[PATCH 2/5] iommu/s390: Add I/O TLB ops

Niklas Schnelle
2022-10-18T14:52:01Z

Currently s390-iommu does an I/O TLB flush (RPCIT) for every update of
the I/O translation table explicitly. For one this is wasteful since
RPCIT can be skipped after a mapping operation if zdev->tlb_refresh is
unset. Moreover we can do a single RPCIT for a range of pages including
whne doing lazy unmapping.

Thankfully both of these optimizations can be achieved by implementing
the IOMMU operations common code provides for the different types of I/O
tlb flushes:

* flush_iotlb_all: Flushes the I/O TLB for the entire IOVA space
* iotlb_sync: Flushes the I/O TLB for a range of pages that can be
gathered up, for example to implement lazy unmapping.
* iotlb_sync_map: Flushes the I/O TLB after a mapping operation

Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
---
drivers/iommu/s390-iommu.c | 76 ++++++++++++++++++++++++++++++++------
1 file changed, 65 insertions(+), 11 deletions(-)

diff --git a/drivers/iommu/s390-iommu.c b/drivers/iommu/s390-iommu.c
index ee88e717254b..a4c2e9bc6d83 100644
--- a/drivers/iommu/s390-iommu.c
+++ b/drivers/iommu/s390-iommu.c
@@ -199,14 +199,72 @@ static void s390_iommu_release_device(struct device *dev)
__s390_iommu_detach_device(zdev);
}

+static void s390_iommu_flush_iotlb_all(struct iommu_domain *domain)
+{
+ struct s390_domain *s390_domain = to_s390_domain(domain);
+ struct zpci_dev *zdev;
+ unsigned long flags;
+ int rc;
+
+ spin_lock_irqsave(&s390_domain->list_lock, flags);
+ list_for_each_entry(zdev, &s390_domain->devices, iommu_list) {
+ rc = zpci_refresh_trans((u64)zdev->fh << 32, zdev->start_dma,
+ zdev->end_dma - zdev->start_dma + 1);
+ if (rc)
+ break;
+ }
+ spin_unlock_irqrestore(&s390_domain->list_lock, flags);
+}
+
+static void s390_iommu_iotlb_sync(struct iommu_domain *domain,
+ struct iommu_iotlb_gather *gather)
+{
+ struct s390_domain *s390_domain = to_s390_domain(domain);
+ size_t size = gather->end - gather->start + 1;
+ struct zpci_dev *zdev;
+ unsigned long flags;
+ int rc;
+
+ /* If gather was never added to there is nothing to flush */
+ if (gather->start == ULONG_MAX)
+ return;
+
+ spin_lock_irqsave(&s390_domain->list_lock, flags);
+ list_for_each_entry(zdev, &s390_domain->devices, iommu_list) {
+ rc = zpci_refresh_trans((u64)zdev->fh << 32, gather->start,
+ size);
+ if (rc)
+ break;
+ }
+ spin_unlock_irqrestore(&s390_domain->list_lock, flags);
+}
+
+static void s390_iommu_iotlb_sync_map(struct iommu_domain *domain,
+ unsigned long iova, size_t size)
+{
+ struct s390_domain *s390_domain = to_s390_domain(domain);
+ struct zpci_dev *zdev;
+ unsigned long flags;
+ int rc;
+
+ spin_lock_irqsave(&s390_domain->list_lock, flags);
+ list_for_each_entry(zdev, &s390_domain->devices, iommu_list) {
+ if (!zdev->tlb_refresh)
+ continue;
+ rc = zpci_refresh_trans((u64)zdev->fh << 32,
+ iova, size);
+ if (rc)
+ break;
+ }
+ spin_unlock_irqrestore(&s390_domain->list_lock, flags);
+}
+
static int s390_iommu_update_trans(struct s390_domain *s390_domain,
phys_addr_t pa, dma_addr_t dma_addr,
unsigned long nr_pages, int flags)
{
phys_addr_t page_addr = pa & PAGE_MASK;
- dma_addr_t start_dma_addr = dma_addr;
unsigned long irq_flags, i;
- struct zpci_dev *zdev;
unsigned long *entry;
int rc = 0;

@@ -225,15 +283,6 @@ static int s390_iommu_update_trans(struct s390_domain *s390_domain,
dma_addr += PAGE_SIZE;
}

- spin_lock(&s390_domain->list_lock);
- 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;
- }
- spin_unlock(&s390_domain->list_lock);
-
undo_cpu_trans:
if (rc && ((flags & ZPCI_PTE_VALID_MASK) == ZPCI_PTE_VALID)) {
flags = ZPCI_PTE_INVALID;
@@ -340,6 +389,8 @@ static size_t s390_iommu_unmap_pages(struct iommu_domain *domain,
if (rc)
return 0;

+ iommu_iotlb_gather_add_range(gather, iova, size);
+
return size;
}

@@ -384,6 +435,9 @@ static const struct iommu_ops s390_iommu_ops = {
.detach_dev = s390_iommu_detach_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,
}
--
2.34.1