Re: [PATCH v2] KVM: nVMX: fixes for preemption timer migration

[Stefano Garzarella <sgarzare@redhat.com>]

Hi Paolo,

On Thu, Jul 09, 2020 at 01:28:01PM -0400, Paolo Bonzini wrote:
> Commit 850448f35aaf ("KVM: nVMX: Fix VMX preemption timer migration",
> 2020-06-01) accidentally broke nVMX live migration from older version
> by changing the userspace ABI.  Restore it and, while at it, ensure
> that vmx->nested.has_preemption_timer_deadline is always initialized
> according to the KVM_STATE_VMX_PREEMPTION_TIMER_DEADLINE flag.
> 
> Cc: Makarand Sonare <makarandsonare@google.com>
> Fixes: 850448f35aaf ("KVM: nVMX: Fix VMX preemption timer migration")
> Reviewed-by: Jim Mattson <jmattson@google.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
> v1->v2: coding style [Jim]
> 
>  arch/x86/include/uapi/asm/kvm.h | 5 +++--
>  arch/x86/kvm/vmx/nested.c       | 1 +
>  2 files changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h
> index 17c5a038f42d..0780f97c1850 100644
> --- a/arch/x86/include/uapi/asm/kvm.h
> +++ b/arch/x86/include/uapi/asm/kvm.h
> @@ -408,14 +408,15 @@ struct kvm_vmx_nested_state_data {
>  };
>  
>  struct kvm_vmx_nested_state_hdr {
> -	__u32 flags;
>  	__u64 vmxon_pa;
>  	__u64 vmcs12_pa;
> -	__u64 preemption_timer_deadline;
>  
>  	struct {
>  		__u16 flags;
>  	} smm;
> +
> +	__u32 flags;
> +	__u64 preemption_timer_deadline;
>  };
>  

Should we update also Documentation/virt/kvm/api.rst to be consistent?

Thanks,
Stefano