[Xen-changelog] [xen stable-4.2] VMX: disable EPT when !cpu_has_vmx_pat

[patchbot@xxxxxxx]

commit f1e0df14412ccc6933a68eda66ac5b7d89186b62
Author:     Liu Jinsong <jinsong.liu@xxxxxxxxx>
AuthorDate: Mon Dec 9 14:40:51 2013 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Mon Dec 9 14:40:51 2013 +0100

    VMX: disable EPT when !cpu_has_vmx_pat
    
    Recently Oracle developers found a Xen security issue as DOS affecting,
    named as XSA-60. Please refer http://xenbits.xen.org/xsa/advisory-60.html
    Basically it involves how to handle guest cr0.cd setting, which under
    some environment it consumes much time resulting in DOS-like behavior.
    
    This is a preparing patch for fixing XSA-60. Later patch will fix XSA-60
    via PAT under Intel EPT case, which depends on cpu_has_vmx_pat.
    
    This is CVE-2013-2212 / XSA-60.
    
    Signed-off-by: Liu Jinsong <jinsong.liu@xxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Reviewed-by: Tim Deegan <tim@xxxxxxx>
    Acked-by: Jun Nakajima <jun.nakajima@xxxxxxxxx>
    master commit: c13b0d65ddedd74508edef5cd66defffe30468fc
    master date: 2013-11-06 10:11:18 +0100
---
 xen/arch/x86/hvm/vmx/vmcs.c |    4 ++--
 xen/arch/x86/hvm/vmx/vmx.c  |   10 +++++++---
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/xen/arch/x86/hvm/vmx/vmcs.c b/xen/arch/x86/hvm/vmx/vmcs.c
index 11c19f1..049267e 100644
--- a/xen/arch/x86/hvm/vmx/vmcs.c
+++ b/xen/arch/x86/hvm/vmx/vmcs.c
@@ -779,7 +779,7 @@ static int construct_vmcs(struct vcpu *v)
         vmx_disable_intercept_for_msr(v, MSR_IA32_SYSENTER_CS);
         vmx_disable_intercept_for_msr(v, MSR_IA32_SYSENTER_ESP);
         vmx_disable_intercept_for_msr(v, MSR_IA32_SYSENTER_EIP);
-        if ( cpu_has_vmx_pat && paging_mode_hap(d) )
+        if ( paging_mode_hap(d) )
             vmx_disable_intercept_for_msr(v, MSR_IA32_CR_PAT);
     }
 
@@ -905,7 +905,7 @@ static int construct_vmcs(struct vcpu *v)
 #endif
     }
 
-    if ( cpu_has_vmx_pat && paging_mode_hap(d) )
+    if ( paging_mode_hap(d) )
     {
         u64 host_pat, guest_pat;
 
diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index 1e30557..f40c276 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -972,7 +972,7 @@ static unsigned long vmx_get_shadow_gs_base(struct vcpu *v)
 
 static int vmx_set_guest_pat(struct vcpu *v, u64 gpat)
 {
-    if ( !cpu_has_vmx_pat || !paging_mode_hap(v->domain) )
+    if ( !paging_mode_hap(v->domain) )
         return 0;
 
     vmx_vmcs_enter(v);
@@ -986,7 +986,7 @@ static int vmx_set_guest_pat(struct vcpu *v, u64 gpat)
 
 static int vmx_get_guest_pat(struct vcpu *v, u64 *gpat)
 {
-    if ( !cpu_has_vmx_pat || !paging_mode_hap(v->domain) )
+    if ( !paging_mode_hap(v->domain) )
         return 0;
 
     vmx_vmcs_enter(v);
@@ -1593,7 +1593,11 @@ struct hvm_function_table * __init start_vmx(void)
         return NULL;
     }
 
-    if ( cpu_has_vmx_ept )
+    /*
+     * Do not enable EPT when (!cpu_has_vmx_pat), to prevent security hole
+     * (refer to http://xenbits.xen.org/xsa/advisory-60.html).
+     */
+    if ( cpu_has_vmx_ept && cpu_has_vmx_pat )
     {
         vmx_function_table.hap_supported = 1;
 
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.2

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