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

   1 // SPDX-License-Identifier: GPL-2.0
   2
   3 /* Glue code to lib/swiotlb-xen.c */
   4
   5 #include <linux/dma-map-ops.h>
   6 #include <linux/pci.h>
   7 #include <xen/swiotlb-xen.h>
   8
   9 #include <asm/xen/hypervisor.h>
  10 #include <xen/xen.h>
  11 #include <asm/iommu_table.h>
  12
  13
  14 #include <asm/xen/swiotlb-xen.h>
  15 #ifdef CONFIG_X86_64
  16 #include <asm/iommu.h>
  17 #include <asm/dma.h>
  18 #endif
  19 #include <linux/export.h>
  20
  21 int xen_swiotlb __read_mostly;
  22
  23 /*
  24  * pci_xen_swiotlb_detect - set xen_swiotlb to 1 if necessary
  25  *
  26  * This returns non-zero if we are forced to use xen_swiotlb (by the boot
  27  * option).
  28  */
  29 int __init pci_xen_swiotlb_detect(void)
  30 {
  31
  32         if (!xen_pv_domain())
  33                 return 0;
  34
  35         /* If running as PV guest, either iommu=soft, or swiotlb=force will
  36          * activate this IOMMU. If running as PV privileged, activate it
  37          * irregardless.
  38          */
  39         if (xen_initial_domain() || swiotlb || swiotlb_force == SWIOTLB_FORCE)
  40                 xen_swiotlb = 1;
  41
  42         /* If we are running under Xen, we MUST disable the native SWIOTLB.
  43          * Don't worry about swiotlb_force flag activating the native, as
  44          * the 'swiotlb' flag is the only one turning it on. */
  45         swiotlb = 0;
  46
  47 #ifdef CONFIG_X86_64
  48         /* pci_swiotlb_detect_4gb turns on native SWIOTLB if no_iommu == 0
  49          * (so no iommu=X command line over-writes).
  50          * Considering that PV guests do not want the *native SWIOTLB* but
  51          * only Xen SWIOTLB it is not useful to us so set no_iommu=1 here.
  52          */
  53         if (max_pfn > MAX_DMA32_PFN)
  54                 no_iommu = 1;
  55 #endif
  56         return xen_swiotlb;
  57 }
  58
  59 void __init pci_xen_swiotlb_init(void)
  60 {
  61         if (xen_swiotlb) {
  62                 xen_swiotlb_init(1, true /* early */);
  63                 dma_ops = &xen_swiotlb_dma_ops;
  64
  65 #ifdef CONFIG_PCI
  66                 /* Make sure ACS will be enabled */
  67                 pci_request_acs();
  68 #endif
  69         }
  70 }
  71
  72 int pci_xen_swiotlb_init_late(void)
  73 {
  74         int rc;
  75
  76         if (xen_swiotlb)
  77                 return 0;
  78
  79         rc = xen_swiotlb_init(1, false /* late */);
  80         if (rc)
  81                 return rc;
  82
  83         dma_ops = &xen_swiotlb_dma_ops;
  84 #ifdef CONFIG_PCI
  85         /* Make sure ACS will be enabled */
  86         pci_request_acs();
  87 #endif
  88
  89         return 0;
  90 }
  91 EXPORT_SYMBOL_GPL(pci_xen_swiotlb_init_late);
  92
  93 IOMMU_INIT_FINISH(pci_xen_swiotlb_detect,
  94                   NULL,
  95                   pci_xen_swiotlb_init,
  96                   NULL);