linux-kernel - Re: [PATCH 2/3] KVM: x86: fix nested guest live migration with PML

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Message-ID: <f04f7517-67d9-856b-58e4-f3efdc4566d7@google.com>
Date:   Thu, 26 Sep 2019 19:39:34 -0700
From:   Junaid Shahid <junaids@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Cc:     Vitaly Kuznetsov <vkuznets@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>
Subject: Re: [PATCH 2/3] KVM: x86: fix nested guest live migration with PML

On 9/26/19 10:18 AM, Paolo Bonzini wrote:
> @@ -1597,8 +1615,11 @@ static bool spte_clear_dirty(u64 *sptep)
>  
>  	rmap_printk("rmap_clear_dirty: spte %p %llx\n", sptep, *sptep);
>  
> -	spte &= ~shadow_dirty_mask;
> +	WARN_ON(!spte_ad_enabled(spte));
> +	if (spte_ad_need_write_protect(spte))
> +		return spte_write_protect(sptep, false);
>  
> +	spte &= ~shadow_dirty_mask;
>  	return mmu_spte_update(sptep, spte);
>  }
>  

I think that it would be a bit cleaner to move the spte_ad_need_write_protect() check to the if statement inside __rmap_clear_dirty() instead, since it already checks for spte_ad_enabled() to decide between write-protection and dirty-clearing.


Reviewed-by: Junaid Shahid <junaids@...gle.com>