Commit 64af12c6 authored by Matthew Rosato's avatar Matthew Rosato Committed by Joerg Roedel
Browse files

iommu/s390: implement iommu passthrough via identity domain 



Enabled via the kernel command-line 'iommu.passthrough=1' option.

Introduce the concept of identity domains to s390-iommu, which relies on
the bus_dma_region to offset identity mappings to the start of the DMA
aperture advertized by CLP.

Tested-by: default avatarNiklas Schnelle <schnelle@linux.ibm.com>
Reviewed-by: default avatarNiklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: default avatarMatthew Rosato <mjrosato@linux.ibm.com>
Reviewed-by: default avatarJason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/20250212213418.182902-5-mjrosato@linux.ibm.com


Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
parent 0ed5967a

drivers/iommu/s390-iommu.c

+72 −23
Original line number Diff line number Diff line
@@ -16,7 +16,7 @@ 


#include "dma-iommu.h"



static const struct iommu_ops s390_iommu_ops;

static const struct iommu_ops s390_iommu_ops, s390_iommu_rtr_ops;



static struct kmem_cache *dma_region_table_cache;

static struct kmem_cache *dma_page_table_cache;
@@ -432,9 +432,11 @@ static int blocking_domain_attach_device(struct iommu_domain *domain, 
		return 0;



	s390_domain = to_s390_domain(zdev->s390_domain);

	if (zdev->dma_table) {

		spin_lock_irqsave(&s390_domain->list_lock, flags);

		list_del_rcu(&zdev->iommu_list);

		spin_unlock_irqrestore(&s390_domain->list_lock, flags);

	}



	zpci_unregister_ioat(zdev, 0);

	zdev->dma_table = NULL;
@@ -762,7 +764,13 @@ int zpci_init_iommu(struct zpci_dev *zdev) 
	if (rc)

		goto out_err;



	rc = iommu_device_register(&zdev->iommu_dev, &s390_iommu_ops, NULL);

	if (zdev->rtr_avail) {

		rc = iommu_device_register(&zdev->iommu_dev,

					   &s390_iommu_rtr_ops, NULL);

	} else {

		rc = iommu_device_register(&zdev->iommu_dev, &s390_iommu_ops,

					   NULL);

	}

	if (rc)

		goto out_sysfs;
@@ -826,6 +834,39 @@ static int __init s390_iommu_init(void) 
}

subsys_initcall(s390_iommu_init);



static int s390_attach_dev_identity(struct iommu_domain *domain,

				    struct device *dev)

{

	struct zpci_dev *zdev = to_zpci_dev(dev);

	u8 status;

	int cc;



	blocking_domain_attach_device(&blocking_domain, dev);



	/* If we fail now DMA remains blocked via blocking domain */

	cc = s390_iommu_domain_reg_ioat(zdev, domain, &status);



	/*

	 * If the device is undergoing error recovery the reset code

	 * will re-establish the new domain.

	 */

	if (cc && status != ZPCI_PCI_ST_FUNC_NOT_AVAIL)

		return -EIO;



	zdev_s390_domain_update(zdev, domain);



	return 0;

}



static const struct iommu_domain_ops s390_identity_ops = {

	.attach_dev = s390_attach_dev_identity,

};



static struct iommu_domain s390_identity_domain = {

	.type = IOMMU_DOMAIN_IDENTITY,

	.ops = &s390_identity_ops,

};



static struct iommu_domain blocking_domain = {

	.type = IOMMU_DOMAIN_BLOCKED,

	.ops = &(const struct iommu_domain_ops) {
@@ -833,23 +874,31 @@ static struct iommu_domain blocking_domain = { 
	}

};



static const struct iommu_ops s390_iommu_ops = {

	.blocked_domain		= &blocking_domain,

	.release_domain		= &blocking_domain,

	.capable = s390_iommu_capable,

	.domain_alloc_paging = s390_domain_alloc_paging,

	.probe_device = s390_iommu_probe_device,

	.device_group = generic_device_group,

	.pgsize_bitmap = SZ_4K,

	.get_resv_regions = s390_iommu_get_resv_regions,

	.default_domain_ops = &(const struct iommu_domain_ops) {

		.attach_dev	= s390_iommu_attach_device,

		.map_pages	= s390_iommu_map_pages,

		.unmap_pages	= s390_iommu_unmap_pages,

		.flush_iotlb_all = s390_iommu_flush_iotlb_all,

		.iotlb_sync      = s390_iommu_iotlb_sync,

		.iotlb_sync_map  = s390_iommu_iotlb_sync_map,

		.iova_to_phys	= s390_iommu_iova_to_phys,

		.free		= s390_domain_free,

#define S390_IOMMU_COMMON_OPS() \

	.blocked_domain		= &blocking_domain, \

	.release_domain		= &blocking_domain, \

	.capable = s390_iommu_capable, \

	.domain_alloc_paging = s390_domain_alloc_paging, \

	.probe_device = s390_iommu_probe_device, \

	.device_group = generic_device_group, \

	.pgsize_bitmap = SZ_4K, \

	.get_resv_regions = s390_iommu_get_resv_regions, \

	.default_domain_ops = &(const struct iommu_domain_ops) { \

		.attach_dev	= s390_iommu_attach_device, \

		.map_pages	= s390_iommu_map_pages, \

		.unmap_pages	= s390_iommu_unmap_pages, \

		.flush_iotlb_all = s390_iommu_flush_iotlb_all, \

		.iotlb_sync      = s390_iommu_iotlb_sync, \

		.iotlb_sync_map  = s390_iommu_iotlb_sync_map, \

		.iova_to_phys	= s390_iommu_iova_to_phys, \

		.free		= s390_domain_free, \

	}



static const struct iommu_ops s390_iommu_ops = {

	S390_IOMMU_COMMON_OPS()

};



static const struct iommu_ops s390_iommu_rtr_ops = {

	.identity_domain	= &s390_identity_domain,

	S390_IOMMU_COMMON_OPS()

};