linux-kernel - Re: [PATCH v4 3/3] KVM: nVMX: Emulate EPTP switching for the L1 hypervisor

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Message-ID: <8c58f57d-091f-103d-5d8c-fc49b9d00e13@redhat.com>
Date:   Thu, 13 Jul 2017 17:39:48 +0200
From:   David Hildenbrand <david@...hat.com>
To:     Bandan Das <bsd@...hat.com>
Cc:     kvm@...r.kernel.org, pbonzini@...hat.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 3/3] KVM: nVMX: Emulate EPTP switching for the L1
 hypervisor

>>> +	/*
>>> +	 * If the (L2) guest does a vmfunc to the currently
>>> +	 * active ept pointer, we don't have to do anything else
>>> +	 */
>>> +	if (vmcs12->ept_pointer != address) {
>>> +		if (address >> cpuid_maxphyaddr(vcpu) ||
>>> +		    !IS_ALIGNED(address, 4096))
>>
>> Couldn't the pfn still be invalid and make kvm_mmu_reload() fail?
>> (triggering a KVM_REQ_TRIPLE_FAULT)
> 
> If there's a triple fault, I think it's a good idea to inject it
> back. Basically, there's no need to take care of damage control
> that L1 is intentionally doing.

I quickly rushed over the massive amount of comments. Sounds like you'll
be preparing a v5. Would be great if you could add some comments that
were the result of this discussion (for parts that are not that obvious
- triple faults) - thanks!

-- 

Thanks,

David