Re: [Xen-devel] [PATCH 6/9] x86/vmx: Pass an MSR value into vmx_msr_add()

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 22.05.18 at 13:20, <andrew.cooper3@xxxxxxxxxx> wrote:
> The main purpose of this change is to allow us to set a specific MSR value,
> without needing to know whether there is already a load/save list slot for 
> it.
> Previously, callers wanting this property needed to call both vmx_add_*_msr()
> and vmx_write_*_msr() to cover both cases.
> 
> As a result of this API improvement, the default value for guest MSRs need not
> be 0, and the default for host MSRs need not be passed via hardware register.
> In practice, this cleans up the VPMU allocation logic, and avoids an MSR read
> as part of vcpu construction.

But this also means: If there already is such an entry, the previous value will
now be blindly overwritten. Are you sure this is always what is wanted?

Jan



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