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 
pvh_get_root_pointer(void)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  */
mem_map_via_hcall(struct boot_params * ptr __maybe_unused)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 
init_pvh_bootparams(bool xen_guest)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 	pvh_bootparams.hdr.cmd_line_ptr =
79 		pvh_start_info.cmdline_paddr;
80 
81 	/* The first module is always ramdisk. */
82 	if (pvh_start_info.nr_modules) {
83 		struct hvm_modlist_entry *modaddr =
84 			__va(pvh_start_info.modlist_paddr);
85 		pvh_bootparams.hdr.ramdisk_image = modaddr->paddr;
86 		pvh_bootparams.hdr.ramdisk_size = modaddr->size;
87 	}
88 
89 	/*
90 	 * See Documentation/arch/x86/boot.rst.
91 	 *
92 	 * Version 2.12 supports Xen entry point but we will use default x86/PC
93 	 * environment (i.e. hardware_subarch 0).
94 	 */
95 	pvh_bootparams.hdr.version = (2 << 8) | 12;
96 	pvh_bootparams.hdr.type_of_loader = ((xen_guest ? 0x9 : 0xb) << 4) | 0;
97 
98 	x86_init.acpi.get_root_pointer = pvh_get_root_pointer;
99 }
100 
101 /*
102  * If we are trying to boot a Xen PVH guest, it is expected that the kernel
103  * will have been configured to provide the required override for this routine.
104  */
xen_pvh_init(struct boot_params * boot_params)105 void __init __weak xen_pvh_init(struct boot_params *boot_params)
106 {
107 	xen_raw_printk("Error: Missing xen PVH initialization\n");
108 	BUG();
109 }
110 
hypervisor_specific_init(bool xen_guest)111 static void __init hypervisor_specific_init(bool xen_guest)
112 {
113 	if (xen_guest)
114 		xen_pvh_init(&pvh_bootparams);
115 }
116 
117 /*
118  * This routine (and those that it might call) should not use
119  * anything that lives in .bss since that segment will be cleared later.
120  */
xen_prepare_pvh(void)121 void __init xen_prepare_pvh(void)
122 {
123 
124 	u32 msr = xen_cpuid_base();
125 	bool xen_guest = !!msr;
126 
127 	if (pvh_start_info.magic != XEN_HVM_START_MAGIC_VALUE) {
128 		xen_raw_printk("Error: Unexpected magic value (0x%08x)\n",
129 				pvh_start_info.magic);
130 		BUG();
131 	}
132 
133 	/*
134 	 * This must not compile to "call memset" because memset() may be
135 	 * instrumented.
136 	 */
137 	__builtin_memset(&pvh_bootparams, 0, sizeof(pvh_bootparams));
138 
139 	hypervisor_specific_init(xen_guest);
140 
141 	init_pvh_bootparams(xen_guest);
142 }
143