Re: [QEMU PATCH v2 0/2]: KVM: i386: Add support for save and restore nested state

[Liran Alon <liran.alon@oracle.com>]

Gentle ping on v2 of this series.
(I noticed 1st patch of series was already applied)

Thanks,
-Liran

> On 16 Sep 2018, at 15:46, Liran Alon <liran.alon@oracle.com> wrote:
> 
> Hi,
> 
> This series aims to add support for QEMU to be able to migrate VMs that
> are running nested hypervisors. In order to do so, it utilizes the new
> IOCTLs introduced in KVM commit 8fcc4b5923af ("kvm: nVMX: Introduce
> KVM_CAP_NESTED_STATE") which were created for this purpose.
> 
> 1st patch is not really related to the goal of the patch series. It just
> makes CPUX86State->xsave_buf to be compiled only when needed (When
> compiling with KVM or HVF CPU accelerator).
> 
> 2nd patch adds the support to migrate VMs that are running nested
> hypervisors.
> 
> Regards,
> -Liran
> 
> v1->v2 Changes:
> * Renamed kvm_nested_state_length() to kvm_max_nested_state_length()
> to better indicate it represents the max nested state size that can
> be returned from kernel.
> * Added error_report() calls to nested_state_post_load() to make
> failures in migration easier to diagnose.
> * Fixed support of migrating with various nested_state buffer sizes.
> The following scenarios were tested:
> (a) src and dest have same nested state size.
> 	==> Migration succeeds.
> (b) src don't have nested state while dest do.
> 	==> Migration succeed and src don't send it's nested state.
> (c) src have nested state while dest don't.
> 	==> Migration fails as it cannot restore nested state.
> (d) dest have bigger max nested state size than src
> 	==> Migration succeeds.
> (e) dest have smaller max nested state size than src but enough to store it's saved nested state
> 	==> Migration succeeds
> (f) dest have smaller max nested state size than src but not enough to store it's saved nested state
> 	==> Migration fails
>