Re: [PATCH 16/20] iommu/sun50i: Add an IOMMU_IDENTITIY_DOMAIN

From: Jason Gunthorpe <jgg@nvidia.com>
To: Robin Murphy <robin.murphy@arm.com>
Cc: Andy Gross <agross@kernel.org>,
	Alim Akhtar <alim.akhtar@samsung.com>,
	Bjorn Andersson <andersson@kernel.org>,
	AngeloGioacchino Del Regno 
	<angelogioacchino.delregno@collabora.com>,
	Baolin Wang <baolin.wang@linux.alibaba.com>,
	Gerald Schaefer <gerald.schaefer@linux.ibm.com>,
	Heiko Stuebner <heiko@sntech.de>,
	iommu@lists.linux.dev, Jernej Skrabec <jernej.skrabec@gmail.com>,
	Jonathan Hunter <jonathanh@nvidia.com>,
	Joerg Roedel <joro@8bytes.org>,
	Konrad Dybcio <konrad.dybcio@linaro.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>,
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	Niklas Schnelle <schnelle@linux.ibm.com>,
	Thierry Reding <thierry.reding@gmail.com>,
	Krishna Reddy <vdumpa@nvidia.com>, Chen-Yu Tsai <wens@csie.org>,
	Will Deacon <will@kernel.org>, Yong Wu <yong.wu@mediatek.com>,
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	Kevin Tian <kevin.tian@intel.com>,
	Nicolin Chen <nicolinc@nvidia.com>,
	Steven Price <steven.price@arm.com>
Subject: Re: [PATCH 16/20] iommu/sun50i: Add an IOMMU_IDENTITIY_DOMAIN
Date: Wed, 3 May 2023 13:49:17 -0300	[thread overview]
Message-ID: <ZFKQjcvUv96qQAVQ@nvidia.com> (raw)
In-Reply-To: <e73c6192-8fd5-042d-ce03-095b336270ee@arm.com>

On Wed, May 03, 2023 at 04:54:28PM +0100, Robin Murphy wrote:
> 
> On 2023-05-01 19:03, Jason Gunthorpe wrote:
> > This brings back the ops->detach_dev() code that commit
> > 1b932ceddd19 ("iommu: Remove detach_dev callbacks") deleted and turns it
> > into an IDENTITY domain.
> > 
> > Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
> > ---
> >   drivers/iommu/sun50i-iommu.c | 21 +++++++++++++++++++++
> >   1 file changed, 21 insertions(+)
> > 
> > diff --git a/drivers/iommu/sun50i-iommu.c b/drivers/iommu/sun50i-iommu.c
> > index 74c5cb93e90027..15fd62d360778f 100644
> > --- a/drivers/iommu/sun50i-iommu.c
> > +++ b/drivers/iommu/sun50i-iommu.c
> > @@ -772,6 +772,26 @@ static void sun50i_iommu_detach_device(struct iommu_domain *domain,
> >   		sun50i_iommu_detach_domain(iommu, sun50i_domain);
> >   }
> > +static int sun50i_iommu_identity_attach(struct iommu_domain *identity_domain,
> > +					struct device *dev)
> > +{
> > +	struct sun50i_iommu *iommu = dev_iommu_priv_get(dev);
> > +
> > +	if (iommu->domain == identity_domain || !iommu->domain)
> 
> I don't think that first condition could ever be true.

Oh yes, this needs more work.. I folded sun50i_iommu_detach_device()
into sun50i_iommu_identity_attach() and made iommu->domain be set to
identity immediately after allocation. Now it can't be NULL

Thanks
Jason