On Sat, Feb 08, 2025 at 01:02:39AM -0800, Nicolin Chen wrote:
> +static struct iommufd_attach_handle *
> +iommu_group_get_iommufd_handle(struct iommu_group *group)
> +{
> + struct iommu_attach_handle *handle;
> +
> + handle = iommu_attach_handle_get(group, IOMMU_NO_PASID, 0);
> + if (IS_ERR(handle))
> + return NULL;
> + return to_iommufd_handle(handle);
> +}
> +
> +/*
> + * Called by the irq code if the platform translates the MSI address through the
> + * IOMMU. msi_addr is the physical address of the MSI page. iommufd will
> + * allocate a fd global iova for the physical page that is the same on all
> + * domains and devices.
> + */
> +#ifdef CONFIG_IRQ_MSI_IOMMU
> +int iommufd_sw_msi(struct iommu_domain *domain, struct msi_desc *desc,
> + phys_addr_t msi_addr)
> +{
> + struct device *dev = msi_desc_to_dev(desc);
> + struct iommufd_hwpt_paging *hwpt_paging;
> + struct iommufd_attach_handle *handle;
> + struct iommufd_sw_msi_map *msi_map;
> + struct iommufd_ctx *ictx;
> + unsigned long iova;
> + int rc;
> +
> + handle = iommu_group_get_iommufd_handle(dev->iommu_group);
> + if (!handle)
> + return 0;
I think you should open code this and leave the other function
alone. The locking rules are different here.
iommufd_device_get_attach_handle() should be locked under the
igroup->lock
While in this context we are locked under the iommu core group mutex.
A comment will help
/*
* It is safe to call iommu_attach_handle_get() here because the iommu
* core code invokes this under the group mutex which also prevents any
* change of the attach handle for the duration of this function.
*/
iommu_group_mutex_assert(dev);
Jason
