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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: Niklas Schnelle <schnelle@linux.ibm.com>
Reviewed-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/20250212213418.182902-5-mjrosato@linux.ibm.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
pull/1188/head
Matthew Rosato 2025-02-12 16:34:18 -05:00 committed by Joerg Roedel
parent 0ed5967a0a
commit 64af12c6ec
1 changed files with 72 additions and 23 deletions
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95
drivers/iommu/s390-iommu.c
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@ -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);
spin_lock_irqsave(&s390_domain->list_lock, flags);
list_del_rcu(&zdev->iommu_list);
spin_unlock_irqrestore(&s390_domain->list_lock, flags);
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()
};