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From: David Hildenbrand <david@redhat.com>
To: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	Paolo Bonzini <pbonzini@redhat.com>
Cc: kvm@vger.kernel.org, "Radim Krčmář" <rkrcmar@redhat.com>,
	"Bandan Das" <bsd@redhat.com>
Subject: Re: [PATCH v1 2/2] KVM: VMX: always require WB memory type for EPT
Date: Thu, 10 Aug 2017 22:09:33 +0200	[thread overview]
Message-ID: <231aba07-07c9-9f3e-d61f-a270cb88cc83@redhat.com> (raw)
In-Reply-To: <20170810183056.GY2547@char.us.oracle.com>

On 10.08.2017 20:30, Konrad Rzeszutek Wilk wrote:
> On Thu, Aug 10, 2017 at 04:42:02PM +0200, Paolo Bonzini wrote:
>> On 10/08/2017 15:35, David Hildenbrand wrote:
>>> We already always set that type but don't check if it is supported. Also
>>> for nVMX, we only support WB for now. Let's just require it.
>>>
>>> Signed-off-by: David Hildenbrand <david@redhat.com>
>>
>> It may only happen on a broken nested hypervisor, so the patch is okay.
> 
> Is there one in the wild?

I think only the following scenario would see a change:

Hypervisor supports but doesn't announce the WB memory type for EPT.
KVM runs as nested hypervisor. It will now refuse to use EPT but should
continue to work without EPT.

In this case, the hypervisor would have a BUG and we as a nested
hypervisor would do the right thing.

>>
>> Paolo
>>


-- 

Thanks,

David

  reply	other threads:[~2017-08-10 20:09 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-08-10 13:35 [PATCH v1 0/2] KVM: VMX: require EPTP WB (write-back) support David Hildenbrand
2017-08-10 13:35 ` [PATCH v1 1/2] KVM: VMX: cleanup EPTP definitions David Hildenbrand
2017-08-10 19:38   ` Bandan Das
2017-08-10 19:53     ` David Hildenbrand
2017-08-10 20:58   ` David Hildenbrand
2017-08-10 13:35 ` [PATCH v1 2/2] KVM: VMX: always require WB memory type for EPT David Hildenbrand
2017-08-10 14:42   ` Paolo Bonzini
2017-08-10 18:30     ` Konrad Rzeszutek Wilk
2017-08-10 20:09       ` David Hildenbrand [this message]
2017-08-10 19:40   ` Bandan Das
2017-08-10 19:54     ` David Hildenbrand
2017-08-10 14:23 ` [PATCH v1 0/2] KVM: VMX: require EPTP WB (write-back) support Radim Krčmář
2017-08-10 14:25   ` David Hildenbrand
2017-08-10 16:34     ` Radim Krčmář

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