x86/sev-es: Compile early handler code into kernel image

Setup sev-es.c and include the code from the pre-decompression stage
to also build it into the image of the running kernel. Temporarily add
__maybe_unused annotations to avoid build warnings until the functions
get used.

 [ bp: Use the non-tracing rd/wrmsr variants because:
   vmlinux.o: warning: objtool: __sev_es_nmi_complete()+0x11f: \
	   call to do_trace_write_msr() leaves .noinstr.text section
   as __sev_es_nmi_complete() is noinstr due to being called from the
   NMI handler exc_nmi(). ]

Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200907131613.12703-39-joro@8bytes.org

1 files changed, 11 insertions, 10 deletions

diff --git a/arch/x86/kernel/sev-es-shared.c b/arch/x86/kernel/sev-es-shared.c
index a6b41910b8ab..18619279a46f 100644
--- a/arch/x86/kernel/sev-es-shared.c
+++ b/arch/x86/kernel/sev-es-shared.c
@@ -9,7 +9,7 @@
  * and is included directly into both code-bases.
  */
 
-static void sev_es_terminate(unsigned int reason)
+static void __maybe_unused sev_es_terminate(unsigned int reason)
 {
 	u64 val = GHCB_SEV_TERMINATE;
 
@@ -27,7 +27,7 @@ static void sev_es_terminate(unsigned int reason)
 		asm volatile("hlt\n" : : : "memory");
 }
 
-static bool sev_es_negotiate_protocol(void)
+static bool __maybe_unused sev_es_negotiate_protocol(void)
 {
 	u64 val;
 
@@ -46,7 +46,7 @@ static bool sev_es_negotiate_protocol(void)
 	return true;
 }
 
-static void vc_ghcb_invalidate(struct ghcb *ghcb)
+static void __maybe_unused vc_ghcb_invalidate(struct ghcb *ghcb)
 {
 	memset(ghcb->save.valid_bitmap, 0, sizeof(ghcb->save.valid_bitmap));
 }
@@ -58,9 +58,9 @@ static bool vc_decoding_needed(unsigned long exit_code)
 		 exit_code <= SVM_EXIT_LAST_EXCP);
 }
 
-static enum es_result vc_init_em_ctxt(struct es_em_ctxt *ctxt,
-				      struct pt_regs *regs,
-				      unsigned long exit_code)
+static enum es_result __maybe_unused vc_init_em_ctxt(struct es_em_ctxt *ctxt,
+						     struct pt_regs *regs,
+						     unsigned long exit_code)
 {
 	enum es_result ret = ES_OK;
 
@@ -73,7 +73,7 @@ static enum es_result vc_init_em_ctxt(struct es_em_ctxt *ctxt,
 	return ret;
 }
 
-static void vc_finish_insn(struct es_em_ctxt *ctxt)
+static void __maybe_unused vc_finish_insn(struct es_em_ctxt *ctxt)
 {
 	ctxt->regs->ip += ctxt->insn.length;
 }
@@ -325,7 +325,8 @@ static enum es_result vc_ioio_exitinfo(struct es_em_ctxt *ctxt, u64 *exitinfo)
 	return ES_OK;
 }
 
-static enum es_result vc_handle_ioio(struct ghcb *ghcb, struct es_em_ctxt *ctxt)
+static enum es_result __maybe_unused
+vc_handle_ioio(struct ghcb *ghcb, struct es_em_ctxt *ctxt)
 {
 	struct pt_regs *regs = ctxt->regs;
 	u64 exit_info_1, exit_info_2;
@@ -433,8 +434,8 @@ static enum es_result vc_handle_ioio(struct ghcb *ghcb, struct es_em_ctxt *ctxt)
 	return ret;
 }
 
-static enum es_result vc_handle_cpuid(struct ghcb *ghcb,
-				      struct es_em_ctxt *ctxt)
+static enum es_result __maybe_unused vc_handle_cpuid(struct ghcb *ghcb,
+						     struct es_em_ctxt *ctxt)
 {
 	struct pt_regs *regs = ctxt->regs;
 	u32 cr4 = native_read_cr4();