Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.32 as permitted sender) client-ip=23.128.96.32;
From:   Jia He <justin.he@arm.com>
To:     Christoph Hellwig <hch@lst.de>,
        Marek Szyprowski <m.szyprowski@samsung.com>,
        Robin Murphy <robin.murphy@arm.com>, iommu@lists.linux.dev
Cc:     linux-kernel@vger.kernel.org, Jia He <justin.he@arm.com>
Subject: [PATCH] dma-mapping: fix dma_addressing_limited if dma_range_map is scanned
Date:   Tue, 12 Sep 2023 08:40:02 +0000
Message-Id: <20230912084002.2168-1-justin.he@arm.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

After scanning the dma_range_map, if it is found that not all of the
system RAM ranges are encompassed within it, an incorrect calculation
occurs for dma_addressing_limited(), which prevents the nvme device
dma mapping in the checking path of phys_to_dma().

E.g. On an Armv8 Ampere server, the dsdt ACPI table is:
 Method (_DMA, 0, Serialized)  // _DMA: Direct Memory Access
            {
                Name (RBUF, ResourceTemplate ()
                {
                    QWordMemory (ResourceConsumer, PosDecode, MinFixed,
MaxFixed, Cacheable, ReadWrite,
                        0x0000000000000000, // Granularity
                        0x0000000000000000, // Range Minimum
                        0x00000000FFFFFFFF, // Range Maximum
                        0x0000000000000000, // Translation Offset
                        0x0000000100000000, // Length
                        ,, , AddressRangeMemory, TypeStatic)
                    QWordMemory (ResourceConsumer, PosDecode, MinFixed,
MaxFixed, Cacheable, ReadWrite,
                        0x0000000000000000, // Granularity
                        0x0000006010200000, // Range Minimum
                        0x000000602FFFFFFF, // Range Maximum
                        0x0000000000000000, // Translation Offset
                        0x000000001FE00000, // Length
                        ,, , AddressRangeMemory, TypeStatic)
                    QWordMemory (ResourceConsumer, PosDecode, MinFixed,
MaxFixed, Cacheable, ReadWrite,
                        0x0000000000000000, // Granularity
                        0x00000060F0000000, // Range Minimum
                        0x00000060FFFFFFFF, // Range Maximum
                        0x0000000000000000, // Translation Offset
                        0x0000000010000000, // Length
                        ,, , AddressRangeMemory, TypeStatic)
                    QWordMemory (ResourceConsumer, PosDecode, MinFixed,
MaxFixed, Cacheable, ReadWrite,
                        0x0000000000000000, // Granularity
                        0x0000007000000000, // Range Minimum
                        0x000003FFFFFFFFFF, // Range Maximum
                        0x0000000000000000, // Translation Offset
                        0x0000039000000000, // Length
                        ,, , AddressRangeMemory, TypeStatic)
                })

But the System RAM ranges are:
cat /proc/iomem |grep -i ram
90000000-91ffffff : System RAM
92900000-fffbffff : System RAM
880000000-fffffffff : System RAM
8800000000-bff5990fff : System RAM
bff59d0000-bff5a4ffff : System RAM
bff8000000-bfffffffff : System RAM
So some RAM ranges are out of dma_range_map.

Fixes it by checking whether each of the system RAM resources can be
properly encompassed within the dma_range_map.

Signed-off-by: Jia He <justin.he@arm.com>
---
 include/linux/dma-mapping.h |  8 +++++--
 kernel/dma/mapping.c        | 45 +++++++++++++++++++++++++++++++++++++
 2 files changed, 51 insertions(+), 2 deletions(-)

diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index f0ccca16a0ac..d9d1c67c8579 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -144,6 +144,7 @@ bool dma_pci_p2pdma_supported(struct device *dev);
 int dma_set_mask(struct device *dev, u64 mask);
 int dma_set_coherent_mask(struct device *dev, u64 mask);
 u64 dma_get_required_mask(struct device *dev);
+bool all_ram_in_dma_range_map(struct device *dev);
 size_t dma_max_mapping_size(struct device *dev);
 size_t dma_opt_mapping_size(struct device *dev);
 bool dma_need_sync(struct device *dev, dma_addr_t dma_addr);
@@ -475,8 +476,11 @@ static inline int dma_coerce_mask_and_coherent(struct device *dev, u64 mask)
  */
 static inline bool dma_addressing_limited(struct device *dev)
 {
-	return min_not_zero(dma_get_mask(dev), dev->bus_dma_limit) <
-			    dma_get_required_mask(dev);
+	if (min_not_zero(dma_get_mask(dev), dev->bus_dma_limit) <
+						dma_get_required_mask(dev))
+		return true;
+
+	return !all_ram_in_dma_range_map(dev);
 }
 
 static inline unsigned int dma_get_max_seg_size(struct device *dev)
diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c
index e323ca48f7f2..ab407deb81b8 100644
--- a/kernel/dma/mapping.c
+++ b/kernel/dma/mapping.c
@@ -14,6 +14,7 @@
 #include <linux/of_device.h>
 #include <linux/slab.h>
 #include <linux/vmalloc.h>
+#include <linux/dma-direct.h>
 #include "debug.h"
 #include "direct.h"
 
@@ -819,6 +820,50 @@ size_t dma_opt_mapping_size(struct device *dev)
 }
 EXPORT_SYMBOL_GPL(dma_opt_mapping_size);
 
+/*
+ * To check whether all ram resource ranges are mapped in dma range map
+ * Returns 0 when continuous check is needed
+ * Returns 1 if there is some ram range can't be mapped to dma_range_map
+ */
+static int check_ram_in_range_map(unsigned long start_pfn,
+				  unsigned long nr_pages, void *data)
+{
+	phys_addr_t end_paddr = (start_pfn + nr_pages) << PAGE_SHIFT;
+	phys_addr_t start_paddr = start_pfn << PAGE_SHIFT;
+	struct device *dev = (struct device *)data;
+	struct bus_dma_region *region = NULL;
+	const struct bus_dma_region *m;
+
+	while (start_paddr < end_paddr) {
+		// find region containing start_paddr
+		for (m = dev->dma_range_map; m->size; m++) {
+			if (start_paddr >= m->cpu_start
+			    && start_paddr - m->cpu_start < m->size) {
+				region = (struct bus_dma_region *)m;
+				break;
+			}
+		}
+		if (!region)
+			return 1;
+
+		start_paddr = region->cpu_start + region->size;
+		/* handle overflow of phys_addr_t */
+		if (start_paddr == 0)
+			break;
+	}
+
+	return 0;
+}
+
+bool all_ram_in_dma_range_map(struct device *dev)
+{
+	if (!dev->dma_range_map)
+		return 1;
+
+	return !walk_system_ram_range(0, ULONG_MAX, dev, check_ram_in_range_map);
+}
+EXPORT_SYMBOL_GPL(all_ram_in_dma_range_map);
+
 bool dma_need_sync(struct device *dev, dma_addr_t dma_addr)
 {
 	const struct dma_map_ops *ops = get_dma_ops(dev);
-- 
2.25.1