From: Avi Kivity <avi@redhat.com>
To: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>,
LKML <linux-kernel@vger.kernel.org>, KVM <kvm@vger.kernel.org>
Subject: Re: [PATCH v6 12/12] KVM: indicate readonly access fault
Date: Wed, 12 Sep 2012 18:34:33 +0300 [thread overview]
Message-ID: <5050AB89.20705@redhat.com> (raw)
In-Reply-To: <20120911143901.GA11792@amt.cnet>
On 09/11/2012 05:39 PM, Marcelo Tosatti wrote:
> On Tue, Sep 11, 2012 at 12:18:22PM +0300, Avi Kivity wrote:
>> > The same can happen with slot deletion, for example.
>> >
>> > Userspace (which performed the modification which can result in faults
>> > to non-existant/read-only/.../new-tag memslot), must handle the faults
>> > properly or avoid the possibility for reference to memslot information
>> > from the past.
>> >
>> > I think its worthwhile to add a note about this in the API
>> > documentation: "The user of this interface is responsible for handling
>> > references to stale memslot information, either by handling
>> > exit notifications which reference stale memslot information or not
>> > allowing these notifications to exist by stopping all vcpus in userspace
>> > before performing modifications to the memslots map".
>>
>> Or we can drop the new interface and rely on userspace to perform the
>> lookup under its own locking rules.
>>
>> It's slow, but writes to ROM or ROM/device are rare anyway.
>
> Lookup what information?
Where to dispatch the write.
In fact userspace has to do that anyway if it's a ROM/device. There's
no way userspace can guess that unless we pass in the slot number (which
isn't synchronized with anything).
--
error compiling committee.c: too many arguments to function
next prev parent reply other threads:[~2012-09-12 15:34 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
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 [this message]
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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