[PATCH kernel v3 3/5] vfio/spapr_tce: Invalidate multiple TCEs at once

[Alexey Kardashevskiy]

Invalidating a TCE cache entry for each updated TCE is quite expensive.
This makes use of the new iommu_table_ops::xchg_no_kill()/tce_kill()
callbacks to bring down the time spent in mapping a huge guest DMA window.

Signed-off-by: Alexey Kardashevskiy <a...@ozlabs.ru>
---
 drivers/vfio/vfio_iommu_spapr_tce.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c 
b/drivers/vfio/vfio_iommu_spapr_tce.c
index babef8b00daf..3b18fa4d090a 100644
--- a/drivers/vfio/vfio_iommu_spapr_tce.c
+++ b/drivers/vfio/vfio_iommu_spapr_tce.c
@@ -435,7 +435,7 @@ static int tce_iommu_clear(struct tce_container *container,
        unsigned long oldhpa;
        long ret;
        enum dma_data_direction direction;
-       unsigned long lastentry = entry + pages;
+       unsigned long lastentry = entry + pages, firstentry = entry;
 
        for ( ; entry < lastentry; ++entry) {
                if (tbl->it_indirect_levels && tbl->it_userspace) {
@@ -460,7 +460,7 @@ static int tce_iommu_clear(struct tce_container *container,
 
                direction = DMA_NONE;
                oldhpa = 0;
-               ret = iommu_tce_xchg(container->mm, tbl, entry, &oldhpa,
+               ret = iommu_tce_xchg_no_kill(container->mm, tbl, entry, &oldhpa,
                                &direction);
                if (ret)
                        continue;
@@ -476,6 +476,8 @@ static int tce_iommu_clear(struct tce_container *container,
                tce_iommu_unuse_page(container, oldhpa);
        }
 
+       iommu_tce_kill(tbl, firstentry, pages);
+
        return 0;
 }
 
@@ -518,8 +520,8 @@ static long tce_iommu_build(struct tce_container *container,
 
                hpa |= offset;
                dirtmp = direction;
-               ret = iommu_tce_xchg(container->mm, tbl, entry + i, &hpa,
-                               &dirtmp);
+               ret = iommu_tce_xchg_no_kill(container->mm, tbl, entry + i,
+                               &hpa, &dirtmp);
                if (ret) {
                        tce_iommu_unuse_page(container, hpa);
                        pr_err("iommu_tce: %s failed ioba=%lx, tce=%lx, 
ret=%ld\n",
@@ -536,6 +538,8 @@ static long tce_iommu_build(struct tce_container *container,
 
        if (ret)
                tce_iommu_clear(container, tbl, entry, i);
+       else
+               iommu_tce_kill(tbl, entry, pages);
 
        return ret;
 }
@@ -572,8 +576,8 @@ static long tce_iommu_build_v2(struct tce_container 
*container,
                if (mm_iommu_mapped_inc(mem))
                        break;
 
-               ret = iommu_tce_xchg(container->mm, tbl, entry + i, &hpa,
-                               &dirtmp);
+               ret = iommu_tce_xchg_no_kill(container->mm, tbl, entry + i,
+                               &hpa, &dirtmp);
                if (ret) {
                        /* dirtmp cannot be DMA_NONE here */
                        tce_iommu_unuse_page_v2(container, tbl, entry + i);
@@ -593,6 +597,8 @@ static long tce_iommu_build_v2(struct tce_container 
*container,
 
        if (ret)
                tce_iommu_clear(container, tbl, entry, i);
+       else
+               iommu_tce_kill(tbl, entry, pages);
 
        return ret;
 }
-- 
2.17.1