Re: [Xen-devel] [PATCH 4/5] xen/swiotlb: Use the swiotlb_late_init_with_tbl to init Xen-SWIOTLB late when PV PCI is used.

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Fri, Aug 17, 2012 at 06:25:56PM +0100, Stefano Stabellini wrote:
> On Thu, 16 Aug 2012, Konrad Rzeszutek Wilk wrote:
> > With this patch we provide the functionality to initialize the
> > Xen-SWIOTLB late in the bootup cycle - specifically for
> > Xen PCI-frontend. We still will work if the user had
> > supplied 'iommu=soft' on the Linux command line.
> > 
> > CC: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
> > [v1: Fix smatch warnings]
> > Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> > ---
> >  arch/x86/include/asm/xen/swiotlb-xen.h |    2 +
> >  arch/x86/xen/pci-swiotlb-xen.c         |   17 +++++++++-
> >  drivers/xen/swiotlb-xen.c              |   54 ++++++++++++++++++++++++++-----
> >  include/xen/swiotlb-xen.h              |    1 +
> >  4 files changed, 64 insertions(+), 10 deletions(-)
> > 
> > diff --git a/arch/x86/include/asm/xen/swiotlb-xen.h b/arch/x86/include/asm/xen/swiotlb-xen.h
> > index 1be1ab7..ee52fca 100644
> > --- a/arch/x86/include/asm/xen/swiotlb-xen.h
> > +++ b/arch/x86/include/asm/xen/swiotlb-xen.h
> > @@ -5,10 +5,12 @@
> >  extern int xen_swiotlb;
> >  extern int __init pci_xen_swiotlb_detect(void);
> >  extern void __init pci_xen_swiotlb_init(void);
> > +extern int pci_xen_swiotlb_init_late(void);
> >  #else
> >  #define xen_swiotlb (0)
> >  static inline int __init pci_xen_swiotlb_detect(void) { return 0; }
> >  static inline void __init pci_xen_swiotlb_init(void) { }
> > +static inline int pci_xen_swiotlb_init_late(void) { return -ENXIO; }
> >  #endif
> >  
> >  #endif /* _ASM_X86_SWIOTLB_XEN_H */
> > diff --git a/arch/x86/xen/pci-swiotlb-xen.c b/arch/x86/xen/pci-swiotlb-xen.c
> > index 1c17227..031d8bc 100644
> > --- a/arch/x86/xen/pci-swiotlb-xen.c
> > +++ b/arch/x86/xen/pci-swiotlb-xen.c
> > @@ -12,7 +12,7 @@
> >  #include <asm/iommu.h>
> >  #include <asm/dma.h>
> >  #endif
> > -
> > +#include <linux/export.h>
> >  int xen_swiotlb __read_mostly;
> >  
> >  static struct dma_map_ops xen_swiotlb_dma_ops = {
> > @@ -76,6 +76,21 @@ void __init pci_xen_swiotlb_init(void)
> >  		pci_request_acs();
> >  	}
> >  }
> > +
> > +int pci_xen_swiotlb_init_late(void)
> > +{
> > +	int rc = xen_swiotlb_late_init(1);
> > +	if (rc)
> > +		return rc;
> > +
> > +	dma_ops = &xen_swiotlb_dma_ops;
> > +	/* Make sure ACS will be enabled */
> > +	pci_request_acs();
> > +
> > +	return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(pci_xen_swiotlb_init_late);
> 
> shouldn't we be checking whether the xen_swiotlb has already been
> initialized?

Yes.
> 
> 
> >  IOMMU_INIT_FINISH(pci_xen_swiotlb_detect,
> >  		  0,
> >  		  pci_xen_swiotlb_init,
> > diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
> > index 1afb4fb..1942a3e 100644
> > --- a/drivers/xen/swiotlb-xen.c
> > +++ b/drivers/xen/swiotlb-xen.c
> > @@ -145,13 +145,14 @@ xen_swiotlb_fixup(void *buf, size_t size, unsigned long nslabs)
> >  	return 0;
> >  }
> >  
> > -void __init xen_swiotlb_init(int verbose)
> > +static int __ref __xen_swiotlb_init(int verbose, bool early)
> >  {
> >  	unsigned long bytes;
> >  	int rc = -ENOMEM;
> >  	unsigned long nr_tbl;
> >  	char *m = NULL;
> >  	unsigned int repeat = 3;
> > +	unsigned long order;
> >
> >  	nr_tbl = swiotlb_nr_tbl();
> >  	if (nr_tbl)
> > @@ -161,12 +162,31 @@ void __init xen_swiotlb_init(int verbose)
> >  		xen_io_tlb_nslabs = ALIGN(xen_io_tlb_nslabs, IO_TLB_SEGSIZE);
> >  	}
> >  retry:
> > +	order = get_order(xen_io_tlb_nslabs << IO_TLB_SHIFT);
> >  	bytes = xen_io_tlb_nslabs << IO_TLB_SHIFT;
> >  
> >  	/*
> >  	 * Get IO TLB memory from any location.
> >  	 */
> > -	xen_io_tlb_start = alloc_bootmem_pages(PAGE_ALIGN(bytes));
> > +	if (early)
> > +		xen_io_tlb_start = alloc_bootmem_pages(PAGE_ALIGN(bytes));
> > +	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 *)__get_free_pages(__GFP_NOWARN, order);
> > +			if (xen_io_tlb_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;
> > +		}
> > +	}
> >  	if (!xen_io_tlb_start) {
> >  		m = "Cannot allocate Xen-SWIOTLB buffer!\n";
> >  		goto error;
> > @@ -179,17 +199,22 @@ retry:
> >  			       bytes,
> >  			       xen_io_tlb_nslabs);
> >  	if (rc) {
> > -		free_bootmem(__pa(xen_io_tlb_start), PAGE_ALIGN(bytes));
> > +		if (early)
> > +			free_bootmem(__pa(xen_io_tlb_start), PAGE_ALIGN(bytes));
> >  		m = "Failed to get contiguous memory for DMA from Xen!\n"\
> >  		    "You either: don't have the permissions, do not have"\
> >  		    " enough free memory under 4GB, or the hypervisor memory"\
> > -		    "is too fragmented!";
> > +		    " is too fragmented!";
> >  		goto error;
> >  	}
> >  	start_dma_addr = xen_virt_to_bus(xen_io_tlb_start);
> > -	swiotlb_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs, verbose);
> >  
> > -	return;
> > +	rc = 0;
> > +	if (early)
> > +		swiotlb_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs, verbose);
> > +	else
> > +		rc = swiotlb_late_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs);
> > +	return rc;
> >  error:
> >  	if (repeat--) {
> >  		xen_io_tlb_nslabs = max(1024UL, /* Min is 2MB */
> > @@ -198,10 +223,21 @@ error:
> >  		      (xen_io_tlb_nslabs << IO_TLB_SHIFT) >> 20);
> >  		goto retry;
> >  	}
> > -	xen_raw_printk("%s (rc:%d)", m, rc);
> > -	panic("%s (rc:%d)", m, rc);
> > +	pr_err("%s (rc:%d)", m, rc);
> > +	if (early)
> > +		panic("%s (rc:%d)", m, rc);
> > +	else
> > +		free_pages((unsigned long)xen_io_tlb_start, order);
> > +	return rc;
> > +}
> 
> All these "if" make the code a harder to read. Would it be possible at
> least to unify the error paths and just check on after_bootmem whether
> we need to call free_pages or free_bootmem?
> In fact using after_bootmem you might get away without an early
> parameter.


Sure thing. Here is a stab at it.


>From 573db1dbc6adf3f5efc8c699714329caffa43daf Mon Sep 17 00:00:00 2001
From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Date: Thu, 23 Aug 2012 13:55:26 -0400
Subject: [PATCH 1/3] xen/swiotlb: Move the nr_tbl determination in its own
 function.

Moving the function out of the way to prepare for the late
SWIOTLB init.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
 drivers/xen/swiotlb-xen.c |   21 +++++++++++----------
 1 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index 1afb4fb..a2aad6e 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -144,25 +144,26 @@ 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;
+}
 void __init xen_swiotlb_init(int verbose)
 {
 	unsigned long bytes;
 	int rc = -ENOMEM;
-	unsigned long nr_tbl;
 	char *m = NULL;
 	unsigned int repeat = 3;
 
-	nr_tbl = swiotlb_nr_tbl();
-	if (nr_tbl)
-		xen_io_tlb_nslabs = nr_tbl;
-	else {
-		xen_io_tlb_nslabs = (64 * 1024 * 1024 >> IO_TLB_SHIFT);
-		xen_io_tlb_nslabs = ALIGN(xen_io_tlb_nslabs, IO_TLB_SEGSIZE);
-	}
+	xen_io_tlb_nslabs = swiotlb_nr_tbl();
 retry:
-	bytes = xen_io_tlb_nslabs << IO_TLB_SHIFT;
-
+	bytes = xen_set_nslabs(xen_io_tlb_nslabs);
 	/*
 	 * Get IO TLB memory from any location.
 	 */
-- 
1.7.7.6



>From 1bee8a244d1fed47e307c5951a98f7922cab7993 Mon Sep 17 00:00:00 2001
From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Date: Thu, 23 Aug 2012 14:03:55 -0400
Subject: [PATCH 2/3] xen/swiotlb: Move the error strings to its own function.

That way we can more easily reuse those errors when using the
late SWIOTLB init.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
 drivers/xen/swiotlb-xen.c |   35 +++++++++++++++++++++++++++--------
 1 files changed, 27 insertions(+), 8 deletions(-)

diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index a2aad6e..701b103 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -154,11 +154,33 @@ static unsigned long xen_set_nslabs(unsigned long nr_tbl)
 
 	return xen_io_tlb_nslabs << IO_TLB_SHIFT;
 }
+
+enum xen_swiotlb_err {
+	XEN_SWIOTLB_UNKNOWN = 0,
+	XEN_SWIOTLB_ENOMEM,
+	XEN_SWIOTLB_EFIXUP
+};
+
+static const char *xen_swiotlb_error(enum xen_swiotlb_err err)
+{
+	switch (err) {
+	case XEN_SWIOTLB_ENOMEM:
+		return "Cannot allocate Xen-SWIOTLB buffer\n";
+	case XEN_SWIOTLB_EFIXUP:
+		return "Failed to get contiguous memory for DMA from Xen!\n"\
+		    "You either: don't have the permissions, do not have"\
+		    " enough free memory under 4GB, or the hypervisor memory"\
+		    " is too fragmented!";
+	default:
+		break;
+	}
+	return "";
+}
 void __init xen_swiotlb_init(int verbose)
 {
 	unsigned long bytes;
 	int rc = -ENOMEM;
-	char *m = NULL;
+	enum xen_swiotlb_err m_ret = XEN_SWIOTLB_UNKNOWN;
 	unsigned int repeat = 3;
 
 	xen_io_tlb_nslabs = swiotlb_nr_tbl();
@@ -169,7 +191,7 @@ retry:
 	 */
 	xen_io_tlb_start = alloc_bootmem_pages(PAGE_ALIGN(bytes));
 	if (!xen_io_tlb_start) {
-		m = "Cannot allocate Xen-SWIOTLB buffer!\n";
+		m_ret = XEN_SWIOTLB_ENOMEM;
 		goto error;
 	}
 	xen_io_tlb_end = xen_io_tlb_start + bytes;
@@ -181,10 +203,7 @@ retry:
 			       xen_io_tlb_nslabs);
 	if (rc) {
 		free_bootmem(__pa(xen_io_tlb_start), PAGE_ALIGN(bytes));
-		m = "Failed to get contiguous memory for DMA from Xen!\n"\
-		    "You either: don't have the permissions, do not have"\
-		    " enough free memory under 4GB, or the hypervisor memory"\
-		    "is too fragmented!";
+		m_ret = XEN_SWIOTLB_EFIXUP;
 		goto error;
 	}
 	start_dma_addr = xen_virt_to_bus(xen_io_tlb_start);
@@ -199,8 +218,8 @@ error:
 		      (xen_io_tlb_nslabs << IO_TLB_SHIFT) >> 20);
 		goto retry;
 	}
-	xen_raw_printk("%s (rc:%d)", m, rc);
-	panic("%s (rc:%d)", m, rc);
+	xen_raw_printk("%s (rc:%d)", xen_swiotlb_error(m_ret), rc);
+	panic("%s (rc:%d)", xen_swiotlb_error(m_ret), rc);
 }
 
 void *
-- 
1.7.7.6


and the last one:


>From d815253cbf26a5273e77f829cc414e0808500263 Mon Sep 17 00:00:00 2001
From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Date: Thu, 23 Aug 2012 14:36:15 -0400
Subject: [PATCH 3/3] xen/swiotlb: Use the swiotlb_late_init_with_tbl to init
 Xen-SWIOTLB late when PV PCI is used.

With this patch we provide the functionality to initialize the
Xen-SWIOTLB late in the bootup cycle - specifically for
Xen PCI-frontend. We still will work if the user had
supplied 'iommu=soft' on the Linux command line.

CC: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
[v1: Fix smatch warnings]
[v2: Added check for xen_swiotlb]
[v3: Rebased with new xen-swiotlb changes]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
 arch/x86/include/asm/xen/swiotlb-xen.h |    2 +
 arch/x86/xen/pci-swiotlb-xen.c         |   22 ++++++++++++++-
 drivers/xen/swiotlb-xen.c              |   48 +++++++++++++++++++++++++------
 include/xen/swiotlb-xen.h              |    2 +-
 4 files changed, 62 insertions(+), 12 deletions(-)

diff --git a/arch/x86/include/asm/xen/swiotlb-xen.h b/arch/x86/include/asm/xen/swiotlb-xen.h
index 1be1ab7..ee52fca 100644
--- a/arch/x86/include/asm/xen/swiotlb-xen.h
+++ b/arch/x86/include/asm/xen/swiotlb-xen.h
@@ -5,10 +5,12 @@
 extern int xen_swiotlb;
 extern int __init pci_xen_swiotlb_detect(void);
 extern void __init pci_xen_swiotlb_init(void);
+extern int pci_xen_swiotlb_init_late(void);
 #else
 #define xen_swiotlb (0)
 static inline int __init pci_xen_swiotlb_detect(void) { return 0; }
 static inline void __init pci_xen_swiotlb_init(void) { }
+static inline int pci_xen_swiotlb_init_late(void) { return -ENXIO; }
 #endif
 
 #endif /* _ASM_X86_SWIOTLB_XEN_H */
diff --git a/arch/x86/xen/pci-swiotlb-xen.c b/arch/x86/xen/pci-swiotlb-xen.c
index 1c17227..406f9c4 100644
--- a/arch/x86/xen/pci-swiotlb-xen.c
+++ b/arch/x86/xen/pci-swiotlb-xen.c
@@ -12,7 +12,7 @@
 #include <asm/iommu.h>
 #include <asm/dma.h>
 #endif
-
+#include <linux/export.h>
 int xen_swiotlb __read_mostly;
 
 static struct dma_map_ops xen_swiotlb_dma_ops = {
@@ -76,6 +76,26 @@ void __init pci_xen_swiotlb_init(void)
 		pci_request_acs();
 	}
 }
+
+int pci_xen_swiotlb_init_late(void)
+{
+	int rc;
+
+	if (xen_swiotlb)
+		return 0;
+
+	rc = xen_swiotlb_init(1);
+	if (rc)
+		return rc;
+
+	dma_ops = &xen_swiotlb_dma_ops;
+	/* Make sure ACS will be enabled */
+	pci_request_acs();
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(pci_xen_swiotlb_init_late);
+
 IOMMU_INIT_FINISH(pci_xen_swiotlb_detect,
 		  0,
 		  pci_xen_swiotlb_init,
diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index 701b103..f0825cb 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -176,9 +176,9 @@ static const char *xen_swiotlb_error(enum xen_swiotlb_err err)
 	}
 	return "";
 }
-void __init xen_swiotlb_init(int verbose)
+int __ref xen_swiotlb_init(int verbose)
 {
-	unsigned long bytes;
+	unsigned long bytes, order;
 	int rc = -ENOMEM;
 	enum xen_swiotlb_err m_ret = XEN_SWIOTLB_UNKNOWN;
 	unsigned int repeat = 3;
@@ -186,10 +186,28 @@ void __init xen_swiotlb_init(int verbose)
 	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);
 	/*
 	 * Get IO TLB memory from any location.
 	 */
-	xen_io_tlb_start = alloc_bootmem_pages(PAGE_ALIGN(bytes));
+	if (!after_bootmem)
+		xen_io_tlb_start = alloc_bootmem_pages(PAGE_ALIGN(bytes));
+	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 *)__get_free_pages(__GFP_NOWARN, order);
+			if (xen_io_tlb_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;
+		}
+	}
 	if (!xen_io_tlb_start) {
 		m_ret = XEN_SWIOTLB_ENOMEM;
 		goto error;
@@ -202,14 +220,21 @@ retry:
 			       bytes,
 			       xen_io_tlb_nslabs);
 	if (rc) {
-		free_bootmem(__pa(xen_io_tlb_start), PAGE_ALIGN(bytes));
+		if (!after_bootmem)
+			free_bootmem(__pa(xen_io_tlb_start), PAGE_ALIGN(bytes));
+		else {
+			free_pages((unsigned long)xen_io_tlb_start, order);
+			xen_io_tlb_start = NULL;
+		}
 		m_ret = XEN_SWIOTLB_EFIXUP;
 		goto error;
 	}
 	start_dma_addr = xen_virt_to_bus(xen_io_tlb_start);
-	swiotlb_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs, verbose);
-
-	return;
+	if (!after_bootmem)
+		swiotlb_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs, verbose);
+	else
+		rc = swiotlb_late_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs);
+	return rc;
 error:
 	if (repeat--) {
 		xen_io_tlb_nslabs = max(1024UL, /* Min is 2MB */
@@ -218,10 +243,13 @@ error:
 		      (xen_io_tlb_nslabs << IO_TLB_SHIFT) >> 20);
 		goto retry;
 	}
-	xen_raw_printk("%s (rc:%d)", xen_swiotlb_error(m_ret), rc);
-	panic("%s (rc:%d)", xen_swiotlb_error(m_ret), rc);
+	pr_err("%s (rc:%d)", xen_swiotlb_error(m_ret), rc);
+	if (!after_bootmem)
+		panic("%s (rc:%d)", xen_swiotlb_error(m_ret), rc);
+	else
+		free_pages((unsigned long)xen_io_tlb_start, order);
+	return rc;
 }
-
 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 4f4d449..f26f9f3 100644
--- a/include/xen/swiotlb-xen.h
+++ b/include/xen/swiotlb-xen.h
@@ -3,7 +3,7 @@
 
 #include <linux/swiotlb.h>
 
-extern void xen_swiotlb_init(int verbose);
+extern int xen_swiotlb_init(int verbose);
 
 extern void
 *xen_swiotlb_alloc_coherent(struct device *hwdev, size_t size,
-- 
1.7.7.6