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

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Message-ID: <311c1b21-82fb-396b-382e-d4caca0cb691@redhat.com>
Date:   Fri, 10 Jul 2020 11:27:41 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Stefano Garzarella <sgarzare@...hat.com>
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        Makarand Sonare <makarandsonare@...gle.com>,
        Jim Mattson <jmattson@...gle.com>
Subject: Re: [PATCH v2] KVM: nVMX: fixes for preemption timer migration

On 10/07/20 11:05, Stefano Garzarella wrote:
> 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@...gle.com>
>> Fixes: 850448f35aaf ("KVM: nVMX: Fix VMX preemption timer migration")
>> Reviewed-by: Jim Mattson <jmattson@...gle.com>
>> Signed-off-by: Paolo Bonzini <pbonzini@...hat.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?

Yes, of course.  Thanks for pointing it out.

Paolo