Re: [PATCH v6 2/2] i386: Add notify VM exit support

From: Chenyi Qiang <chenyi.qiang@intel.com>
To: Peter Xu <peterx@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
	Marcelo Tosatti <mtosatti@redhat.com>,
	Richard Henderson <richard.henderson@linaro.org>,
	Eduardo Habkost <eduardo@habkost.net>,
	Xiaoyao Li <xiaoyao.li@intel.com>,
	qemu-devel@nongnu.org, kvm@vger.kernel.org
Subject: Re: [PATCH v6 2/2] i386: Add notify VM exit support
Date: Wed, 21 Sep 2022 11:07:40 +0800	[thread overview]
Message-ID: <38a4d1c0-25e6-0836-c2bc-5ae580c95715@intel.com> (raw)
In-Reply-To: <YynHXI+Vtrf9J/Ae@xz-m1.local>

On 9/20/2022 9:59 PM, Peter Xu wrote:
> On Tue, Sep 20, 2022 at 01:55:20PM +0800, Chenyi Qiang wrote:
>>>> @@ -5213,6 +5213,7 @@ int kvm_arch_handle_exit(CPUState *cs, struct kvm_run
>>>> *run)
>>>>            break;
>>>>        case KVM_EXIT_NOTIFY:
>>>>            ret = 0;
>>>> +        warn_report_once("KVM: notify window was exceeded in guest");
>>>
>>> Is there more informative way to dump this?  If it's 99% that the guest was
>>> doing something weird and needs attention, maybe worthwhile to point that
>>> out directly to the admin?
>>>
>>
>> Do you mean to use other method to dump the info? i.e. printing a message is
>> not so clear. Or the output message ("KVM: notify window was exceeded in
>> guest") is not obvious and we need other wording.
> 
> I meant something like:
> 
>    KVM received notify exit.  It means there can be possible misbehaves in
>    the guest, please have a look.

Get your point. Then I can print this message behind as well.

Thanks.

> 
> Or something similar.  What I'm worried is the admin may not understand
> what's "notify window" and that message got simply ignored.
> 
> Though I am not even sure whether that's accurate in the wordings.
> 
>>
>>>>            if (run->notify.flags & KVM_NOTIFY_CONTEXT_INVALID) {
>>>>                warn_report("KVM: invalid context due to notify vmexit");
>>>>                if (has_triple_fault_event) {
>>>
>>> Adding a warning looks good to me, with that (or in any better form of
>>> wording):
>>>
>> If no objection, I'll follow Xiaoyao's suggestion to form the wording like:
> 
> No objection here.  Thanks.
> 