Re: [PATCH RESEND v4 2/2] arm/arm64: KVM: Add KVM_GET/SET_VCPU_EVENTS

[gengdongjiu <gengdongjiu@huawei.com>]

On 2018/6/11 21:36, James Morse wrote:
> Hi Dongjiu Geng,
> 
> On 09/06/18 13:40, Marc Zyngier wrote:
>> On Fri, 08 Jun 2018 20:48:40 +0100, Dongjiu Geng wrote:
>>> For the migrating VMs, user space may need to know the exception
>>> state. For example, in the machine A, KVM make an SError pending,
>>> when migrate to B, KVM also needs to pend an SError.
>>>
>>> This new IOCTL exports user-invisible states related to SError.
>>> Together with appropriate user space changes, user space can get/set
>>> the SError exception state to do migrate/snapshot/suspend.
> 
>>> diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
>>> index 04b3256..df4faee 100644
>>> --- a/arch/arm64/include/uapi/asm/kvm.h
>>> +++ b/arch/arm64/include/uapi/asm/kvm.h
>>> @@ -153,6 +154,18 @@ struct kvm_sync_regs {
>>>  struct kvm_arch_memory_slot {
>>>  };
>>>  
>>> +/* for KVM_GET/SET_VCPU_EVENTS */
>>> +struct kvm_vcpu_events {
>>> +	struct {
>>> +		__u8 serror_pending;
>>> +		__u8 serror_has_esr;
>>> +		/* Align it to 8 bytes */
>>> +		__u8 pad[6];
>>> +		__u64 serror_esr;
>>> +	} exception;
>>> +	__u32 reserved[12];
>>> +};
> 
>>> diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
>>> index 56a0260..4426915 100644
>>> --- a/arch/arm64/kvm/guest.c
>>> +++ b/arch/arm64/kvm/guest.c
> 
>>> +int kvm_arm_vcpu_set_events(struct kvm_vcpu *vcpu,
>>> +			struct kvm_vcpu_events *events)
>>> +{
>>> +	bool serror_pending = events->exception.serror_pending;
>>> +	bool has_esr = events->exception.serror_has_esr;
>>> +
>>> +	if (serror_pending && has_esr) {
>>> +		if (!cpus_have_const_cap(ARM64_HAS_RAS_EXTN))
>>> +			return -EINVAL;
>>> +
>>> +		kvm_set_sei_esr(vcpu, events->exception.serror_esr);
>>> +	} else if (serror_pending) {
>>> +		kvm_inject_vabt(vcpu);
>>> +	}
>>> +
>>> +	return 0;
>>
>> There was an earlier request to check that all the padding is set to
>> zero. I still think this makes sense.
> 
> I agree, not just the exception.padding[], but reserved[] too.
  Ok, thanks for the reminder again.

> 
> 
> Thanks,
> 
> James
> 
> .
>