From: Paul Durrant <paul.durrant@citrix.com>
Date: Fri, 8 Jul 2011 07:31:10 +0000 (+0100)
Subject: x86/hvm: Don't expose CPUID time leaf when not using PVRDTSCP
X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~10068
X-Git-Url: https://dgit.raspbian.org/%22http://www.example.com/cgi/success//%22http:/www.example.com/cgi/success/?a=commitdiff_plain;h=80ecb40362365ba77e68fc609de8bd3b7208ae19;p=xen.git

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@citrix.com>
---

diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c
index 28703ec89b..266db18b49 100644
--- a/xen/arch/x86/traps.c
+++ b/xen/arch/x86/traps.c
@@ -704,15 +704,23 @@ int cpuid_hypervisor_leaves( uint32_t idx, uint32_t sub_idx,
     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;