[PATCH] iommu: map reserved memory as cacheable if device is coherent

[PATCH] iommu: map reserved memory as cacheable if device is coherent

[laurentiu.tudor]

From: Laurentiu Tudor <laurentiu.tudor@nxp.com>

Check if the device is marked as DMA coherent in the DT and if so,
map its reserved memory as cacheable in the IOMMU.
This fixes the recently added IOMMU reserved memory support which
uses IOMMU_RESV_DIRECT without properly building the PROT for the
mapping.

Fixes: a5bf3cfce8cb ("iommu: Implement of_iommu_get_resv_regions()")
Signed-off-by: Laurentiu Tudor <laurentiu.tudor@nxp.com>
---
 drivers/iommu/of_iommu.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c
index 40f57d293a79..ccb912049b88 100644
--- a/drivers/iommu/of_iommu.c
+++ b/drivers/iommu/of_iommu.c
@@ -254,6 +254,9 @@ void of_iommu_get_resv_regions(struct device *dev, struct list_head *list)
 				phys_addr_t iova;
 				size_t length;
 
+				if (of_dma_is_coherent(dev->of_node))
+					prot |= IOMMU_CACHE;
+
 				maps = of_translate_dma_region(np, maps, &iova, &length);
 				type = iommu_resv_region_get_type(dev, &phys, iova, length);
 
-- 
2.17.1

Re: [PATCH] iommu: map reserved memory as cacheable if device is coherent

[Jason Gunthorpe]

On Wed, Jul 26, 2023 at 03:50:59PM +0300, laurentiu.tudor@nxp.com wrote:
> From: Laurentiu Tudor <laurentiu.tudor@nxp.com>
> 
> Check if the device is marked as DMA coherent in the DT and if so,
> map its reserved memory as cacheable in the IOMMU.
> This fixes the recently added IOMMU reserved memory support which
> uses IOMMU_RESV_DIRECT without properly building the PROT for the
> mapping.
> 
> Fixes: a5bf3cfce8cb ("iommu: Implement of_iommu_get_resv_regions()")
> Signed-off-by: Laurentiu Tudor <laurentiu.tudor@nxp.com>
> ---
>  drivers/iommu/of_iommu.c | 3 +++
>  1 file changed, 3 insertions(+)

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Jason