swiotlb cleanups

swiotlb cleanups

[Christoph Hellwig]

Hi Konrad,

this series contains a bunch of swiotlb cleanups, mostly to reduce the
amount of internals exposed to code outside of swiotlb.c, which should
helper to prepare for supporting multiple different bounce buffer pools.
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[PATCH 1/8] powerpc/svm: stop using io_tlb_start

[Christoph Hellwig]

Use the local variable that is passed to swiotlb_init_with_tbl for
freeing the memory in the failure case to isolate the code a little
better from swiotlb internals.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/powerpc/platforms/pseries/svm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/platforms/pseries/svm.c b/arch/powerpc/platforms/pseries/svm.c
index 7b739cc7a8a93e..b9968ac7cc0789 100644
--- a/arch/powerpc/platforms/pseries/svm.c
+++ b/arch/powerpc/platforms/pseries/svm.c
@@ -56,7 +56,7 @@ void __init svm_swiotlb_init(void)
 		return;
 
 	if (io_tlb_start)
-		memblock_free_early(io_tlb_start,
+		memblock_free_early(__pa(vstart),
 				    PAGE_ALIGN(io_tlb_nslabs << IO_TLB_SHIFT));
 	panic("SVM: Cannot allocate SWIOTLB buffer");
 }
-- 
2.29.2

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[PATCH 2/8] xen-swiotlb: use is_swiotlb_buffer in is_xen_swiotlb_buffer

[Christoph Hellwig]

Use the is_swiotlb_buffer to check if a physical address is
a swiotlb buffer.  This works because xen-swiotlb does use the
same buffer as the main swiotlb code, and xen_io_tlb_{start,end}
are just the addresses for it that went through phys_to_virt.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/xen/swiotlb-xen.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index 2b385c1b4a99cb..a4026822a889f7 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -111,10 +111,8 @@ static int is_xen_swiotlb_buffer(struct device *dev, dma_addr_t dma_addr)
 	 * have the same virtual address as another address
 	 * in our domain. Therefore _only_ check address within our domain.
 	 */
-	if (pfn_valid(PFN_DOWN(paddr))) {
-		return paddr >= virt_to_phys(xen_io_tlb_start) &&
-		       paddr < virt_to_phys(xen_io_tlb_end);
-	}
+	if (pfn_valid(PFN_DOWN(paddr)))
+		return is_swiotlb_buffer(paddr);
 	return 0;
 }
 
-- 
2.29.2

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[PATCH 3/8] xen-swiotlb: use io_tlb_end in xen_swiotlb_dma_supported

[Christoph Hellwig]

Use the existing variable that holds the physical address for
xen_io_tlb_end to simplify xen_swiotlb_dma_supported a bit, and remove
the otherwise unused xen_io_tlb_end variable and the xen_virt_to_bus
helper.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/xen/swiotlb-xen.c | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index a4026822a889f7..4298f74a083985 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -46,7 +46,7 @@
  * API.
  */
 
-static char *xen_io_tlb_start, *xen_io_tlb_end;
+static char *xen_io_tlb_start;
 static unsigned long xen_io_tlb_nslabs;
 /*
  * Quick lookup value of the bus address of the IOTLB.
@@ -82,11 +82,6 @@ static inline phys_addr_t xen_dma_to_phys(struct device *dev,
 	return xen_bus_to_phys(dev, dma_to_phys(dev, dma_addr));
 }
 
-static inline dma_addr_t xen_virt_to_bus(struct device *dev, void *address)
-{
-	return xen_phys_to_dma(dev, virt_to_phys(address));
-}
-
 static inline int range_straddles_page_boundary(phys_addr_t p, size_t size)
 {
 	unsigned long next_bfn, xen_pfn = XEN_PFN_DOWN(p);
@@ -250,7 +245,6 @@ int __ref xen_swiotlb_init(int verbose, bool early)
 		rc = swiotlb_late_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs);
 
 end:
-	xen_io_tlb_end = xen_io_tlb_start + bytes;
 	if (!rc)
 		swiotlb_set_max_segment(PAGE_SIZE);
 
@@ -558,7 +552,7 @@ xen_swiotlb_sync_sg_for_device(struct device *dev, struct scatterlist *sgl,
 static int
 xen_swiotlb_dma_supported(struct device *hwdev, u64 mask)
 {
-	return xen_virt_to_bus(hwdev, xen_io_tlb_end - 1) <= mask;
+	return xen_phys_to_dma(hwdev, io_tlb_end - 1) <= mask;
 }
 
 const struct dma_map_ops xen_swiotlb_dma_ops = {
-- 
2.29.2

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[PATCH 4/8] xen-swiotlb: remove xen_set_nslabs

[Christoph Hellwig]

The xen_set_nslabs function is a little weird, as it has just one
caller, that caller passes a global variable as the argument,
which is then overriden in the function and a derivative of it
returned.  Just add a cpp symbol for the default size using a readable
constant and open code the remaining three lines in the caller.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/xen/swiotlb-xen.c | 19 +++++++------------
 1 file changed, 7 insertions(+), 12 deletions(-)

diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index 4298f74a083985..57f8d5fadc1fcd 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -138,16 +138,6 @@ xen_swiotlb_fixup(void *buf, size_t size, unsigned long nslabs)
 	} while (i < nslabs);
 	return 0;
 }
-static unsigned long xen_set_nslabs(unsigned long nr_tbl)
-{
-	if (!nr_tbl) {
-		xen_io_tlb_nslabs = (64 * 1024 * 1024 >> IO_TLB_SHIFT);
-		xen_io_tlb_nslabs = ALIGN(xen_io_tlb_nslabs, IO_TLB_SEGSIZE);
-	} else
-		xen_io_tlb_nslabs = nr_tbl;
-
-	return xen_io_tlb_nslabs << IO_TLB_SHIFT;
-}
 
 enum xen_swiotlb_err {
 	XEN_SWIOTLB_UNKNOWN = 0,
@@ -170,6 +160,9 @@ static const char *xen_swiotlb_error(enum xen_swiotlb_err err)
 	}
 	return "";
 }
+
+#define DEFAULT_NSLABS		ALIGN(SZ_64M >> IO_TLB_SHIFT, IO_TLB_SEGSIZE)
+
 int __ref xen_swiotlb_init(int verbose, bool early)
 {
 	unsigned long bytes, order;
@@ -179,8 +172,10 @@ int __ref xen_swiotlb_init(int verbose, bool early)
 
 	xen_io_tlb_nslabs = swiotlb_nr_tbl();
 retry:
-	bytes = xen_set_nslabs(xen_io_tlb_nslabs);
-	order = get_order(xen_io_tlb_nslabs << IO_TLB_SHIFT);
+	if (!xen_io_tlb_nslabs)
+		xen_io_tlb_nslabs = DEFAULT_NSLABS;
+	bytes = xen_io_tlb_nslabs << IO_TLB_SHIFT;
+	order = get_order(bytes);
 
 	/*
 	 * IO TLB memory already allocated. Just use it.
-- 
2.29.2

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[PATCH 5/8] xen-swiotlb: remove xen_io_tlb_start and xen_io_tlb_nslabs

[Christoph Hellwig]

The xen_io_tlb_start and xen_io_tlb_nslabs variables ar now only used in
xen_swiotlb_init, so replace them with local variables.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/xen/swiotlb-xen.c | 57 +++++++++++++++++----------------------
 1 file changed, 25 insertions(+), 32 deletions(-)

diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index 57f8d5fadc1fcd..6e0f2c5ecd1a2f 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -40,14 +40,7 @@
 
 #include <trace/events/swiotlb.h>
 #define MAX_DMA_BITS 32
-/*
- * Used to do a quick range check in swiotlb_tbl_unmap_single and
- * swiotlb_tbl_sync_single_*, to see if the memory was in fact allocated by this
- * API.
- */
 
-static char *xen_io_tlb_start;
-static unsigned long xen_io_tlb_nslabs;
 /*
  * Quick lookup value of the bus address of the IOTLB.
  */
@@ -169,75 +162,75 @@ int __ref xen_swiotlb_init(int verbose, bool early)
 	int rc = -ENOMEM;
 	enum xen_swiotlb_err m_ret = XEN_SWIOTLB_UNKNOWN;
 	unsigned int repeat = 3;
+	char *start;
+	unsigned long nslabs;
 
-	xen_io_tlb_nslabs = swiotlb_nr_tbl();
+	nslabs = swiotlb_nr_tbl();
 retry:
-	if (!xen_io_tlb_nslabs)
-		xen_io_tlb_nslabs = DEFAULT_NSLABS;
-	bytes = xen_io_tlb_nslabs << IO_TLB_SHIFT;
+	if (!nslabs)
+		nslabs = DEFAULT_NSLABS;
+	bytes = nslabs << IO_TLB_SHIFT;
 	order = get_order(bytes);
 
 	/*
 	 * IO TLB memory already allocated. Just use it.
 	 */
-	if (io_tlb_start != 0) {
-		xen_io_tlb_start = phys_to_virt(io_tlb_start);
+	if (io_tlb_start != 0)
 		goto end;
-	}
 
 	/*
 	 * Get IO TLB memory from any location.
 	 */
 	if (early) {
-		xen_io_tlb_start = memblock_alloc(PAGE_ALIGN(bytes),
+		start = memblock_alloc(PAGE_ALIGN(bytes),
 						  PAGE_SIZE);
-		if (!xen_io_tlb_start)
+		if (!start)
 			panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
 			      __func__, PAGE_ALIGN(bytes), PAGE_SIZE);
 	} else {
 #define SLABS_PER_PAGE (1 << (PAGE_SHIFT - IO_TLB_SHIFT))
 #define IO_TLB_MIN_SLABS ((1<<20) >> IO_TLB_SHIFT)
 		while ((SLABS_PER_PAGE << order) > IO_TLB_MIN_SLABS) {
-			xen_io_tlb_start = (void *)xen_get_swiotlb_free_pages(order);
-			if (xen_io_tlb_start)
+			start = (void *)xen_get_swiotlb_free_pages(order);
+			if (start)
 				break;
 			order--;
 		}
 		if (order != get_order(bytes)) {
 			pr_warn("Warning: only able to allocate %ld MB for software IO TLB\n",
 				(PAGE_SIZE << order) >> 20);
-			xen_io_tlb_nslabs = SLABS_PER_PAGE << order;
-			bytes = xen_io_tlb_nslabs << IO_TLB_SHIFT;
+			nslabs = SLABS_PER_PAGE << order;
+			bytes = nslabs << IO_TLB_SHIFT;
 		}
 	}
-	if (!xen_io_tlb_start) {
+	if (!start) {
 		m_ret = XEN_SWIOTLB_ENOMEM;
 		goto error;
 	}
 	/*
 	 * And replace that memory with pages under 4GB.
 	 */
-	rc = xen_swiotlb_fixup(xen_io_tlb_start,
+	rc = xen_swiotlb_fixup(start,
 			       bytes,
-			       xen_io_tlb_nslabs);
+			       nslabs);
 	if (rc) {
 		if (early)
-			memblock_free(__pa(xen_io_tlb_start),
+			memblock_free(__pa(start),
 				      PAGE_ALIGN(bytes));
 		else {
-			free_pages((unsigned long)xen_io_tlb_start, order);
-			xen_io_tlb_start = NULL;
+			free_pages((unsigned long)start, order);
+			start = NULL;
 		}
 		m_ret = XEN_SWIOTLB_EFIXUP;
 		goto error;
 	}
 	if (early) {
-		if (swiotlb_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs,
+		if (swiotlb_init_with_tbl(start, nslabs,
 			 verbose))
 			panic("Cannot allocate SWIOTLB buffer");
 		rc = 0;
 	} else
-		rc = swiotlb_late_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs);
+		rc = swiotlb_late_init_with_tbl(start, nslabs);
 
 end:
 	if (!rc)
@@ -246,17 +239,17 @@ int __ref xen_swiotlb_init(int verbose, bool early)
 	return rc;
 error:
 	if (repeat--) {
-		xen_io_tlb_nslabs = max(1024UL, /* Min is 2MB */
-					(xen_io_tlb_nslabs >> 1));
+		nslabs = max(1024UL, /* Min is 2MB */
+					(nslabs >> 1));
 		pr_info("Lowering to %luMB\n",
-			(xen_io_tlb_nslabs << IO_TLB_SHIFT) >> 20);
+			(nslabs << IO_TLB_SHIFT) >> 20);
 		goto retry;
 	}
 	pr_err("%s (rc:%d)\n", xen_swiotlb_error(m_ret), rc);
 	if (early)
 		panic("%s (rc:%d)", xen_swiotlb_error(m_ret), rc);
 	else
-		free_pages((unsigned long)xen_io_tlb_start, order);
+		free_pages((unsigned long)start, order);
 	return rc;
 }
 
-- 
2.29.2

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[PATCH 6/8] swiotlb: lift the double initialization protection from xen-swiotlb

[Christoph Hellwig]

Lift the double initialization protection from xen-swiotlb to the core
code to avoid exposing too many swiotlb internals.  Also upgrade the
check to a warning as it should not happen.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/xen/swiotlb-xen.c | 7 -------
 kernel/dma/swiotlb.c      | 8 ++++++++
 2 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index 6e0f2c5ecd1a2f..e6c8556e879ee6 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -172,12 +172,6 @@ int __ref xen_swiotlb_init(int verbose, bool early)
 	bytes = nslabs << IO_TLB_SHIFT;
 	order = get_order(bytes);
 
-	/*
-	 * IO TLB memory already allocated. Just use it.
-	 */
-	if (io_tlb_start != 0)
-		goto end;
-
 	/*
 	 * Get IO TLB memory from any location.
 	 */
@@ -232,7 +226,6 @@ int __ref xen_swiotlb_init(int verbose, bool early)
 	} else
 		rc = swiotlb_late_init_with_tbl(start, nslabs);
 
-end:
 	if (!rc)
 		swiotlb_set_max_segment(PAGE_SIZE);
 
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index adcc3c87e10078..a3737961ae5769 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -224,6 +224,10 @@ int __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
 	unsigned long i, bytes;
 	size_t alloc_size;
 
+	/* protect against double initialization */
+	if (WARN_ON_ONCE(io_tlb_start))
+		return -ENOMEM;
+
 	bytes = nslabs << IO_TLB_SHIFT;
 
 	io_tlb_nslabs = nslabs;
@@ -355,6 +359,10 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
 {
 	unsigned long i, bytes;
 
+	/* protect against double initialization */
+	if (WARN_ON_ONCE(io_tlb_start))
+		return -ENOMEM;
+
 	bytes = nslabs << IO_TLB_SHIFT;
 
 	io_tlb_nslabs = nslabs;
-- 
2.29.2

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[PATCH 7/8] xen-swiotlb: split xen_swiotlb_init

[Christoph Hellwig]

Split xen_swiotlb_init into a normal an an early case.  That makes both
much simpler and more readable, and also allows marking the early
code as __init and x86-only.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/arm/xen/mm.c              |   2 +-
 arch/x86/xen/pci-swiotlb-xen.c |   4 +-
 drivers/xen/swiotlb-xen.c      | 124 +++++++++++++++++++--------------
 include/xen/swiotlb-xen.h      |   3 +-
 4 files changed, 75 insertions(+), 58 deletions(-)

diff --git a/arch/arm/xen/mm.c b/arch/arm/xen/mm.c
index 467fa225c3d0ed..aae950cd053fea 100644
--- a/arch/arm/xen/mm.c
+++ b/arch/arm/xen/mm.c
@@ -140,7 +140,7 @@ static int __init xen_mm_init(void)
 	struct gnttab_cache_flush cflush;
 	if (!xen_initial_domain())
 		return 0;
-	xen_swiotlb_init(1, false);
+	xen_swiotlb_init();
 
 	cflush.op = 0;
 	cflush.a.dev_bus_addr = 0;
diff --git a/arch/x86/xen/pci-swiotlb-xen.c b/arch/x86/xen/pci-swiotlb-xen.c
index 19ae3e4fe4e98e..54f9aa7e845739 100644
--- a/arch/x86/xen/pci-swiotlb-xen.c
+++ b/arch/x86/xen/pci-swiotlb-xen.c
@@ -59,7 +59,7 @@ int __init pci_xen_swiotlb_detect(void)
 void __init pci_xen_swiotlb_init(void)
 {
 	if (xen_swiotlb) {
-		xen_swiotlb_init(1, true /* early */);
+		xen_swiotlb_init_early();
 		dma_ops = &xen_swiotlb_dma_ops;
 
 #ifdef CONFIG_PCI
@@ -76,7 +76,7 @@ int pci_xen_swiotlb_init_late(void)
 	if (xen_swiotlb)
 		return 0;
 
-	rc = xen_swiotlb_init(1, false /* late */);
+	rc = xen_swiotlb_init();
 	if (rc)
 		return rc;
 
diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index e6c8556e879ee6..b2d9e77059bf5a 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -156,96 +156,112 @@ static const char *xen_swiotlb_error(enum xen_swiotlb_err err)
 
 #define DEFAULT_NSLABS		ALIGN(SZ_64M >> IO_TLB_SHIFT, IO_TLB_SEGSIZE)
 
-int __ref xen_swiotlb_init(int verbose, bool early)
+int __ref xen_swiotlb_init(void)
 {
-	unsigned long bytes, order;
-	int rc = -ENOMEM;
 	enum xen_swiotlb_err m_ret = XEN_SWIOTLB_UNKNOWN;
+	unsigned long nslabs, bytes, order;
 	unsigned int repeat = 3;
+	int rc = -ENOMEM;
 	char *start;
-	unsigned long nslabs;
 
 	nslabs = swiotlb_nr_tbl();
-retry:
 	if (!nslabs)
 		nslabs = DEFAULT_NSLABS;
+retry:
+	m_ret = XEN_SWIOTLB_ENOMEM;
 	bytes = nslabs << IO_TLB_SHIFT;
 	order = get_order(bytes);
 
 	/*
 	 * Get IO TLB memory from any location.
 	 */
-	if (early) {
-		start = memblock_alloc(PAGE_ALIGN(bytes),
-						  PAGE_SIZE);
-		if (!start)
-			panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
-			      __func__, PAGE_ALIGN(bytes), PAGE_SIZE);
-	} else {
 #define SLABS_PER_PAGE (1 << (PAGE_SHIFT - IO_TLB_SHIFT))
 #define IO_TLB_MIN_SLABS ((1<<20) >> IO_TLB_SHIFT)
-		while ((SLABS_PER_PAGE << order) > IO_TLB_MIN_SLABS) {
-			start = (void *)xen_get_swiotlb_free_pages(order);
-			if (start)
-				break;
-			order--;
-		}
-		if (order != get_order(bytes)) {
-			pr_warn("Warning: only able to allocate %ld MB for software IO TLB\n",
-				(PAGE_SIZE << order) >> 20);
-			nslabs = SLABS_PER_PAGE << order;
-			bytes = nslabs << IO_TLB_SHIFT;
-		}
+	while ((SLABS_PER_PAGE << order) > IO_TLB_MIN_SLABS) {
+		start = (void *)xen_get_swiotlb_free_pages(order);
+		if (start)
+			break;
+		order--;
 	}
-	if (!start) {
-		m_ret = XEN_SWIOTLB_ENOMEM;
+	if (!start)
 		goto error;
+	if (order != get_order(bytes)) {
+		pr_warn("Warning: only able to allocate %ld MB for software IO TLB\n",
+			(PAGE_SIZE << order) >> 20);
+		nslabs = SLABS_PER_PAGE << order;
+		bytes = nslabs << IO_TLB_SHIFT;
 	}
+
 	/*
 	 * And replace that memory with pages under 4GB.
 	 */
-	rc = xen_swiotlb_fixup(start,
-			       bytes,
-			       nslabs);
+	rc = xen_swiotlb_fixup(start, bytes, nslabs);
 	if (rc) {
-		if (early)
-			memblock_free(__pa(start),
-				      PAGE_ALIGN(bytes));
-		else {
-			free_pages((unsigned long)start, order);
-			start = NULL;
-		}
+		free_pages((unsigned long)start, order);
 		m_ret = XEN_SWIOTLB_EFIXUP;
 		goto error;
 	}
-	if (early) {
-		if (swiotlb_init_with_tbl(start, nslabs,
-			 verbose))
-			panic("Cannot allocate SWIOTLB buffer");
-		rc = 0;
-	} else
-		rc = swiotlb_late_init_with_tbl(start, nslabs);
-
-	if (!rc)
-		swiotlb_set_max_segment(PAGE_SIZE);
-
-	return rc;
+	rc = swiotlb_late_init_with_tbl(start, nslabs);
+	if (rc)
+		return rc;
+	swiotlb_set_max_segment(PAGE_SIZE);
+	return 0;
 error:
 	if (repeat--) {
-		nslabs = max(1024UL, /* Min is 2MB */
-					(nslabs >> 1));
+		/* Min is 2MB */
+		nslabs = max(1024UL, (nslabs >> 1));
 		pr_info("Lowering to %luMB\n",
 			(nslabs << IO_TLB_SHIFT) >> 20);
 		goto retry;
 	}
 	pr_err("%s (rc:%d)\n", xen_swiotlb_error(m_ret), rc);
-	if (early)
-		panic("%s (rc:%d)", xen_swiotlb_error(m_ret), rc);
-	else
-		free_pages((unsigned long)start, order);
+	free_pages((unsigned long)start, order);
 	return rc;
 }
 
+#ifdef CONFIG_X86
+void __init xen_swiotlb_init_early(void)
+{
+	unsigned long nslabs, bytes;
+	unsigned int repeat = 3;
+	char *start;
+	int rc;
+
+	nslabs = swiotlb_nr_tbl();
+	if (!nslabs)
+		nslabs = DEFAULT_NSLABS;
+retry:
+	/*
+	 * Get IO TLB memory from any location.
+	 */
+	bytes = nslabs << IO_TLB_SHIFT;
+	start = memblock_alloc(PAGE_ALIGN(bytes), PAGE_SIZE);
+	if (!start)
+		panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
+		      __func__, PAGE_ALIGN(bytes), PAGE_SIZE);
+
+	/*
+	 * And replace that memory with pages under 4GB.
+	 */
+	rc = xen_swiotlb_fixup(start, bytes, nslabs);
+	if (rc) {
+		memblock_free(__pa(start), PAGE_ALIGN(bytes));
+		if (repeat--) {
+			/* Min is 2MB */
+			nslabs = max(1024UL, (nslabs >> 1));
+			pr_info("Lowering to %luMB\n",
+				(nslabs << IO_TLB_SHIFT) >> 20);
+			goto retry;
+		}
+		panic("%s (rc:%d)", xen_swiotlb_error(XEN_SWIOTLB_EFIXUP), rc);
+	}
+
+	if (swiotlb_init_with_tbl(start, nslabs, false))
+		panic("Cannot allocate SWIOTLB buffer");
+	swiotlb_set_max_segment(PAGE_SIZE);
+}
+#endif /* CONFIG_X86 */
+
 static void *
 xen_swiotlb_alloc_coherent(struct device *hwdev, size_t size,
 			   dma_addr_t *dma_handle, gfp_t flags,
diff --git a/include/xen/swiotlb-xen.h b/include/xen/swiotlb-xen.h
index d5eaf9d682b804..6206b1ec99168a 100644
--- a/include/xen/swiotlb-xen.h
+++ b/include/xen/swiotlb-xen.h
@@ -9,7 +9,8 @@ void xen_dma_sync_for_cpu(struct device *dev, dma_addr_t handle,
 void xen_dma_sync_for_device(struct device *dev, dma_addr_t handle,
 			     size_t size, enum dma_data_direction dir);
 
-extern int xen_swiotlb_init(int verbose, bool early);
+int xen_swiotlb_init(void);
+void __init xen_swiotlb_init_early(void);
 extern const struct dma_map_ops xen_swiotlb_dma_ops;
 
 #endif /* __LINUX_SWIOTLB_XEN_H */
-- 
2.29.2

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[PATCH 8/8] xen-swiotlb: remove the unused size argument from xen_swiotlb_fixup

[Christoph Hellwig]

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/xen/swiotlb-xen.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index b2d9e77059bf5a..621a20c1143597 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -104,8 +104,7 @@ static int is_xen_swiotlb_buffer(struct device *dev, dma_addr_t dma_addr)
 	return 0;
 }
 
-static int
-xen_swiotlb_fixup(void *buf, size_t size, unsigned long nslabs)
+static int xen_swiotlb_fixup(void *buf, unsigned long nslabs)
 {
 	int i, rc;
 	int dma_bits;
@@ -195,7 +194,7 @@ int __ref xen_swiotlb_init(void)
 	/*
 	 * And replace that memory with pages under 4GB.
 	 */
-	rc = xen_swiotlb_fixup(start, bytes, nslabs);
+	rc = xen_swiotlb_fixup(start, nslabs);
 	if (rc) {
 		free_pages((unsigned long)start, order);
 		m_ret = XEN_SWIOTLB_EFIXUP;
@@ -243,7 +242,7 @@ void __init xen_swiotlb_init_early(void)
 	/*
 	 * And replace that memory with pages under 4GB.
 	 */
-	rc = xen_swiotlb_fixup(start, bytes, nslabs);
+	rc = xen_swiotlb_fixup(start, nslabs);
 	if (rc) {
 		memblock_free(__pa(start), PAGE_ALIGN(bytes));
 		if (repeat--) {
-- 
2.29.2

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Re: [PATCH 2/8] xen-swiotlb: use is_swiotlb_buffer in is_xen_swiotlb_buffer

[Konrad Rzeszutek Wilk]

On Sun, Feb 07, 2021 at 05:09:28PM +0100, Christoph Hellwig wrote:
> Use the is_swiotlb_buffer to check if a physical address is
> a swiotlb buffer.  This works because xen-swiotlb does use the
> same buffer as the main swiotlb code, and xen_io_tlb_{start,end}
> are just the addresses for it that went through phys_to_virt.
> 

Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  drivers/xen/swiotlb-xen.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
> index 2b385c1b4a99cb..a4026822a889f7 100644
> --- a/drivers/xen/swiotlb-xen.c
> +++ b/drivers/xen/swiotlb-xen.c
> @@ -111,10 +111,8 @@ static int is_xen_swiotlb_buffer(struct device *dev, dma_addr_t dma_addr)
>  	 * have the same virtual address as another address
>  	 * in our domain. Therefore _only_ check address within our domain.
>  	 */
> -	if (pfn_valid(PFN_DOWN(paddr))) {
> -		return paddr >= virt_to_phys(xen_io_tlb_start) &&
> -		       paddr < virt_to_phys(xen_io_tlb_end);
> -	}
> +	if (pfn_valid(PFN_DOWN(paddr)))
> +		return is_swiotlb_buffer(paddr);
>  	return 0;
>  }
>  
> -- 
> 2.29.2
> 
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Re: [PATCH 3/8] xen-swiotlb: use io_tlb_end in xen_swiotlb_dma_supported

[Konrad Rzeszutek Wilk]

On Sun, Feb 07, 2021 at 05:09:29PM +0100, Christoph Hellwig wrote:
> Use the existing variable that holds the physical address for
> xen_io_tlb_end to simplify xen_swiotlb_dma_supported a bit, and remove
> the otherwise unused xen_io_tlb_end variable and the xen_virt_to_bus
> helper.
> 
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  drivers/xen/swiotlb-xen.c | 10 ++--------
>  1 file changed, 2 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
> index a4026822a889f7..4298f74a083985 100644
> --- a/drivers/xen/swiotlb-xen.c
> +++ b/drivers/xen/swiotlb-xen.c
> @@ -46,7 +46,7 @@
>   * API.
>   */
>  
> -static char *xen_io_tlb_start, *xen_io_tlb_end;
> +static char *xen_io_tlb_start;
>  static unsigned long xen_io_tlb_nslabs;
>  /*
>   * Quick lookup value of the bus address of the IOTLB.
> @@ -82,11 +82,6 @@ static inline phys_addr_t xen_dma_to_phys(struct device *dev,
>  	return xen_bus_to_phys(dev, dma_to_phys(dev, dma_addr));
>  }
>  
> -static inline dma_addr_t xen_virt_to_bus(struct device *dev, void *address)
> -{
> -	return xen_phys_to_dma(dev, virt_to_phys(address));
> -}
> -
>  static inline int range_straddles_page_boundary(phys_addr_t p, size_t size)
>  {
>  	unsigned long next_bfn, xen_pfn = XEN_PFN_DOWN(p);
> @@ -250,7 +245,6 @@ int __ref xen_swiotlb_init(int verbose, bool early)
>  		rc = swiotlb_late_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs);
>  
>  end:
> -	xen_io_tlb_end = xen_io_tlb_start + bytes;
>  	if (!rc)
>  		swiotlb_set_max_segment(PAGE_SIZE);
>  
> @@ -558,7 +552,7 @@ xen_swiotlb_sync_sg_for_device(struct device *dev, struct scatterlist *sgl,
>  static int
>  xen_swiotlb_dma_supported(struct device *hwdev, u64 mask)
>  {
> -	return xen_virt_to_bus(hwdev, xen_io_tlb_end - 1) <= mask;
> +	return xen_phys_to_dma(hwdev, io_tlb_end - 1) <= mask;
>  }
>  
>  const struct dma_map_ops xen_swiotlb_dma_ops = {
> -- 
> 2.29.2
> 
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