1 // SPDX-License-Identifier: GPL-2.0
3 * AMD Encrypted Register State Support
5 * Author: Joerg Roedel <jroedel@suse.de>
9 * misc.h needs to be first because it knows how to include the other kernel
10 * headers in the pre-decompression code in a way that does not break
15 #include <asm/pgtable_types.h>
17 #include <asm/trapnr.h>
18 #include <asm/trap_pf.h>
19 #include <asm/msr-index.h>
20 #include <asm/fpu/xcr.h>
21 #include <asm/ptrace.h>
26 struct ghcb boot_ghcb_page __aligned(PAGE_SIZE);
27 struct ghcb *boot_ghcb;
30 * Copy a version of this function here - insn-eval.c can't be used in
31 * pre-decompression code.
33 static bool insn_has_rep_prefix(struct insn *insn)
38 insn_get_prefixes(insn);
40 for_each_insn_prefix(insn, i, p) {
41 if (p == 0xf2 || p == 0xf3)
49 * Only a dummy for insn_get_seg_base() - Early boot-code is 64bit only and
50 * doesn't use segments.
52 static unsigned long insn_get_seg_base(struct pt_regs *regs, int seg_reg_idx)
57 static inline u64 sev_es_rd_ghcb_msr(void)
59 unsigned long low, high;
61 asm volatile("rdmsr" : "=a" (low), "=d" (high) :
62 "c" (MSR_AMD64_SEV_ES_GHCB));
64 return ((high << 32) | low);
67 static inline void sev_es_wr_ghcb_msr(u64 val)
71 low = val & 0xffffffffUL;
74 asm volatile("wrmsr" : : "c" (MSR_AMD64_SEV_ES_GHCB),
75 "a"(low), "d" (high) : "memory");
78 static enum es_result vc_decode_insn(struct es_em_ctxt *ctxt)
80 char buffer[MAX_INSN_SIZE];
83 memcpy(buffer, (unsigned char *)ctxt->regs->ip, MAX_INSN_SIZE);
85 ret = insn_decode(&ctxt->insn, buffer, MAX_INSN_SIZE, INSN_MODE_64);
87 return ES_DECODE_FAILED;
92 static enum es_result vc_write_mem(struct es_em_ctxt *ctxt,
93 void *dst, char *buf, size_t size)
95 memcpy(dst, buf, size);
100 static enum es_result vc_read_mem(struct es_em_ctxt *ctxt,
101 void *src, char *buf, size_t size)
103 memcpy(buf, src, size);
108 static enum es_result vc_ioio_check(struct es_em_ctxt *ctxt, u16 port, size_t size)
113 static bool fault_in_kernel_space(unsigned long address)
121 #define __pa(x) ((unsigned long)(x))
123 #define __BOOT_COMPRESSED
125 /* Basic instruction decoding support needed */
126 #include "../../lib/inat.c"
127 #include "../../lib/insn.c"
129 /* Include code for early handlers */
130 #include "../../kernel/sev-shared.c"
132 static bool early_setup_sev_es(void)
134 if (!sev_es_negotiate_protocol())
135 sev_es_terminate(GHCB_SEV_ES_REASON_PROTOCOL_UNSUPPORTED);
137 if (set_page_decrypted((unsigned long)&boot_ghcb_page))
140 /* Page is now mapped decrypted, clear it */
141 memset(&boot_ghcb_page, 0, sizeof(boot_ghcb_page));
143 boot_ghcb = &boot_ghcb_page;
145 /* Initialize lookup tables for the instruction decoder */
151 void sev_es_shutdown_ghcb(void)
156 if (!sev_es_check_cpu_features())
157 error("SEV-ES CPU Features missing.");
160 * GHCB Page must be flushed from the cache and mapped encrypted again.
161 * Otherwise the running kernel will see strange cache effects when
162 * trying to use that page.
164 if (set_page_encrypted((unsigned long)&boot_ghcb_page))
165 error("Can't map GHCB page encrypted");
168 * GHCB page is mapped encrypted again and flushed from the cache.
169 * Mark it non-present now to catch bugs when #VC exceptions trigger
172 if (set_page_non_present((unsigned long)&boot_ghcb_page))
173 error("Can't unmap GHCB page");
176 bool sev_es_check_ghcb_fault(unsigned long address)
178 /* Check whether the fault was on the GHCB page */
179 return ((address & PAGE_MASK) == (unsigned long)&boot_ghcb_page);
182 void do_boot_stage2_vc(struct pt_regs *regs, unsigned long exit_code)
184 struct es_em_ctxt ctxt;
185 enum es_result result;
187 if (!boot_ghcb && !early_setup_sev_es())
188 sev_es_terminate(GHCB_SEV_ES_REASON_GENERAL_REQUEST);
190 vc_ghcb_invalidate(boot_ghcb);
191 result = vc_init_em_ctxt(&ctxt, regs, exit_code);
197 case SVM_EXIT_RDTSCP:
198 result = vc_handle_rdtsc(boot_ghcb, &ctxt, exit_code);
201 result = vc_handle_ioio(boot_ghcb, &ctxt);
204 result = vc_handle_cpuid(boot_ghcb, &ctxt);
207 result = ES_UNSUPPORTED;
213 vc_finish_insn(&ctxt);
214 else if (result != ES_RETRY)
215 sev_es_terminate(GHCB_SEV_ES_REASON_GENERAL_REQUEST);