From mboxrd@z Thu Jan  1 00:00:00 1970
From: Avi Kivity <avi@redhat.com>
Subject: Re: [patch 02/10] KVM: MMU: move local TLB flush to mmu_set_spte
Date: Fri, 19 Sep 2008 17:21:09 -0700
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Cc: Avi Kivity <avi@qumranet.com>, kvm@vger.kernel.org,
	"David S. Ahern" <daahern@cisco.com>
To: Marcelo Tosatti <mtosatti@redhat.com>
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Marcelo Tosatti wrote:
> Since the sync page path can collapse flushes.
>
> Also only flush if the spte was writable before.
>
> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
>
> @@ -1241,9 +1239,12 @@ static void mmu_set_spte(struct kvm_vcpu
>  		}
>  	}
>  	if (set_spte(vcpu, shadow_pte, pte_access, user_fault, write_fault,
> -		      dirty, largepage, gfn, pfn, speculative))
> +		      dirty, largepage, gfn, pfn, speculative)) {
>  		if (write_fault)
>  			*ptwrite = 1;
> +		if (was_writeble)
> +			kvm_x86_ops->tlb_flush(vcpu);
> +	}
>  
>   

I think we had cases where the spte.pfn contents changed, for example 
when a large page was replaced by a normal page, and also:

        } else if (pfn != spte_to_pfn(*shadow_pte)) {


-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.