x86/hvm: disallow access to unknown MSRs

Change the catch-all behavior for MSR not explicitly handled. Instead
of allow full read-access to the MSR space and silently dropping
writes return an exception when the MSR is not explicitly handled.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
[remove rdmsr_safe from default case in svm_msr_read_intercept]
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>

xen/arch/x86/hvm/svm/svm.c

@@ -1961,8 +1961,7 @@ static int svm_msr_read_intercept(unsigned int msr, uint64_t *msr_content)
         break;
 
     default:
-        if ( rdmsr_safe(msr, *msr_content) == 0 )
-            break;
+        gdprintk(XENLOG_WARNING, "RDMSR 0x%08x unimplemented\n", msr);
         goto gpf;
     }
 
@@ -2147,10 +2146,9 @@ static int svm_msr_write_intercept(unsigned int msr, uint64_t msr_content)
         break;
 
     default:
-        /* Match up with the RDMSR side; ultimately this should go away. */
-        if ( rdmsr_safe(msr, msr_content) == 0 )
-            break;
-
+        gdprintk(XENLOG_WARNING,
+                 "WRMSR 0x%08x val 0x%016"PRIx64" unimplemented\n",
+                 msr, msr_content);
         goto gpf;
     }
 

xen/arch/x86/hvm/vmx/vmx.c

@@ -3015,9 +3015,7 @@ static int vmx_msr_read_intercept(unsigned int msr, uint64_t *msr_content)
             break;
         }
 
-        if ( rdmsr_safe(msr, *msr_content) == 0 )
-            break;
-
+        gdprintk(XENLOG_WARNING, "RDMSR 0x%08x unimplemented\n", msr);
         goto gp_fault;
     }
 
@@ -3290,11 +3288,6 @@ static int vmx_msr_write_intercept(unsigned int msr, uint64_t msr_content)
         __vmwrite(GUEST_IA32_DEBUGCTL, msr_content);
         break;
 
-    case MSR_IA32_FEATURE_CONTROL:
-    case MSR_IA32_VMX_BASIC ... MSR_IA32_VMX_VMFUNC:
-        /* None of these MSRs are writeable. */
-        goto gp_fault;
-
     case MSR_IA32_MISC_ENABLE:
         /*
          * Silently drop writes that don't change the reported value: At least
@@ -3324,10 +3317,9 @@ static int vmx_msr_write_intercept(unsigned int msr, uint64_t msr_content)
              is_last_branch_msr(msr) )
             break;
 
-        /* Match up with the RDMSR side; ultimately this should go away. */
-        if ( rdmsr_safe(msr, msr_content) == 0 )
-            break;
-
+        gdprintk(XENLOG_WARNING,
+                 "WRMSR 0x%08x val 0x%016"PRIx64" unimplemented\n",
+                 msr, msr_content);
         goto gp_fault;
     }