From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
Subject: Re: [RFC 09/13] iommu/smmuv3: Get prepared for nested stage support
Date: Fri, 31 Aug 2018 14:20:34 +0100
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Cc: marc.zyngier@arm.com, peter.maydell@linaro.org,
        christoffer.dall@arm.com
To: Eric Auger <eric.auger@redhat.com>, "\"eric.auger.pro"@gmail.com,
        eric.auger@redhat.com, iommu@lists.linux-foundation.org,
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On 23/08/18 13:17, Eric Auger wrote:
>  	if (ste->s1_cfg) {
> -		BUG_ON(ste_live);

Scary! :) The current code assumes that it can make modifications to the
STE in any order and enable translation after a sync. So far I haven't
been able to find anything that violates this rule in the spec: "If
software modifies the structure while it is valid, it must not allow the
structure to enter an invalid intermediate state." So maybe it's fine,
though to be safe I would have started with disabling the STE
(http://www.linux-arm.org/git?p=linux-jpb.git;a=commitdiff;h=936e49f923e101c061269eadd5fa43fef819d2e9)

Thanks,
Jean