linux-kernel - [PATCH v5 2/4] s390/pci: store DMA offset in bus_dma

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Message-ID: <20250212213418.182902-3-mjrosato@linux.ibm.com>
Date: Wed, 12 Feb 2025 16:34:16 -0500
From: Matthew Rosato <mjrosato@...ux.ibm.com>
To: joro@...tes.org, will@...nel.org, robin.murphy@....com,
        gerald.schaefer@...ux.ibm.com, schnelle@...ux.ibm.com
Cc: hca@...ux.ibm.com, gor@...ux.ibm.com, agordeev@...ux.ibm.com,
        svens@...ux.ibm.com, borntraeger@...ux.ibm.com, farman@...ux.ibm.com,
        clegoate@...hat.com, jgg@...dia.com, iommu@...ts.linux.dev,
        linux-kernel@...r.kernel.org, linux-s390@...r.kernel.org
Subject: [PATCH v5 2/4] s390/pci: store DMA offset in bus_dma_region

PCI devices on s390 have a DMA offset that is reported via CLP.  In
preparation for allowing identity domains, setup the bus_dma_region
for all PCI devices using the reported CLP value.

Signed-off-by: Matthew Rosato <mjrosato@...ux.ibm.com>
---
 arch/s390/pci/pci_bus.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/arch/s390/pci/pci_bus.c b/arch/s390/pci/pci_bus.c
index 857afbc4828f..3fa113c4ad8f 100644
--- a/arch/s390/pci/pci_bus.c
+++ b/arch/s390/pci/pci_bus.c
@@ -19,6 +19,7 @@
 #include <linux/jump_label.h>
 #include <linux/pci.h>
 #include <linux/printk.h>
+#include <linux/dma-direct.h>
 
 #include <asm/pci_clp.h>
 #include <asm/pci_dma.h>
@@ -283,10 +284,34 @@ static struct zpci_bus *zpci_bus_alloc(int topo, bool topo_is_tid)
 	return zbus;
 }
 
+static void pci_dma_range_setup(struct pci_dev *pdev)
+{
+	struct zpci_dev *zdev = to_zpci(pdev);
+	struct bus_dma_region *map;
+	u64 aligned_end;
+
+	map = kzalloc(sizeof(*map), GFP_KERNEL);
+	if (!map)
+		return;
+
+	map->cpu_start = 0;
+	map->dma_start = PAGE_ALIGN(zdev->start_dma);
+	aligned_end = PAGE_ALIGN_DOWN(zdev->end_dma + 1);
+	if (aligned_end >= map->dma_start)
+		map->size = aligned_end - map->dma_start;
+	else
+		map->size = 0;
+	WARN_ON_ONCE(map->size == 0);
+
+	pdev->dev.dma_range_map = map;
+}
+
 void pcibios_bus_add_device(struct pci_dev *pdev)
 {
 	struct zpci_dev *zdev = to_zpci(pdev);
 
+	pci_dma_range_setup(pdev);
+
 	/*
 	 * With pdev->no_vf_scan the common PCI probing code does not
 	 * perform PF/VF linking.
-- 
2.48.1