x86/sev: Move instruction decoder into separate source file

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

diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
index 0fcad7b7e0078be7520388f28b64601e77be768f..f4f7b22d81137cf6d9619c39e59dcc5269419249 100644 (file)
--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile
@@ -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

diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h
index dd8d1a85f6716a2e23a3e74ddd2044f106a93ad8..04de48c8d4cf6833d5c3ec7be1f9d4dd01096c93 100644 (file)
--- a/arch/x86/boot/compressed/misc.h
+++ b/arch/x86/boot/compressed/misc.h
@@ -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)
 {

diff --git a/arch/x86/boot/compressed/sev-handle-vc.c b/arch/x86/boot/compressed/sev-handle-vc.c
new file mode 100644 (file)
index 0000000..b1aa073
--- /dev/null
+++ b/arch/x86/boot/compressed/sev-handle-vc.c
@@ -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);

diff --git a/arch/x86/boot/compressed/sev.c b/arch/x86/boot/compressed/sev.c
index f4b7f1784bea41d20cd7e7282571c0bb02d09078..6fe7e85ade6bb9cd5c62336c87546da4f6e6c11c 100644 (file)
--- a/arch/x86/boot/compressed/sev.c
+++ b/arch/x86/boot/compressed/sev.c
@@ -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())