1/* SPDX-License-Identifier: GPL-2.0 */
2
3/*
4 * Copyright C 2016, Oracle and/or its affiliates. All rights reserved.
5 */
6
7	.code32
8	.text
9#define _pa(x)          ((x) - __START_KERNEL_map)
10
11#include <linux/elfnote.h>
12#include <linux/init.h>
13#include <linux/linkage.h>
14#include <asm/desc_defs.h>
15#include <asm/segment.h>
16#include <asm/asm.h>
17#include <asm/boot.h>
18#include <asm/processor-flags.h>
19#include <asm/msr.h>
20#include <asm/nospec-branch.h>
21#include <xen/interface/elfnote.h>
22
23	__HEAD
24
25/*
26 * Entry point for PVH guests.
27 *
28 * Xen ABI specifies the following register state when we come here:
29 *
30 * - `ebx`: contains the physical memory address where the loader has placed
31 *          the boot start info structure.
32 * - `cr0`: bit 0 (PE) must be set. All the other writeable bits are cleared.
33 * - `cr4`: all bits are cleared.
34 * - `cs `: must be a 32-bit read/execute code segment with a base of `0`
35 *          and a limit of `0xFFFFFFFF`. The selector value is unspecified.
36 * - `ds`, `es`: must be a 32-bit read/write data segment with a base of
37 *               `0` and a limit of `0xFFFFFFFF`. The selector values are all
38 *               unspecified.
39 * - `tr`: must be a 32-bit TSS (active) with a base of '0' and a limit
40 *         of '0x67'.
41 * - `eflags`: bit 17 (VM) must be cleared. Bit 9 (IF) must be cleared.
42 *             Bit 8 (TF) must be cleared. Other bits are all unspecified.
43 *
44 * All other processor registers and flag bits are unspecified. The OS is in
45 * charge of setting up its own stack, GDT and IDT.
46 */
47
48#define PVH_GDT_ENTRY_CS	1
49#define PVH_GDT_ENTRY_DS	2
50#define PVH_CS_SEL		(PVH_GDT_ENTRY_CS * 8)
51#define PVH_DS_SEL		(PVH_GDT_ENTRY_DS * 8)
52
53SYM_CODE_START_LOCAL(pvh_start_xen)
54	UNWIND_HINT_END_OF_STACK
55	cld
56
57	lgdt (_pa(gdt))
58
59	mov $PVH_DS_SEL,%eax
60	mov %eax,%ds
61	mov %eax,%es
62	mov %eax,%ss
63
64	/* Stash hvm_start_info. */
65	mov $_pa(pvh_start_info), %edi
66	mov %ebx, %esi
67	mov _pa(pvh_start_info_sz), %ecx
68	shr $2,%ecx
69	rep
70	movsl
71
72	mov $_pa(early_stack_end), %esp
73
74	/* Enable PAE mode. */
75	mov %cr4, %eax
76	orl $X86_CR4_PAE, %eax
77	mov %eax, %cr4
78
79#ifdef CONFIG_X86_64
80	/* Enable Long mode. */
81	mov $MSR_EFER, %ecx
82	rdmsr
83	btsl $_EFER_LME, %eax
84	wrmsr
85
86	/* Enable pre-constructed page tables. */
87	mov $_pa(init_top_pgt), %eax
88	mov %eax, %cr3
89	mov $(X86_CR0_PG | X86_CR0_PE), %eax
90	mov %eax, %cr0
91
92	/* Jump to 64-bit mode. */
93	ljmp $PVH_CS_SEL, $_pa(1f)
94
95	/* 64-bit entry point. */
96	.code64
971:
98	/* Set base address in stack canary descriptor. */
99	mov $MSR_GS_BASE,%ecx
100	mov $_pa(canary), %eax
101	xor %edx, %edx
102	wrmsr
103
104	call xen_prepare_pvh
105
106	/* startup_64 expects boot_params in %rsi. */
107	mov $_pa(pvh_bootparams), %rsi
108	mov $_pa(startup_64), %rax
109	ANNOTATE_RETPOLINE_SAFE
110	jmp *%rax
111
112#else /* CONFIG_X86_64 */
113
114	call mk_early_pgtbl_32
115
116	mov $_pa(initial_page_table), %eax
117	mov %eax, %cr3
118
119	mov %cr0, %eax
120	or $(X86_CR0_PG | X86_CR0_PE), %eax
121	mov %eax, %cr0
122
123	ljmp $PVH_CS_SEL, $1f
1241:
125	call xen_prepare_pvh
126	mov $_pa(pvh_bootparams), %esi
127
128	/* startup_32 doesn't expect paging and PAE to be on. */
129	ljmp $PVH_CS_SEL, $_pa(2f)
1302:
131	mov %cr0, %eax
132	and $~X86_CR0_PG, %eax
133	mov %eax, %cr0
134	mov %cr4, %eax
135	and $~X86_CR4_PAE, %eax
136	mov %eax, %cr4
137
138	ljmp $PVH_CS_SEL, $_pa(startup_32)
139#endif
140SYM_CODE_END(pvh_start_xen)
141
142	.section ".init.data","aw"
143	.balign 8
144SYM_DATA_START_LOCAL(gdt)
145	.word gdt_end - gdt_start
146	.long _pa(gdt_start)
147	.word 0
148SYM_DATA_END(gdt)
149SYM_DATA_START_LOCAL(gdt_start)
150	.quad 0x0000000000000000            /* NULL descriptor */
151#ifdef CONFIG_X86_64
152	.quad GDT_ENTRY(DESC_CODE64, 0, 0xfffff) /* PVH_CS_SEL */
153#else
154	.quad GDT_ENTRY(DESC_CODE32, 0, 0xfffff) /* PVH_CS_SEL */
155#endif
156	.quad GDT_ENTRY(DESC_DATA32, 0, 0xfffff) /* PVH_DS_SEL */
157SYM_DATA_END_LABEL(gdt_start, SYM_L_LOCAL, gdt_end)
158
159	.balign 16
160SYM_DATA_LOCAL(canary, .fill 48, 1, 0)
161
162SYM_DATA_START_LOCAL(early_stack)
163	.fill BOOT_STACK_SIZE, 1, 0
164SYM_DATA_END_LABEL(early_stack, SYM_L_LOCAL, early_stack_end)
165
166	ELFNOTE(Xen, XEN_ELFNOTE_PHYS32_ENTRY,
167	             _ASM_PTR (pvh_start_xen - __START_KERNEL_map))
168