5 files changed, 477 insertions, 46 deletions

diff --git a/arch/x86/coco/sev/Makefile b/arch/x86/coco/sev/Makefile
index 342d79f0ab6a..3b8ae214a6a6 100644
--- a/arch/x86/coco/sev/Makefile
+++ b/arch/x86/coco/sev/Makefile
@@ -1,10 +1,10 @@
 # SPDX-License-Identifier: GPL-2.0
 
-obj-y += core.o sev-nmi.o vc-handle.o
+obj-y += core.o noinstr.o vc-handle.o
 
 # Clang 14 and older may fail to respect __no_sanitize_undefined when inlining
-UBSAN_SANITIZE_sev-nmi.o	:= n
+UBSAN_SANITIZE_noinstr.o	:= n
 
 # GCC may fail to respect __no_sanitize_address or __no_kcsan when inlining
-KASAN_SANITIZE_sev-nmi.o	:= n
-KCSAN_SANITIZE_sev-nmi.o	:= n
+KASAN_SANITIZE_noinstr.o	:= n
+KCSAN_SANITIZE_noinstr.o	:= n
diff --git a/arch/x86/coco/sev/core.c b/arch/x86/coco/sev/core.c
index 14ef5908fb27..9ae3b11754e6 100644
--- a/arch/x86/coco/sev/core.c
+++ b/arch/x86/coco/sev/core.c
@@ -46,6 +46,48 @@
 #include <asm/cmdline.h>
 #include <asm/msr.h>
 
+/* Bitmap of SEV features supported by the hypervisor */
+u64 sev_hv_features __ro_after_init;
+SYM_PIC_ALIAS(sev_hv_features);
+
+/* Secrets page physical address from the CC blob */
+u64 sev_secrets_pa __ro_after_init;
+SYM_PIC_ALIAS(sev_secrets_pa);
+
+/* For early boot SVSM communication */
+struct svsm_ca boot_svsm_ca_page __aligned(PAGE_SIZE);
+SYM_PIC_ALIAS(boot_svsm_ca_page);
+
+/*
+ * SVSM related information:
+ *   During boot, the page tables are set up as identity mapped and later
+ *   changed to use kernel virtual addresses. Maintain separate virtual and
+ *   physical addresses for the CAA to allow SVSM functions to be used during
+ *   early boot, both with identity mapped virtual addresses and proper kernel
+ *   virtual addresses.
+ */
+u64 boot_svsm_caa_pa __ro_after_init;
+SYM_PIC_ALIAS(boot_svsm_caa_pa);
+
+DEFINE_PER_CPU(struct svsm_ca *, svsm_caa);
+DEFINE_PER_CPU(u64, svsm_caa_pa);
+
+static inline struct svsm_ca *svsm_get_caa(void)
+{
+	if (sev_cfg.use_cas)
+		return this_cpu_read(svsm_caa);
+	else
+		return rip_rel_ptr(&boot_svsm_ca_page);
+}
+
+static inline u64 svsm_get_caa_pa(void)
+{
+	if (sev_cfg.use_cas)
+		return this_cpu_read(svsm_caa_pa);
+	else
+		return boot_svsm_caa_pa;
+}
+
 /* AP INIT values as documented in the APM2  section "Processor Initialization State" */
 #define AP_INIT_CS_LIMIT		0xffff
 #define AP_INIT_DS_LIMIT		0xffff
@@ -79,6 +121,7 @@ static const char * const sev_status_feat_names[] = {
 	[MSR_AMD64_SNP_IBS_VIRT_BIT]		= "IBSVirt",
 	[MSR_AMD64_SNP_VMSA_REG_PROT_BIT]	= "VMSARegProt",
 	[MSR_AMD64_SNP_SMT_PROT_BIT]		= "SMTProt",
+	[MSR_AMD64_SNP_SECURE_AVIC_BIT]		= "SecureAVIC",
 };
 
 /*
@@ -100,6 +143,26 @@ DEFINE_PER_CPU(struct sev_es_save_area *, sev_vmsa);
  */
 u8 snp_vmpl __ro_after_init;
 EXPORT_SYMBOL_GPL(snp_vmpl);
+SYM_PIC_ALIAS(snp_vmpl);
+
+/*
+ * Since feature negotiation related variables are set early in the boot
+ * process they must reside in the .data section so as not to be zeroed
+ * out when the .bss section is later cleared.
+ *
+ * GHCB protocol version negotiated with the hypervisor.
+ */
+u16 ghcb_version __ro_after_init;
+SYM_PIC_ALIAS(ghcb_version);
+
+/* For early boot hypervisor communication in SEV-ES enabled guests */
+static struct ghcb boot_ghcb_page __bss_decrypted __aligned(PAGE_SIZE);
+
+/*
+ * Needs to be in the .data section because we need it NULL before bss is
+ * cleared
+ */
+struct ghcb *boot_ghcb __section(".data");
 
 static u64 __init get_snp_jump_table_addr(void)
 {
@@ -154,6 +217,73 @@ static u64 __init get_jump_table_addr(void)
 	return ret;
 }
 
+static int svsm_perform_ghcb_protocol(struct ghcb *ghcb, struct svsm_call *call)
+{
+	struct es_em_ctxt ctxt;
+	u8 pending = 0;
+
+	vc_ghcb_invalidate(ghcb);
+
+	/*
+	 * Fill in protocol and format specifiers. This can be called very early
+	 * in the boot, so use rip-relative references as needed.
+	 */
+	ghcb->protocol_version = ghcb_version;
+	ghcb->ghcb_usage       = GHCB_DEFAULT_USAGE;
+
+	ghcb_set_sw_exit_code(ghcb, SVM_VMGEXIT_SNP_RUN_VMPL);
+	ghcb_set_sw_exit_info_1(ghcb, 0);
+	ghcb_set_sw_exit_info_2(ghcb, 0);
+
+	sev_es_wr_ghcb_msr(__pa(ghcb));
+
+	svsm_issue_call(call, &pending);
+
+	if (pending)
+		return -EINVAL;
+
+	switch (verify_exception_info(ghcb, &ctxt)) {
+	case ES_OK:
+		break;
+	case ES_EXCEPTION:
+		vc_forward_exception(&ctxt);
+		fallthrough;
+	default:
+		return -EINVAL;
+	}
+
+	return svsm_process_result_codes(call);
+}
+
+static int svsm_perform_call_protocol(struct svsm_call *call)
+{
+	struct ghcb_state state;
+	unsigned long flags;
+	struct ghcb *ghcb;
+	int ret;
+
+	flags = native_local_irq_save();
+
+	if (sev_cfg.ghcbs_initialized)
+		ghcb = __sev_get_ghcb(&state);
+	else if (boot_ghcb)
+		ghcb = boot_ghcb;
+	else
+		ghcb = NULL;
+
+	do {
+		ret = ghcb ? svsm_perform_ghcb_protocol(ghcb, call)
+			   : __pi_svsm_perform_msr_protocol(call);
+	} while (ret == -EAGAIN);
+
+	if (sev_cfg.ghcbs_initialized)
+		__sev_put_ghcb(&state);
+
+	native_local_irq_restore(flags);
+
+	return ret;
+}
+
 static inline void __pval_terminate(u64 pfn, bool action, unsigned int page_size,
 				    int ret, u64 svsm_ret)
 {
@@ -531,8 +661,11 @@ static void set_pages_state(unsigned long vaddr, unsigned long npages, int op)
 	unsigned long vaddr_end;
 
 	/* Use the MSR protocol when a GHCB is not available. */
-	if (!boot_ghcb)
-		return early_set_pages_state(vaddr, __pa(vaddr), npages, op);
+	if (!boot_ghcb) {
+		struct psc_desc d = { op, svsm_get_caa(), svsm_get_caa_pa() };
+
+		return early_set_pages_state(vaddr, __pa(vaddr), npages, &d);
+	}
 
 	vaddr = vaddr & PAGE_MASK;
 	vaddr_end = vaddr + (npages << PAGE_SHIFT);
@@ -973,6 +1106,9 @@ static int wakeup_cpu_via_vmgexit(u32 apic_id, unsigned long start_ip, unsigned
 	vmsa->x87_ftw		= AP_INIT_X87_FTW_DEFAULT;
 	vmsa->x87_fcw		= AP_INIT_X87_FCW_DEFAULT;
 
+	if (cc_platform_has(CC_ATTR_SNP_SECURE_AVIC))
+		vmsa->vintr_ctrl |= V_GIF_MASK | V_NMI_ENABLE_MASK;
+
 	/* SVME must be set. */
 	vmsa->efer		= EFER_SVME;
 
@@ -1107,6 +1243,105 @@ int __init sev_es_efi_map_ghcbs_cas(pgd_t *pgd)
 	return 0;
 }
 
+u64 savic_ghcb_msr_read(u32 reg)
+{
+	u64 msr = APIC_BASE_MSR + (reg >> 4);
+	struct pt_regs regs = { .cx = msr };
+	struct es_em_ctxt ctxt = { .regs = &regs };
+	struct ghcb_state state;
+	enum es_result res;
+	struct ghcb *ghcb;
+
+	guard(irqsave)();
+
+	ghcb = __sev_get_ghcb(&state);
+	vc_ghcb_invalidate(ghcb);
+
+	res = sev_es_ghcb_handle_msr(ghcb, &ctxt, false);
+	if (res != ES_OK) {
+		pr_err("Secure AVIC MSR (0x%llx) read returned error (%d)\n", msr, res);
+		/* MSR read failures are treated as fatal errors */
+		sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_SAVIC_FAIL);
+	}
+
+	__sev_put_ghcb(&state);
+
+	return regs.ax | regs.dx << 32;
+}
+
+void savic_ghcb_msr_write(u32 reg, u64 value)
+{
+	u64 msr = APIC_BASE_MSR + (reg >> 4);
+	struct pt_regs regs = {
+		.cx = msr,
+		.ax = lower_32_bits(value),
+		.dx = upper_32_bits(value)
+	};
+	struct es_em_ctxt ctxt = { .regs = &regs };
+	struct ghcb_state state;
+	enum es_result res;
+	struct ghcb *ghcb;
+
+	guard(irqsave)();
+
+	ghcb = __sev_get_ghcb(&state);
+	vc_ghcb_invalidate(ghcb);
+
+	res = sev_es_ghcb_handle_msr(ghcb, &ctxt, true);
+	if (res != ES_OK) {
+		pr_err("Secure AVIC MSR (0x%llx) write returned error (%d)\n", msr, res);
+		/* MSR writes should never fail. Any failure is fatal error for SNP guest */
+		sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_SAVIC_FAIL);
+	}
+
+	__sev_put_ghcb(&state);
+}
+
+enum es_result savic_register_gpa(u64 gpa)
+{
+	struct ghcb_state state;
+	struct es_em_ctxt ctxt;
+	enum es_result res;
+	struct ghcb *ghcb;
+
+	guard(irqsave)();
+
+	ghcb = __sev_get_ghcb(&state);
+	vc_ghcb_invalidate(ghcb);
+
+	ghcb_set_rax(ghcb, SVM_VMGEXIT_SAVIC_SELF_GPA);
+	ghcb_set_rbx(ghcb, gpa);
+	res = sev_es_ghcb_hv_call(ghcb, &ctxt, SVM_VMGEXIT_SAVIC,
+				  SVM_VMGEXIT_SAVIC_REGISTER_GPA, 0);
+
+	__sev_put_ghcb(&state);
+
+	return res;
+}
+
+enum es_result savic_unregister_gpa(u64 *gpa)
+{
+	struct ghcb_state state;
+	struct es_em_ctxt ctxt;
+	enum es_result res;
+	struct ghcb *ghcb;
+
+	guard(irqsave)();
+
+	ghcb = __sev_get_ghcb(&state);
+	vc_ghcb_invalidate(ghcb);
+
+	ghcb_set_rax(ghcb, SVM_VMGEXIT_SAVIC_SELF_GPA);
+	res = sev_es_ghcb_hv_call(ghcb, &ctxt, SVM_VMGEXIT_SAVIC,
+				  SVM_VMGEXIT_SAVIC_UNREGISTER_GPA, 0);
+	if (gpa && res == ES_OK)
+		*gpa = ghcb->save.rbx;
+
+	__sev_put_ghcb(&state);
+
+	return res;
+}
+
 static void snp_register_per_cpu_ghcb(void)
 {
 	struct sev_es_runtime_data *data;
@@ -1233,7 +1468,8 @@ static void __init alloc_runtime_data(int cpu)
 		struct svsm_ca *caa;
 
 		/* Allocate the SVSM CA page if an SVSM is present */
-		caa = memblock_alloc_or_panic(sizeof(*caa), PAGE_SIZE);
+		caa = cpu ? memblock_alloc_or_panic(sizeof(*caa), PAGE_SIZE)
+			  : &boot_svsm_ca_page;
 
 		per_cpu(svsm_caa, cpu) = caa;
 		per_cpu(svsm_caa_pa, cpu) = __pa(caa);
@@ -1287,32 +1523,9 @@ void __init sev_es_init_vc_handling(void)
 		init_ghcb(cpu);
 	}
 
-	/* If running under an SVSM, switch to the per-cpu CA */
-	if (snp_vmpl) {
-		struct svsm_call call = {};
-		unsigned long flags;
-		int ret;
-
-		local_irq_save(flags);
-
-		/*
-		 * SVSM_CORE_REMAP_CA call:
-		 *   RAX = 0 (Protocol=0, CallID=0)
-		 *   RCX = New CA GPA
-		 */
-		call.caa = svsm_get_caa();
-		call.rax = SVSM_CORE_CALL(SVSM_CORE_REMAP_CA);
-		call.rcx = this_cpu_read(svsm_caa_pa);
-		ret = svsm_perform_call_protocol(&call);
-		if (ret)
-			panic("Can't remap the SVSM CA, ret=%d, rax_out=0x%llx\n",
-			      ret, call.rax_out);
-
+	if (snp_vmpl)
 		sev_cfg.use_cas = true;
 
-		local_irq_restore(flags);
-	}
-
 	sev_es_setup_play_dead();
 
 	/* Secondary CPUs use the runtime #VC handler */
@@ -1590,15 +1803,6 @@ void sev_show_status(void)
 	pr_cont("\n");
 }
 
-void __init snp_update_svsm_ca(void)
-{
-	if (!snp_vmpl)
-		return;
-
-	/* Update the CAA to a proper kernel address */
-	boot_svsm_caa = &boot_svsm_ca_page;
-}
-
 #ifdef CONFIG_SYSFS
 static ssize_t vmpl_show(struct kobject *kobj,
 			 struct kobj_attribute *attr, char *buf)
diff --git a/arch/x86/coco/sev/sev-nmi.c b/arch/x86/coco/sev/noinstr.c
index d8dfaddfb367..b527eafb6312 100644
--- a/arch/x86/coco/sev/sev-nmi.c
+++ b/arch/x86/coco/sev/noinstr.c
@@ -106,3 +106,77 @@ void noinstr __sev_es_nmi_complete(void)
 
 	__sev_put_ghcb(&state);
 }
+
+/*
+ * Nothing shall interrupt this code path while holding the per-CPU
+ * GHCB. The backup GHCB is only for NMIs interrupting this path.
+ *
+ * Callers must disable local interrupts around it.
+ */
+noinstr struct ghcb *__sev_get_ghcb(struct ghcb_state *state)
+{
+	struct sev_es_runtime_data *data;
+	struct ghcb *ghcb;
+
+	WARN_ON(!irqs_disabled());
+
+	data = this_cpu_read(runtime_data);
+	ghcb = &data->ghcb_page;
+
+	if (unlikely(data->ghcb_active)) {
+		/* GHCB is already in use - save its contents */
+
+		if (unlikely(data->backup_ghcb_active)) {
+			/*
+			 * Backup-GHCB is also already in use. There is no way
+			 * to continue here so just kill the machine. To make
+			 * panic() work, mark GHCBs inactive so that messages
+			 * can be printed out.
+			 */
+			data->ghcb_active        = false;
+			data->backup_ghcb_active = false;
+
+			instrumentation_begin();
+			panic("Unable to handle #VC exception! GHCB and Backup GHCB are already in use");
+			instrumentation_end();
+		}
+
+		/* Mark backup_ghcb active before writing to it */
+		data->backup_ghcb_active = true;
+
+		state->ghcb = &data->backup_ghcb;
+
+		/* Backup GHCB content */
+		*state->ghcb = *ghcb;
+	} else {
+		state->ghcb = NULL;
+		data->ghcb_active = true;
+	}
+
+	return ghcb;
+}
+
+noinstr void __sev_put_ghcb(struct ghcb_state *state)
+{
+	struct sev_es_runtime_data *data;
+	struct ghcb *ghcb;
+
+	WARN_ON(!irqs_disabled());
+
+	data = this_cpu_read(runtime_data);
+	ghcb = &data->ghcb_page;
+
+	if (state->ghcb) {
+		/* Restore GHCB from Backup */
+		*ghcb = *state->ghcb;
+		data->backup_ghcb_active = false;
+		state->ghcb = NULL;
+	} else {
+		/*
+		 * Invalidate the GHCB so a VMGEXIT instruction issued
+		 * from userspace won't appear to be valid.
+		 */
+		vc_ghcb_invalidate(ghcb);
+		data->ghcb_active = false;
+	}
+}
diff --git a/arch/x86/coco/sev/vc-handle.c b/arch/x86/coco/sev/vc-handle.c
index c3b4acbde0d8..7fc136a35334 100644
--- a/arch/x86/coco/sev/vc-handle.c
+++ b/arch/x86/coco/sev/vc-handle.c
@@ -351,6 +351,8 @@ fault:
 }
 
 #define sev_printk(fmt, ...)		printk(fmt, ##__VA_ARGS__)
+#define error(v)
+#define has_cpuflag(f)			boot_cpu_has(f)
 
 #include "vc-shared.c"
 
@@ -402,14 +404,10 @@ static enum es_result __vc_handle_secure_tsc_msrs(struct es_em_ctxt *ctxt, bool
 	return ES_OK;
 }
 
-static enum es_result vc_handle_msr(struct ghcb *ghcb, struct es_em_ctxt *ctxt)
+enum es_result sev_es_ghcb_handle_msr(struct ghcb *ghcb, struct es_em_ctxt *ctxt, bool write)
 {
 	struct pt_regs *regs = ctxt->regs;
 	enum es_result ret;
-	bool write;
-
-	/* Is it a WRMSR? */
-	write = ctxt->insn.opcode.bytes[1] == 0x30;
 
 	switch (regs->cx) {
 	case MSR_SVSM_CAA:
@@ -419,6 +417,15 @@ static enum es_result vc_handle_msr(struct ghcb *ghcb, struct es_em_ctxt *ctxt)
 		if (sev_status & MSR_AMD64_SNP_SECURE_TSC)
 			return __vc_handle_secure_tsc_msrs(ctxt, write);
 		break;
+	case MSR_AMD64_SAVIC_CONTROL:
+		/*
+		 * AMD64_SAVIC_CONTROL should not be intercepted when
+		 * Secure AVIC is enabled. Terminate the Secure AVIC guest
+		 * if the interception is enabled.
+		 */
+		if (cc_platform_has(CC_ATTR_SNP_SECURE_AVIC))
+			return ES_VMM_ERROR;
+		break;
 	default:
 		break;
 	}
@@ -439,6 +446,11 @@ static enum es_result vc_handle_msr(struct ghcb *ghcb, struct es_em_ctxt *ctxt)
 	return ret;
 }
 
+static enum es_result vc_handle_msr(struct ghcb *ghcb, struct es_em_ctxt *ctxt)
+{
+	return sev_es_ghcb_handle_msr(ghcb, ctxt, ctxt->insn.opcode.bytes[1] == 0x30);
+}
+
 static void __init vc_early_forward_exception(struct es_em_ctxt *ctxt)
 {
 	int trapnr = ctxt->fi.vector;
diff --git a/arch/x86/coco/sev/vc-shared.c b/arch/x86/coco/sev/vc-shared.c
index 2c0ab0fdc060..9b01c9ad81be 100644
--- a/arch/x86/coco/sev/vc-shared.c
+++ b/arch/x86/coco/sev/vc-shared.c
@@ -409,15 +409,109 @@ static enum es_result vc_handle_ioio(struct ghcb *ghcb, struct es_em_ctxt *ctxt)
 	return ret;
 }
 
+enum es_result verify_exception_info(struct ghcb *ghcb, struct es_em_ctxt *ctxt)
+{
+	u32 ret;
+
+	ret = ghcb->save.sw_exit_info_1 & GENMASK_ULL(31, 0);
+	if (!ret)
+		return ES_OK;
+
+	if (ret == 1) {
+		u64 info = ghcb->save.sw_exit_info_2;
+		unsigned long v = info & SVM_EVTINJ_VEC_MASK;
+
+		/* Check if exception information from hypervisor is sane. */
+		if ((info & SVM_EVTINJ_VALID) &&
+		    ((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;
+
+			return ES_EXCEPTION;
+		}
+	}
+
+	return ES_VMM_ERROR;
+}
+
+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)
+{
+	/* Fill in protocol and format specifiers */
+	ghcb->protocol_version = ghcb_version;
+	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);
+
+	sev_es_wr_ghcb_msr(__pa(ghcb));
+	VMGEXIT();
+
+	return verify_exception_info(ghcb, ctxt);
+}
+
+static int __sev_cpuid_hv_ghcb(struct ghcb *ghcb, struct es_em_ctxt *ctxt, struct cpuid_leaf *leaf)
+{
+	u32 cr4 = native_read_cr4();
+	int ret;
+
+	ghcb_set_rax(ghcb, leaf->fn);
+	ghcb_set_rcx(ghcb, leaf->subfn);
+
+	if (cr4 & X86_CR4_OSXSAVE)
+		/* Safe to read xcr0 */
+		ghcb_set_xcr0(ghcb, xgetbv(XCR_XFEATURE_ENABLED_MASK));
+	else
+		/* xgetbv will cause #UD - use reset value for xcr0 */
+		ghcb_set_xcr0(ghcb, 1);
+
+	ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_CPUID, 0, 0);
+	if (ret != ES_OK)
+		return ret;
+
+	if (!(ghcb_rax_is_valid(ghcb) &&
+	      ghcb_rbx_is_valid(ghcb) &&
+	      ghcb_rcx_is_valid(ghcb) &&
+	      ghcb_rdx_is_valid(ghcb)))
+		return ES_VMM_ERROR;
+
+	leaf->eax = ghcb->save.rax;
+	leaf->ebx = ghcb->save.rbx;
+	leaf->ecx = ghcb->save.rcx;
+	leaf->edx = ghcb->save.rdx;
+
+	return ES_OK;
+}
+
+struct cpuid_ctx {
+	struct ghcb *ghcb;
+	struct es_em_ctxt *ctxt;
+};
+
+static void snp_cpuid_hv_ghcb(void *p, struct cpuid_leaf *leaf)
+{
+	struct cpuid_ctx *ctx = p;
+
+	if (__sev_cpuid_hv_ghcb(ctx->ghcb, ctx->ctxt, leaf))
+		sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_CPUID_HV);
+}
+
 static int vc_handle_cpuid_snp(struct ghcb *ghcb, struct es_em_ctxt *ctxt)
 {
+	struct cpuid_ctx ctx = { ghcb, ctxt };
 	struct pt_regs *regs = ctxt->regs;
 	struct cpuid_leaf leaf;
 	int ret;
 
 	leaf.fn = regs->ax;
 	leaf.subfn = regs->cx;
-	ret = snp_cpuid(ghcb, ctxt, &leaf);
+	ret = snp_cpuid(snp_cpuid_hv_ghcb, &ctx, &leaf);
 	if (!ret) {
 		regs->ax = leaf.eax;
 		regs->bx = leaf.ebx;
@@ -502,3 +596,50 @@ static enum es_result vc_handle_rdtsc(struct ghcb *ghcb,
 
 	return ES_OK;
 }
+
+void snp_register_ghcb_early(unsigned long paddr)
+{
+	unsigned long pfn = paddr >> PAGE_SHIFT;
+	u64 val;
+
+	sev_es_wr_ghcb_msr(GHCB_MSR_REG_GPA_REQ_VAL(pfn));
+	VMGEXIT();
+
+	val = sev_es_rd_ghcb_msr();
+
+	/* If the response GPA is not ours then abort the guest */
+	if ((GHCB_RESP_CODE(val) != GHCB_MSR_REG_GPA_RESP) ||
+	    (GHCB_MSR_REG_GPA_RESP_VAL(val) != pfn))
+		sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_REGISTER);
+}
+
+bool __init sev_es_check_cpu_features(void)
+{
+	if (!has_cpuflag(X86_FEATURE_RDRAND)) {
+		error("RDRAND instruction not supported - no trusted source of randomness available\n");
+		return false;
+	}
+
+	return true;
+}
+
+bool sev_es_negotiate_protocol(void)
+{
+	u64 val;
+
+	/* Do the GHCB protocol version negotiation */
+	sev_es_wr_ghcb_msr(GHCB_MSR_SEV_INFO_REQ);
+	VMGEXIT();
+	val = sev_es_rd_ghcb_msr();
+
+	if (GHCB_MSR_INFO(val) != GHCB_MSR_SEV_INFO_RESP)
+		return false;
+
+	if (GHCB_MSR_PROTO_MAX(val) < GHCB_PROTOCOL_MIN ||
+	    GHCB_MSR_PROTO_MIN(val) > GHCB_PROTOCOL_MAX)
+		return false;
+
+	ghcb_version = min_t(size_t, GHCB_MSR_PROTO_MAX(val), GHCB_PROTOCOL_MAX);
+
+	return true;
+}