From: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
To: Avi Kivity <avi@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>,
LKML <linux-kernel@vger.kernel.org>, KVM <kvm@vger.kernel.org>
Subject: Re: [PATCH v6 12/12] KVM: indicate readonly access fault
Date: Fri, 07 Sep 2012 17:56:39 +0800 [thread overview]
Message-ID: <5049C4D7.50101@linux.vnet.ibm.com> (raw)
In-Reply-To: <5048AE96.3050909@redhat.com>
On 09/06/2012 10:09 PM, Avi Kivity wrote:
> On 08/22/2012 03:47 PM, Xiao Guangrong wrote:
>> On 08/22/2012 08:06 PM, Avi Kivity wrote:
>>> On 08/21/2012 06:03 AM, Xiao Guangrong wrote:
>>>> Introduce write_readonly_mem in mmio-exit-info to indicate this exit is
>>>> caused by write access on readonly memslot
>>>
>>> Please document this in chapter 5 of apic.txt.
>>>
>>
>> Okay, please review this one.
>>
>> Subject: [PATCH v6 12/12] KVM: indicate readonly access fault
>>
>> Introduce write_readonly_mem in mmio-exit-info to indicate this exit is
>> caused by write access on readonly memslot
>>
>
> I'm not sure whether this indication can be trusted by userspace. By
> the time userspace gets to process this, the slot may no longer exist,
> or it may be writable.
The case of deleting memslot is ok, because userspace just skips this fault
if no readonly mem or no fault handler can be found.
Switching memslot from readonly to writable sounds strange, i agree with you
that this flag is untrusty under this case.
Marcelo, any comments?
>
> (in the same way an mmio exit might actually hit RAM)
So, in the userspace, for the safe reason, we should walk all memslots not
just walking mmio handlers?
next prev parent reply other threads:[~2012-09-07 9:56 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-21 2:57 [PATCH v6 00/12] KVM: introduce readonly memslot Xiao Guangrong
2012-08-21 2:57 ` [PATCH v6 01/12] KVM: x86: fix possible infinite loop caused by reexecute_instruction Xiao Guangrong
2012-08-22 12:01 ` Avi Kivity
2012-08-22 12:49 ` Xiao Guangrong
2012-08-21 2:58 ` [PATCH v6 02/12] KVM: fix missing check for memslot flags Xiao Guangrong
2012-08-21 2:58 ` [PATCH v6 03/12] KVM: hide KVM_MEMSLOT_INVALID from userspace Xiao Guangrong
2012-08-21 2:59 ` [PATCH v6 04/12] KVM: introduce gfn_to_pfn_memslot_atomic Xiao Guangrong
2012-08-21 2:59 ` [PATCH v6 05/12] KVM: introduce gfn_to_hva_read/kvm_read_hva/kvm_read_hva_atomic Xiao Guangrong
2012-08-21 3:00 ` [PATCH v6 06/12] KVM: reorganize hva_to_pfn Xiao Guangrong
2012-08-21 3:00 ` [PATCH v6 07/12] KVM: use 'writable' as a hint to map writable pfn Xiao Guangrong
2012-08-21 3:01 ` [PATCH v6 08/12] KVM: introduce KVM_PFN_ERR_RO_FAULT Xiao Guangrong
2012-08-21 3:01 ` [PATCH v6 09/12] KVM: introduce KVM_HVA_ERR_BAD Xiao Guangrong
2012-08-21 3:02 ` [PATCH v6 10/12] KVM: introduce KVM_HVA_ERR_RO_BAD Xiao Guangrong
2012-08-21 3:02 ` [PATCH v6 11/12] KVM: introduce readonly memslot Xiao Guangrong
2012-09-07 10:23 ` Jan Kiszka
2012-09-07 10:47 ` Xiao Guangrong
2012-09-07 11:14 ` Jan Kiszka
2012-09-09 13:42 ` Avi Kivity
2012-09-09 13:52 ` Jan Kiszka
2012-08-21 3:03 ` [PATCH v6 12/12] KVM: indicate readonly access fault Xiao Guangrong
2012-08-22 12:06 ` Avi Kivity
2012-08-22 12:47 ` Xiao Guangrong
2012-09-06 14:09 ` Avi Kivity
2012-09-07 9:56 ` Xiao Guangrong [this message]
2012-09-09 13:46 ` Avi Kivity
2012-09-10 22:31 ` Marcelo Tosatti
2012-09-11 9:18 ` Avi Kivity
2012-09-11 14:39 ` Marcelo Tosatti
2012-09-12 15:27 ` Marcelo Tosatti
2012-09-12 15:34 ` Avi Kivity
2012-09-12 15:44 ` Marcelo Tosatti
2012-09-12 15:55 ` Avi Kivity
2012-08-22 12:09 ` [PATCH v6 00/12] KVM: introduce readonly memslot Avi Kivity
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