Re: [PATCH v3 7/7] dmaengine/idxd: Re-enable kernel workqueue under DMA API

[Baolu Lu]

On 2023/4/1 7:11, Jacob Pan wrote:
>   static void idxd_disable_system_pasid(struct idxd_device *idxd)
>   {
> +	struct pci_dev *pdev = idxd->pdev;
> +	struct device *dev = &pdev->dev;
> +	struct iommu_domain *domain;
> +	union gencfg_reg gencfg;
> +
> +	domain = iommu_get_domain_for_dev(dev);
> +	if (!domain || domain->type == IOMMU_DOMAIN_BLOCKED)
> +		return;

Out of curiosity, why do you need to check the domain type? And, in
which case could the domain for the device be changed to a blocking one?

Once a driver is bound to the device, the driver "owns" the DMA of the
device. No one else could change the domain except the driver itself.

> +
> +	iommu_detach_device_pasid(domain, dev, idxd->pasid);
> +	iommu_free_global_pasid(idxd->pasid);
>   
> -	iommu_sva_unbind_device(idxd->sva);
> +	gencfg.bits = ioread32(idxd->reg_base + IDXD_GENCFG_OFFSET);
> +	gencfg.user_int_en = 0;
> +	iowrite32(gencfg.bits, idxd->reg_base + IDXD_GENCFG_OFFSET);
>   	idxd->sva = NULL;
> +	idxd->pasid = IOMMU_PASID_INVALID;
>   }

Best regards,
baolu