lkml.org 
[lkml]   [2019]   [Mar]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v2 03/10] iommu/vt-d: Add address walk helper
Date
This adds a helper to walk a contiguous dma address
and divide the address space into possiblely three
parts: a start partial page, middle full pages and
an end partial page, and call the callback for each
part of the address.

Cc: Ashok Raj <ashok.raj@intel.com>
Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Tested-by: Xu Pengfei <pengfei.xu@intel.com>
Tested-by: Mika Westerberg <mika.westerberg@intel.com>
---
drivers/iommu/Makefile | 2 +-
drivers/iommu/intel-pgtable.c | 130 ++++++++++++++++++++++++++++++++++
2 files changed, 131 insertions(+), 1 deletion(-)
create mode 100644 drivers/iommu/intel-pgtable.c

diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
index 8b5fb8051281..562c6a526d63 100644
--- a/drivers/iommu/Makefile
+++ b/drivers/iommu/Makefile
@@ -17,7 +17,7 @@ obj-$(CONFIG_ARM_SMMU) += arm-smmu.o
obj-$(CONFIG_ARM_SMMU_V3) += arm-smmu-v3.o
obj-$(CONFIG_DMAR_TABLE) += dmar.o
obj-$(CONFIG_INTEL_IOMMU) += intel-iommu.o intel-pasid.o
-obj-$(CONFIG_INTEL_IOMMU) += intel-trace.o
+obj-$(CONFIG_INTEL_IOMMU) += intel-trace.o intel-pgtable.o
obj-$(CONFIG_INTEL_IOMMU_DEBUGFS) += intel-iommu-debugfs.o
obj-$(CONFIG_INTEL_IOMMU_SVM) += intel-svm.o
obj-$(CONFIG_IPMMU_VMSA) += ipmmu-vmsa.o
diff --git a/drivers/iommu/intel-pgtable.c b/drivers/iommu/intel-pgtable.c
new file mode 100644
index 000000000000..fd170157325a
--- /dev/null
+++ b/drivers/iommu/intel-pgtable.c
@@ -0,0 +1,130 @@
+// SPDX-License-Identifier: GPL-2.0
+/**
+ * intel-pgtable.c - Utilities for page table manipulation
+ *
+ * Copyright (C) 2019 Intel Corporation
+ *
+ * Author: Lu Baolu <baolu.lu@linux.intel.com>
+ */
+
+#define pr_fmt(fmt) "DMAR: " fmt
+
+#include <asm/cacheflush.h>
+#include <asm/pgtable.h>
+#include <linux/dmar.h>
+#include <linux/dma-direct.h>
+#include <linux/export.h>
+#include <linux/highmem.h>
+#include <linux/intel-iommu.h>
+#include <linux/io.h>
+#include <linux/iommu.h>
+#include <linux/mm.h>
+#include <linux/sched.h>
+#include <linux/vmalloc.h>
+#include <trace/events/intel_iommu.h>
+
+struct addr_walk {
+ int (*low)(struct device *dev, struct dmar_domain *domain,
+ dma_addr_t addr, phys_addr_t paddr,
+ size_t size, enum dma_data_direction dir,
+ unsigned long attrs, void *data);
+ int (*middle)(struct device *dev, struct dmar_domain *domain,
+ dma_addr_t addr, phys_addr_t paddr,
+ size_t size, enum dma_data_direction dir,
+ unsigned long attrs, void *data);
+ int (*high)(struct device *dev, struct dmar_domain *domain,
+ dma_addr_t addr, phys_addr_t paddr,
+ size_t size, enum dma_data_direction dir,
+ unsigned long attrs, void *data);
+};
+
+/*
+ * Bounce buffer support for external devices:
+ *
+ * Intel VT-d hardware uses paging for DMA remapping. The minimum mapped
+ * window is a page size. The device drivers may map buffers not filling
+ * whole IOMMU window. This allows device to access to possibly unrelated
+ * memory and malicious device can exploit this to perform a DMA attack.
+ * Use a bounce page for the buffer which doesn't fill a whole IOMU page.
+ */
+
+static inline unsigned long domain_page_size(struct dmar_domain *domain)
+{
+ return VTD_PAGE_SIZE;
+}
+
+/* Calculate how many pages does a range of [addr, addr + size) cross. */
+static inline unsigned long
+range_nrpages(dma_addr_t addr, size_t size, unsigned long page_size)
+{
+ unsigned long offset = page_size - 1;
+
+ return ALIGN((addr & offset) + size, page_size) >> __ffs(page_size);
+}
+
+int
+domain_walk_addr_range(const struct addr_walk *walk, struct device *dev,
+ struct dmar_domain *domain, dma_addr_t addr,
+ phys_addr_t paddr, size_t size,
+ enum dma_data_direction dir,
+ unsigned long attrs,
+ void *data)
+{
+ u64 page_size = domain_page_size(domain);
+ u64 page_offset = page_size - 1;
+ u64 page_mask = ~page_offset;
+ u64 length = 0;
+ int ret;
+
+ /*
+ * The first vt-d page is partial. Use bounce buffer for
+ * security concern if necessary.
+ */
+ if (addr & page_offset) {
+ length = ALIGN(addr, page_size) - addr;
+ if (length > size)
+ length = size;
+ if (walk->low) {
+ ret = walk->low(dev, domain, addr, paddr,
+ length, dir, attrs, data);
+ if (ret)
+ return ret;
+ }
+
+ /* The buffer only covers on page. */
+ if (range_nrpages(addr, size, page_size) <= 1)
+ return 0;
+
+ size -= length;
+ addr = ALIGN(addr, page_size);
+ paddr = ALIGN(paddr, page_size);
+ }
+
+ /*
+ * There might be several pages which could totally accessed
+ * by a device in the middle. It's unnecessary to use bounce
+ * buffer against these pages.
+ */
+ if (size & page_mask) {
+ length = size & page_mask;
+ if (walk->middle) {
+ ret = walk->middle(dev, domain, addr, paddr,
+ length, dir, attrs, data);
+ if (ret)
+ return ret;
+ }
+
+ addr += size & page_mask;
+ paddr += size & page_mask;
+ size &= page_offset;
+ }
+
+ /*
+ * Okay, last page might be partial. Use bounce buffer if necessary.
+ */
+ if (size && walk->high)
+ return walk->high(dev, domain, addr, paddr,
+ size, dir, attrs, data);
+
+ return 0;
+}
--
2.17.1
\
 
 \ /
  Last update: 2019-03-27 07:42    [W:0.072 / U:43.708 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site