Re: [PATCH 1/2] KVM: x86 emulator: don't update vcpu state if instruction is restarted.

Avi Kivity
2010-08-02T05:04:24Z

On 08/01/2010 04:27 PM, Gleb Natapov wrote:
>
> When we are going to enable e_i_g_s by default?

Optimistically, 2.6.37, so six months.

> May be we have enough
> time to fix userspace?

Sure we do, but will users update?

0.12 is mature enough that some users will forget about it and not
update it.

> Too ancient userspace already does not run on recent
> kvm. Or may be we can make userspace enable e_i_g_s per guest. This way
> userspace that knows it is OK can tell kernel so.

Let's make it the other way round, enable the optimization for userspace
that declares that it does not make use of rip during emulation
(kvm-tpr-opt can be changed by queueing a signal and re-entering the
guest to complete the operation).

Later we can make the optimization unconditional.

--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.