Re: [PATCH v8 20/24] iommu: Require a default_domain for all iommu drivers

From: Jason Gunthorpe <jgg@nvidia.com>
To: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Cc: Rob Clark <robdclark@gmail.com>, 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>,
	Christophe Leroy <christophe.leroy@csgroup.eu>,
	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>, Kevin Tian <kevin.tian@intel.com>,
	Konrad Dybcio <konrad.dybcio@linaro.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>,
	linux-arm-kernel@lists.infradead.org,
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	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>,
	Chunyan Zhang <zhang.lyra@gmail.com>,
	Lu Baolu <baolu.lu@linux.intel.com>,
	Dmitry Osipenko <digetx@gmail.com>,
	Jerry Snitselaar <jsnitsel@redhat.com>,
	Marek Szyprowski <m.szyprowski@samsung.com>,
	Nicolin Chen <nicolinc@nvidia.com>,
	Niklas Schnelle <schnelle@linux.ibm.com>,
	Steven Price <steven.price@arm.com>,
	Thierry Reding <treding@nvidia.com>
Subject: Re: [PATCH v8 20/24] iommu: Require a default_domain for all iommu drivers
Date: Mon, 2 Oct 2023 20:00:00 -0300	[thread overview]
Message-ID: <20231002230000.GA682044@nvidia.com> (raw)
In-Reply-To: <CAA8EJprz7VVmBG68U9zLuqPd0UdSRHYoLDJSP6tCj6H6qanuTQ@mail.gmail.com>

On Tue, Oct 03, 2023 at 12:21:59AM +0300, Dmitry Baryshkov wrote:
> On Wed, 13 Sept 2023 at 16:45, Jason Gunthorpe <jgg@nvidia.com> wrote:
> >
> > At this point every iommu driver will cause a default_domain to be
> > selected, so we can finally remove this gap from the core code.
> >
> > The following table explains what each driver supports and what the
> > resulting default_domain will be:
> >
> >                                         ops->defaut_domain
> >                     IDENTITY   DMA  PLATFORM    v      ARM32          dma-iommu  ARCH
> > amd/iommu.c             Y       Y                       N/A             either
> > apple-dart.c            Y       Y                       N/A             either
> > arm-smmu.c              Y       Y                       IDENTITY        either
> > qcom_iommu.c            G       Y                       IDENTITY        either
> > arm-smmu-v3.c           Y       Y                       N/A             either
> > exynos-iommu.c          G       Y                       IDENTITY        either
> > fsl_pamu_domain.c                       Y       Y       N/A             N/A     PLATFORM
> > intel/iommu.c           Y       Y                       N/A             either
> > ipmmu-vmsa.c            G       Y                       IDENTITY        either
> > msm_iommu.c             G                               IDENTITY        N/A
> 
> Unfortunately this patch breaks msm_iommu platforms. This driver
> doesn't select ARM_DMA_USE_IOMMU, so iommu_get_default_domain_type()
> returns 0, bus_iommu_probe() fails with -ENODEV.
> If I make MSM_IOMMU select ARM_DMA_USE_IOMMU, then GPU probing fails
> with -EBUSY.

Oh, OK.

Does this fix it?

diff --git a/drivers/iommu/msm_iommu.c b/drivers/iommu/msm_iommu.c
index cdc7b730192a35..f7ef081c33dcb2 100644
--- a/drivers/iommu/msm_iommu.c
+++ b/drivers/iommu/msm_iommu.c
@@ -685,10 +685,16 @@ irqreturn_t msm_iommu_fault_handler(int irq, void *dev_id)
 	return 0;
 }
 
+static int msm_iommu_def_domain_type(struct device *dev)
+{
+	return IOMMU_DOMAIN_IDENTITY;
+}
+
 static struct iommu_ops msm_iommu_ops = {
 	.identity_domain = &msm_iommu_identity_domain,
 	.domain_alloc_paging = msm_iommu_domain_alloc_paging,
 	.probe_device = msm_iommu_probe_device,
+	.def_domain_type = msm_iommu_def_domain_type,
 	.device_group = generic_device_group,
 	.pgsize_bitmap = MSM_IOMMU_PGSIZES,
 	.of_xlate = qcom_iommu_of_xlate,
