1 files changed, 41 insertions, 27 deletions

diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c
index 9f90f460a28c..787dc5f568b5 100644
--- a/arch/x86/kernel/sev-shared.c
+++ b/arch/x86/kernel/sev-shared.c
@@ -64,7 +64,7 @@ static bool sev_es_negotiate_protocol(void)
 static __always_inline void vc_ghcb_invalidate(struct ghcb *ghcb)
 {
 	ghcb->save.sw_exit_code = 0;
-	memset(ghcb->save.valid_bitmap, 0, sizeof(ghcb->save.valid_bitmap));
+	__builtin_memset(ghcb->save.valid_bitmap, 0, sizeof(ghcb->save.valid_bitmap));
 }
 
 static bool vc_decoding_needed(unsigned long exit_code)
@@ -94,25 +94,15 @@ static void vc_finish_insn(struct es_em_ctxt *ctxt)
 	ctxt->regs->ip += ctxt->insn.length;
 }
 
-static enum es_result sev_es_ghcb_hv_call(struct ghcb *ghcb,
-					  struct es_em_ctxt *ctxt,
-					  u64 exit_code, u64 exit_info_1,
-					  u64 exit_info_2)
+static enum es_result verify_exception_info(struct ghcb *ghcb, struct es_em_ctxt *ctxt)
 {
-	enum es_result ret;
-
-	/* Fill in protocol and format specifiers */
-	ghcb->protocol_version = GHCB_PROTOCOL_MAX;
-	ghcb->ghcb_usage       = GHCB_DEFAULT_USAGE;
-
-	ghcb_set_sw_exit_code(ghcb, exit_code);
-	ghcb_set_sw_exit_info_1(ghcb, exit_info_1);
-	ghcb_set_sw_exit_info_2(ghcb, exit_info_2);
+	u32 ret;
 
-	sev_es_wr_ghcb_msr(__pa(ghcb));
-	VMGEXIT();
+	ret = ghcb->save.sw_exit_info_1 & GENMASK_ULL(31, 0);
+	if (!ret)
+		return ES_OK;
 
-	if ((ghcb->save.sw_exit_info_1 & 0xffffffff) == 1) {
+	if (ret == 1) {
 		u64 info = ghcb->save.sw_exit_info_2;
 		unsigned long v;
 
@@ -124,17 +114,40 @@ static enum es_result sev_es_ghcb_hv_call(struct ghcb *ghcb,
 		    ((v == X86_TRAP_GP) || (v == X86_TRAP_UD)) &&
 		    ((info & SVM_EVTINJ_TYPE_MASK) == SVM_EVTINJ_TYPE_EXEPT)) {
 			ctxt->fi.vector = v;
+
 			if (info & SVM_EVTINJ_VALID_ERR)
 				ctxt->fi.error_code = info >> 32;
-			ret = ES_EXCEPTION;
-		} else {
-			ret = ES_VMM_ERROR;
+
+			return ES_EXCEPTION;
 		}
-	} else {
-		ret = ES_OK;
 	}
 
-	return ret;
+	return ES_VMM_ERROR;
+}
+
+enum es_result sev_es_ghcb_hv_call(struct ghcb *ghcb, bool set_ghcb_msr,
+				   struct es_em_ctxt *ctxt, u64 exit_code,
+				   u64 exit_info_1, u64 exit_info_2)
+{
+	/* Fill in protocol and format specifiers */
+	ghcb->protocol_version = GHCB_PROTOCOL_MAX;
+	ghcb->ghcb_usage       = GHCB_DEFAULT_USAGE;
+
+	ghcb_set_sw_exit_code(ghcb, exit_code);
+	ghcb_set_sw_exit_info_1(ghcb, exit_info_1);
+	ghcb_set_sw_exit_info_2(ghcb, exit_info_2);
+
+	/*
+	 * Hyper-V unenlightened guests use a paravisor for communicating and
+	 * GHCB pages are being allocated and set up by that paravisor. Linux
+	 * should not change the GHCB page's physical address.
+	 */
+	if (set_ghcb_msr)
+		sev_es_wr_ghcb_msr(__pa(ghcb));
+
+	VMGEXIT();
+
+	return verify_exception_info(ghcb, ctxt);
 }
 
 /*
@@ -411,7 +424,7 @@ static enum es_result vc_handle_ioio(struct ghcb *ghcb, struct es_em_ctxt *ctxt)
 		 */
 		sw_scratch = __pa(ghcb) + offsetof(struct ghcb, shared_buffer);
 		ghcb_set_sw_scratch(ghcb, sw_scratch);
-		ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_IOIO,
+		ret = sev_es_ghcb_hv_call(ghcb, true, ctxt, SVM_EXIT_IOIO,
 					  exit_info_1, exit_info_2);
 		if (ret != ES_OK)
 			return ret;
@@ -453,7 +466,8 @@ static enum es_result vc_handle_ioio(struct ghcb *ghcb, struct es_em_ctxt *ctxt)
 
 		ghcb_set_rax(ghcb, rax);
 
-		ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_IOIO, exit_info_1, 0);
+		ret = sev_es_ghcb_hv_call(ghcb, true, ctxt,
+					  SVM_EXIT_IOIO, exit_info_1, 0);
 		if (ret != ES_OK)
 			return ret;
 
@@ -484,7 +498,7 @@ static enum es_result vc_handle_cpuid(struct ghcb *ghcb,
 		/* xgetbv will cause #GP - use reset value for xcr0 */
 		ghcb_set_xcr0(ghcb, 1);
 
-	ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_CPUID, 0, 0);
+	ret = sev_es_ghcb_hv_call(ghcb, true, ctxt, SVM_EXIT_CPUID, 0, 0);
 	if (ret != ES_OK)
 		return ret;
 
@@ -509,7 +523,7 @@ static enum es_result vc_handle_rdtsc(struct ghcb *ghcb,
 	bool rdtscp = (exit_code == SVM_EXIT_RDTSCP);
 	enum es_result ret;
 
-	ret = sev_es_ghcb_hv_call(ghcb, ctxt, exit_code, 0, 0);
+	ret = sev_es_ghcb_hv_call(ghcb, true, ctxt, exit_code, 0, 0);
 	if (ret != ES_OK)
 		return ret;