XEN_CPUID_SIGNATURE_EBX;
         *ecx = XEN_CPUID_SIGNATURE_ECX;
         *edx = XEN_CPUID_SIGNATURE_EDX;

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