Re: [Xen-devel] Information required on TRACE_VMEXIT working.

["George Dunlap " <dunlapg@xxxxxxxxx>]

On 11/27/06, aditya shevalkar <aditya27783@xxxxxxxxxxx> wrote:
> Hi all,
>
> Can anybody explain the process of TRACE_VMEXIT ?
> I am trying to understand its use in xen3.0.3\xen\arch\x86\hvm\vmx\vmx.c
> file in the vmx_vmexit_handler function.
> Also explain the meaning of its arguments and from where does it fetches
> the values for different arguments.
> Some code snippets from above file are given below:
>
>
> TRACE_VMEXIT(0,exit_reason);
> switch ( exit_reason )
> {
> case EXIT_REASON_EXCEPTION_NMI:
>
>
>
> vector &= INTR_INFO_VECTOR_MASK;
> TRACE_VMEXIT(1,vector);
>
>
> __vmread(EXIT_QUALIFICATION, &va);
> __vmread(VM_EXIT_INTR_ERROR_CODE, &regs->error_code);
> TRACE_VMEXIT(3, regs->error_code);
> TRACE_VMEXIT(4, va);
>
> Also trying to understand the following expression in the same file:
> #define TRACE_VMEXIT(index,value) this_cpu(trace_values)[index]=value
I think the missing piece of the puzzle are the following functions,
also found in vmx.c:

asmlinkage void vmx_trace_vmentry(void)
{
   struct vcpu *v = current;
   TRACE_5D(TRC_VMX_VMENTRY + current->vcpu_id,
            v->arch.hvm_vcpu.hvm_trace_values[0],
            v->arch.hvm_vcpu.hvm_trace_values[1],
            v->arch.hvm_vcpu.hvm_trace_values[2],
            v->arch.hvm_vcpu.hvm_trace_values[3],
            v->arch.hvm_vcpu.hvm_trace_values[4]);

   TRACE_VMEXIT(0, 0);
   TRACE_VMEXIT(1, 0);
   TRACE_VMEXIT(2, 0);
   TRACE_VMEXIT(3, 0);
   TRACE_VMEXIT(4, 0);
}

asmlinkage void vmx_trace_vmexit (void)
{
   TRACE_3D(TRC_VMX_VMEXIT + current->vcpu_id, 0, 0, 0);
}

When a VMEXIT happens, vmx_trace_vmexit() is called, and a trace
record is generated. (This includes an RDTSC timetamp).  Then, as the
VMEXIT is handled, the various trace_values[] are filled in, depending
upon what kind of vmexit it is.  Then, just before the next


> With Regards,
> Aditya Shevalkar.
>
>
>
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