arch/x86/xen/pci-swiotlb-xen.c

   1 /* Glue code to lib/swiotlb-xen.c */
   2
   3 #include <linux/dma-mapping.h>
   4 #include <linux/pci.h>
   5 #include <xen/swiotlb-xen.h>
   6
   7 #include <asm/xen/hypervisor.h>
   8 #include <xen/xen.h>
   9 #include <asm/iommu_table.h>
  10
  11
  12 #include <asm/xen/swiotlb-xen.h>
  13 #ifdef CONFIG_X86_64
  14 #include <asm/iommu.h>
  15 #include <asm/dma.h>
  16 #endif
  17 #include <linux/export.h>
  18
  19 int xen_swiotlb __read_mostly;
  20
  21 /*
  22  * pci_xen_swiotlb_detect - set xen_swiotlb to 1 if necessary
  23  *
  24  * This returns non-zero if we are forced to use xen_swiotlb (by the boot
  25  * option).
  26  */
  27 int __init pci_xen_swiotlb_detect(void)
  28 {
  29
  30         if (!xen_pv_domain())
  31                 return 0;
  32
  33         /* If running as PV guest, either iommu=soft, or swiotlb=force will
  34          * activate this IOMMU. If running as PV privileged, activate it
  35          * irregardless.
  36          */
  37         if (xen_initial_domain() || swiotlb || swiotlb_force == SWIOTLB_FORCE)
  38                 xen_swiotlb = 1;
  39
  40         /* If we are running under Xen, we MUST disable the native SWIOTLB.
  41          * Don't worry about swiotlb_force flag activating the native, as
  42          * the 'swiotlb' flag is the only one turning it on. */
  43         swiotlb = 0;
  44
  45 #ifdef CONFIG_X86_64
  46         /* pci_swiotlb_detect_4gb turns on native SWIOTLB if no_iommu == 0
  47          * (so no iommu=X command line over-writes).
  48          * Considering that PV guests do not want the *native SWIOTLB* but
  49          * only Xen SWIOTLB it is not useful to us so set no_iommu=1 here.
  50          */
  51         if (max_pfn > MAX_DMA32_PFN)
  52                 no_iommu = 1;
  53 #endif
  54         return xen_swiotlb;
  55 }
  56
  57 void __init pci_xen_swiotlb_init(void)
  58 {
  59         if (xen_swiotlb) {
  60                 xen_swiotlb_init(1, true /* early */);
  61                 dma_ops = &xen_swiotlb_dma_ops;
  62
  63 #ifdef CONFIG_PCI
  64                 /* Make sure ACS will be enabled */
  65                 pci_request_acs();
  66 #endif
  67         }
  68 }
  69
  70 int pci_xen_swiotlb_init_late(void)
  71 {
  72         int rc;
  73
  74         if (xen_swiotlb)
  75                 return 0;
  76
  77         rc = xen_swiotlb_init(1, false /* late */);
  78         if (rc)
  79                 return rc;
  80
  81         dma_ops = &xen_swiotlb_dma_ops;
  82 #ifdef CONFIG_PCI
  83         /* Make sure ACS will be enabled */
  84         pci_request_acs();
  85 #endif
  86
  87         return 0;
  88 }
  89 EXPORT_SYMBOL_GPL(pci_xen_swiotlb_init_late);
  90
  91 IOMMU_INIT_FINISH(pci_xen_swiotlb_detect,
  92                   NULL,
  93                   pci_xen_swiotlb_init,
  94                   NULL);