From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrew Cooper <andrew.cooper3@citrix.com>
Subject: Re: [PATCHv1 3/3] x86/ept: defer the invalidation until
 the p2m lock is released
Date: Fri, 6 Nov 2015 18:39:30 +0000
Message-ID: <563CF3E2.3030604@citrix.com>
References: <1446831437-5897-1-git-send-email-david.vrabel@citrix.com>
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To: David Vrabel <david.vrabel@citrix.com>, xen-devel@lists.xenproject.org
Cc: Kevin Tian <kevin.tian@intel.com>, Jan Beulich <jbeulich@suse.com>, Jun Nakajima <jun.nakajima@intel.com>
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On 06/11/15 17:37, David Vrabel wrote:
>  out:
>      if ( fdom )
>          rcu_unlock_domain(fdom);
>      return rc;
>  }
> +
> +int p2m_setup(void)
> +{
> +    unsigned int cpu;
> +
> +    for_each_present_cpu(cpu)
> +        INIT_PAGE_LIST_HEAD(&per_cpu(p2m_deferred_free_pages, cpu));
> +
> +    return 0;
> +}
> +__initcall(p2m_setup);
> +

This is going to create problems for cpu hotplug, and some power
governers.  The INIT_PAGE_LIST_HEAD() needs to be in a CPU_PREPARE notifier.

It might also be wise to have the DYING side confirm that the list is empty.

~Andrew