2013-07-26 11:26:35

by Cho KyongHo

Subject: [PATCH v8 02/12] iommu/exynos: add missing cache flush for removed page table entries

This commit adds cache flush for removed small and large page entries
in exynos_iommu_unmap(). Missing cache flush of removed page table
entries can cause missing page fault interrupt when a master IP
accesses an unmapped area.

Signed-off-by: Cho KyongHo <[email protected]>
---
drivers/iommu/exynos-iommu.c | 2 ++
1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/drivers/iommu/exynos-iommu.c b/drivers/iommu/exynos-iommu.c
index 233f382..e3be3e5 100644
--- a/drivers/iommu/exynos-iommu.c
+++ b/drivers/iommu/exynos-iommu.c
@@ -1002,6 +1002,7 @@ static size_t exynos_iommu_unmap(struct iommu_domain *domain,
if (lv2ent_small(ent)) {
*ent = 0;
size = SPAGE_SIZE;
+ pgtable_flush(ent, ent +1);
priv->lv2entcnt[lv1ent_offset(iova)] += 1;
goto done;
}
@@ -1010,6 +1011,7 @@ static size_t exynos_iommu_unmap(struct iommu_domain *domain,
BUG_ON(size < LPAGE_SIZE);

memset(ent, 0, sizeof(*ent) * SPAGES_PER_LPAGE);
+ pgtable_flush(ent, ent + SPAGES_PER_LPAGE);

size = LPAGE_SIZE;
priv->lv2entcnt[lv1ent_offset(iova)] += SPAGES_PER_LPAGE;
--
1.7.2.5

2013-07-26 15:59:03

by Grant Grundler

Subject: Re: [PATCH v8 02/12] iommu/exynos: add missing cache flush for removed page table entries

On Fri, Jul 26, 2013 at 4:26 AM, Cho KyongHo <[email protected]> wrote:
> This commit adds cache flush for removed small and large page entries
> in exynos_iommu_unmap(). Missing cache flush of removed page table
> entries can cause missing page fault interrupt when a master IP
> accesses an unmapped area.
>
> Signed-off-by: Cho KyongHo <[email protected]>

Tested-by: Grant Grundler <[email protected]>

I'm convinced this is a critical fix to apply. Any time we touch the
IOMMU Page Table, we need to flush so the change is immediately
visible to the IOMMU.

thanks,
grant

> ---
> drivers/iommu/exynos-iommu.c | 2 ++
> 1 files changed, 2 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/iommu/exynos-iommu.c b/drivers/iommu/exynos-iommu.c
> index 233f382..e3be3e5 100644
> --- a/drivers/iommu/exynos-iommu.c
> +++ b/drivers/iommu/exynos-iommu.c
> @@ -1002,6 +1002,7 @@ static size_t exynos_iommu_unmap(struct iommu_domain *domain,
> if (lv2ent_small(ent)) {
> *ent = 0;
> size = SPAGE_SIZE;
> + pgtable_flush(ent, ent +1);
> priv->lv2entcnt[lv1ent_offset(iova)] += 1;
> goto done;
> }
> @@ -1010,6 +1011,7 @@ static size_t exynos_iommu_unmap(struct iommu_domain *domain,
> BUG_ON(size < LPAGE_SIZE);
>
> memset(ent, 0, sizeof(*ent) * SPAGES_PER_LPAGE);
> + pgtable_flush(ent, ent + SPAGES_PER_LPAGE);
>
> size = LPAGE_SIZE;
> priv->lv2entcnt[lv1ent_offset(iova)] += SPAGES_PER_LPAGE;
> --
> 1.7.2.5
>
>