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x86/sev: Move instruction decoder into separate source file

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As a first step towards disentangling the SEV #VC handling code -which
is shared between the decompressor and the core kernel- from the SEV
startup code, move the decompressor's copy of the instruction decoder
into a separate source file.

Code movement only - no functional change intended.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: David Woodhouse <dwmw@amazon.co.uk>
Cc: Dionna Amalie Glaze <dionnaglaze@google.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Kevin Loughlin <kevinloughlin@google.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: linux-efi@vger.kernel.org
Link: https://lore.kernel.org/r/20250504095230.2932860-30-ardb+git@google.com
This commit is contained in:
Ard Biesheuvel 2025-05-04 11:52:35 +02:00 committed by Ingo Molnar
parent fae89bbfdd
commit ae862964cb
4 changed files with 62 additions and 41 deletions
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6
arch/x86/boot/compressed/Makefile
View File

@ -44,10 +44,10 @@ KBUILD_CFLAGS += -D__DISABLE_EXPORTS
KBUILD_CFLAGS += $(call cc-option,-Wa$(comma)-mrelax-relocations=no)
KBUILD_CFLAGS += -include $(srctree)/include/linux/hidden.h
# sev.c indirectly includes inat-table.h which is generated during
# sev-decode-insn.c indirectly includes inat-table.c which is generated during
# compilation and stored in $(objtree). Add the directory to the includes so
# that the compiler finds it even with out-of-tree builds (make O=/some/path).
CFLAGS_sev.o += -I$(objtree)/arch/x86/lib/
CFLAGS_sev-handle-vc.o += -I$(objtree)/arch/x86/lib/
KBUILD_AFLAGS := $(KBUILD_CFLAGS) -D__ASSEMBLY__
@ -96,7 +96,7 @@ ifdef CONFIG_X86_64
vmlinux-objs-y += $(obj)/idt_64.o $(obj)/idt_handlers_64.o
vmlinux-objs-$(CONFIG_AMD_MEM_ENCRYPT) += $(obj)/mem_encrypt.o
vmlinux-objs-y += $(obj)/pgtable_64.o
vmlinux-objs-$(CONFIG_AMD_MEM_ENCRYPT) += $(obj)/sev.o
vmlinux-objs-$(CONFIG_AMD_MEM_ENCRYPT) += $(obj)/sev.o $(obj)/sev-handle-vc.o
endif
vmlinux-objs-$(CONFIG_ACPI) += $(obj)/acpi.o

7
arch/x86/boot/compressed/misc.h
View File

@ -136,6 +136,9 @@ static inline void console_init(void)
#endif
#ifdef CONFIG_AMD_MEM_ENCRYPT
struct es_em_ctxt;
struct insn;
void sev_enable(struct boot_params *bp);
void snp_check_features(void);
void sev_es_shutdown_ghcb(void);
@ -143,6 +146,10 @@ extern bool sev_es_check_ghcb_fault(unsigned long address);
void snp_set_page_private(unsigned long paddr);
void snp_set_page_shared(unsigned long paddr);
void sev_prep_identity_maps(unsigned long top_level_pgt);
enum es_result vc_decode_insn(struct es_em_ctxt *ctxt);
bool insn_has_rep_prefix(struct insn *insn);
void sev_insn_decode_init(void);
#else
static inline void sev_enable(struct boot_params *bp)
{

51
arch/x86/boot/compressed/sev-handle-vc.c Normal file
View File

@ -0,0 +1,51 @@
// SPDX-License-Identifier: GPL-2.0
#include "misc.h"
#include <linux/kernel.h>
#include <linux/string.h>
#include <asm/insn.h>
#include <asm/pgtable_types.h>
#include <asm/ptrace.h>
#include <asm/sev.h>
#define __BOOT_COMPRESSED
/* Basic instruction decoding support needed */
#include "../../lib/inat.c"
#include "../../lib/insn.c"
/*
* Copy a version of this function here - insn-eval.c can't be used in
* pre-decompression code.
*/
bool insn_has_rep_prefix(struct insn *insn)
{
insn_byte_t p;
int i;
insn_get_prefixes(insn);
for_each_insn_prefix(insn, i, p) {
if (p == 0xf2 || p == 0xf3)
return true;
}
return false;
}
enum es_result vc_decode_insn(struct es_em_ctxt *ctxt)
{
char buffer[MAX_INSN_SIZE];
int ret;
memcpy(buffer, (unsigned char *)ctxt->regs->ip, MAX_INSN_SIZE);
ret = insn_decode(&ctxt->insn, buffer, MAX_INSN_SIZE, INSN_MODE_64);
if (ret < 0)
return ES_DECODE_FAILED;
return ES_OK;
}
extern void sev_insn_decode_init(void) __alias(inat_init_tables);

39
arch/x86/boot/compressed/sev.c
View File

@ -29,25 +29,6 @@
static struct ghcb boot_ghcb_page __aligned(PAGE_SIZE);
struct ghcb *boot_ghcb;
/*
* Copy a version of this function here - insn-eval.c can't be used in
* pre-decompression code.
*/
static bool insn_has_rep_prefix(struct insn *insn)
{
insn_byte_t p;
int i;
insn_get_prefixes(insn);
for_each_insn_prefix(insn, i, p) {
if (p == 0xf2 || p == 0xf3)
return true;
}
return false;
}
/*
* Only a dummy for insn_get_seg_base() - Early boot-code is 64bit only and
* doesn't use segments.
@ -74,20 +55,6 @@ static inline void sev_es_wr_ghcb_msr(u64 val)
boot_wrmsr(MSR_AMD64_SEV_ES_GHCB, &m);
}
static enum es_result vc_decode_insn(struct es_em_ctxt *ctxt)
{
char buffer[MAX_INSN_SIZE];
int ret;
memcpy(buffer, (unsigned char *)ctxt->regs->ip, MAX_INSN_SIZE);
ret = insn_decode(&ctxt->insn, buffer, MAX_INSN_SIZE, INSN_MODE_64);
if (ret < 0)
return ES_DECODE_FAILED;
return ES_OK;
}
static enum es_result vc_write_mem(struct es_em_ctxt *ctxt,
void *dst, char *buf, size_t size)
{
@ -122,10 +89,6 @@ static bool fault_in_kernel_space(unsigned long address)
#define __BOOT_COMPRESSED
/* Basic instruction decoding support needed */
#include "../../lib/inat.c"
#include "../../lib/insn.c"
extern struct svsm_ca *boot_svsm_caa;
extern u64 boot_svsm_caa_pa;
@ -230,7 +193,7 @@ static bool early_setup_ghcb(void)
boot_ghcb = &boot_ghcb_page;
/* Initialize lookup tables for the instruction decoder */
inat_init_tables();
sev_insn_decode_init();
/* SNP guest requires the GHCB GPA must be registered */
if (sev_snp_enabled())