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s390/pci_dma: split dma_update_trans 

Split dma_update_trans into __dma_update_trans which handles updating
the dma translation tables and __dma_purge_tlb which takes care of
purging associated entries in the dma translation lookaside buffer.

The map_sg API makes use of this split approach by calling
__dma_update_trans once per physically contiguous address range but
__dma_purge_tlb only once per dma contiguous address range.

This results in less invocations of the expensive RPCIT instruction
when using map_sg.

Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Reviewed-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Sebastian Ott 2016-09-05 17:49:17 +02:00 committed by Martin Schwidefsky
parent ee877b81c6
commit 1f166e9e5c
1 changed files with 44 additions and 21 deletions
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65
arch/s390/pci/pci_dma.c
View File

@ -129,12 +129,11 @@ void dma_update_cpu_trans(unsigned long *entry, void *page_addr, int flags)
entry_clr_protected(entry);
}
static int dma_update_trans(struct zpci_dev *zdev, unsigned long pa,
dma_addr_t dma_addr, size_t size, int flags)
static int __dma_update_trans(struct zpci_dev *zdev, unsigned long pa,
dma_addr_t dma_addr, size_t size, int flags)
{
unsigned int nr_pages = PAGE_ALIGN(size) >> PAGE_SHIFT;
u8 *page_addr = (u8 *) (pa & PAGE_MASK);
dma_addr_t start_dma_addr = dma_addr;
unsigned long irq_flags;
unsigned long *entry;
int i, rc = 0;
@ -145,7 +144,7 @@ static int dma_update_trans(struct zpci_dev *zdev, unsigned long pa,
spin_lock_irqsave(&zdev->dma_table_lock, irq_flags);
if (!zdev->dma_table) {
rc = -EINVAL;
goto no_refresh;
goto out_unlock;
}
for (i = 0; i < nr_pages; i++) {
@ -159,20 +158,6 @@ static int dma_update_trans(struct zpci_dev *zdev, unsigned long pa,
dma_addr += PAGE_SIZE;
}
/*
* With zdev->tlb_refresh == 0, rpcit is not required to establish new
* translations when previously invalid translation-table entries are
* validated. With lazy unmap, it also is skipped for previously valid
* entries, but a global rpcit is then required before any address can
* be re-used, i.e. after each iommu bitmap wrap-around.
*/
if (!zdev->tlb_refresh &&
(!s390_iommu_strict ||
((flags & ZPCI_PTE_VALID_MASK) == ZPCI_PTE_VALID)))
goto no_refresh;
rc = zpci_refresh_trans((u64) zdev->fh << 32, start_dma_addr,
nr_pages * PAGE_SIZE);
undo_cpu_trans:
if (rc && ((flags & ZPCI_PTE_VALID_MASK) == ZPCI_PTE_VALID)) {
flags = ZPCI_PTE_INVALID;
@ -185,12 +170,46 @@ undo_cpu_trans:
dma_update_cpu_trans(entry, page_addr, flags);
}
}
no_refresh:
out_unlock:
spin_unlock_irqrestore(&zdev->dma_table_lock, irq_flags);
return rc;
}
static int __dma_purge_tlb(struct zpci_dev *zdev, dma_addr_t dma_addr,
size_t size, int flags)
{
/*
* With zdev->tlb_refresh == 0, rpcit is not required to establish new
* translations when previously invalid translation-table entries are
* validated. With lazy unmap, it also is skipped for previously valid
* entries, but a global rpcit is then required before any address can
* be re-used, i.e. after each iommu bitmap wrap-around.
*/
if (!zdev->tlb_refresh &&
(!s390_iommu_strict ||
((flags & ZPCI_PTE_VALID_MASK) == ZPCI_PTE_VALID)))
return 0;
return zpci_refresh_trans((u64) zdev->fh << 32, dma_addr,
PAGE_ALIGN(size));
}
static int dma_update_trans(struct zpci_dev *zdev, unsigned long pa,
dma_addr_t dma_addr, size_t size, int flags)
{
int rc;
rc = __dma_update_trans(zdev, pa, dma_addr, size, flags);
if (rc)
return rc;
rc = __dma_purge_tlb(zdev, dma_addr, size, flags);
if (rc && ((flags & ZPCI_PTE_VALID_MASK) == ZPCI_PTE_VALID))
__dma_update_trans(zdev, pa, dma_addr, size, ZPCI_PTE_INVALID);
return rc;
}
void dma_free_seg_table(unsigned long entry)
{
unsigned long *sto = get_rt_sto(entry);
@ -411,12 +430,16 @@ static int __s390_dma_map_sg(struct device *dev, struct scatterlist *sg,
for (s = sg; dma_addr < dma_addr_base + size; s = sg_next(s)) {
pa = page_to_phys(sg_page(s)) + s->offset;
ret = dma_update_trans(zdev, pa, dma_addr, s->length, flags);
ret = __dma_update_trans(zdev, pa, dma_addr, s->length, flags);
if (ret)
goto unmap;
dma_addr += s->length;
}
ret = __dma_purge_tlb(zdev, dma_addr_base, size, flags);
if (ret)
goto unmap;
*handle = dma_addr_base;
atomic64_add(size >> PAGE_SHIFT, &zdev->mapped_pages);