From: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
To: Gleb Natapov <gleb@redhat.com>
Cc: markus@trippelsdorf.de, mtosatti@redhat.com, pbonzini@redhat.com,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Subject: Re: [PATCH] KVM: MMU: avoid fast page fault fixing mmio page fault
Date: Thu, 18 Jul 2013 14:01:47 +0800 [thread overview]
Message-ID: <51E784CB.1040402@linux.vnet.ibm.com> (raw)
In-Reply-To: <20130718053154.GY11772@redhat.com>
On 07/18/2013 01:31 PM, Gleb Natapov wrote:
> On Thu, Jul 18, 2013 at 12:52:37PM +0800, Xiao Guangrong wrote:
>> Currently, fast page fault tries to fix mmio page fault when the
>> generation number is invalid (spte.gen != kvm.gen) and returns to
>> guest to retry the fault since it sees the last spte is nonpresent
>> which causes infinity loop
>>
>> It can be triggered only on AMD host since the mmio page fault is
>> recognized as ept-misconfig
>>
> We still call into regular page fault handler from ept-misconfig
> handler, but fake zero error_code we provide makes page_fault_can_be_fast()
> return false.
Yes.
>
> Shouldn't shadow paging trigger this too? I haven't encountered this on
> Intel without ept.
Since currently fast page fault only works for direct mmu. :)
next prev parent reply other threads:[~2013-07-18 6:01 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-18 4:52 [PATCH] KVM: MMU: avoid fast page fault fixing mmio page fault Xiao Guangrong
2013-07-18 4:55 ` Xiao Guangrong
2013-07-18 5:31 ` Gleb Natapov
2013-07-18 6:01 ` Xiao Guangrong [this message]
2013-07-18 6:06 ` Gleb Natapov
2013-07-18 6:25 ` Xiao Guangrong
2013-07-18 6:28 ` Gleb Natapov
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