arch/x86/platform/pvh/enlighten.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/acpi.h>
   3
   4 #include <xen/hvc-console.h>
   5
   6 #include <asm/bootparam.h>
   7 #include <asm/io_apic.h>
   8 #include <asm/hypervisor.h>
   9 #include <asm/e820/api.h>
  10 #include <asm/x86_init.h>
  11
  12 #include <asm/xen/interface.h>
  13
  14 #include <xen/xen.h>
  15 #include <xen/interface/hvm/start_info.h>
  16
  17 /*
  18  * PVH variables.
  19  *
  20  * pvh_bootparams and pvh_start_info need to live in a data segment since
  21  * they are used after startup_{32|64}, which clear .bss, are invoked.
  22  */
  23 struct boot_params __initdata pvh_bootparams;
  24 struct hvm_start_info __initdata pvh_start_info;
  25
  26 const unsigned int __initconst pvh_start_info_sz = sizeof(pvh_start_info);
  27
  28 static u64 __init pvh_get_root_pointer(void)
  29 {
  30         return pvh_start_info.rsdp_paddr;
  31 }
  32
  33 /*
  34  * Xen guests are able to obtain the memory map from the hypervisor via the
  35  * HYPERVISOR_memory_op hypercall.
  36  * If we are trying to boot a Xen PVH guest, it is expected that the kernel
  37  * will have been configured to provide an override for this routine to do
  38  * just that.
  39  */
  40 void __init __weak mem_map_via_hcall(struct boot_params *ptr __maybe_unused)
  41 {
  42         xen_raw_printk("Error: Could not find memory map\n");
  43         BUG();
  44 }
  45
  46 static void __init init_pvh_bootparams(bool xen_guest)
  47 {
  48         if ((pvh_start_info.version > 0) && (pvh_start_info.memmap_entries)) {
  49                 struct hvm_memmap_table_entry *ep;
  50                 int i;
  51
  52                 ep = __va(pvh_start_info.memmap_paddr);
  53                 pvh_bootparams.e820_entries = pvh_start_info.memmap_entries;
  54
  55                 for (i = 0; i < pvh_bootparams.e820_entries ; i++, ep++) {
  56                         pvh_bootparams.e820_table[i].addr = ep->addr;
  57                         pvh_bootparams.e820_table[i].size = ep->size;
  58                         pvh_bootparams.e820_table[i].type = ep->type;
  59                 }
  60         } else if (xen_guest) {
  61                 mem_map_via_hcall(&pvh_bootparams);
  62         } else {
  63                 /* Non-xen guests are not supported by version 0 */
  64                 BUG();
  65         }
  66
  67         if (pvh_bootparams.e820_entries < E820_MAX_ENTRIES_ZEROPAGE - 1) {
  68                 pvh_bootparams.e820_table[pvh_bootparams.e820_entries].addr =
  69                         ISA_START_ADDRESS;
  70                 pvh_bootparams.e820_table[pvh_bootparams.e820_entries].size =
  71                         ISA_END_ADDRESS - ISA_START_ADDRESS;
  72                 pvh_bootparams.e820_table[pvh_bootparams.e820_entries].type =
  73                         E820_TYPE_RESERVED;
  74                 pvh_bootparams.e820_entries++;
  75         } else
  76                 xen_raw_printk("Warning: Can fit ISA range into e820\n");
  77
  78         if (xen_guest)
  79                 xen_reserve_extra_memory(&pvh_bootparams);
  80
  81         pvh_bootparams.hdr.cmd_line_ptr =
  82                 pvh_start_info.cmdline_paddr;
  83
  84         /* The first module is always ramdisk. */
  85         if (pvh_start_info.nr_modules) {
  86                 struct hvm_modlist_entry *modaddr =
  87                         __va(pvh_start_info.modlist_paddr);
  88                 pvh_bootparams.hdr.ramdisk_image = modaddr->paddr;
  89                 pvh_bootparams.hdr.ramdisk_size = modaddr->size;
  90         }
  91
  92         /*
  93          * See Documentation/arch/x86/boot.rst.
  94          *
  95          * Version 2.12 supports Xen entry point but we will use default x86/PC
  96          * environment (i.e. hardware_subarch 0).
  97          */
  98         pvh_bootparams.hdr.version = (2 << 8) | 12;
  99         pvh_bootparams.hdr.type_of_loader = ((xen_guest ? 0x9 : 0xb) << 4) | 0;
 100
 101         x86_init.acpi.get_root_pointer = pvh_get_root_pointer;
 102 }
 103
 104 /*
 105  * If we are trying to boot a Xen PVH guest, it is expected that the kernel
 106  * will have been configured to provide the required override for this routine.
 107  */
 108 void __init __weak xen_pvh_init(struct boot_params *boot_params)
 109 {
 110         xen_raw_printk("Error: Missing xen PVH initialization\n");
 111         BUG();
 112 }
 113
 114 static void __init hypervisor_specific_init(bool xen_guest)
 115 {
 116         if (xen_guest)
 117                 xen_pvh_init(&pvh_bootparams);
 118 }
 119
 120 /*
 121  * This routine (and those that it might call) should not use
 122  * anything that lives in .bss since that segment will be cleared later.
 123  */
 124 void __init xen_prepare_pvh(void)
 125 {
 126
 127         u32 msr = xen_cpuid_base();
 128         bool xen_guest = !!msr;
 129
 130         if (pvh_start_info.magic != XEN_HVM_START_MAGIC_VALUE) {
 131                 xen_raw_printk("Error: Unexpected magic value (0x%08x)\n",
 132                                 pvh_start_info.magic);
 133                 BUG();
 134         }
 135
 136         memset(&pvh_bootparams, 0, sizeof(pvh_bootparams));
 137
 138         hypervisor_specific_init(xen_guest);
 139
 140         init_pvh_bootparams(xen_guest);
 141 }