Merge tag 'x86_sev_for_v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 SEV updates from Borislav Petkov:

 - Do the proper memory conversion of guest memory in order to be able
   to kexec kernels in SNP guests along with other adjustments and
   cleanups to that effect

 - Start converting and moving functionality from the sev-guest driver
   into core code with the purpose of supporting the secure TSC SNP
   feature where the hypervisor cannot influence the TSC exposed to the
   guest anymore

 - Add a "nosnp" cmdline option in order to be able to disable SNP
   support in the hypervisor and thus free-up resources which are not
   going to be used

 - Cleanups

[ Reminding myself about the endless TLA's again: SEV is the AMD Secure
  Encrypted Virtualization    - Linus ]

* tag 'x86_sev_for_v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/sev: Cleanup vc_handle_msr()
  x86/sev: Convert shared memory back to private on kexec
  x86/mm: Refactor __set_clr_pte_enc()
  x86/boot: Skip video memory access in the decompressor for SEV-ES/SNP
  virt: sev-guest: Carve out SNP message context structure
  virt: sev-guest: Reduce the scope of SNP command mutex
  virt: sev-guest: Consolidate SNP guest messaging parameters to a struct
  x86/sev: Cache the secrets page address
  x86/sev: Handle failures from snp_init()
  virt: sev-guest: Use AES GCM crypto library
  x86/virt: Provide "nosnp" boot option for sev kernel command line
  x86/virt: Move SEV-specific parsing into arch/x86/virt/svm

8 files changed, 377 insertions, 135 deletions

diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
index 04a35b2c26e9..0d37420cad02 100644
--- a/arch/x86/boot/compressed/misc.c
+++ b/arch/x86/boot/compressed/misc.c
@@ -385,6 +385,19 @@ static void parse_mem_encrypt(struct setup_header *hdr)
 		hdr->xloadflags |= XLF_MEM_ENCRYPTION;
 }
 
+static void early_sev_detect(void)
+{
+	/*
+	 * Accessing video memory causes guest termination because
+	 * the boot stage2 #VC handler of SEV-ES/SNP guests does not
+	 * support MMIO handling and kexec -c adds screen_info to the
+	 * boot parameters passed to the kexec kernel, which causes
+	 * console output to be dumped to both video and serial.
+	 */
+	if (sev_status & MSR_AMD64_SEV_ES_ENABLED)
+		lines = cols = 0;
+}
+
 /*
  * The compressed kernel image (ZO), has been moved so that its position
  * is against the end of the buffer used to hold the uncompressed kernel
@@ -440,6 +453,8 @@ asmlinkage __visible void *extract_kernel(void *rmode, unsigned char *output)
 	 */
 	early_tdx_detect();
 
+	early_sev_detect();
+
 	console_init();
 
 	/*
diff --git a/arch/x86/coco/sev/core.c b/arch/x86/coco/sev/core.c
index de1df0cb45da..c5b0148b8c0a 100644
--- a/arch/x86/coco/sev/core.c
+++ b/arch/x86/coco/sev/core.c
@@ -92,6 +92,9 @@ static struct ghcb *boot_ghcb __section(".data");
 /* Bitmap of SEV features supported by the hypervisor */
 static u64 sev_hv_features __ro_after_init;
 
+/* Secrets page physical address from the CC blob */
+static u64 secrets_pa __ro_after_init;
+
 /* #VC handler runtime per-CPU data */
 struct sev_es_runtime_data {
 	struct ghcb ghcb_page;
@@ -141,33 +144,6 @@ static DEFINE_PER_CPU(struct sev_es_save_area *, sev_vmsa);
 static DEFINE_PER_CPU(struct svsm_ca *, svsm_caa);
 static DEFINE_PER_CPU(u64, svsm_caa_pa);
 
-struct sev_config {
-	__u64 debug		: 1,
-
-	      /*
-	       * Indicates when the per-CPU GHCB has been created and registered
-	       * and thus can be used by the BSP instead of the early boot GHCB.
-	       *
-	       * For APs, the per-CPU GHCB is created before they are started
-	       * and registered upon startup, so this flag can be used globally
-	       * for the BSP and APs.
-	       */
-	      ghcbs_initialized	: 1,
-
-	      /*
-	       * Indicates when the per-CPU SVSM CA is to be used instead of the
-	       * boot SVSM CA.
-	       *
-	       * For APs, the per-CPU SVSM CA is created as part of the AP
-	       * bringup, so this flag can be used globally for the BSP and APs.
-	       */
-	      use_cas		: 1,
-
-	      __reserved	: 61;
-};
-
-static struct sev_config sev_cfg __read_mostly;
-
 static __always_inline bool on_vc_stack(struct pt_regs *regs)
 {
 	unsigned long sp = regs->sp;
@@ -722,45 +698,13 @@ void noinstr __sev_es_nmi_complete(void)
 	__sev_put_ghcb(&state);
 }
 
-static u64 __init get_secrets_page(void)
-{
-	u64 pa_data = boot_params.cc_blob_address;
-	struct cc_blob_sev_info info;
-	void *map;
-
-	/*
-	 * The CC blob contains the address of the secrets page, check if the
-	 * blob is present.
-	 */
-	if (!pa_data)
-		return 0;
-
-	map = early_memremap(pa_data, sizeof(info));
-	if (!map) {
-		pr_err("Unable to locate SNP secrets page: failed to map the Confidential Computing blob.\n");
-		return 0;
-	}
-	memcpy(&info, map, sizeof(info));
-	early_memunmap(map, sizeof(info));
-
-	/* smoke-test the secrets page passed */
-	if (!info.secrets_phys || info.secrets_len != PAGE_SIZE)
-		return 0;
-
-	return info.secrets_phys;
-}
-
 static u64 __init get_snp_jump_table_addr(void)
 {
 	struct snp_secrets_page *secrets;
 	void __iomem *mem;
-	u64 pa, addr;
+	u64 addr;
 
-	pa = get_secrets_page();
-	if (!pa)
-		return 0;
-
-	mem = ioremap_encrypted(pa, PAGE_SIZE);
+	mem = ioremap_encrypted(secrets_pa, PAGE_SIZE);
 	if (!mem) {
 		pr_err("Unable to locate AP jump table address: failed to map the SNP secrets page.\n");
 		return 0;
@@ -1010,6 +954,137 @@ void snp_accept_memory(phys_addr_t start, phys_addr_t end)
 	set_pages_state(vaddr, npages, SNP_PAGE_STATE_PRIVATE);
 }
 
+static void set_pte_enc(pte_t *kpte, int level, void *va)
+{
+	struct pte_enc_desc d = {
+		.kpte	   = kpte,
+		.pte_level = level,
+		.va	   = va,
+		.encrypt   = true
+	};
+
+	prepare_pte_enc(&d);
+	set_pte_enc_mask(kpte, d.pfn, d.new_pgprot);
+}
+
+static void unshare_all_memory(void)
+{
+	unsigned long addr, end, size, ghcb;
+	struct sev_es_runtime_data *data;
+	unsigned int npages, level;
+	bool skipped_addr;
+	pte_t *pte;
+	int cpu;
+
+	/* Unshare the direct mapping. */
+	addr = PAGE_OFFSET;
+	end  = PAGE_OFFSET + get_max_mapped();
+
+	while (addr < end) {
+		pte = lookup_address(addr, &level);
+		size = page_level_size(level);
+		npages = size / PAGE_SIZE;
+		skipped_addr = false;
+
+		if (!pte || !pte_decrypted(*pte) || pte_none(*pte)) {
+			addr += size;
+			continue;
+		}
+
+		/*
+		 * Ensure that all the per-CPU GHCBs are made private at the
+		 * end of the unsharing loop so that the switch to the slower
+		 * MSR protocol happens last.
+		 */
+		for_each_possible_cpu(cpu) {
+			data = per_cpu(runtime_data, cpu);
+			ghcb = (unsigned long)&data->ghcb_page;
+
+			if (addr <= ghcb && ghcb <= addr + size) {
+				skipped_addr = true;
+				break;
+			}
+		}
+
+		if (!skipped_addr) {
+			set_pte_enc(pte, level, (void *)addr);
+			snp_set_memory_private(addr, npages);
+		}
+		addr += size;
+	}
+
+	/* Unshare all bss decrypted memory. */
+	addr = (unsigned long)__start_bss_decrypted;
+	end  = (unsigned long)__start_bss_decrypted_unused;
+	npages = (end - addr) >> PAGE_SHIFT;
+
+	for (; addr < end; addr += PAGE_SIZE) {
+		pte = lookup_address(addr, &level);
+		if (!pte || !pte_decrypted(*pte) || pte_none(*pte))
+			continue;
+
+		set_pte_enc(pte, level, (void *)addr);
+	}
+	addr = (unsigned long)__start_bss_decrypted;
+	snp_set_memory_private(addr, npages);
+
+	__flush_tlb_all();
+}
+
+/* Stop new private<->shared conversions */
+void snp_kexec_begin(void)
+{
+	if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP))
+		return;
+
+	if (!IS_ENABLED(CONFIG_KEXEC_CORE))
+		return;
+
+	/*
+	 * Crash kernel ends up here with interrupts disabled: can't wait for
+	 * conversions to finish.
+	 *
+	 * If race happened, just report and proceed.
+	 */
+	if (!set_memory_enc_stop_conversion())
+		pr_warn("Failed to stop shared<->private conversions\n");
+}
+
+void snp_kexec_finish(void)
+{
+	struct sev_es_runtime_data *data;
+	unsigned int level, cpu;
+	unsigned long size;
+	struct ghcb *ghcb;
+	pte_t *pte;
+
+	if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP))
+		return;
+
+	if (!IS_ENABLED(CONFIG_KEXEC_CORE))
+		return;
+
+	unshare_all_memory();
+
+	/*
+	 * Switch to using the MSR protocol to change per-CPU GHCBs to
+	 * private. All the per-CPU GHCBs have been switched back to private,
+	 * so can't do any more GHCB calls to the hypervisor beyond this point
+	 * until the kexec'ed kernel starts running.
+	 */
+	boot_ghcb = NULL;
+	sev_cfg.ghcbs_initialized = false;
+
+	for_each_possible_cpu(cpu) {
+		data = per_cpu(runtime_data, cpu);
+		ghcb = &data->ghcb_page;
+		pte = lookup_address((unsigned long)ghcb, &level);
+		size = page_level_size(level);
+		set_pte_enc(pte, level, (void *)ghcb);
+		snp_set_memory_private((unsigned long)ghcb, (size / PAGE_SIZE));
+	}
+}
+
 static int snp_set_vmsa(void *va, void *caa, int apic_id, bool make_vmsa)
 {
 	int ret;
@@ -1331,35 +1406,39 @@ int __init sev_es_efi_map_ghcbs(pgd_t *pgd)
 	return 0;
 }
 
+/* Writes to the SVSM CAA MSR are ignored */
+static enum es_result __vc_handle_msr_caa(struct pt_regs *regs, bool write)
+{
+	if (write)
+		return ES_OK;
+
+	regs->ax = lower_32_bits(this_cpu_read(svsm_caa_pa));
+	regs->dx = upper_32_bits(this_cpu_read(svsm_caa_pa));
+
+	return ES_OK;
+}
+
 static enum es_result vc_handle_msr(struct ghcb *ghcb, struct es_em_ctxt *ctxt)
 {
 	struct pt_regs *regs = ctxt->regs;
 	enum es_result ret;
-	u64 exit_info_1;
+	bool write;
 
 	/* Is it a WRMSR? */
-	exit_info_1 = (ctxt->insn.opcode.bytes[1] == 0x30) ? 1 : 0;
+	write = ctxt->insn.opcode.bytes[1] == 0x30;
 
-	if (regs->cx == MSR_SVSM_CAA) {
-		/* Writes to the SVSM CAA msr are ignored */
-		if (exit_info_1)
-			return ES_OK;
-
-		regs->ax = lower_32_bits(this_cpu_read(svsm_caa_pa));
-		regs->dx = upper_32_bits(this_cpu_read(svsm_caa_pa));
-
-		return ES_OK;
-	}
+	if (regs->cx == MSR_SVSM_CAA)
+		return __vc_handle_msr_caa(regs, write);
 
 	ghcb_set_rcx(ghcb, regs->cx);
-	if (exit_info_1) {
+	if (write) {
 		ghcb_set_rax(ghcb, regs->ax);
 		ghcb_set_rdx(ghcb, regs->dx);
 	}
 
-	ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_MSR, exit_info_1, 0);
+	ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_MSR, write, 0);
 
-	if ((ret == ES_OK) && (!exit_info_1)) {
+	if ((ret == ES_OK) && !write) {
 		regs->ax = ghcb->save.rax;
 		regs->dx = ghcb->save.rdx;
 	}
@@ -2300,6 +2379,11 @@ bool __head snp_init(struct boot_params *bp)
 	if (!cc_info)
 		return false;
 
+	if (cc_info->secrets_phys && cc_info->secrets_len == PAGE_SIZE)
+		secrets_pa = cc_info->secrets_phys;
+	else
+		return false;
+
 	setup_cpuid_table(cc_info);
 
 	svsm_setup(cc_info);
@@ -2374,23 +2458,6 @@ static int __init report_snp_info(void)
 }
 arch_initcall(report_snp_info);
 
-static int __init init_sev_config(char *str)
-{
-	char *s;
-
-	while ((s = strsep(&str, ","))) {
-		if (!strcmp(s, "debug")) {
-			sev_cfg.debug = true;
-			continue;
-		}
-
-		pr_info("SEV command-line option '%s' was not recognized\n", s);
-	}
-
-	return 1;
-}
-__setup("sev=", init_sev_config);
-
 static void update_attest_input(struct svsm_call *call, struct svsm_attest_call *input)
 {
 	/* If (new) lengths have been returned, propagate them up */
@@ -2441,7 +2508,8 @@ int snp_issue_svsm_attest_req(u64 call_id, struct svsm_call *call,
 }
 EXPORT_SYMBOL_GPL(snp_issue_svsm_attest_req);
 
-int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, struct snp_guest_request_ioctl *rio)
+int snp_issue_guest_request(struct snp_guest_req *req, struct snp_req_data *input,
+			    struct snp_guest_request_ioctl *rio)
 {
 	struct ghcb_state state;
 	struct es_em_ctxt ctxt;
@@ -2465,12 +2533,12 @@ int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, struct sn
 
 	vc_ghcb_invalidate(ghcb);
 
-	if (exit_code == SVM_VMGEXIT_EXT_GUEST_REQUEST) {
+	if (req->exit_code == SVM_VMGEXIT_EXT_GUEST_REQUEST) {
 		ghcb_set_rax(ghcb, input->data_gpa);
 		ghcb_set_rbx(ghcb, input->data_npages);
 	}
 
-	ret = sev_es_ghcb_hv_call(ghcb, &ctxt, exit_code, input->req_gpa, input->resp_gpa);
+	ret = sev_es_ghcb_hv_call(ghcb, &ctxt, req->exit_code, input->req_gpa, input->resp_gpa);
 	if (ret)
 		goto e_put;
 
@@ -2485,7 +2553,7 @@ int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, struct sn
 
 	case SNP_GUEST_VMM_ERR(SNP_GUEST_VMM_ERR_INVALID_LEN):
 		/* Number of expected pages are returned in RBX */
-		if (exit_code == SVM_VMGEXIT_EXT_GUEST_REQUEST) {
+		if (req->exit_code == SVM_VMGEXIT_EXT_GUEST_REQUEST) {
 			input->data_npages = ghcb_get_rbx(ghcb);
 			ret = -ENOSPC;
 			break;
@@ -2513,16 +2581,11 @@ static struct platform_device sev_guest_device = {
 static int __init snp_init_platform_device(void)
 {
 	struct sev_guest_platform_data data;
-	u64 gpa;
 
 	if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP))
 		return -ENODEV;
 
-	gpa = get_secrets_page();
-	if (!gpa)
-		return -ENODEV;
-
-	data.secrets_gpa = gpa;
+	data.secrets_gpa = secrets_pa;
 	if (platform_device_add_data(&sev_guest_device, &data, sizeof(data)))
 		return -ENODEV;
 
diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-common.h
index 98726c2b04f8..50f5666938c0 100644
--- a/arch/x86/include/asm/sev-common.h
+++ b/arch/x86/include/asm/sev-common.h
@@ -220,4 +220,31 @@ struct snp_psc_desc {
 #define GHCB_ERR_INVALID_INPUT		5
 #define GHCB_ERR_INVALID_EVENT		6
 
+struct sev_config {
+	__u64 debug		: 1,
+
+	      /*
+	       * Indicates when the per-CPU GHCB has been created and registered
+	       * and thus can be used by the BSP instead of the early boot GHCB.
+	       *
+	       * For APs, the per-CPU GHCB is created before they are started
+	       * and registered upon startup, so this flag can be used globally
+	       * for the BSP and APs.
+	       */
+	      ghcbs_initialized	: 1,
+
+	      /*
+	       * Indicates when the per-CPU SVSM CA is to be used instead of the
+	       * boot SVSM CA.
+	       *
+	       * For APs, the per-CPU SVSM CA is created as part of the AP
+	       * bringup, so this flag can be used globally for the BSP and APs.
+	       */
+	      use_cas		: 1,
+
+	      __reserved	: 61;
+};
+
+extern struct sev_config sev_cfg;
+
 #endif
diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h
index ee34ab00a8d6..91f08af31078 100644
--- a/arch/x86/include/asm/sev.h
+++ b/arch/x86/include/asm/sev.h
@@ -120,6 +120,9 @@ struct snp_req_data {
 };
 
 #define MAX_AUTHTAG_LEN		32
+#define AUTHTAG_LEN		16
+#define AAD_LEN			48
+#define MSG_HDR_VER		1
 
 /* See SNP spec SNP_GUEST_REQUEST section for the structure */
 enum msg_type {
@@ -171,6 +174,19 @@ struct sev_guest_platform_data {
 	u64 secrets_gpa;
 };
 
+struct snp_guest_req {
+	void *req_buf;
+	size_t req_sz;
+
+	void *resp_buf;
+	size_t resp_sz;
+
+	u64 exit_code;
+	unsigned int vmpck_id;
+	u8 msg_version;
+	u8 msg_type;
+};
+
 /*
  * The secrets page contains 96-bytes of reserved field that can be used by
  * the guest OS. The guest OS uses the area to save the message sequence
@@ -218,6 +234,27 @@ struct snp_secrets_page {
 	u8 rsvd4[3744];
 } __packed;
 
+struct snp_msg_desc {
+	/* request and response are in unencrypted memory */
+	struct snp_guest_msg *request, *response;
+
+	/*
+	 * Avoid information leakage by double-buffering shared messages
+	 * in fields that are in regular encrypted memory.
+	 */
+	struct snp_guest_msg secret_request, secret_response;
+
+	struct snp_secrets_page *secrets;
+	struct snp_req_data input;
+
+	void *certs_data;
+
+	struct aesgcm_ctx *ctx;
+
+	u32 *os_area_msg_seqno;
+	u8 *vmpck;
+};
+
 /*
  * The SVSM Calling Area (CA) related structures.
  */
@@ -285,6 +322,22 @@ struct svsm_attest_call {
 	u8 rsvd[4];
 };
 
+/* PTE descriptor used for the prepare_pte_enc() operations. */
+struct pte_enc_desc {
+	pte_t *kpte;
+	int pte_level;
+	bool encrypt;
+	/* pfn of the kpte above */
+	unsigned long pfn;
+	/* physical address of @pfn */
+	unsigned long pa;
+	/* virtual address of @pfn */
+	void *va;
+	/* memory covered by the pte */
+	unsigned long size;
+	pgprot_t new_pgprot;
+};
+
 /*
  * SVSM protocol structure
  */
@@ -392,13 +445,18 @@ void snp_set_wakeup_secondary_cpu(void);
 bool snp_init(struct boot_params *bp);
 void __noreturn snp_abort(void);
 void snp_dmi_setup(void);
-int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, struct snp_guest_request_ioctl *rio);
+int snp_issue_guest_request(struct snp_guest_req *req, struct snp_req_data *input,
+			    struct snp_guest_request_ioctl *rio);
 int snp_issue_svsm_attest_req(u64 call_id, struct svsm_call *call, struct svsm_attest_call *input);
 void snp_accept_memory(phys_addr_t start, phys_addr_t end);
 u64 snp_get_unsupported_features(u64 status);
 u64 sev_get_status(void);
 void sev_show_status(void);
 void snp_update_svsm_ca(void);
+int prepare_pte_enc(struct pte_enc_desc *d);
+void set_pte_enc_mask(pte_t *kpte, unsigned long pfn, pgprot_t new_prot);
+void snp_kexec_finish(void);
+void snp_kexec_begin(void);
 
 #else	/* !CONFIG_AMD_MEM_ENCRYPT */
 
@@ -422,7 +480,8 @@ static inline void snp_set_wakeup_secondary_cpu(void) { }
 static inline bool snp_init(struct boot_params *bp) { return false; }
 static inline void snp_abort(void) { }
 static inline void snp_dmi_setup(void) { }
-static inline int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, struct snp_guest_request_ioctl *rio)
+static inline int snp_issue_guest_request(struct snp_guest_req *req, struct snp_req_data *input,
+					  struct snp_guest_request_ioctl *rio)
 {
 	return -ENOTTY;
 }
@@ -435,6 +494,10 @@ static inline u64 snp_get_unsupported_features(u64 status) { return 0; }
 static inline u64 sev_get_status(void) { return 0; }
 static inline void sev_show_status(void) { }
 static inline void snp_update_svsm_ca(void) { }
+static inline int prepare_pte_enc(struct pte_enc_desc *d) { return 0; }
+static inline void set_pte_enc_mask(pte_t *kpte, unsigned long pfn, pgprot_t new_prot) { }
+static inline void snp_kexec_finish(void) { }
+static inline void snp_kexec_begin(void) { }
 
 #endif	/* CONFIG_AMD_MEM_ENCRYPT */
 
diff --git a/arch/x86/mm/mem_encrypt_amd.c b/arch/x86/mm/mem_encrypt_amd.c
index 86a476a426c2..774f9677458f 100644
--- a/arch/x86/mm/mem_encrypt_amd.c
+++ b/arch/x86/mm/mem_encrypt_amd.c
@@ -311,59 +311,82 @@ static int amd_enc_status_change_finish(unsigned long vaddr, int npages, bool en
 	return 0;
 }
 
-static void __init __set_clr_pte_enc(pte_t *kpte, int level, bool enc)
+int prepare_pte_enc(struct pte_enc_desc *d)
 {
-	pgprot_t old_prot, new_prot;
-	unsigned long pfn, pa, size;
-	pte_t new_pte;
+	pgprot_t old_prot;
 
-	pfn = pg_level_to_pfn(level, kpte, &old_prot);
-	if (!pfn)
-		return;
+	d->pfn = pg_level_to_pfn(d->pte_level, d->kpte, &old_prot);
+	if (!d->pfn)
+		return 1;
 
-	new_prot = old_prot;
-	if (enc)
-		pgprot_val(new_prot) |= _PAGE_ENC;
+	d->new_pgprot = old_prot;
+	if (d->encrypt)
+		pgprot_val(d->new_pgprot) |= _PAGE_ENC;
 	else
-		pgprot_val(new_prot) &= ~_PAGE_ENC;
+		pgprot_val(d->new_pgprot) &= ~_PAGE_ENC;
 
 	/* If prot is same then do nothing. */
-	if (pgprot_val(old_prot) == pgprot_val(new_prot))
-		return;
+	if (pgprot_val(old_prot) == pgprot_val(d->new_pgprot))
+		return 1;
 
-	pa = pfn << PAGE_SHIFT;
-	size = page_level_size(level);
+	d->pa = d->pfn << PAGE_SHIFT;
+	d->size = page_level_size(d->pte_level);
 
 	/*
-	 * We are going to perform in-place en-/decryption and change the
-	 * physical page attribute from C=1 to C=0 or vice versa. Flush the
-	 * caches to ensure that data gets accessed with the correct C-bit.
+	 * In-place en-/decryption and physical page attribute change
+	 * from C=1 to C=0 or vice versa will be performed. Flush the
+	 * caches to ensure that data gets accessed with the correct
+	 * C-bit.
 	 */
-	clflush_cache_range(__va(pa), size);
+	if (d->va)
+		clflush_cache_range(d->va, d->size);
+	else
+		clflush_cache_range(__va(d->pa), d->size);
+
+	return 0;
+}
+
+void set_pte_enc_mask(pte_t *kpte, unsigned long pfn, pgprot_t new_prot)
+{
+	pte_t new_pte;
+
+	/* Change the page encryption mask. */
+	new_pte = pfn_pte(pfn, new_prot);
+	set_pte_atomic(kpte, new_pte);
+}
+
+static void __init __set_clr_pte_enc(pte_t *kpte, int level, bool enc)
+{
+	struct pte_enc_desc d = {
+		.kpte	     = kpte,
+		.pte_level   = level,
+		.encrypt     = enc
+	};
+
+	if (prepare_pte_enc(&d))
+		return;
 
 	/* Encrypt/decrypt the contents in-place */
 	if (enc) {
-		sme_early_encrypt(pa, size);
+		sme_early_encrypt(d.pa, d.size);
 	} else {
-		sme_early_decrypt(pa, size);
+		sme_early_decrypt(d.pa, d.size);
 
 		/*
 		 * ON SNP, the page state in the RMP table must happen
 		 * before the page table updates.
 		 */
-		early_snp_set_memory_shared((unsigned long)__va(pa), pa, 1);
+		early_snp_set_memory_shared((unsigned long)__va(d.pa), d.pa, 1);
 	}
 
-	/* Change the page encryption mask. */
-	new_pte = pfn_pte(pfn, new_prot);
-	set_pte_atomic(kpte, new_pte);
+	set_pte_enc_mask(kpte, d.pfn, d.new_pgprot);
 
 	/*
 	 * If page is set encrypted in the page table, then update the RMP table to
 	 * add this page as private.
 	 */
 	if (enc)
-		early_snp_set_memory_private((unsigned long)__va(pa), pa, 1);
+		early_snp_set_memory_private((unsigned long)__va(d.pa), d.pa, 1);
 }
 
 static int __init early_set_memory_enc_dec(unsigned long vaddr,
@@ -467,6 +490,8 @@ void __init sme_early_init(void)
 	x86_platform.guest.enc_status_change_finish  = amd_enc_status_change_finish;
 	x86_platform.guest.enc_tlb_flush_required    = amd_enc_tlb_flush_required;
 	x86_platform.guest.enc_cache_flush_required  = amd_enc_cache_flush_required;
+	x86_platform.guest.enc_kexec_begin	     = snp_kexec_begin;
+	x86_platform.guest.enc_kexec_finish	     = snp_kexec_finish;
 
 	/*
 	 * AMD-SEV-ES intercepts the RDMSR to read the X2APIC ID in the
diff --git a/arch/x86/mm/mem_encrypt_identity.c b/arch/x86/mm/mem_encrypt_identity.c
index ac33b2263a43..e6c7686f443a 100644
--- a/arch/x86/mm/mem_encrypt_identity.c
+++ b/arch/x86/mm/mem_encrypt_identity.c
@@ -495,10 +495,10 @@ void __head sme_enable(struct boot_params *bp)
 	unsigned int eax, ebx, ecx, edx;
 	unsigned long feature_mask;
 	unsigned long me_mask;
-	bool snp;
+	bool snp_en;
 	u64 msr;
 
-	snp = snp_init(bp);
+	snp_en = snp_init(bp);
 
 	/* Check for the SME/SEV support leaf */
 	eax = 0x80000000;
@@ -531,8 +531,11 @@ void __head sme_enable(struct boot_params *bp)
 	RIP_REL_REF(sev_status) = msr = __rdmsr(MSR_AMD64_SEV);
 	feature_mask = (msr & MSR_AMD64_SEV_ENABLED) ? AMD_SEV_BIT : AMD_SME_BIT;
 
-	/* The SEV-SNP CC blob should never be present unless SEV-SNP is enabled. */
-	if (snp && !(msr & MSR_AMD64_SEV_SNP_ENABLED))
+	/*
+	 * Any discrepancies between the presence of a CC blob and SNP
+	 * enablement abort the guest.
+	 */
+	if (snp_en ^ !!(msr & MSR_AMD64_SEV_SNP_ENABLED))
 		snp_abort();
 
 	/* Check if memory encryption is enabled */
diff --git a/arch/x86/virt/svm/Makefile b/arch/x86/virt/svm/Makefile
index ef2a31bdcc70..eca6d71355fa 100644
--- a/arch/x86/virt/svm/Makefile
+++ b/arch/x86/virt/svm/Makefile
@@ -1,3 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0
 
 obj-$(CONFIG_KVM_AMD_SEV) += sev.o
+obj-$(CONFIG_CPU_SUP_AMD) += cmdline.o
diff --git a/arch/x86/virt/svm/cmdline.c b/arch/x86/virt/svm/cmdline.c
new file mode 100644
index 000000000000..affa2759fa20
--- /dev/null
+++ b/arch/x86/virt/svm/cmdline.c
@@ -0,0 +1,45 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * AMD SVM-SEV command line parsing support
+ *
+ * Copyright (C) 2023 - 2024 Advanced Micro Devices, Inc.
+ *
+ * Author: Michael Roth <michael.roth@amd.com>
+ */
+
+#include <linux/string.h>
+#include <linux/printk.h>
+#include <linux/cache.h>
+#include <linux/cpufeature.h>
+
+#include <asm/sev-common.h>
+
+struct sev_config sev_cfg __read_mostly;
+
+static int __init init_sev_config(char *str)
+{
+	char *s;
+
+	while ((s = strsep(&str, ","))) {
+		if (!strcmp(s, "debug")) {
+			sev_cfg.debug = true;
+			continue;
+		}
+
+		if (!strcmp(s, "nosnp")) {
+			if (!cpu_feature_enabled(X86_FEATURE_HYPERVISOR)) {
+				setup_clear_cpu_cap(X86_FEATURE_SEV_SNP);
+				cc_platform_clear(CC_ATTR_HOST_SEV_SNP);
+				continue;
+			} else {
+				goto warn;
+			}
+		}
+
+warn:
+		pr_info("SEV command-line option '%s' was not recognized\n", s);
+	}
+
+	return 1;
+}
+__setup("sev=", init_sev_config);