linux-kernel - Re: [PATCH v3 6/7] iommu/vt-d: Implement set_dev

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Date:   Sat, 1 Apr 2023 21:48:36 +0800
From:   Baolu Lu <baolu.lu@...ux.intel.com>
To:     Jacob Pan <jacob.jun.pan@...ux.intel.com>,
        LKML <linux-kernel@...r.kernel.org>, iommu@...ts.linux.dev,
        Robin Murphy <robin.murphy@....com>,
        Jason Gunthorpe <jgg@...dia.com>,
        Joerg Roedel <joro@...tes.org>, dmaengine@...r.kernel.org,
        vkoul@...nel.org
Cc:     baolu.lu@...ux.intel.com, Will Deacon <will@...nel.org>,
        David Woodhouse <dwmw2@...radead.org>,
        Raj Ashok <ashok.raj@...el.com>,
        "Tian, Kevin" <kevin.tian@...el.com>, Yi Liu <yi.l.liu@...el.com>,
        "Yu, Fenghua" <fenghua.yu@...el.com>,
        Dave Jiang <dave.jiang@...el.com>,
        Tony Luck <tony.luck@...el.com>,
        "Zanussi, Tom" <tom.zanussi@...el.com>
Subject: Re: [PATCH v3 6/7] iommu/vt-d: Implement set_dev_pasid domain op

On 2023/4/1 7:11, Jacob Pan wrote:
> Devices that use ENQCMDS to submit work on buffers mapped by DMA API
> must attach a PASID to the default domain of the device. In preparation
> for this use case, this patch implements set_dev_pasid() for the
> default_domain_ops.
> 
> If the device context has not been set up prior to this call, this will
> set up the device context in addition to PASID attachment.
> 
> Signed-off-by: Jacob Pan <jacob.jun.pan@...ux.intel.com>
> ---
>   drivers/iommu/intel/iommu.c | 21 +++++++++++++++++++++
>   1 file changed, 21 insertions(+)
> 
> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> index 52b9d0d3a02c..1ad9c5a4bd8f 100644
> --- a/drivers/iommu/intel/iommu.c
> +++ b/drivers/iommu/intel/iommu.c
> @@ -4784,6 +4784,26 @@ static void intel_iommu_remove_dev_pasid(struct device *dev, ioasid_t pasid)
>   	domain_detach_iommu(dmar_domain, info->iommu);
>   }
>   
> +static int intel_iommu_attach_device_pasid(struct iommu_domain *domain,
> +					   struct device *dev, ioasid_t pasid)
> +{
> +	struct device_domain_info *info = dev_iommu_priv_get(dev);
> +	struct dmar_domain *dmar_domain = to_dmar_domain(domain);
> +	struct intel_iommu *iommu = info->iommu;
> +	int ret;
> +
> +	if (!pasid_supported(iommu))
> +		return -ENODEV;

As the domain ID will be set to the pasid entry, need to get a refcount
of the domain ID. Call domain_attach_iommu() here, and release it after
the pasid entry is torn down.

> +	ret = prepare_domain_attach_device(domain, dev);
> +	if (ret)
> +		return ret;
> +
> +	return dmar_domain_attach_device_pasid(dmar_domain, dev, pasid);
> +}
> +
> +
> +
>   const struct iommu_ops intel_iommu_ops = {
>   	.capable		= intel_iommu_capable,
>   	.domain_alloc		= intel_iommu_domain_alloc,
> @@ -4803,6 +4823,7 @@ const struct iommu_ops intel_iommu_ops = {
>   #endif
>   	.default_domain_ops = &(const struct iommu_domain_ops) {
>   		.attach_dev		= intel_iommu_attach_device,
> +		.set_dev_pasid          = intel_iommu_attach_device_pasid,
>   		.map_pages		= intel_iommu_map_pages,
>   		.unmap_pages		= intel_iommu_unmap_pages,
>   		.iotlb_sync_map		= intel_iommu_iotlb_sync_map,

Best regards,
baolu