Hi Robin,

-----Original Message-----
From: Will Deacon [mailto:will.deacon at arm.com]
Sent: Friday, October 13, 2017 8:24 PM
To: Shameerali Kolothum Thodi <redacted>
Cc: lorenzo.pieralisi at arm.com; marc.zyngier at arm.com;
sudeep.holla at arm.com; robin.murphy at arm.com; joro at 8bytes.org;
bhelgaas at google.com; Gabriele Paoloni [off-list ref];
John Garry [off-list ref]; iommu at lists.linux-foundation.org;
linux-arm-kernel at lists.infradead.org; linux-acpi at vger.kernel.org; linux-
pci at vger.kernel.org; devel at acpica.org; Linuxarm [off-list ref];
Wangzhou (B) [off-list ref]; Guohanjun (Hanjun Guo)
[off-list ref]
Subject: Re: [PATCH v9 2/4] iommu/dma: Add a helper function to reserve HW
MSI address regions for IOMMU drivers

On Fri, Oct 06, 2017 at 03:04:48PM +0100, Shameer Kolothum wrote:

quoted

IOMMU drivers can use this to implement their .get_resv_regions callback
for HW MSI specific reservations(e.g. ARM GICv3 ITS MSI region).

Signed-off-by: Shameer Kolothum <redacted>
---
 drivers/iommu/dma-iommu.c | 20 ++++++++++++++++++++
 include/linux/dma-iommu.h |  7 +++++++
 2 files changed, 27 insertions(+)

I'd like to see Robin's Ack on this, because this is his code and he had
ideas on ways to solve this problem properly.

Please let us know if it is ok to go ahead with ACPI support for now.
It will help our customers to start using pass-through for PCIe.

Thanks,
Shameer

Will

quoted

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 9d1cebe..bae677e 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c

@@ -19,6 +19,7 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */

+#include <linux/acpi_iort.h>
 #include <linux/device.h>
 #include <linux/dma-iommu.h>
 #include <linux/gfp.h>

@@ -27,6 +28,7 @@
 #include <linux/iova.h>
 #include <linux/irq.h>
 #include <linux/mm.h>
+#include <linux/of_iommu.h>
 #include <linux/pci.h>
 #include <linux/scatterlist.h>
 #include <linux/vmalloc.h>

@@ -198,6 +200,24 @@ void iommu_dma_get_resv_regions(struct device

*dev, struct list_head *list)

quoted

 }
 EXPORT_SYMBOL(iommu_dma_get_resv_regions);

+/**
+ * iommu_dma_get_msi_resv_regions - Reserved region driver helper
+ * @dev: Device from iommu_get_resv_regions()
+ * @list: Reserved region list from iommu_get_resv_regions()
+ *
+ * IOMMU drivers can use this to implement their .get_resv_regions
+ * callback for HW MSI specific reservations. For now, this only
+ * covers ITS MSI region reservation using ACPI IORT helper function.
+ */
+int iommu_dma_get_msi_resv_regions(struct device *dev, struct list_head

*list)

quoted

+{
+	if (!is_of_node(dev->iommu_fwspec->iommu_fwnode))
+		return iort_iommu_msi_get_resv_regions(dev, list);
+
+	return -ENODEV;
+}
+EXPORT_SYMBOL(iommu_dma_get_msi_resv_regions);
+
 static int cookie_init_hw_msi_region(struct iommu_dma_cookie *cookie,
 		phys_addr_t start, phys_addr_t end)
 {

diff --git a/include/linux/dma-iommu.h b/include/linux/dma-iommu.h
index 92f2083..6062ef0 100644
--- a/include/linux/dma-iommu.h
+++ b/include/linux/dma-iommu.h

@@ -74,6 +74,8 @@ void iommu_dma_unmap_resource(struct device *dev,

dma_addr_t handle,

quoted

 void iommu_dma_map_msi_msg(int irq, struct msi_msg *msg);
 void iommu_dma_get_resv_regions(struct device *dev, struct list_head

*list);

quoted

+int iommu_dma_get_msi_resv_regions(struct device *dev, struct list_head

*list);

quoted

+
 #else

 struct iommu_domain;

@@ -107,6 +109,11 @@ static inline void

iommu_dma_get_resv_regions(struct device *dev, struct list_he

quoted

 {
 }

+static inline int iommu_dma_get_msi_resv_regions(struct device *dev,

struct list_head *list)

quoted

+{
+	return -ENODEV;
+}
+
 #endif	/* CONFIG_IOMMU_DMA */
 #endif	/* __KERNEL__ */
 #endif	/* __DMA_IOMMU_H */
--
1.9.1