Re: [PATCH] KVM: x86: Forcibly leave nested virt when SMM state is toggled

[Sean Christopherson]

On Wed, Jan 26, 2022, Maxim Levitsky wrote:
> On Tue, 2022-01-25 at 22:03 +0000, Sean Christopherson wrote:
> > Peeking at QEMU source, AFAICT QEMU restores nested state before events,
> > but I don't see how that can possibly work.  I assume QEMU does something
> > where it restores the "run" state first and then does a full restore?
> 
> Well, according to my testing, nested migration with SMM *is* still quite broken,
> (on both SVM and VMX)
> resulting in various issues up to L1 crash. 
> 
> When I last tackled SMM, I fixed most issues that
> happen just when the L2 is running and I inject flood of SMIs to L1 - even that
> was crashing things all around, so this might be as well the reason for that.

Heh, that would certainly explain why QEMU's code looks broken.  Thanks!