[PATCH Part1 v5 07/38] x86/sev: Add support for hypervisor feature VMGEXIT

@@ -26,6 +26,7 @@ enum sev_feature_type {
 
 extern u64 sme_me_mask;
 extern u64 sev_status;
+extern u64 sev_hv_features;
 
 void sme_encrypt_execute(unsigned long encrypted_kernel_vaddr,
 			 unsigned long decrypted_kernel_vaddr,

@@ -66,6 +67,7 @@ bool sev_feature_enabled(unsigned int feature_type);
 #else	/* !CONFIG_AMD_MEM_ENCRYPT */
 
 #define sme_me_mask	0ULL
+#define sev_hv_features	0ULL
 
 static inline void __init sme_early_encrypt(resource_size_t paddr,
 					    unsigned long size) { }

@@ -60,6 +60,9 @@
 /* GHCB Hypervisor Feature Request/Response */
 #define GHCB_MSR_HV_FT_REQ		0x080
 #define GHCB_MSR_HV_FT_RESP		0x081
+#define GHCB_MSR_HV_FT_RESP_VAL(v)			\
+	/* GHCBData[63:12] */				\
+	(((u64)(v) & GENMASK_ULL(63, 12)) >> 12)
 
 #define GHCB_MSR_TERM_REQ		0x100
 #define GHCB_MSR_TERM_REASON_SET_POS	12

@@ -13,7 +13,7 @@
 #include <asm/sev-common.h>
 
 #define GHCB_PROTOCOL_MIN	1ULL
-#define GHCB_PROTOCOL_MAX	1ULL
+#define GHCB_PROTOCOL_MAX	2ULL
 #define GHCB_DEFAULT_USAGE	0ULL
 
 #define	VMGEXIT()			{ asm volatile("rep; vmmcall\n\r"); }

@@ -108,6 +108,7 @@
 #define SVM_VMGEXIT_AP_JUMP_TABLE		0x80000005
 #define SVM_VMGEXIT_SET_AP_JUMP_TABLE		0
 #define SVM_VMGEXIT_GET_AP_JUMP_TABLE		1
+#define SVM_VMGEXIT_HV_FEATURES			0x8000fffd
 #define SVM_VMGEXIT_UNSUPPORTED_EVENT		0x8000ffff
 
 /* Exit code reserved for hypervisor/software use */

@@ -218,6 +219,7 @@
 	{ SVM_VMGEXIT_NMI_COMPLETE,	"vmgexit_nmi_complete" }, \
 	{ SVM_VMGEXIT_AP_HLT_LOOP,	"vmgexit_ap_hlt_loop" }, \
 	{ SVM_VMGEXIT_AP_JUMP_TABLE,	"vmgexit_ap_jump_table" }, \
+	{ SVM_VMGEXIT_HV_FEATURES,	"vmgexit_hypervisor_feature" }, \
 	{ SVM_EXIT_ERR,         "invalid_guest_state" }
 
 

@@ -23,6 +23,9 @@
  */
 static u16 __ro_after_init ghcb_version;
 
+/* Bitmap of SEV features supported by the hypervisor */
+u64 __ro_after_init sev_hv_features = 0;
+
 static bool __init sev_es_check_cpu_features(void)
 {
 	if (!has_cpuflag(X86_FEATURE_RDRAND)) {

@@ -48,6 +51,22 @@ static void __noreturn sev_es_terminate(unsigned int set, unsigned int reason)
 		asm volatile("hlt\n" : : : "memory");
 }
 
+static bool get_hv_features(void)
+{
+	u64 val;
+
+	sev_es_wr_ghcb_msr(GHCB_MSR_HV_FT_REQ);
+	VMGEXIT();
+
+	val = sev_es_rd_ghcb_msr();
+	if (GHCB_RESP_CODE(val) != GHCB_MSR_HV_FT_RESP)
+		return false;
+
+	sev_hv_features = GHCB_MSR_HV_FT_RESP_VAL(val);
+
+	return true;
+}
+
 static bool sev_es_negotiate_protocol(void)
 {
 	u64 val;

@@ -66,6 +85,10 @@ static bool sev_es_negotiate_protocol(void)
 
 	ghcb_version = min_t(size_t, GHCB_MSR_PROTO_MAX(val), GHCB_PROTOCOL_MAX);
 
+	/* The hypervisor features are available from version 2 onward. */
+	if (ghcb_version >= 2 && !get_hv_features())
+		return false;
+
 	return true;
 }