[Xen-changelog] [xen stable-4.4] VMX: fix PAT value seen by guest

[patchbot@xxxxxxx]

commit be5c793b143825bca6f231f0c648982ac1afef0c
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Fri Apr 4 10:46:13 2014 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri Apr 4 10:46:13 2014 +0200

    VMX: fix PAT value seen by guest
    
    The XSA-60 fixes introduced a window during which the guest PAT gets
    forced to all zeros. This shouldn't be visible to the guest. Therefore
    we need to intercept PAT MSR accesses during that time period.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Liu Jinsong <jinsong.liu@xxxxxxxxx>
    master commit: fce79f8ce91dc45f3a4d699ee67c49e6cbeb1197
    master date: 2014-04-01 16:49:18 +0200
---
 xen/arch/x86/hvm/vmx/vmx.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index fb514a6..39c6d83 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -984,6 +984,8 @@ static void vmx_handle_cd(struct vcpu *v, unsigned long 
value)
 
             vmx_get_guest_pat(v, pat);
             vmx_set_guest_pat(v, uc_pat);
+            vmx_enable_intercept_for_msr(v, MSR_IA32_CR_PAT,
+                                         MSR_TYPE_R | MSR_TYPE_W);
 
             wbinvd();               /* flush possibly polluted cache */
             hvm_asid_flush_vcpu(v); /* invalidate memory type cached in TLB */
@@ -993,6 +995,9 @@ static void vmx_handle_cd(struct vcpu *v, unsigned long 
value)
         {
             v->arch.hvm_vcpu.cache_mode = NORMAL_CACHE_MODE;
             vmx_set_guest_pat(v, *pat);
+            if ( !iommu_enabled || iommu_snoop )
+                vmx_disable_intercept_for_msr(v, MSR_IA32_CR_PAT,
+                                              MSR_TYPE_R | MSR_TYPE_W);
             hvm_asid_flush_vcpu(v); /* no need to flush cache */
         }
     }
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.4

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