From mboxrd@z Thu Jan  1 00:00:00 1970
From: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Subject: Re: [PATCH v3 15/15] KVM: MMU: replace kvm_zap_all with kvm_mmu_invalid_all_pages
Date: Thu, 18 Apr 2013 12:03:45 +0800
Message-ID: <516F70A1.7010007@linux.vnet.ibm.com>
References: <1366093973-2617-1-git-send-email-xiaoguangrong@linux.vnet.ibm.com> <1366093973-2617-16-git-send-email-xiaoguangrong@linux.vnet.ibm.com> <20130418000812.GF31059@amt.cnet>
Mime-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit
Cc: gleb@redhat.com, avi.kivity@gmail.com,
	linux-kernel@vger.kernel.org, kvm@vger.kernel.org
To: Marcelo Tosatti <mtosatti@redhat.com>
Return-path: <linux-kernel-owner@vger.kernel.org>
In-Reply-To: <20130418000812.GF31059@amt.cnet>
Sender: linux-kernel-owner@vger.kernel.org
List-Id: kvm.vger.kernel.org

On 04/18/2013 08:08 AM, Marcelo Tosatti wrote:
> On Tue, Apr 16, 2013 at 02:32:53PM +0800, Xiao Guangrong wrote:
>> Use kvm_mmu_invalid_all_pages in kvm_arch_flush_shadow_all and
>> rename kvm_zap_all to kvm_free_all which is used to free all
>> memmory used by kvm mmu when vm is being destroyed, at this time,
>> no vcpu exists and mmu-notify has been unregistered, so we can
>> free the shadow pages out of mmu-lock
> 
> Since there is no contention for mmu-lock its also not a problem to 
> grab the lock right?

This still has contention. Other mmu-notify can happen when we handle
->release(). On the other handle, spin-lock is not preemptable.

> 
> Automated verification of locking/srcu might complain.

We hold slot-lock to free shadow page out of mmu-lock, it can avoid
the complain. No?