Re: [PATCH 2/2] kvm: nVMX: Introduce KVM_CAP_STATE

From: Raslan, KarimAllah
Date: Mon Apr 16 2018 - 13:15:50 EST

On Mon, 2018-04-16 at 09:22 -0700, Jim Mattson wrote:
> On Thu, Apr 12, 2018 at 8:12 AM, KarimAllah Ahmed <karahmed@xxxxxxxxx> wrote:
> >
> > v2 -> v3:
> > - Remove the forced VMExit from L2 after reading the kvm_state. The actual
> > problem is solved.
> > - Rebase again!
> > - Set nested_run_pending during restore (not sure if it makes sense yet or
> > not).
> This doesn't actually make sense. Nested_run_pending should only be
> set between L1 doing a VMLAUNCH/VMRESUME and the first instruction
> executing in L2. That is extremely unlikely at a restore point.

Yeah, I am afraid I put very little thought into it as I was focused
on the TSC issue :)

Will handle it properly in next version.

> To deal with nested_run_pending and nested save/restore,
> nested_run_pending should be set to 1 before calling
> enter_vmx_non_root_mode, as it was prior to commit 7af40ad37b3f. That
> means that it has to be cleared when emulating VM-entry to the halted
> state (prior to calling kvm_vcpu_halt). And all of the from_vmentry
> arguments that Paolo added when rebasing commit cf8b84f48a59 should be
> removed, so that nested_run_pending is propagated correctly duting a
> restore.
> It should be possible to eliminate this strange little wart, but I
> haven't looked deeply into it.
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