Re: [PATCH v2 2/2] x86/hvm: Don't intercept #UD exceptions in general

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 28/01/16 09:42, Jan Beulich wrote:
>>>> On 27.01.16 at 20:13, <andrew.cooper3@citrix.com> wrote:
>> --- a/xen/arch/x86/hvm/svm/vmcb.c
>> +++ b/xen/arch/x86/hvm/svm/vmcb.c
>> @@ -192,6 +192,7 @@ static int construct_vmcb(struct vcpu *v)
>>  
>>      vmcb->_exception_intercepts =
>>          HVM_TRAP_MASK
>> +        | (opt_hvm_fep ? (1U << TRAP_invalid_op) : 0)
>>          | (1U << TRAP_no_device);
> This assumes a certain sequence of hypercalls by the tool stack
> (i.e. set-cpuid only after all vCPU-s got created, or else the
> intercept won't get enabled), which I think we should avoid.
> Instead I think you'd better call the new hook from
> hvm_vcpu_initialise().

Something like this (to be folded in) ?

andrewcoop@andrewcoop:/local/xen.git/xen$ git diff
diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 7a15d49..be5ead0 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -2484,6 +2484,8 @@ int hvm_vcpu_initialise(struct vcpu *v)
         hvm_set_guest_tsc(v, 0);
     }
 
+    hvm_update_guest_vendor(v);
+
     return 0;
 
  fail7:
diff --git a/xen/arch/x86/hvm/svm/vmcb.c b/xen/arch/x86/hvm/svm/vmcb.c
index be2dc32..9ea014f 100644
--- a/xen/arch/x86/hvm/svm/vmcb.c
+++ b/xen/arch/x86/hvm/svm/vmcb.c
@@ -192,7 +192,6 @@ static int construct_vmcb(struct vcpu *v)
 
     vmcb->_exception_intercepts =
         HVM_TRAP_MASK
-        | (opt_hvm_fep ? (1U << TRAP_invalid_op) : 0)
         | (1U << TRAP_no_device);
 
     if ( paging_mode_hap(v->domain) )
diff --git a/xen/arch/x86/hvm/vmx/vmcs.c b/xen/arch/x86/hvm/vmx/vmcs.c
index a12813a..5bc3c74 100644
--- a/xen/arch/x86/hvm/vmx/vmcs.c
+++ b/xen/arch/x86/hvm/vmx/vmcs.c
@@ -1237,7 +1237,6 @@ static int construct_vmcs(struct vcpu *v)
 
     v->arch.hvm_vmx.exception_bitmap = HVM_TRAP_MASK
               | (paging_mode_hap(d) ? 0 : (1U << TRAP_page_fault))
-              | (opt_hvm_fep ? (1U << TRAP_invalid_op) : 0)
               | (1U << TRAP_no_device);
     vmx_update_exception_bitmap(v);