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Subject[PATCH 04/10] x86/swiotlb: Simplify SWIOTLB pci_swiotlb_detect routine.
Date
In 'pci_swiotlb_detect' we used to do two different things:
a). If user provided 'iommu=soft' or 'swiotlb=force' we
would set swiotlb=1 and return 1 (and forcing pci-dma.c
to call pci_swiotlb_init() immediately).
b). If 4GB or more would be detected and if user did not specify
iommu=off, we would set 'swiotlb=1' and return whatever 'a)'
figured out.

We simplify this by splitting a) and b) in two different routines.

CC: H. Peter Anvin <hpa@zytor.com>
CC: Fujita Tomonori <fujita.tomonori@lab.ntt.co.jp>
CC: x86@kernel.org
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
arch/x86/include/asm/iommu_table.h | 4 ++--
arch/x86/include/asm/swiotlb.h | 13 +++++++++++--
arch/x86/kernel/pci-dma.c | 4 +++-
arch/x86/kernel/pci-swiotlb.c | 33 +++++++++++++++++++++++++++------
4 files changed, 43 insertions(+), 11 deletions(-)
diff --git a/arch/x86/include/asm/iommu_table.h b/arch/x86/include/asm/iommu_table.h
index 2124e3e..df55a78 100644
--- a/arch/x86/include/asm/iommu_table.h
+++ b/arch/x86/include/asm/iommu_table.h
@@ -64,10 +64,10 @@ struct iommu_table_entry {
* to stop detecting the other IOMMUs after yours has been detected.
*/
#define IOMMU_INIT_POST(_detect) \
- __IOMMU_INIT(_detect, pci_swiotlb_detect, 0, 0, 0)
+ __IOMMU_INIT(_detect, pci_swiotlb_detect_4gb, 0, 0, 0)

#define IOMMU_INIT_POST_FINISH(detect) \
- __IOMMU_INIT(_detect, pci_swiotlb_detect, 0, 0, 1)
+ __IOMMU_INIT(_detect, pci_swiotlb_detect_4gb, 0, 0, 1)

/*
* A more sophisticated version of IOMMU_INIT. This variant requires:
diff --git a/arch/x86/include/asm/swiotlb.h b/arch/x86/include/asm/swiotlb.h
index 8085277..977f176 100644
--- a/arch/x86/include/asm/swiotlb.h
+++ b/arch/x86/include/asm/swiotlb.h
@@ -5,17 +5,26 @@

#ifdef CONFIG_SWIOTLB
extern int swiotlb;
-extern int __init pci_swiotlb_detect(void);
+extern int __init pci_swiotlb_detect_override(void);
+extern int __init pci_swiotlb_detect_4gb(void);
extern void __init pci_swiotlb_init(void);
+extern void __init pci_swiotlb_late_init(void);
#else
#define swiotlb 0
-static inline int pci_swiotlb_detect(void)
+static inline int pci_swiotlb_detect_override(void)
+{
+ return 0;
+}
+static inline int pci_swiotlb_detect_4gb(void)
{
return 0;
}
static inline void pci_swiotlb_init(void)
{
}
+static inline void pci_swiotlb_late_init(void)
+{
+}
#endif

static inline void dma_mark_clean(void *addr, size_t size) {}
diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
index 9f07cfc..1b3beb5 100644
--- a/arch/x86/kernel/pci-dma.c
+++ b/arch/x86/kernel/pci-dma.c
@@ -133,9 +133,11 @@ void __init pci_iommu_alloc(void)
/* free the range so iommu could get some range less than 4G */
dma32_free_bootmem();

- if (pci_xen_swiotlb_detect() || pci_swiotlb_detect())
+ if (pci_xen_swiotlb_detect() || pci_swiotlb_detect_override())
goto out;

+ pci_swiotlb_detect_4gb();
+
gart_iommu_hole_init();

detect_calgary();
diff --git a/arch/x86/kernel/pci-swiotlb.c b/arch/x86/kernel/pci-swiotlb.c
index a5bc528..c7a72fa 100644
--- a/arch/x86/kernel/pci-swiotlb.c
+++ b/arch/x86/kernel/pci-swiotlb.c
@@ -41,24 +41,33 @@ static struct dma_map_ops swiotlb_dma_ops = {
};

/*
- * pci_swiotlb_detect - set swiotlb to 1 if necessary
+ * pci_swiotlb_detect_override - set swiotlb to 1 if necessary
*
* This returns non-zero if we are forced to use swiotlb (by the boot
* option).
*/
-int __init pci_swiotlb_detect(void)
+int __init pci_swiotlb_detect_override(void)
{
int use_swiotlb = swiotlb | swiotlb_force;

+ if (swiotlb_force)
+ swiotlb = 1;
+
+ return use_swiotlb;
+}
+
+/*
+ * if 4GB or more detected (and iommu=off not set) return 1
+ * and set swiotlb to 1.
+ */
+int __init pci_swiotlb_detect_4gb(void)
+{
/* don't initialize swiotlb if iommu=off (no_iommu=1) */
#ifdef CONFIG_X86_64
if (!no_iommu && max_pfn > MAX_DMA32_PFN)
swiotlb = 1;
#endif
- if (swiotlb_force)
- swiotlb = 1;
-
- return use_swiotlb;
+ return swiotlb;
}

void __init pci_swiotlb_init(void)
@@ -68,3 +77,15 @@ void __init pci_swiotlb_init(void)
dma_ops = &swiotlb_dma_ops;
}
}
+
+void __init pci_swiotlb_late_init(void)
+{
+ /* An IOMMU turned us off. */
+ if (!swiotlb)
+ swiotlb_free();
+ else {
+ printk(KERN_INFO "PCI-DMA: "
+ "Using software bounce buffering for IO (SWIOTLB)\n");
+ swiotlb_print_info();
+ }
+}
--
1.7.0.1


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