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Subject[PATCH 4/5] xen/swiotlb: Use the swiotlb_late_init_with_tbl to init Xen-SWIOTLB late when PV PCI is used.
Date
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>
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 | 50 +++++++++++++++++++++++++++----
include/xen/swiotlb-xen.h | 1 +
4 files changed, 62 insertions(+), 8 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 0d5a214..bc2daf6 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 = {
@@ -74,6 +74,21 @@ 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);
+
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..8805e94 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)
+int __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;
@@ -179,7 +199,8 @@ 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"\
@@ -187,9 +208,13 @@ retry:
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 */
@@ -199,9 +224,20 @@ error:
goto retry;
}
xen_raw_printk("%s (rc:%d)", m, rc);
- panic("%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;
+}
+void __init xen_swiotlb_init(int verbose)
+{
+ __xen_swiotlb_init(verbose, true /* early */);
+}
+int xen_swiotlb_late_init(int verbose)
+{
+ return __xen_swiotlb_init(verbose, false /* late */);
}
-
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..d38d984 100644
--- a/include/xen/swiotlb-xen.h
+++ b/include/xen/swiotlb-xen.h
@@ -4,6 +4,7 @@
#include <linux/swiotlb.h>

extern void xen_swiotlb_init(int verbose);
+extern int xen_swiotlb_late_init(int verbose);

extern void
*xen_swiotlb_alloc_coherent(struct device *hwdev, size_t size,
--
1.7.7.6


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