[Xen-changelog] [xen master] VMX/Viridian: suppress MSR-based APIC suggestion when having APIC-V

[patchbot@xxxxxxx]

commit 7f2e992b824ec62a2818e64390ac2ccfbd74e6b7
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Tue Jun 25 15:57:44 2013 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Jun 25 15:57:44 2013 +0200

    VMX/Viridian: suppress MSR-based APIC suggestion when having APIC-V
    
    When the CPU has the necessary capabilities, having Windows use
    synthetic MSR reads/writes is bogus, as this still requires emulation
    (which is pretty much guaranteed to be slower than having the hardware
    carry out the operation).
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Acked-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
    Acked-by: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
---
 xen/arch/x86/hvm/viridian.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/hvm/viridian.c b/xen/arch/x86/hvm/viridian.c
index 1ee0f7f..46492cb 100644
--- a/xen/arch/x86/hvm/viridian.c
+++ b/xen/arch/x86/hvm/viridian.c
@@ -87,8 +87,9 @@ int cpuid_viridian_leaves(unsigned int leaf, unsigned int 
*eax,
         if ( (d->arch.hvm_domain.viridian.guest_os_id.raw == 0) ||
              (d->arch.hvm_domain.viridian.guest_os_id.fields.os < 4) )
             break;
-        *eax = (CPUID4A_MSR_BASED_APIC |
-                CPUID4A_RELAX_TIMER_INT);
+        *eax = CPUID4A_RELAX_TIMER_INT;
+        if ( !cpu_has_vmx_apic_reg_virt )
+            *eax |= CPUID4A_MSR_BASED_APIC;
         *ebx = 2047; /* long spin count */
         break;
     }
--
generated by git-patchbot for /home/xen/git/xen.git#master

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