[PATCH v7 2/6] iommu/s390: Get rid of s390_domain_device

Niklas Schnelle
2022-10-17T12:46:24Z

The struct s390_domain_device serves the sole purpose as list entry for
the devices list of a struct s390_domain. As it contains no additional
information besides a list_head and a pointer to the struct zpci_dev we
can simplify things and just thread the device list through struct
zpci_dev directly. This removes the need to allocate during domain
attach and gets rid of one level of indirection during mapping
operations.

Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
---
v5->v6:
- On attach failure make sure the IOAT is not registered
and zdev->dma_table == NULL
- Dropped Jason's R-b

arch/s390/include/asm/pci.h | 1 +
drivers/iommu/s390-iommu.c | 37 +++++++------------------------------
2 files changed, 8 insertions(+), 30 deletions(-)

diff --git a/arch/s390/include/asm/pci.h b/arch/s390/include/asm/pci.h
index 108e732d7b14..15f8714ca9b7 100644
--- a/arch/s390/include/asm/pci.h
+++ b/arch/s390/include/asm/pci.h
@@ -117,6 +117,7 @@ struct zpci_bus {
struct zpci_dev {
struct zpci_bus *zbus;
struct list_head entry; /* list of all zpci_devices, needed for hotplug, etc. */
+ struct list_head iommu_list;
struct kref kref;
struct hotplug_slot hotplug_slot;

diff --git a/drivers/iommu/s390-iommu.c b/drivers/iommu/s390-iommu.c
index c2e5e81d609e..af83ccde16a4 100644
--- a/drivers/iommu/s390-iommu.c
+++ b/drivers/iommu/s390-iommu.c
@@ -29,11 +29,6 @@ struct s390_domain {
spinlock_t list_lock;
};

-struct s390_domain_device {
- struct list_head list;
- struct zpci_dev *zdev;
-};
-
static struct s390_domain *to_s390_domain(struct iommu_domain *dom)
{
return container_of(dom, struct s390_domain, domain);
@@ -87,21 +82,13 @@ static void s390_domain_free(struct iommu_domain *domain)
static void __s390_iommu_detach_device(struct zpci_dev *zdev)
{
struct s390_domain *s390_domain = zdev->s390_domain;
- struct s390_domain_device *domain_device, *tmp;
unsigned long flags;

if (!s390_domain)
return;

spin_lock_irqsave(&s390_domain->list_lock, flags);
- list_for_each_entry_safe(domain_device, tmp, &s390_domain->devices,
- list) {
- if (domain_device->zdev == zdev) {
- list_del(&domain_device->list);
- kfree(domain_device);
- break;
- }
- }
+ list_del_init(&zdev->iommu_list);
spin_unlock_irqrestore(&s390_domain->list_lock, flags);

zpci_unregister_ioat(zdev, 0);
@@ -114,17 +101,12 @@ static int s390_iommu_attach_device(struct iommu_domain *domain,
{
struct s390_domain *s390_domain = to_s390_domain(domain);
struct zpci_dev *zdev = to_zpci_dev(dev);
- struct s390_domain_device *domain_device;
unsigned long flags;
int cc, rc = 0;

if (!zdev)
return -ENODEV;

- domain_device = kzalloc(sizeof(*domain_device), GFP_KERNEL);
- if (!domain_device)
- return -ENOMEM;
-
if (zdev->s390_domain)
__s390_iommu_detach_device(zdev);
else if (zdev->dma_table)
@@ -132,10 +114,8 @@ static int s390_iommu_attach_device(struct iommu_domain *domain,

cc = zpci_register_ioat(zdev, 0, zdev->start_dma, zdev->end_dma,
virt_to_phys(s390_domain->dma_table));
- if (cc) {
- rc = -EIO;
- goto out_free;
- }
+ if (cc)
+ return -EIO;
zdev->dma_table = s390_domain->dma_table;

spin_lock_irqsave(&s390_domain->list_lock, flags);
@@ -151,9 +131,8 @@ static int s390_iommu_attach_device(struct iommu_domain *domain,
rc = -EINVAL;
goto out_unregister;
}
- domain_device->zdev = zdev;
zdev->s390_domain = s390_domain;
- list_add(&domain_device->list, &s390_domain->devices);
+ list_add(&zdev->iommu_list, &s390_domain->devices);
spin_unlock_irqrestore(&s390_domain->list_lock, flags);

return 0;
@@ -161,8 +140,6 @@ static int s390_iommu_attach_device(struct iommu_domain *domain,
out_unregister:
zpci_unregister_ioat(zdev, 0);
zdev->dma_table = NULL;
-out_free:
- kfree(domain_device);

return rc;
}
@@ -206,10 +183,10 @@ static int s390_iommu_update_trans(struct s390_domain *s390_domain,
phys_addr_t pa, dma_addr_t dma_addr,
size_t size, int flags)
{
- struct s390_domain_device *domain_device;
phys_addr_t page_addr = pa & PAGE_MASK;
dma_addr_t start_dma_addr = dma_addr;
unsigned long irq_flags, nr_pages, i;
+ struct zpci_dev *zdev;
unsigned long *entry;
int rc = 0;

@@ -234,8 +211,8 @@ static int s390_iommu_update_trans(struct s390_domain *s390_domain,
}

spin_lock(&s390_domain->list_lock);
- list_for_each_entry(domain_device, &s390_domain->devices, list) {
- rc = zpci_refresh_trans((u64) domain_device->zdev->fh << 32,
+ list_for_each_entry(zdev, &s390_domain->devices, iommu_list) {
+ rc = zpci_refresh_trans((u64)zdev->fh << 32,
start_dma_addr, nr_pages * PAGE_SIZE);
if (rc)
break;
--
2.34.1