From: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
To: Gleb Natapov <gleb@redhat.com>
Cc: avi.kivity@gmail.com, mtosatti@redhat.com, pbonzini@redhat.com,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Subject: Re: [PATCH v8 00/11] KVM: MMU: fast zap all shadow pages
Date: Sun, 09 Jun 2013 17:06:24 +0800 [thread overview]
Message-ID: <51B44590.7030009@linux.vnet.ibm.com> (raw)
In-Reply-To: <20130609085342.GI4725@redhat.com>
On 06/09/2013 04:53 PM, Gleb Natapov wrote:
> On Fri, May 31, 2013 at 08:36:19AM +0800, Xiao Guangrong wrote:
>> Hi Gleb, Paolo, Marcelo,
>>
>> I have putted the potential controversial patches to the latter that are
>> patch 8 ~ 10, patch 11 depends on patch 9. Other patches are fully reviewed,
>> I think its are ready for being merged. If not luck enough, further discussion
>> is needed, could you please apply that patches first? :)
>>
>> Thank you in advance!
>>
>> Some points are raised during discussion but missed in this version:
>> 1) Gleb's idea that skip obsolete pages in the hast list walker
>>
>> Unfortunately, it is not safe. There has a window between updating
>> valid-gen and reloading mmu, in that window, the obsolete page can
>> be used by vcpu, but the guest page table fail to be write-protected
>> (since the obsolete page is skipped in mmu_need_write_protect()).
>>
> Can you elaborate on how this can happen. valid_gen is updated under
> mmu_lock and reloading of mmus happens under the same lock, so for all
> other vcpus this should look like atomic thing.
You're right.
Actually, i made another optimization patch in this version that moves
kvm_reload_remote_mmus() out of mmu-lock, but did not attach it into this
series. It seems my brain is not parallel-able enough. :(
next prev parent reply other threads:[~2013-06-09 9:06 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-05-31 0:36 [PATCH v8 00/11] KVM: MMU: fast zap all shadow pages Xiao Guangrong
2013-05-31 0:36 ` [PATCH v8 01/11] KVM: x86: drop calling kvm_mmu_zap_all in emulator_fix_hypercall Xiao Guangrong
2013-05-31 0:36 ` [PATCH v8 02/11] KVM: MMU: drop unnecessary kvm_reload_remote_mmus Xiao Guangrong
2013-05-31 0:36 ` [PATCH v8 03/11] KVM: MMU: fast invalidate all pages Xiao Guangrong
2013-05-31 0:36 ` [PATCH v8 04/11] KVM: x86: use the fast way to " Xiao Guangrong
2013-05-31 0:36 ` [PATCH v8 05/11] KVM: MMU: show mmu_valid_gen in shadow page related tracepoints Xiao Guangrong
2013-05-31 0:36 ` [PATCH v8 06/11] KVM: MMU: add tracepoint for kvm_mmu_invalidate_all_pages Xiao Guangrong
2013-05-31 0:36 ` [PATCH v8 07/11] KVM: MMU: do not reuse the obsolete page Xiao Guangrong
2013-05-31 0:36 ` [PATCH v8 08/11] KVM: MMU: zap pages in batch Xiao Guangrong
2013-05-31 0:36 ` [PATCH v8 09/11] KVM: MMU: collapse TLB flushes when zap all pages Xiao Guangrong
2013-05-31 0:36 ` [PATCH v8 10/11] KVM: MMU: reclaim the zapped-obsolete page first Xiao Guangrong
2013-05-31 0:36 ` [PATCH v8 11/11] KVM: MMU: reduce KVM_REQ_MMU_RELOAD when root page is zapped Xiao Guangrong
2013-06-05 1:26 ` [PATCH v8 00/11] KVM: MMU: fast zap all shadow pages Marcelo Tosatti
2013-06-05 9:51 ` Gleb Natapov
2013-06-05 9:52 ` Gleb Natapov
2013-06-09 8:53 ` Gleb Natapov
2013-06-09 9:06 ` Xiao Guangrong [this message]
2013-06-09 9:09 ` Gleb Natapov
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