Re: [Xen-devel] [PATCH 20 of 20] n2 MSR handling and capability exposure

[Tim Deegan <Tim.Deegan@xxxxxxxxxx>]

At 16:07 +0100 on 02 Jun (1307030872), Tim Deegan wrote:
> At 16:57 +0800 on 02 Jun (1307033853), Eddie Dong wrote:
> > +    case MSR_IA32_VMX_PINBASED_CTLS:
> > +#define REMOVED_PIN_CONTROL_CAP (PIN_BASED_PREEMPT_TIMER)
> > +        rdmsr(msr, eax, edx);
> > +        data = edx;
> > +        data = (data << 32) | eax;
> > +        break;
> 
> You don't actually mask the value here. 
> 
> BTW, I don't really like defining all these REMOVED_* macros, each
> of which is used only once a few lines from the definition (here and
> elsewhere in the series).  It just adds clutter for no benefit.
> 

Oh, I forgot to say: will this feature-blacklisting work over live
migration to a machine with a different CPU?  There isn't an equivalnet
of the CPUID masking feature to make all the machines in a cluster seem
to have the same VMX features. 

Elsewhere we use whitelisting for passsing hardware capability flags to
HVM guests; I think we should use whitelists here too. 

Cheers,

Tim.

 
> > +    case MSR_IA32_VMX_PROCBASED_CTLS:
> > +        rdmsr(msr, eax, edx);
> > +#define REMOVED_EXEC_CONTROL_CAP (CPU_BASED_TPR_SHADOW \
> > +            | CPU_BASED_ACTIVATE_MSR_BITMAP            \
> > +            | CPU_BASED_ACTIVATE_SECONDARY_CONTROLS)
> > +        data = edx & ~REMOVED_EXEC_CONTROL_CAP;
> > +        data = (data << 32) | eax;
> > +        break;
> > +    case MSR_IA32_VMX_EXIT_CTLS:
> > +        rdmsr(msr, eax, edx);
> > +#define REMOVED_EXIT_CONTROL_CAP (VM_EXIT_SAVE_GUEST_PAT \
> > +            | VM_EXIT_LOAD_HOST_PAT                      \
> > +            | VM_EXIT_SAVE_GUEST_EFER                    \
> > +            | VM_EXIT_LOAD_HOST_EFER                     \
> > +            | VM_EXIT_SAVE_PREEMPT_TIMER)
> > +        data = edx & ~REMOVED_EXIT_CONTROL_CAP;
> > +        data = (data << 32) | eax;
> > +        break;
> > +    case MSR_IA32_VMX_ENTRY_CTLS:
> > +        rdmsr(msr, eax, edx);
> > +#define REMOVED_ENTRY_CONTROL_CAP (VM_ENTRY_LOAD_GUEST_PAT \
> > +            | VM_ENTRY_LOAD_GUEST_EFER)
> > +        data = edx & ~REMOVED_ENTRY_CONTROL_CAP;
> > +        data = (data << 32) | eax;
> > +        break;
> > +    case MSR_IA32_VMX_PROCBASED_CTLS2:
> > +        mask = 0;
> > +
> > +        rdmsr(msr, eax, edx);
> > +        data = edx & mask;
> > +        data = (data << 32) | eax;
> > +        break;
> > +
> 

-- 
Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Principal Software Engineer, Xen Platform Team
Citrix Systems UK Ltd.  (Company #02937203, SL9 0BG)

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