Re: [Xen-devel] [PATCH 3/5] X86: MPX IA32_BNDCFGS msr handle

["Liu, Jinsong" <jinsong.liu@xxxxxxxxx>]

Jan Beulich wrote:
>>>> On 21.11.13 at 16:30, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
>>>> wrote: 
>> On 19/11/13 10:51, Liu, Jinsong wrote:
>>> @@ -955,6 +956,9 @@ static int construct_vmcs(struct vcpu *v)
>>>          vmx_disable_intercept_for_msr(v, MSR_IA32_SYSENTER_EIP,
>>>          MSR_TYPE_R | MSR_TYPE_W); if ( paging_mode_hap(d) &&
>>>              (!iommu_enabled || iommu_snoop) )
>>> vmx_disable_intercept_for_msr(v, MSR_IA32_CR_PAT, MSR_TYPE_R |
>>> MSR_TYPE_W); +        if ( (vmexit_ctl & VM_EXIT_CLEAR_BNDCFGS) &&
>>> +             (vmentry_ctl & VM_ENTRY_LOAD_BNDCFGS) ) +           
>>> vmx_disable_intercept_for_msr(v, MSR_IA32_BNDCFGS, MSR_TYPE_R |
>>> MSR_TYPE_W);  
>> 
>> So if vmentry/exit supports loading/clearing BNDCFGS, we don't
>> intercept the MSRs. 
>> 
>> Are they stored in the VMCS in this case?
>> 
>> In the case that we intercept the MSRs, how and where do they get
>> saved/restored on context switch?
> 
> Yeah,m the code is clearly missing a vmx_add_guest_msr() or some
> such.
> 

Thanks! and we also need vmx_add_host_load_msr() and implicitly clear host 
MSR_IA32_BNDCFGS, right?
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