1// SPDX-License-Identifier: GPL-2.0-only
 2#include <asm/trap_pf.h>
 3#include <asm/segment.h>
 4#include <asm/trapnr.h>
 5#include "misc.h"
 6
 7static void set_idt_entry(int vector, void (*handler)(void))
 8{
 9	unsigned long address = (unsigned long)handler;
10	gate_desc entry;
11
12	memset(&entry, 0, sizeof(entry));
13
14	entry.offset_low    = (u16)(address & 0xffff);
15	entry.segment       = __KERNEL_CS;
16	entry.bits.type     = GATE_TRAP;
17	entry.bits.p        = 1;
18	entry.offset_middle = (u16)((address >> 16) & 0xffff);
19	entry.offset_high   = (u32)(address >> 32);
20
21	memcpy(&boot_idt[vector], &entry, sizeof(entry));
22}
23
24/* Have this here so we don't need to include <asm/desc.h> */
25static void load_boot_idt(const struct desc_ptr *dtr)
26{
27	asm volatile("lidt %0"::"m" (*dtr));
28}
29
30/* Setup IDT before kernel jumping to  .Lrelocated */
31void load_stage1_idt(void)
32{
33	boot_idt_desc.address = (unsigned long)boot_idt;
34
35
36	if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT))
37		set_idt_entry(X86_TRAP_VC, boot_stage1_vc);
38
39	load_boot_idt(&boot_idt_desc);
40}
41
42/*
43 * Setup IDT after kernel jumping to  .Lrelocated.
44 *
45 * initialize_identity_maps() needs a #PF handler to be setup
46 * in order to be able to fault-in identity mapping ranges; see
47 * do_boot_page_fault().
48 *
49 * This #PF handler setup needs to happen in load_stage2_idt() where the
50 * IDT is loaded and there the #VC IDT entry gets setup too.
51 *
52 * In order to be able to handle #VCs, one needs a GHCB which
53 * gets setup with an already set up pagetable, which is done in
54 * initialize_identity_maps(). And there's the catch 22: the boot #VC
55 * handler do_boot_stage2_vc() needs to call early_setup_ghcb() itself
56 * (and, especially set_page_decrypted()) because the SEV-ES setup code
57 * cannot initialize a GHCB as there's no #PF handler yet...
58 */
59void load_stage2_idt(void)
60{
61	boot_idt_desc.address = (unsigned long)boot_idt;
62
63	set_idt_entry(X86_TRAP_PF, boot_page_fault);
64
65#ifdef CONFIG_AMD_MEM_ENCRYPT
66	set_idt_entry(X86_TRAP_VC, boot_stage2_vc);
67#endif
68
69	load_boot_idt(&boot_idt_desc);
70}
71
72void cleanup_exception_handling(void)
73{
74	/*
75	 * Flush GHCB from cache and map it encrypted again when running as
76	 * SEV-ES guest.
77	 */
78	sev_es_shutdown_ghcb();
79
80	/* Set a null-idt, disabling #PF and #VC handling */
81	boot_idt_desc.size    = 0;
82	boot_idt_desc.address = 0;
83	load_boot_idt(&boot_idt_desc);
84}