linux-kernel - Re: [PATCH v9 12/13] iommu/amd: Clear out the GV flag when handle deferred domain attach

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Message-ID: <20170804131320.GO1874@x1>
Date:   Fri, 4 Aug 2017 21:13:20 +0800
From:   Baoquan He <bhe@...hat.com>
To:     Joerg Roedel <jroedel@...e.de>
Cc:     iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v9 12/13] iommu/amd: Clear out the GV flag when handle
 deferred domain attach

On 08/04/17 at 02:30pm, Joerg Roedel wrote:
> On Tue, Aug 01, 2017 at 07:37:28PM +0800, Baoquan He wrote:
> > @@ -2466,11 +2472,21 @@ static struct protection_domain *get_domain(struct device *dev)
> >  		return ERR_PTR(-EINVAL);
> >  
> >  	domain = get_dev_data(dev)->domain;
> > -	if (domain == NULL && get_dev_data(dev)->defer_attach) {
> > +	if (domain == NULL && dev_data->defer_attach) {
> > +		u16 alias = amd_iommu_alias_table[dev_data->devid];
> >  		get_dev_data(dev)->defer_attach = false;
> >  		io_domain = iommu_get_domain_for_dev(dev);
> >  		domain = to_pdomain(io_domain);
> >  		attach_device(dev, domain);
> > +		/*
> > +		 * If the deferred attached domain is not v2, should clear out
> > +		 * the old GV flag.
> > +		 */
> > +		if (!(domain->flags & PD_IOMMUV2_MASK)) {
> > +			clear_dte_flag_gv(dev_data->devid);
> > +			if (alias != dev_data->devid)
> > +				clear_dte_flag_gv(dev_data->devid);
> 
> Hmm, thinking more about it, I am not sure what the IOMMU responds to
> PRI/PASID prefixes if the GV flag is 0.
> 
> But until we know it causes problems we should just disable the bit
> while doing the copy in the previous patch and avoid any special
> handling like done here.

So just drop this patch, right? Will do if I got it right. Thanks.

>