Re: [PATCH] iommu: iommu_group_claim_dma_owner() must always assign a domain

From: Jason Gunthorpe via iommu <iommu@lists.linux-foundation.org>
To: Nicolin Chen <nicolinc@nvidia.com>
Cc: Kevin Tian <kevin.tian@intel.com>, Will Deacon <will@kernel.org>,
	Qian Cai <quic_qiancai@quicinc.com>,
	iommu@lists.linux-foundation.org,
	Robin Murphy <robin.murphy@arm.com>
Subject: Re: [PATCH] iommu: iommu_group_claim_dma_owner() must always assign a domain
Date: Wed, 4 May 2022 08:57:09 -0300	[thread overview]
Message-ID: <20220504115709.GB50202@nvidia.com> (raw)
In-Reply-To: <YnI3qKBIBR1RlN1A@Asurada-Nvidia>

On Wed, May 04, 2022 at 01:22:00AM -0700, Nicolin Chen wrote:

> I am able to repro the issue on ARM64 and give this a quick try.
> But the patch seems to need to include the following change too.
> 
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 94d99768023c..9bb108d01baa 100644
> +++ b/drivers/iommu/iommu.c
> @@ -2040,7 +2040,8 @@ static int __iommu_attach_group(struct iommu_domain *domain,
>  {
>  	int ret;
>  
> -	if (group->domain && group->domain != group->default_domain)
> +	if (group->domain && group->domain != group->default_domain &&
> +	    group->domain != group->blocking_domain)
>  		return -EBUSY;
>  
>  	ret = __iommu_group_for_each_dev(group, domain,

Make sense, thanks

> >  	/*
> > -	 * If the group has been claimed already, do not re-attach the default
> > -	 * domain.
> > +	 * A NULL domain means to call the detach_dev() op. New drivers should
> > +	 * use a IOMMU_DOMAIN_IDENTITY domain instead of a NULL default_domain
> 
> an IOMMU_DOMAIN_IDENTITY?

Done

Jason
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu