Re: [PATCH] x86, kvm: Clear paravirt_enabled on KVM guests for espfix32's benefit

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On Wed, Dec 10, 2014 at 3:49 AM, Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote:
>
>
> On 06/12/2014 04:03, Andy Lutomirski wrote:
>> paravirt_enabled has the following effects:
>>
>>  - Disables the F00F bug workaround warning.  There is no F00F bug
>>    workaround any more because Linux's standard IDT handling already
>>    works around the F00F bug, but the warning still exists.  This
>>    is only cosmetic, and, in any event, there is no such thing as
>>    KVM on a CPU with the F00F bug.
>>
>>  - Disables 32-bit APM BIOS detection.  On a KVM paravirt system,
>>    there should be no APM BIOS anyway.
>>
>>  - Disables tboot.  I think that the tboot code should check the
>>    CPUID hypervisor bit directly if it matters.
>>
>>  - paravirt_enabled disables espfix32.  espfix32 should *not* be
>>    disabled under KVM paravirt.
>>
>> The last point is the purpose of this patch.  It fixes a leak of the
>> high 16 bits of the kernel stack address on 32-bit KVM paravirt
>> guests.
>>
>> While I'm at it, this removes pv_info setup from kvmclock.  That
>> code seems to serve no purpose.
>
> kvmclock_init runs before kvm_guest_init, and this is a stable@ patch so
> for the sake of extra safety I've left the pv_info.name assignment in.
> Applied (locally for now), will be in 3.19.
>

In the interest of reduced future confusion, would it make sense to
drop the duplicate initialization for 3.20?

--Andy
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