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From: Paolo Bonzini <pbonzini@redhat.com>
To: "Tian, Kevin" <kevin.tian@intel.com>,
	"Song, Jike" <jike.song@intel.com>,
	Xiao Guangrong <guangrong.xiao@linux.intel.com>
Cc: "gleb@kernel.org" <gleb@kernel.org>,
	"mtosatti@redhat.com" <mtosatti@redhat.com>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"kai.huang@linux.intel.com" <kai.huang@linux.intel.com>,
	Andrea Arcangeli <aarcange@redhat.com>,
	"Alex Williamson (alex.williamson@redhat.com)" 
	<alex.williamson@redhat.com>
Subject: Re: [PATCH v3 00/11] KVM: x86: track guest page access
Date: Tue, 23 Feb 2016 13:13:22 +0100	[thread overview]
Message-ID: <56CC4CE2.1020209@redhat.com> (raw)
In-Reply-To: <AADFC41AFE54684AB9EE6CBC0274A5D15F7BC601@SHSMSX101.ccr.corp.intel.com>



On 23/02/2016 06:44, Tian, Kevin wrote:
>> From: Song, Jike
>> Sent: Tuesday, February 23, 2016 11:02 AM
>>
>> +Kevin
>>
>> On 02/22/2016 06:05 PM, Xiao Guangrong wrote:
>>>
>>> On 02/19/2016 08:00 PM, Paolo Bonzini wrote:
>>>>
>>>> I still have a doubt: how are you going to handle invalidation of GPU
>>>> shadow page tables if a device (emulated in QEMU or even vhost) does DMA
>>>> to the PPGTT?
>>>
>>> I think Jike is the better one to answer this question, Jike, could you
>>> please clarify it? :)
>>>
>>
>> Sure :)
>>
>> Actually in guest PPGTT is manipulated by CPU rather than GPU. The
>> PPGTT page table itself are plain memory, composed & modified by the
>> GPU driver, i.e. by CPU in Non-Root mode.
>>
>> Given that, we write-protected guest PPGTT, when VM writes PPGTT, EPT
>> violation rather than DMA fault happens.
> 
> 'DMA to PPGTT' is NOT SUPPORTED on our vGPU device model. Today
> Intel gfx driver doesn't use this method, and we explicitly list it as a
> guest driver requirement to support a vGPU. If a malicious driver does 
> program DMA to modify PPGTT, it can only modify guest PPGTT instead
> of shadow PPGTT (being guest invisible). So there is no security issue 
> either.

Ok, thanks for confirming.

Paolo

  reply	other threads:[~2016-02-23 12:13 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-02-14 11:31 [PATCH v3 00/11] KVM: x86: track guest page access Xiao Guangrong
2016-02-14 11:31 ` [PATCH v3 01/11] KVM: MMU: rename has_wrprotected_page to mmu_gfn_lpage_is_disallowed Xiao Guangrong
2016-02-19 11:08   ` Paolo Bonzini
2016-02-14 11:31 ` [PATCH v3 02/11] KVM: MMU: introduce kvm_mmu_gfn_{allow,disallow}_lpage Xiao Guangrong
2016-02-19 11:09   ` Paolo Bonzini
2016-02-14 11:31 ` [PATCH v3 03/11] KVM: MMU: introduce kvm_mmu_slot_gfn_write_protect Xiao Guangrong
2016-02-19 11:18   ` Paolo Bonzini
2016-02-14 11:31 ` [PATCH v3 04/11] KVM: page track: add the framework of guest page tracking Xiao Guangrong
2016-02-19 11:24   ` Paolo Bonzini
2016-02-23  3:57     ` Xiao Guangrong
2016-02-14 11:31 ` [PATCH v3 05/11] KVM: page track: introduce kvm_page_track_{add,remove}_page Xiao Guangrong
2016-02-19 11:37   ` Paolo Bonzini
2016-02-23  4:18     ` Xiao Guangrong
2016-02-23 14:15       ` Paolo Bonzini
2016-02-19 11:37   ` Paolo Bonzini
2016-02-23  4:18     ` Xiao Guangrong
2016-02-14 11:31 ` [PATCH v3 06/11] KVM: MMU: let page fault handler be aware tracked page Xiao Guangrong
2016-02-19 11:45   ` Paolo Bonzini
2016-02-23  4:19     ` Xiao Guangrong
2016-02-14 11:31 ` [PATCH v3 07/11] KVM: page track: add notifier support Xiao Guangrong
2016-02-19 11:51   ` Paolo Bonzini
2016-02-23  4:34     ` Xiao Guangrong
2016-02-23 14:16       ` Paolo Bonzini
2016-02-14 11:31 ` [PATCH v3 08/11] KVM: MMU: use page track for non-leaf shadow pages Xiao Guangrong
2016-02-14 11:31 ` [PATCH v3 09/11] KVM: MMU: simplify mmu_need_write_protect Xiao Guangrong
2016-02-14 11:31 ` [PATCH v3 10/11] KVM: MMU: clear write-flooding on the fast path of tracked page Xiao Guangrong
2016-02-19 11:55   ` Paolo Bonzini
2016-02-23  4:36     ` Xiao Guangrong
2016-02-14 11:31 ` [PATCH v3 11/11] KVM: MMU: apply page track notifier Xiao Guangrong
2016-02-19 11:56   ` Paolo Bonzini
2016-02-23  4:40     ` Xiao Guangrong
2016-02-23 14:17       ` Paolo Bonzini
2016-02-19 12:00 ` [PATCH v3 00/11] KVM: x86: track guest page access Paolo Bonzini
2016-02-22 10:05   ` Xiao Guangrong
2016-02-23  3:02     ` Jike Song
2016-02-23  3:02       ` Jike Song
2016-02-23  5:44       ` Tian, Kevin
2016-02-23  5:44         ` Tian, Kevin
2016-02-23 12:13         ` Paolo Bonzini [this message]
2016-02-23 12:13           ` Paolo Bonzini
2016-02-23 10:01       ` Paolo Bonzini
2016-02-23 11:50         ` Jike Song

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