[PATCH v2 5.10 0/9] preserve DMA offsets when using swiotlb

[PATCH v2 5.10 0/9] preserve DMA offsets when using swiotlb

[Jianxiong Gao]

We observed several NVMe failures when running with SWIOTLB. The root
cause of the issue is that when data is mapped via SWIOTLB, the address
offset is not preserved. Several device drivers including the NVMe
driver relies on this offset to function correctly.

Even though we discovered the error when running using AMD SEV, we have
reproduced the same error in Rhel 8 without SEV. By adding swiotlb=force
option to the boot command line parameter, NVMe funcionality is
impacted. For example formatting a disk into xfs format returns an
error.


----
Changes in v2:
Rebased patches to 5.10.33
Updated patch description to correct format.

Jianxiong Gao (9):
  driver core: add a min_align_mask field to struct
    device_dma_parameters
  swiotlb: add a IO_TLB_SIZE define
  swiotlb: factor out an io_tlb_offset helper
  swiotlb: factor out a nr_slots helper
  swiotlb: clean up swiotlb_tbl_unmap_single
  swiotlb: refactor swiotlb_tbl_map_single
  swiotlb: don't modify orig_addr in swiotlb_tbl_sync_single
  swiotlb: respect min_align_mask
  nvme-pci: set min_align_mask

 drivers/nvme/host/pci.c     |   1 +
 include/linux/device.h      |   1 +
 include/linux/dma-mapping.h |  16 +++
 include/linux/swiotlb.h     |   1 +
 kernel/dma/swiotlb.c        | 259 ++++++++++++++++++++----------------
 5 files changed, 164 insertions(+), 114 deletions(-)

-- 
2.31.1.498.g6c1eba8ee3d-goog

[PATCH v2 5.10 1/9] driver core: add a min_align_mask field to struct device_dma_parameters

[Jianxiong Gao]

commit: 36950f2da1ea4cb683be174f6f581e25b2d33e71

Some devices rely on the address offset in a page to function
correctly (NVMe driver as an example). These devices may use
a different page size than the Linux kernel. The address offset
has to be preserved upon mapping, and in order to do so, we
need to record the page_offset_mask first.

Signed-off-by: Jianxiong Gao <jxgao@google.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
 include/linux/device.h      |  1 +
 include/linux/dma-mapping.h | 16 ++++++++++++++++
 2 files changed, 17 insertions(+)

diff --git a/include/linux/device.h b/include/linux/device.h
index 2b39de35525a..75a24b32fee8 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -291,6 +291,7 @@ struct device_dma_parameters {
 	 * sg limitations.
 	 */
 	unsigned int max_segment_size;
+	unsigned int min_align_mask;
 	unsigned long segment_boundary_mask;
 };
 
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index 956151052d45..a7d70cdee25e 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -500,6 +500,22 @@ static inline int dma_set_seg_boundary(struct device *dev, unsigned long mask)
 	return -EIO;
 }
 
+static inline unsigned int dma_get_min_align_mask(struct device *dev)
+{
+	if (dev->dma_parms)
+		return dev->dma_parms->min_align_mask;
+	return 0;
+}
+
+static inline int dma_set_min_align_mask(struct device *dev,
+		unsigned int min_align_mask)
+{
+	if (WARN_ON_ONCE(!dev->dma_parms))
+		return -EIO;
+	dev->dma_parms->min_align_mask = min_align_mask;
+	return 0;
+}
+
 static inline int dma_get_cache_alignment(void)
 {
 #ifdef ARCH_DMA_MINALIGN
-- 
2.31.1.498.g6c1eba8ee3d-goog

[PATCH v2 5.10 2/9] swiotlb: add a IO_TLB_SIZE define

[Jianxiong Gao]

commit: b5d7ccb7aac3895c2138fe0980a109116ce15eff

Add a new IO_TLB_SIZE define instead open coding it using
IO_TLB_SHIFT all over.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jianxiong Gao <jxgao@google.com>
Tested-by: Jianxiong Gao <jxgao@google.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Jianxiong Gao <jxgao@google.com>
---
 include/linux/swiotlb.h |  1 +
 kernel/dma/swiotlb.c    | 12 ++++++------
 2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
index fbdc65782195..5d2dbe7e04c3 100644
--- a/include/linux/swiotlb.h
+++ b/include/linux/swiotlb.h
@@ -29,6 +29,7 @@ enum swiotlb_force {
  * controllable.
  */
 #define IO_TLB_SHIFT 11
+#define IO_TLB_SIZE (1 << IO_TLB_SHIFT)
 
 extern void swiotlb_init(int verbose);
 int swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose);
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index 781b9dca197c..fb88c2982645 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -475,20 +475,20 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev, phys_addr_t orig_addr,
 
 	tbl_dma_addr &= mask;
 
-	offset_slots = ALIGN(tbl_dma_addr, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
+	offset_slots = ALIGN(tbl_dma_addr, IO_TLB_SIZE) >> IO_TLB_SHIFT;
 
 	/*
 	 * Carefully handle integer overflow which can occur when mask == ~0UL.
 	 */
 	max_slots = mask + 1
-		    ? ALIGN(mask + 1, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT
+		    ? ALIGN(mask + 1, IO_TLB_SIZE) >> IO_TLB_SHIFT
 		    : 1UL << (BITS_PER_LONG - IO_TLB_SHIFT);
 
 	/*
 	 * For mappings greater than or equal to a page, we limit the stride
 	 * (and hence alignment) to a page size.
 	 */
-	nslots = ALIGN(alloc_size, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
+	nslots = ALIGN(alloc_size, IO_TLB_SIZE) >> IO_TLB_SHIFT;
 	if (alloc_size >= PAGE_SIZE)
 		stride = (1 << (PAGE_SHIFT - IO_TLB_SHIFT));
 	else
@@ -582,7 +582,7 @@ void swiotlb_tbl_unmap_single(struct device *hwdev, phys_addr_t tlb_addr,
 			      enum dma_data_direction dir, unsigned long attrs)
 {
 	unsigned long flags;
-	int i, count, nslots = ALIGN(alloc_size, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
+	int i, count, nslots = ALIGN(alloc_size, IO_TLB_SIZE) >> IO_TLB_SHIFT;
 	int index = (tlb_addr - io_tlb_start) >> IO_TLB_SHIFT;
 	phys_addr_t orig_addr = io_tlb_orig_addr[index];
 
@@ -633,7 +633,7 @@ void swiotlb_tbl_sync_single(struct device *hwdev, phys_addr_t tlb_addr,
 
 	if (orig_addr == INVALID_PHYS_ADDR)
 		return;
-	orig_addr += (unsigned long)tlb_addr & ((1 << IO_TLB_SHIFT) - 1);
+	orig_addr += (unsigned long)tlb_addr & (IO_TLB_SIZE - 1);
 
 	switch (target) {
 	case SYNC_FOR_CPU:
@@ -691,7 +691,7 @@ dma_addr_t swiotlb_map(struct device *dev, phys_addr_t paddr, size_t size,
 
 size_t swiotlb_max_mapping_size(struct device *dev)
 {
-	return ((size_t)1 << IO_TLB_SHIFT) * IO_TLB_SEGSIZE;
+	return ((size_t)IO_TLB_SIZE) * IO_TLB_SEGSIZE;
 }
 
 bool is_swiotlb_active(void)
-- 
2.31.1.498.g6c1eba8ee3d-goog

[PATCH v2 5.10 3/9] swiotlb: factor out an io_tlb_offset helper

[Jianxiong Gao]

commit: c7fbeca757fe74135d8b6a4c8ddaef76f5775d68

Replace the very genericly named OFFSET macro with a little inline
helper that hardcodes the alignment to the only value ever passed.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jianxiong Gao <jxgao@google.com>
Tested-by: Jianxiong Gao <jxgao@google.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Jianxiong Gao <jxgao@google.com>
---
 kernel/dma/swiotlb.c | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index fb88c2982645..f55248f16366 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -50,9 +50,6 @@
 #define CREATE_TRACE_POINTS
 #include <trace/events/swiotlb.h>
 
-#define OFFSET(val,align) ((unsigned long)	\
-	                   ( (val) & ( (align) - 1)))
-
 #define SLABS_PER_PAGE (1 << (PAGE_SHIFT - IO_TLB_SHIFT))
 
 /*
@@ -176,6 +173,11 @@ void swiotlb_print_info(void)
 	       bytes >> 20);
 }
 
+static inline unsigned long io_tlb_offset(unsigned long val)
+{
+	return val & (IO_TLB_SEGSIZE - 1);
+}
+
 /*
  * Early SWIOTLB allocation may be too early to allow an architecture to
  * perform the desired operations.  This function allows the architecture to
@@ -225,7 +227,7 @@ int __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
 		      __func__, alloc_size, PAGE_SIZE);
 
 	for (i = 0; i < io_tlb_nslabs; i++) {
-		io_tlb_list[i] = IO_TLB_SEGSIZE - OFFSET(i, IO_TLB_SEGSIZE);
+		io_tlb_list[i] = IO_TLB_SEGSIZE - io_tlb_offset(i);
 		io_tlb_orig_addr[i] = INVALID_PHYS_ADDR;
 	}
 	io_tlb_index = 0;
@@ -359,7 +361,7 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
 		goto cleanup4;
 
 	for (i = 0; i < io_tlb_nslabs; i++) {
-		io_tlb_list[i] = IO_TLB_SEGSIZE - OFFSET(i, IO_TLB_SEGSIZE);
+		io_tlb_list[i] = IO_TLB_SEGSIZE - io_tlb_offset(i);
 		io_tlb_orig_addr[i] = INVALID_PHYS_ADDR;
 	}
 	io_tlb_index = 0;
@@ -530,7 +532,9 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev, phys_addr_t orig_addr,
 
 			for (i = index; i < (int) (index + nslots); i++)
 				io_tlb_list[i] = 0;
-			for (i = index - 1; (OFFSET(i, IO_TLB_SEGSIZE) != IO_TLB_SEGSIZE - 1) && io_tlb_list[i]; i--)
+			for (i = index - 1;
+			     io_tlb_offset(i) != IO_TLB_SEGSIZE - 1 &&
+			     io_tlb_list[i]; i--)
 				io_tlb_list[i] = ++count;
 			tlb_addr = io_tlb_start + (index << IO_TLB_SHIFT);
 
@@ -616,7 +620,9 @@ void swiotlb_tbl_unmap_single(struct device *hwdev, phys_addr_t tlb_addr,
 		 * Step 2: merge the returned slots with the preceding slots,
 		 * if available (non zero)
 		 */
-		for (i = index - 1; (OFFSET(i, IO_TLB_SEGSIZE) != IO_TLB_SEGSIZE -1) && io_tlb_list[i]; i--)
+		for (i = index - 1;
+		     io_tlb_offset(i) != IO_TLB_SEGSIZE - 1 &&
+		     io_tlb_list[i]; i--)
 			io_tlb_list[i] = ++count;
 
 		io_tlb_used -= nslots;
-- 
2.31.1.498.g6c1eba8ee3d-goog

[PATCH v2 5.10 4/9] swiotlb: factor out a nr_slots helper

[Jianxiong Gao]

commit: c32a77fd18780a5192dfb6eec69f239faebf28fd

Factor out a helper to find the number of slots for a given size.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jianxiong Gao <jxgao@google.com>
Tested-by: Jianxiong Gao <jxgao@google.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Jianxiong Gao <jxgao@google.com>
---
 kernel/dma/swiotlb.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index f55248f16366..f0be199da527 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -178,6 +178,11 @@ static inline unsigned long io_tlb_offset(unsigned long val)
 	return val & (IO_TLB_SEGSIZE - 1);
 }
 
+static inline unsigned long nr_slots(u64 val)
+{
+	return DIV_ROUND_UP(val, IO_TLB_SIZE);
+}
+
 /*
  * Early SWIOTLB allocation may be too early to allow an architecture to
  * perform the desired operations.  This function allows the architecture to
@@ -477,20 +482,20 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev, phys_addr_t orig_addr,
 
 	tbl_dma_addr &= mask;
 
-	offset_slots = ALIGN(tbl_dma_addr, IO_TLB_SIZE) >> IO_TLB_SHIFT;
+	offset_slots = nr_slots(tbl_dma_addr);
 
 	/*
 	 * Carefully handle integer overflow which can occur when mask == ~0UL.
 	 */
 	max_slots = mask + 1
-		    ? ALIGN(mask + 1, IO_TLB_SIZE) >> IO_TLB_SHIFT
+		    ? nr_slots(mask + 1)
 		    : 1UL << (BITS_PER_LONG - IO_TLB_SHIFT);
 
 	/*
 	 * For mappings greater than or equal to a page, we limit the stride
 	 * (and hence alignment) to a page size.
 	 */
-	nslots = ALIGN(alloc_size, IO_TLB_SIZE) >> IO_TLB_SHIFT;
+	nslots = nr_slots(alloc_size);
 	if (alloc_size >= PAGE_SIZE)
 		stride = (1 << (PAGE_SHIFT - IO_TLB_SHIFT));
 	else
@@ -586,7 +591,7 @@ void swiotlb_tbl_unmap_single(struct device *hwdev, phys_addr_t tlb_addr,
 			      enum dma_data_direction dir, unsigned long attrs)
 {
 	unsigned long flags;
-	int i, count, nslots = ALIGN(alloc_size, IO_TLB_SIZE) >> IO_TLB_SHIFT;
+	int i, count, nslots = nr_slots(alloc_size);
 	int index = (tlb_addr - io_tlb_start) >> IO_TLB_SHIFT;
 	phys_addr_t orig_addr = io_tlb_orig_addr[index];
 
-- 
2.31.1.498.g6c1eba8ee3d-goog

[PATCH v2 5.10 5/9] swiotlb: clean up swiotlb_tbl_unmap_single

[Jianxiong Gao]

commit: ca10d0f8e530600ec63c603dbace2c30927d70b7

swiotlb: clean up swiotlb_tbl_unmap_single

Remove a layer of pointless indentation, replace a hard to follow
ternary expression with a plain if/else.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jianxiong Gao <jxgao@google.com>
Tested-by: Jianxiong Gao <jxgao@google.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Jianxiong Gao <jxgao@google.com>
---
 kernel/dma/swiotlb.c | 41 +++++++++++++++++++++--------------------
 1 file changed, 21 insertions(+), 20 deletions(-)

diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index f0be199da527..f5530336d7ca 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -610,28 +610,29 @@ void swiotlb_tbl_unmap_single(struct device *hwdev, phys_addr_t tlb_addr,
 	 * with slots below and above the pool being returned.
 	 */
 	spin_lock_irqsave(&io_tlb_lock, flags);
-	{
-		count = ((index + nslots) < ALIGN(index + 1, IO_TLB_SEGSIZE) ?
-			 io_tlb_list[index + nslots] : 0);
-		/*
-		 * Step 1: return the slots to the free list, merging the
-		 * slots with superceeding slots
-		 */
-		for (i = index + nslots - 1; i >= index; i--) {
-			io_tlb_list[i] = ++count;
-			io_tlb_orig_addr[i] = INVALID_PHYS_ADDR;
-		}
-		/*
-		 * Step 2: merge the returned slots with the preceding slots,
-		 * if available (non zero)
-		 */
-		for (i = index - 1;
-		     io_tlb_offset(i) != IO_TLB_SEGSIZE - 1 &&
-		     io_tlb_list[i]; i--)
-			io_tlb_list[i] = ++count;
+	if (index + nslots < ALIGN(index + 1, IO_TLB_SEGSIZE))
+		count = io_tlb_list[index + nslots];
+	else
+		count = 0;
 
-		io_tlb_used -= nslots;
+	/*
+	 * Step 1: return the slots to the free list, merging the slots with
+	 * superceeding slots
+	 */
+	for (i = index + nslots - 1; i >= index; i--) {
+		io_tlb_list[i] = ++count;
+		io_tlb_orig_addr[i] = INVALID_PHYS_ADDR;
 	}
+
+	/*
+	 * Step 2: merge the returned slots with the preceding slots, if
+	 * available (non zero)
+	 */
+	for (i = index - 1;
+	     io_tlb_offset(i) != IO_TLB_SEGSIZE - 1 && io_tlb_list[i];
+	     i--)
+		io_tlb_list[i] = ++count;
+	io_tlb_used -= nslots;
 	spin_unlock_irqrestore(&io_tlb_lock, flags);
 }
 
-- 
2.31.1.498.g6c1eba8ee3d-goog

[PATCH v2 5.10 6/9] swiotlb: refactor swiotlb_tbl_map_single

[Jianxiong Gao]

commit: 26a7e094783d482f3e125f09945a5bb1d867b2e6

Split out a bunch of a self-contained helpers to make the function easier
to follow.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jianxiong Gao <jxgao@google.com>
Tested-by: Jianxiong Gao <jxgao@google.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Jianxiong Gao <jxgao@google.com>
---
 kernel/dma/swiotlb.c | 179 +++++++++++++++++++++----------------------
 1 file changed, 89 insertions(+), 90 deletions(-)

diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index f5530336d7ca..243750453b3d 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -452,134 +452,133 @@ static void swiotlb_bounce(phys_addr_t orig_addr, phys_addr_t tlb_addr,
 	}
 }
 
-phys_addr_t swiotlb_tbl_map_single(struct device *hwdev, phys_addr_t orig_addr,
-		size_t mapping_size, size_t alloc_size,
-		enum dma_data_direction dir, unsigned long attrs)
-{
-	dma_addr_t tbl_dma_addr = phys_to_dma_unencrypted(hwdev, io_tlb_start);
-	unsigned long flags;
-	phys_addr_t tlb_addr;
-	unsigned int nslots, stride, index, wrap;
-	int i;
-	unsigned long mask;
-	unsigned long offset_slots;
-	unsigned long max_slots;
-	unsigned long tmp_io_tlb_used;
-
-	if (no_iotlb_memory)
-		panic("Can not allocate SWIOTLB buffer earlier and can't now provide you with the DMA bounce buffer");
-
-	if (mem_encrypt_active())
-		pr_warn_once("Memory encryption is active and system is using DMA bounce buffers\n");
+#define slot_addr(start, idx)	((start) + ((idx) << IO_TLB_SHIFT))
 
-	if (mapping_size > alloc_size) {
-		dev_warn_once(hwdev, "Invalid sizes (mapping: %zd bytes, alloc: %zd bytes)",
-			      mapping_size, alloc_size);
-		return (phys_addr_t)DMA_MAPPING_ERROR;
-	}
-
-	mask = dma_get_seg_boundary(hwdev);
+/*
+ * Carefully handle integer overflow which can occur when boundary_mask == ~0UL.
+ */
+static inline unsigned long get_max_slots(unsigned long boundary_mask)
+{
+	if (boundary_mask == ~0UL)
+		return 1UL << (BITS_PER_LONG - IO_TLB_SHIFT);
+	return nr_slots(boundary_mask + 1);
+}
 
-	tbl_dma_addr &= mask;
+static unsigned int wrap_index(unsigned int index)
+{
+	if (index >= io_tlb_nslabs)
+		return 0;
+	return index;
+}
 
-	offset_slots = nr_slots(tbl_dma_addr);
+/*
+ * Find a suitable number of IO TLB entries size that will fit this request and
+ * allocate a buffer from that IO TLB pool.
+ */
+static int find_slots(struct device *dev, size_t alloc_size)
+{
+	unsigned long boundary_mask = dma_get_seg_boundary(dev);
+	dma_addr_t tbl_dma_addr =
+		phys_to_dma_unencrypted(dev, io_tlb_start) & boundary_mask;
+	unsigned long max_slots = get_max_slots(boundary_mask);
+	unsigned int nslots = nr_slots(alloc_size), stride = 1;
+	unsigned int index, wrap, count = 0, i;
+	unsigned long flags;
 
-	/*
-	 * Carefully handle integer overflow which can occur when mask == ~0UL.
-	 */
-	max_slots = mask + 1
-		    ? nr_slots(mask + 1)
-		    : 1UL << (BITS_PER_LONG - IO_TLB_SHIFT);
+	BUG_ON(!nslots);
 
 	/*
 	 * For mappings greater than or equal to a page, we limit the stride
 	 * (and hence alignment) to a page size.
 	 */
-	nslots = nr_slots(alloc_size);
 	if (alloc_size >= PAGE_SIZE)
-		stride = (1 << (PAGE_SHIFT - IO_TLB_SHIFT));
-	else
-		stride = 1;
+		stride <<= (PAGE_SHIFT - IO_TLB_SHIFT);
 
-	BUG_ON(!nslots);
-
-	/*
-	 * Find suitable number of IO TLB entries size that will fit this
-	 * request and allocate a buffer from that IO TLB pool.
-	 */
 	spin_lock_irqsave(&io_tlb_lock, flags);
-
 	if (unlikely(nslots > io_tlb_nslabs - io_tlb_used))
 		goto not_found;
 
-	index = ALIGN(io_tlb_index, stride);
-	if (index >= io_tlb_nslabs)
-		index = 0;
-	wrap = index;
-
+	index = wrap = wrap_index(ALIGN(io_tlb_index, stride));
 	do {
-		while (iommu_is_span_boundary(index, nslots, offset_slots,
-					      max_slots)) {
-			index += stride;
-			if (index >= io_tlb_nslabs)
-				index = 0;
-			if (index == wrap)
-				goto not_found;
-		}
-
 		/*
 		 * If we find a slot that indicates we have 'nslots' number of
 		 * contiguous buffers, we allocate the buffers from that slot
 		 * and mark the entries as '0' indicating unavailable.
 		 */
-		if (io_tlb_list[index] >= nslots) {
-			int count = 0;
-
-			for (i = index; i < (int) (index + nslots); i++)
-				io_tlb_list[i] = 0;
-			for (i = index - 1;
-			     io_tlb_offset(i) != IO_TLB_SEGSIZE - 1 &&
-			     io_tlb_list[i]; i--)
-				io_tlb_list[i] = ++count;
-			tlb_addr = io_tlb_start + (index << IO_TLB_SHIFT);
-
-			/*
-			 * Update the indices to avoid searching in the next
-			 * round.
-			 */
-			io_tlb_index = ((index + nslots) < io_tlb_nslabs
-					? (index + nslots) : 0);
-
-			goto found;
+		if (!iommu_is_span_boundary(index, nslots,
+					    nr_slots(tbl_dma_addr),
+					    max_slots)) {
+			if (io_tlb_list[index] >= nslots)
+				goto found;
 		}
-		index += stride;
-		if (index >= io_tlb_nslabs)
-			index = 0;
+		index = wrap_index(index + stride);
 	} while (index != wrap);
 
 not_found:
-	tmp_io_tlb_used = io_tlb_used;
-
 	spin_unlock_irqrestore(&io_tlb_lock, flags);
-	if (!(attrs & DMA_ATTR_NO_WARN) && printk_ratelimit())
-		dev_warn(hwdev, "swiotlb buffer is full (sz: %zd bytes), total %lu (slots), used %lu (slots)\n",
-			 alloc_size, io_tlb_nslabs, tmp_io_tlb_used);
-	return (phys_addr_t)DMA_MAPPING_ERROR;
+	return -1;
+
 found:
+	for (i = index; i < index + nslots; i++)
+		io_tlb_list[i] = 0;
+	for (i = index - 1;
+	     io_tlb_offset(i) != IO_TLB_SEGSIZE - 1 &&
+	     io_tlb_list[i]; i--)
+		io_tlb_list[i] = ++count;
+
+	/*
+	 * Update the indices to avoid searching in the next round.
+	 */
+	if (index + nslots < io_tlb_nslabs)
+		io_tlb_index = index + nslots;
+	else
+		io_tlb_index = 0;
 	io_tlb_used += nslots;
+
 	spin_unlock_irqrestore(&io_tlb_lock, flags);
+	return index;
+}
+
+phys_addr_t swiotlb_tbl_map_single(struct device *dev, phys_addr_t orig_addr,
+		size_t mapping_size, size_t alloc_size,
+		enum dma_data_direction dir, unsigned long attrs)
+{
+	unsigned int index, i;
+	phys_addr_t tlb_addr;
+
+	if (no_iotlb_memory)
+		panic("Can not allocate SWIOTLB buffer earlier and can't now provide you with the DMA bounce buffer");
+
+	if (mem_encrypt_active())
+		pr_warn_once("Memory encryption is active and system is using DMA bounce buffers\n");
+
+	if (mapping_size > alloc_size) {
+		dev_warn_once(dev, "Invalid sizes (mapping: %zd bytes, alloc: %zd bytes)",
+			      mapping_size, alloc_size);
+		return (phys_addr_t)DMA_MAPPING_ERROR;
+	}
+
+	index = find_slots(dev, alloc_size);
+	if (index == -1) {
+		if (!(attrs & DMA_ATTR_NO_WARN))
+			dev_warn_ratelimited(dev,
+	"swiotlb buffer is full (sz: %zd bytes), total %lu (slots), used %lu (slots)\n",
+				 alloc_size, io_tlb_nslabs, io_tlb_used);
+		return (phys_addr_t)DMA_MAPPING_ERROR;
+	}
 
 	/*
 	 * Save away the mapping from the original address to the DMA address.
 	 * This is needed when we sync the memory.  Then we sync the buffer if
 	 * needed.
 	 */
-	for (i = 0; i < nslots; i++)
-		io_tlb_orig_addr[index+i] = orig_addr + (i << IO_TLB_SHIFT);
+	for (i = 0; i < nr_slots(alloc_size); i++)
+		io_tlb_orig_addr[index + i] = slot_addr(orig_addr, i);
+
+	tlb_addr = slot_addr(io_tlb_start, index);
 	if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
 	    (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL))
 		swiotlb_bounce(orig_addr, tlb_addr, mapping_size, DMA_TO_DEVICE);
-
 	return tlb_addr;
 }
 
-- 
2.31.1.498.g6c1eba8ee3d-goog

[PATCH v2 5.10 7/9] swiotlb: don't modify orig_addr in swiotlb_tbl_sync_single

[Jianxiong Gao]

commit: 16fc3cef33a04632ab6b31758abdd77563a20759

swiotlb_tbl_map_single currently nevers sets a tlb_addr that is not
aligned to the tlb bucket size.  But we're going to add such a case
soon, for which this adjustment would be bogus.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jianxiong Gao <jxgao@google.com>
Tested-by: Jianxiong Gao <jxgao@google.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Jianxiong Gao <jxgao@google.com>
---
 kernel/dma/swiotlb.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index 243750453b3d..b8f82f96c4c2 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -644,7 +644,6 @@ void swiotlb_tbl_sync_single(struct device *hwdev, phys_addr_t tlb_addr,
 
 	if (orig_addr == INVALID_PHYS_ADDR)
 		return;
-	orig_addr += (unsigned long)tlb_addr & (IO_TLB_SIZE - 1);
 
 	switch (target) {
 	case SYNC_FOR_CPU:
-- 
2.31.1.498.g6c1eba8ee3d-goog

[PATCH v2 5.10 8/9] swiotlb: respect min_align_mask

[Jianxiong Gao]

commit: 1f221a0d0dbf0e48ef3a9c62871281d6a7819f05

swiotlb: respect min_align_mask

Respect the min_align_mask in struct device_dma_parameters in swiotlb.

There are two parts to it:
 1) for the lower bits of the alignment inside the io tlb slot, just
    extent the size of the allocation and leave the start of the slot
     empty
 2) for the high bits ensure we find a slot that matches the high bits
    of the alignment to avoid wasting too much memory

Based on an earlier patch from Jianxiong Gao <jxgao@google.com>.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jianxiong Gao <jxgao@google.com>
Tested-by: Jianxiong Gao <jxgao@google.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Jianxiong Gao <jxgao@google.com>
---
 kernel/dma/swiotlb.c | 41 +++++++++++++++++++++++++++++++----------
 1 file changed, 31 insertions(+), 10 deletions(-)

diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index b8f82f96c4c2..ba4055a192e4 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -454,6 +454,14 @@ static void swiotlb_bounce(phys_addr_t orig_addr, phys_addr_t tlb_addr,
 
 #define slot_addr(start, idx)	((start) + ((idx) << IO_TLB_SHIFT))
 
+/*
+ * Return the offset into a iotlb slot required to keep the device happy.
+ */
+static unsigned int swiotlb_align_offset(struct device *dev, u64 addr)
+{
+	return addr & dma_get_min_align_mask(dev) & (IO_TLB_SIZE - 1);
+}
+
 /*
  * Carefully handle integer overflow which can occur when boundary_mask == ~0UL.
  */
@@ -475,24 +483,29 @@ static unsigned int wrap_index(unsigned int index)
  * Find a suitable number of IO TLB entries size that will fit this request and
  * allocate a buffer from that IO TLB pool.
  */
-static int find_slots(struct device *dev, size_t alloc_size)
+static int find_slots(struct device *dev, phys_addr_t orig_addr,
+		size_t alloc_size)
 {
 	unsigned long boundary_mask = dma_get_seg_boundary(dev);
 	dma_addr_t tbl_dma_addr =
 		phys_to_dma_unencrypted(dev, io_tlb_start) & boundary_mask;
 	unsigned long max_slots = get_max_slots(boundary_mask);
-	unsigned int nslots = nr_slots(alloc_size), stride = 1;
+	unsigned int iotlb_align_mask =
+		dma_get_min_align_mask(dev) & ~(IO_TLB_SIZE - 1);
+	unsigned int nslots = nr_slots(alloc_size), stride;
 	unsigned int index, wrap, count = 0, i;
 	unsigned long flags;
 
 	BUG_ON(!nslots);
 
 	/*
-	 * For mappings greater than or equal to a page, we limit the stride
-	 * (and hence alignment) to a page size.
+	 * For mappings with an alignment requirement don't bother looping to
+	 * unaligned slots once we found an aligned one.  For allocations of
+	 * PAGE_SIZE or larger only look for page aligned allocations.
 	 */
+	stride = (iotlb_align_mask >> IO_TLB_SHIFT) + 1;
 	if (alloc_size >= PAGE_SIZE)
-		stride <<= (PAGE_SHIFT - IO_TLB_SHIFT);
+		stride = max(stride, stride << (PAGE_SHIFT - IO_TLB_SHIFT));
 
 	spin_lock_irqsave(&io_tlb_lock, flags);
 	if (unlikely(nslots > io_tlb_nslabs - io_tlb_used))
@@ -500,6 +513,12 @@ static int find_slots(struct device *dev, size_t alloc_size)
 
 	index = wrap = wrap_index(ALIGN(io_tlb_index, stride));
 	do {
+		if ((slot_addr(tbl_dma_addr, index) & iotlb_align_mask) !=
+		    (orig_addr & iotlb_align_mask)) {
+			index = wrap_index(index + 1);
+			continue;
+		}
+
 		/*
 		 * If we find a slot that indicates we have 'nslots' number of
 		 * contiguous buffers, we allocate the buffers from that slot
@@ -543,6 +562,7 @@ phys_addr_t swiotlb_tbl_map_single(struct device *dev, phys_addr_t orig_addr,
 		size_t mapping_size, size_t alloc_size,
 		enum dma_data_direction dir, unsigned long attrs)
 {
+	unsigned int offset = swiotlb_align_offset(dev, orig_addr);
 	unsigned int index, i;
 	phys_addr_t tlb_addr;
 
@@ -558,7 +578,7 @@ phys_addr_t swiotlb_tbl_map_single(struct device *dev, phys_addr_t orig_addr,
 		return (phys_addr_t)DMA_MAPPING_ERROR;
 	}
 
-	index = find_slots(dev, alloc_size);
+	index = find_slots(dev, orig_addr, alloc_size + offset);
 	if (index == -1) {
 		if (!(attrs & DMA_ATTR_NO_WARN))
 			dev_warn_ratelimited(dev,
@@ -572,10 +592,10 @@ phys_addr_t swiotlb_tbl_map_single(struct device *dev, phys_addr_t orig_addr,
 	 * This is needed when we sync the memory.  Then we sync the buffer if
 	 * needed.
 	 */
-	for (i = 0; i < nr_slots(alloc_size); i++)
+	for (i = 0; i < nr_slots(alloc_size + offset); i++)
 		io_tlb_orig_addr[index + i] = slot_addr(orig_addr, i);
 
-	tlb_addr = slot_addr(io_tlb_start, index);
+	tlb_addr = slot_addr(io_tlb_start, index) + offset;
 	if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
 	    (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL))
 		swiotlb_bounce(orig_addr, tlb_addr, mapping_size, DMA_TO_DEVICE);
@@ -590,8 +610,9 @@ void swiotlb_tbl_unmap_single(struct device *hwdev, phys_addr_t tlb_addr,
 			      enum dma_data_direction dir, unsigned long attrs)
 {
 	unsigned long flags;
-	int i, count, nslots = nr_slots(alloc_size);
-	int index = (tlb_addr - io_tlb_start) >> IO_TLB_SHIFT;
+	unsigned int offset = swiotlb_align_offset(hwdev, tlb_addr);
+	int i, count, nslots = nr_slots(alloc_size + offset);
+	int index = (tlb_addr - offset - io_tlb_start) >> IO_TLB_SHIFT;
 	phys_addr_t orig_addr = io_tlb_orig_addr[index];
 
 	/*
-- 
2.31.1.498.g6c1eba8ee3d-goog

[PATCH v2 5.10 9/9] nvme-pci: set min_align_mask

[Jianxiong Gao]

commit: 3d2d861eb03e8ee96dc430a54361c900cbe28afd

The PRP addressing scheme requires all PRP entries except for the
first one to have a zero offset into the NVMe controller pages (which
can be different from the Linux PAGE_SIZE).  Use the min_align_mask
device parameter to ensure that swiotlb does not change the address
of the buffer modulo the device page size to ensure that the PRPs
won't be malformed.

Signed-off-by: Jianxiong Gao <jxgao@google.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Jianxiong Gao <jxgao@google.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
 drivers/nvme/host/pci.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 4dca58f4afdf..716039ea4450 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -2634,6 +2634,7 @@ static void nvme_reset_work(struct work_struct *work)
 	 * Don't limit the IOMMU merged segment size.
 	 */
 	dma_set_max_seg_size(dev->dev, 0xffffffff);
+	dma_set_min_align_mask(dev->dev, NVME_CTRL_PAGE_SIZE - 1);
 
 	mutex_unlock(&dev->shutdown_lock);
 
-- 
2.31.1.498.g6c1eba8ee3d-goog

Re: [PATCH v2 5.10 0/9] preserve DMA offsets when using swiotlb

[Marc Orr]

On Thu, Apr 29, 2021 at 10:34 AM Jianxiong Gao <jxgao@google.com> wrote:
>
> We observed several NVMe failures when running with SWIOTLB. The root
> cause of the issue is that when data is mapped via SWIOTLB, the address
> offset is not preserved. Several device drivers including the NVMe
> driver relies on this offset to function correctly.
>
> Even though we discovered the error when running using AMD SEV, we have
> reproduced the same error in Rhel 8 without SEV. By adding swiotlb=force
> option to the boot command line parameter, NVMe funcionality is
> impacted. For example formatting a disk into xfs format returns an
> error.

Christoph, are you OK with backporting this patch set to LTS, based on
the rationale in the cover letter above?
Thanks,
Marc

Re: [PATCH v2 5.10 0/9] preserve DMA offsets when using swiotlb

[Christoph Hellwig]

On Tue, May 04, 2021 at 01:22:14PM -0700, Marc Orr wrote:
> Christoph, are you OK with backporting this patch set to LTS, based on
> the rationale in the cover letter above?

I don't object, but I really do not have time to review it in detail.

Re: [PATCH v2 5.10 0/9] preserve DMA offsets when using swiotlb

[Greg KH]

On Thu, Apr 29, 2021 at 05:33:06PM +0000, Jianxiong Gao wrote:
> We observed several NVMe failures when running with SWIOTLB. The root
> cause of the issue is that when data is mapped via SWIOTLB, the address
> offset is not preserved. Several device drivers including the NVMe
> driver relies on this offset to function correctly.
> 
> Even though we discovered the error when running using AMD SEV, we have
> reproduced the same error in Rhel 8 without SEV. By adding swiotlb=force
> option to the boot command line parameter, NVMe funcionality is
> impacted. For example formatting a disk into xfs format returns an
> error.
> 
> 
> ----
> Changes in v2:
> Rebased patches to 5.10.33

It looks like if I were to take these now, we need to also have a
version for 5.11.y because you can not upgrade from an older kernel and
have a "regression" like this, right?

5.11.y will still be alive for at least a week or so, let me see if your
backports work there or not...

thanks,

greg k-h

Re: [PATCH v2 5.10 0/9] preserve DMA offsets when using swiotlb

[Greg KH]

On Wed, May 05, 2021 at 09:23:28AM +0200, Greg KH wrote:
> On Thu, Apr 29, 2021 at 05:33:06PM +0000, Jianxiong Gao wrote:
> > We observed several NVMe failures when running with SWIOTLB. The root
> > cause of the issue is that when data is mapped via SWIOTLB, the address
> > offset is not preserved. Several device drivers including the NVMe
> > driver relies on this offset to function correctly.
> > 
> > Even though we discovered the error when running using AMD SEV, we have
> > reproduced the same error in Rhel 8 without SEV. By adding swiotlb=force
> > option to the boot command line parameter, NVMe funcionality is
> > impacted. For example formatting a disk into xfs format returns an
> > error.
> > 
> > 
> > ----
> > Changes in v2:
> > Rebased patches to 5.10.33
> 
> It looks like if I were to take these now, we need to also have a
> version for 5.11.y because you can not upgrade from an older kernel and
> have a "regression" like this, right?
> 
> 5.11.y will still be alive for at least a week or so, let me see if your
> backports work there or not...

Ok, looks like it worked, now queued up.

greg k-h