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

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> 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.

Jan


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