diff --git a/arch/powerpc/include/asm/exception-64s.h b/arch/powerpc/include/asm/exception-64s.h
index 471b2274fbeb..c40b4380951c 100644
--- a/arch/powerpc/include/asm/exception-64s.h
+++ b/arch/powerpc/include/asm/exception-64s.h
@@ -74,6 +74,27 @@
  */
 #define EX_R3		EX_DAR
 
+#define STF_ENTRY_BARRIER_SLOT						\
+	STF_ENTRY_BARRIER_FIXUP_SECTION;				\
+	nop;								\
+	nop;								\
+	nop
+
+#define STF_EXIT_BARRIER_SLOT						\
+	STF_EXIT_BARRIER_FIXUP_SECTION;					\
+	nop;								\
+	nop;								\
+	nop;								\
+	nop;								\
+	nop;								\
+	nop
+
+/*
+ * r10 must be free to use, r13 must be paca
+ */
+#define INTERRUPT_TO_KERNEL						\
+	STF_ENTRY_BARRIER_SLOT
+
 /*
  * Macros for annotating the expected destination of (h)rfid
  *
@@ -90,16 +111,19 @@
 	rfid
 
 #define RFI_TO_USER							\
+	STF_EXIT_BARRIER_SLOT;						\
 	RFI_FLUSH_SLOT;							\
 	rfid;								\
 	b	rfi_flush_fallback
 
 #define RFI_TO_USER_OR_KERNEL						\
+	STF_EXIT_BARRIER_SLOT;						\
 	RFI_FLUSH_SLOT;							\
 	rfid;								\
 	b	rfi_flush_fallback
 
 #define RFI_TO_GUEST							\
+	STF_EXIT_BARRIER_SLOT;						\
 	RFI_FLUSH_SLOT;							\
 	rfid;								\
 	b	rfi_flush_fallback
@@ -108,21 +132,25 @@
 	hrfid
 
 #define HRFI_TO_USER							\
+	STF_EXIT_BARRIER_SLOT;						\
 	RFI_FLUSH_SLOT;							\
 	hrfid;								\
 	b	hrfi_flush_fallback
 
 #define HRFI_TO_USER_OR_KERNEL						\
+	STF_EXIT_BARRIER_SLOT;						\
 	RFI_FLUSH_SLOT;							\
 	hrfid;								\
 	b	hrfi_flush_fallback
 
 #define HRFI_TO_GUEST							\
+	STF_EXIT_BARRIER_SLOT;						\
 	RFI_FLUSH_SLOT;							\
 	hrfid;								\
 	b	hrfi_flush_fallback
 
 #define HRFI_TO_UNKNOWN							\
+	STF_EXIT_BARRIER_SLOT;						\
 	RFI_FLUSH_SLOT;							\
 	hrfid;								\
 	b	hrfi_flush_fallback
@@ -254,6 +282,7 @@ END_FTR_SECTION_NESTED(ftr,ftr,943)
 #define __EXCEPTION_PROLOG_1_PRE(area)					\
 	OPT_SAVE_REG_TO_PACA(area+EX_PPR, r9, CPU_FTR_HAS_PPR);		\
 	OPT_SAVE_REG_TO_PACA(area+EX_CFAR, r10, CPU_FTR_CFAR);		\
+	INTERRUPT_TO_KERNEL;						\
 	SAVE_CTR(r10, area);						\
 	mfcr	r9;
 
diff --git a/arch/powerpc/include/asm/feature-fixups.h b/arch/powerpc/include/asm/feature-fixups.h
index 1e82eb3caabd..a9b64df34e2a 100644
--- a/arch/powerpc/include/asm/feature-fixups.h
+++ b/arch/powerpc/include/asm/feature-fixups.h
@@ -187,6 +187,22 @@ label##3:					       	\
 	FTR_ENTRY_OFFSET label##1b-label##3b;		\
 	.popsection;
 
+#define STF_ENTRY_BARRIER_FIXUP_SECTION			\
+953:							\
+	.pushsection __stf_entry_barrier_fixup,"a";	\
+	.align 2;					\
+954:							\
+	FTR_ENTRY_OFFSET 953b-954b;			\
+	.popsection;
+
+#define STF_EXIT_BARRIER_FIXUP_SECTION			\
+955:							\
+	.pushsection __stf_exit_barrier_fixup,"a";	\
+	.align 2;					\
+956:							\
+	FTR_ENTRY_OFFSET 955b-956b;			\
+	.popsection;
+
 #define RFI_FLUSH_FIXUP_SECTION				\
 951:							\
 	.pushsection __rfi_flush_fixup,"a";		\
@@ -199,6 +215,9 @@ label##3:					       	\
 #ifndef __ASSEMBLY__
 #include <linux/types.h>
 
+extern long stf_barrier_fallback;
+extern long __start___stf_entry_barrier_fixup, __stop___stf_entry_barrier_fixup;
+extern long __start___stf_exit_barrier_fixup, __stop___stf_exit_barrier_fixup;
 extern long __start___rfi_flush_fixup, __stop___rfi_flush_fixup;
 
 void apply_feature_fixups(void);
diff --git a/arch/powerpc/include/asm/security_features.h b/arch/powerpc/include/asm/security_features.h
index fa4d2e1cf772..44989b22383c 100644
--- a/arch/powerpc/include/asm/security_features.h
+++ b/arch/powerpc/include/asm/security_features.h
@@ -12,6 +12,17 @@
 extern unsigned long powerpc_security_features;
 extern bool rfi_flush;
 
+/* These are bit flags */
+enum stf_barrier_type {
+	STF_BARRIER_NONE	= 0x1,
+	STF_BARRIER_FALLBACK	= 0x2,
+	STF_BARRIER_EIEIO	= 0x4,
+	STF_BARRIER_SYNC_ORI	= 0x8,
+};
+
+void setup_stf_barrier(void);
+void do_stf_barrier_fixups(enum stf_barrier_type types);
+
 static inline void security_ftr_set(unsigned long feature)
 {
 	powerpc_security_features |= feature;
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 1ecfd8ffb098..bf9b94e376fd 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -833,7 +833,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_TM)
 #endif
 
 
-EXC_REAL_MASKABLE(decrementer, 0x900, 0x80, IRQS_DISABLED)
+EXC_REAL_OOL_MASKABLE(decrementer, 0x900, 0x80, IRQS_DISABLED)
 EXC_VIRT_MASKABLE(decrementer, 0x4900, 0x80, 0x900, IRQS_DISABLED)
 TRAMP_KVM(PACA_EXGEN, 0x900)
 EXC_COMMON_ASYNC(decrementer_common, 0x900, timer_interrupt)
@@ -909,6 +909,7 @@ EXC_COMMON(trap_0b_common, 0xb00, unknown_exception)
 	mtctr	r13;							\
 	GET_PACA(r13);							\
 	std	r10,PACA_EXGEN+EX_R10(r13);				\
+	INTERRUPT_TO_KERNEL;						\
 	KVMTEST_PR(0xc00); /* uses r10, branch to do_kvm_0xc00_system_call */ \
 	HMT_MEDIUM;							\
 	mfctr	r9;
@@ -917,7 +918,8 @@ EXC_COMMON(trap_0b_common, 0xb00, unknown_exception)
 #define SYSCALL_KVMTEST							\
 	HMT_MEDIUM;							\
 	mr	r9,r13;							\
-	GET_PACA(r13);
+	GET_PACA(r13);							\
+	INTERRUPT_TO_KERNEL;
 #endif
 	
 #define LOAD_SYSCALL_HANDLER(reg)					\
@@ -1455,6 +1457,19 @@ masked_##_H##interrupt:					\
 	b	.;					\
 	MASKED_DEC_HANDLER(_H)
 
+TRAMP_REAL_BEGIN(stf_barrier_fallback)
+	std	r9,PACA_EXRFI+EX_R9(r13)
+	std	r10,PACA_EXRFI+EX_R10(r13)
+	sync
+	ld	r9,PACA_EXRFI+EX_R9(r13)
+	ld	r10,PACA_EXRFI+EX_R10(r13)
+	ori	31,31,0
+	.rept 14
+	b	1f
+1:
+	.endr
+	blr
+
 TRAMP_REAL_BEGIN(rfi_flush_fallback)
 	SET_SCRATCH0(r13);
 	GET_PACA(r13);
diff --git a/arch/powerpc/kernel/security.c b/arch/powerpc/kernel/security.c
index bab5a27ea805..b98a722da915 100644
--- a/arch/powerpc/kernel/security.c
+++ b/arch/powerpc/kernel/security.c
@@ -8,6 +8,7 @@
 #include <linux/device.h>
 #include <linux/seq_buf.h>
 
+#include <asm/debugfs.h>
 #include <asm/security_features.h>
 
 
@@ -86,3 +87,151 @@ ssize_t cpu_show_spectre_v2(struct device *dev, struct device_attribute *attr, c
 
 	return s.len;
 }
+
+/*
+ * Store-forwarding barrier support.
+ */
+
+static enum stf_barrier_type stf_enabled_flush_types;
+static bool no_stf_barrier;
+bool stf_barrier;
+
+static int __init handle_no_stf_barrier(char *p)
+{
+	pr_info("stf-barrier: disabled on command line.");
+	no_stf_barrier = true;
+	return 0;
+}
+
+early_param("no_stf_barrier", handle_no_stf_barrier);
+
+/* This is the generic flag used by other architectures */
+static int __init handle_ssbd(char *p)
+{
+	if (!p || strncmp(p, "auto", 5) == 0 || strncmp(p, "on", 2) == 0 ) {
+		/* Until firmware tells us, we have the barrier with auto */
+		return 0;
+	} else if (strncmp(p, "off", 3) == 0) {
+		handle_no_stf_barrier(NULL);
+		return 0;
+	} else
+		return 1;
+
+	return 0;
+}
+early_param("spec_store_bypass_disable", handle_ssbd);
+
+/* This is the generic flag used by other architectures */
+static int __init handle_no_ssbd(char *p)
+{
+	handle_no_stf_barrier(NULL);
+	return 0;
+}
+early_param("nospec_store_bypass_disable", handle_no_ssbd);
+
+static void stf_barrier_enable(bool enable)
+{
+	if (enable)
+		do_stf_barrier_fixups(stf_enabled_flush_types);
+	else
+		do_stf_barrier_fixups(STF_BARRIER_NONE);
+
+	stf_barrier = enable;
+}
+
+void setup_stf_barrier(void)
+{
+	enum stf_barrier_type type;
+	bool enable, hv;
+
+	hv = cpu_has_feature(CPU_FTR_HVMODE);
+
+	/* Default to fallback in case fw-features are not available */
+	if (cpu_has_feature(CPU_FTR_ARCH_300))
+		type = STF_BARRIER_EIEIO;
+	else if (cpu_has_feature(CPU_FTR_ARCH_207S))
+		type = STF_BARRIER_SYNC_ORI;
+	else if (cpu_has_feature(CPU_FTR_ARCH_206))
+		type = STF_BARRIER_FALLBACK;
+	else
+		type = STF_BARRIER_NONE;
+
+	enable = security_ftr_enabled(SEC_FTR_FAVOUR_SECURITY) &&
+		(security_ftr_enabled(SEC_FTR_L1D_FLUSH_PR) ||
+		 (security_ftr_enabled(SEC_FTR_L1D_FLUSH_HV) && hv));
+
+	if (type == STF_BARRIER_FALLBACK) {
+		pr_info("stf-barrier: fallback barrier available\n");
+	} else if (type == STF_BARRIER_SYNC_ORI) {
+		pr_info("stf-barrier: hwsync barrier available\n");
+	} else if (type == STF_BARRIER_EIEIO) {
+		pr_info("stf-barrier: eieio barrier available\n");
+	}
+
+	stf_enabled_flush_types = type;
+
+	if (!no_stf_barrier)
+		stf_barrier_enable(enable);
+}
+
+ssize_t cpu_show_spec_store_bypass(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	if (stf_barrier && stf_enabled_flush_types != STF_BARRIER_NONE) {
+		const char *type;
+		switch (stf_enabled_flush_types) {
+		case STF_BARRIER_EIEIO:
+			type = "eieio";
+			break;
+		case STF_BARRIER_SYNC_ORI:
+			type = "hwsync";
+			break;
+		case STF_BARRIER_FALLBACK:
+			type = "fallback";
+			break;
+		default:
+			type = "unknown";
+		}
+		return sprintf(buf, "Mitigation: Kernel entry/exit barrier (%s)\n", type);
+	}
+
+	if (!security_ftr_enabled(SEC_FTR_L1D_FLUSH_HV) &&
+	    !security_ftr_enabled(SEC_FTR_L1D_FLUSH_PR))
+		return sprintf(buf, "Not affected\n");
+
+	return sprintf(buf, "Vulnerable\n");
+}
+
+#ifdef CONFIG_DEBUG_FS
+static int stf_barrier_set(void *data, u64 val)
+{
+	bool enable;
+
+	if (val == 1)
+		enable = true;
+	else if (val == 0)
+		enable = false;
+	else
+		return -EINVAL;
+
+	/* Only do anything if we're changing state */
+	if (enable != stf_barrier)
+		stf_barrier_enable(enable);
+
+	return 0;
+}
+
+static int stf_barrier_get(void *data, u64 *val)
+{
+	*val = stf_barrier ? 1 : 0;
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(fops_stf_barrier, stf_barrier_get, stf_barrier_set, "%llu\n");
+
+static __init int stf_barrier_debugfs_init(void)
+{
+	debugfs_create_file("stf_barrier", 0600, powerpc_debugfs_root, NULL, &fops_stf_barrier);
+	return 0;
+}
+device_initcall(stf_barrier_debugfs_init);
+#endif /* CONFIG_DEBUG_FS */
diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S
index c8af90ff49f0..b8d82678f8b4 100644
--- a/arch/powerpc/kernel/vmlinux.lds.S
+++ b/arch/powerpc/kernel/vmlinux.lds.S
@@ -133,6 +133,20 @@ SECTIONS
 	RO_DATA(PAGE_SIZE)
 
 #ifdef CONFIG_PPC64
+	. = ALIGN(8);
+	__stf_entry_barrier_fixup : AT(ADDR(__stf_entry_barrier_fixup) - LOAD_OFFSET) {
+		__start___stf_entry_barrier_fixup = .;
+		*(__stf_entry_barrier_fixup)
+		__stop___stf_entry_barrier_fixup = .;
+	}
+
+	. = ALIGN(8);
+	__stf_exit_barrier_fixup : AT(ADDR(__stf_exit_barrier_fixup) - LOAD_OFFSET) {
+		__start___stf_exit_barrier_fixup = .;
+		*(__stf_exit_barrier_fixup)
+		__stop___stf_exit_barrier_fixup = .;
+	}
+
 	. = ALIGN(8);
 	__rfi_flush_fixup : AT(ADDR(__rfi_flush_fixup) - LOAD_OFFSET) {
 		__start___rfi_flush_fixup = .;
diff --git a/arch/powerpc/lib/feature-fixups.c b/arch/powerpc/lib/feature-fixups.c
index f61ff5a6bddb..6b3c2d405a6d 100644
--- a/arch/powerpc/lib/feature-fixups.c
+++ b/arch/powerpc/lib/feature-fixups.c
@@ -23,6 +23,7 @@
 #include <asm/page.h>
 #include <asm/sections.h>
 #include <asm/setup.h>
+#include <asm/security_features.h>
 #include <asm/firmware.h>
 
 struct fixup_entry {
@@ -117,6 +118,120 @@ void do_feature_fixups(unsigned long value, void *fixup_start, void *fixup_end)
 }
 
 #ifdef CONFIG_PPC_BOOK3S_64
+void do_stf_entry_barrier_fixups(enum stf_barrier_type types)
+{
+	unsigned int instrs[3], *dest;
+	long *start, *end;
+	int i;
+
+	start = PTRRELOC(&__start___stf_entry_barrier_fixup),
+	end = PTRRELOC(&__stop___stf_entry_barrier_fixup);
+
+	instrs[0] = 0x60000000; /* nop */
+	instrs[1] = 0x60000000; /* nop */
+	instrs[2] = 0x60000000; /* nop */
+
+	i = 0;
+	if (types & STF_BARRIER_FALLBACK) {
+		instrs[i++] = 0x7d4802a6; /* mflr r10		*/
+		instrs[i++] = 0x60000000; /* branch patched below */
+		instrs[i++] = 0x7d4803a6; /* mtlr r10		*/
+	} else if (types & STF_BARRIER_EIEIO) {
+		instrs[i++] = 0x7e0006ac; /* eieio + bit 6 hint */
+	} else if (types & STF_BARRIER_SYNC_ORI) {
+		instrs[i++] = 0x7c0004ac; /* hwsync		*/
+		instrs[i++] = 0xe94d0000; /* ld r10,0(r13)	*/
+		instrs[i++] = 0x63ff0000; /* ori 31,31,0 speculation barrier */
+	}
+
+	for (i = 0; start < end; start++, i++) {
+		dest = (void *)start + *start;
+
+		pr_devel("patching dest %lx\n", (unsigned long)dest);
+
+		patch_instruction(dest, instrs[0]);
+
+		if (types & STF_BARRIER_FALLBACK)
+			patch_branch(dest + 1, (unsigned long)&stf_barrier_fallback,
+				     BRANCH_SET_LINK);
+		else
+			patch_instruction(dest + 1, instrs[1]);
+
+		patch_instruction(dest + 2, instrs[2]);
+	}
+
+	printk(KERN_DEBUG "stf-barrier: patched %d entry locations (%s barrier)\n", i,
+		(types == STF_BARRIER_NONE)                  ? "no" :
+		(types == STF_BARRIER_FALLBACK)              ? "fallback" :
+		(types == STF_BARRIER_EIEIO)                 ? "eieio" :
+		(types == (STF_BARRIER_SYNC_ORI))            ? "hwsync"
+		                                           : "unknown");
+}
+
+void do_stf_exit_barrier_fixups(enum stf_barrier_type types)
+{
+	unsigned int instrs[6], *dest;
+	long *start, *end;
+	int i;
+
+	start = PTRRELOC(&__start___stf_exit_barrier_fixup),
+	end = PTRRELOC(&__stop___stf_exit_barrier_fixup);
+
+	instrs[0] = 0x60000000; /* nop */
+	instrs[1] = 0x60000000; /* nop */
+	instrs[2] = 0x60000000; /* nop */
+	instrs[3] = 0x60000000; /* nop */
+	instrs[4] = 0x60000000; /* nop */
+	instrs[5] = 0x60000000; /* nop */
+
+	i = 0;
+	if (types & STF_BARRIER_FALLBACK || types & STF_BARRIER_SYNC_ORI) {
+		if (cpu_has_feature(CPU_FTR_HVMODE)) {
+			instrs[i++] = 0x7db14ba6; /* mtspr 0x131, r13 (HSPRG1) */
+			instrs[i++] = 0x7db04aa6; /* mfspr r13, 0x130 (HSPRG0) */
+		} else {
+			instrs[i++] = 0x7db243a6; /* mtsprg 2,r13	*/
+			instrs[i++] = 0x7db142a6; /* mfsprg r13,1    */
+	        }
+		instrs[i++] = 0x7c0004ac; /* hwsync		*/
+		instrs[i++] = 0xe9ad0000; /* ld r13,0(r13)	*/
+		instrs[i++] = 0x63ff0000; /* ori 31,31,0 speculation barrier */
+		if (cpu_has_feature(CPU_FTR_HVMODE)) {
+			instrs[i++] = 0x7db14aa6; /* mfspr r13, 0x131 (HSPRG1) */
+		} else {
+			instrs[i++] = 0x7db242a6; /* mfsprg r13,2 */
+		}
+	} else if (types & STF_BARRIER_EIEIO) {
+		instrs[i++] = 0x7e0006ac; /* eieio + bit 6 hint */
+	}
+
+	for (i = 0; start < end; start++, i++) {
+		dest = (void *)start + *start;
+
+		pr_devel("patching dest %lx\n", (unsigned long)dest);
+
+		patch_instruction(dest, instrs[0]);
+		patch_instruction(dest + 1, instrs[1]);
+		patch_instruction(dest + 2, instrs[2]);
+		patch_instruction(dest + 3, instrs[3]);
+		patch_instruction(dest + 4, instrs[4]);
+		patch_instruction(dest + 5, instrs[5]);
+	}
+	printk(KERN_DEBUG "stf-barrier: patched %d exit locations (%s barrier)\n", i,
+		(types == STF_BARRIER_NONE)                  ? "no" :
+		(types == STF_BARRIER_FALLBACK)              ? "fallback" :
+		(types == STF_BARRIER_EIEIO)                 ? "eieio" :
+		(types == (STF_BARRIER_SYNC_ORI))            ? "hwsync"
+		                                           : "unknown");
+}
+
+
+void do_stf_barrier_fixups(enum stf_barrier_type types)
+{
+	do_stf_entry_barrier_fixups(types);
+	do_stf_exit_barrier_fixups(types);
+}
+
 void do_rfi_flush_fixups(enum l1d_flush_type types)
 {
 	unsigned int instrs[3], *dest;
diff --git a/arch/powerpc/platforms/powernv/setup.c b/arch/powerpc/platforms/powernv/setup.c
index 7de050a3736b..fc0412d59149 100644
--- a/arch/powerpc/platforms/powernv/setup.c
+++ b/arch/powerpc/platforms/powernv/setup.c
@@ -131,6 +131,7 @@ static void __init pnv_setup_arch(void)
 	set_arch_panic_timeout(10, ARCH_PANIC_TIMEOUT);
 
 	pnv_setup_rfi_flush();
+	setup_stf_barrier();
 
 	/* Initialize SMP */
 	pnv_smp_init();
diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c
index 6b2152839c48..21fed38bbbd5 100644
--- a/arch/powerpc/platforms/pseries/setup.c
+++ b/arch/powerpc/platforms/pseries/setup.c
@@ -699,6 +699,7 @@ static void __init pSeries_setup_arch(void)
 	fwnmi_init();
 
 	pseries_setup_rfi_flush();
+	setup_stf_barrier();
 
 	/* By default, only probe PCI (can be overridden by rtas_pci) */
 	pci_add_flags(PCI_PROBE_ONLY);
