[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@xxxxxxxxxx>]

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@xxxxxxxxxxxxx>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
---
 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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