Subject: Help on kvm_tlb_flush_vmid_ipa usage

From: [email-masked] (Mario Smarduch)
Date: Thu, 18 Dec 2014 11:55:56 -0800

On 12/18/2014 11:38 AM, Marc Zyngier wrote:
> On 18/12/14 19:27, Mario Smarduch wrote:
>> When this function is called IPA address is used. Looking at the HYP
>> implementation it uses the IPA directly in tlbi instructions. But
>> reading the TLB maintnance instruction syntax, bit [35:0] should be
>> set to IPA[47:12]. I traced the source code but don't see the
>> adjustment. I must be missing something given this function is
>> fundamental to KVM MMU.
> 
> Ermmm... Someone (that is, I) needs a brown paper back again.
> 
> diff --git a/arch/arm64/kvm/hyp.S b/arch/arm64/kvm/hyp.S
> index b72aa9f..a767f6a 100644
> --- a/arch/arm64/kvm/hyp.S
> +++ b/arch/arm64/kvm/hyp.S
> @@ -1014,6 +1014,7 @@ ENTRY(__kvm_tlb_flush_vmid_ipa)
>  	 * Instead, we invalidate Stage-2 for this IPA, and the
>  	 * whole of Stage-1. Weep...
>  	 */
> +	lsr	x1, x1, #12
>  	tlbi	ipas2e1is, x1
>  	/*
>  	 * We have to ensure completion of the invalidation at Stage-2,
> 
> 	M.
> 

Marc,
  thanks.

Another question, is how do you handle a huge tlb
do you need to zero out any PMD/PUD mask
bits or just pass it in as is. The manual says
MMU can figure out which bits are treated as
0 for 16/64KB pages, can same thing be assumed
for huge pages?

- Mario