diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 736457a5898a71..45eafb3306e979 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -820,6 +820,8 @@ config RISCV_EFFICIENT_UNALIGNED_ACCESS
 
 endchoice
 
+source "arch/riscv/Kconfig.vendor"
+
 endmenu # "Platform type"
 
 menu "Kernel features"
diff --git a/arch/riscv/Kconfig.vendor b/arch/riscv/Kconfig.vendor
new file mode 100644
index 00000000000000..6f1cdd32ed29a0
--- /dev/null
+++ b/arch/riscv/Kconfig.vendor
@@ -0,0 +1,19 @@
+menu "Vendor extensions"
+
+config RISCV_ISA_VENDOR_EXT
+	bool
+
+menu "Andes"
+config RISCV_ISA_VENDOR_EXT_ANDES
+	bool "Andes vendor extension support"
+	select RISCV_ISA_VENDOR_EXT
+	default y
+	help
+	  Say N here if you want to disable all Andes vendor extension
+	  support. This will cause any Andes vendor extensions that are
+	  requested by hardware probing to be ignored.
+
+	  If you don't know what to do here, say Y.
+endmenu
+
+endmenu
diff --git a/arch/riscv/errata/andes/errata.c b/arch/riscv/errata/andes/errata.c
index f2708a9494a10f..fc1a34faa5f3bc 100644
--- a/arch/riscv/errata/andes/errata.c
+++ b/arch/riscv/errata/andes/errata.c
@@ -17,6 +17,7 @@
 #include <asm/processor.h>
 #include <asm/sbi.h>
 #include <asm/vendorid_list.h>
+#include <asm/vendor_extensions.h>
 
 #define ANDES_AX45MP_MARCHID		0x8000000000008a45UL
 #define ANDES_AX45MP_MIMPID		0x500UL
@@ -65,6 +66,8 @@ void __init_or_module andes_errata_patch_func(struct alt_entry *begin, struct al
 					      unsigned long archid, unsigned long impid,
 					      unsigned int stage)
 {
+	BUILD_BUG_ON(ERRATA_ANDES_NUMBER >= RISCV_VENDOR_EXT_ALTERNATIVES_BASE);
+
 	if (stage == RISCV_ALTERNATIVES_BOOT)
 		errata_probe_iocp(stage, archid, impid);
 
diff --git a/arch/riscv/errata/sifive/errata.c b/arch/riscv/errata/sifive/errata.c
index 716cfedad3a2a4..cea3b96ade11a6 100644
--- a/arch/riscv/errata/sifive/errata.c
+++ b/arch/riscv/errata/sifive/errata.c
@@ -12,6 +12,7 @@
 #include <asm/alternative.h>
 #include <asm/vendorid_list.h>
 #include <asm/errata_list.h>
+#include <asm/vendor_extensions.h>
 
 struct errata_info_t {
 	char name[32];
@@ -96,6 +97,8 @@ void sifive_errata_patch_func(struct alt_entry *begin, struct alt_entry *end,
 	u32 cpu_apply_errata = 0;
 	u32 tmp;
 
+	BUILD_BUG_ON(ERRATA_SIFIVE_NUMBER >= RISCV_VENDOR_EXT_ALTERNATIVES_BASE);
+
 	if (stage == RISCV_ALTERNATIVES_EARLY_BOOT)
 		return;
 
diff --git a/arch/riscv/errata/thead/errata.c b/arch/riscv/errata/thead/errata.c
index bf6a0a6318ee30..f5120e07c31826 100644
--- a/arch/riscv/errata/thead/errata.c
+++ b/arch/riscv/errata/thead/errata.c
@@ -18,6 +18,7 @@
 #include <asm/io.h>
 #include <asm/patch.h>
 #include <asm/vendorid_list.h>
+#include <asm/vendor_extensions.h>
 
 #define CSR_TH_SXSTATUS		0x5c0
 #define SXSTATUS_MAEE		_AC(0x200000, UL)
@@ -166,6 +167,8 @@ void thead_errata_patch_func(struct alt_entry *begin, struct alt_entry *end,
 	u32 tmp;
 	void *oldptr, *altptr;
 
+	BUILD_BUG_ON(ERRATA_THEAD_NUMBER >= RISCV_VENDOR_EXT_ALTERNATIVES_BASE);
+
 	for (alt = begin; alt < end; alt++) {
 		if (alt->vendor_id != THEAD_VENDOR_ID)
 			continue;
diff --git a/arch/riscv/include/asm/cpufeature.h b/arch/riscv/include/asm/cpufeature.h
index 000796c2d0b123..45f9c1171a486a 100644
--- a/arch/riscv/include/asm/cpufeature.h
+++ b/arch/riscv/include/asm/cpufeature.h
@@ -33,6 +33,31 @@ extern struct riscv_isainfo hart_isa[NR_CPUS];
 
 void riscv_user_isa_enable(void);
 
+#define _RISCV_ISA_EXT_DATA(_name, _id, _subset_exts, _subset_exts_size, _validate) {	\
+	.name = #_name,									\
+	.property = #_name,								\
+	.id = _id,									\
+	.subset_ext_ids = _subset_exts,							\
+	.subset_ext_size = _subset_exts_size,						\
+	.validate = _validate								\
+}
+
+#define __RISCV_ISA_EXT_DATA(_name, _id) _RISCV_ISA_EXT_DATA(_name, _id, NULL, 0, NULL)
+
+#define __RISCV_ISA_EXT_DATA_VALIDATE(_name, _id, _validate) \
+			_RISCV_ISA_EXT_DATA(_name, _id, NULL, 0, _validate)
+
+/* Used to declare pure "lasso" extension (Zk for instance) */
+#define __RISCV_ISA_EXT_BUNDLE(_name, _bundled_exts) \
+	_RISCV_ISA_EXT_DATA(_name, RISCV_ISA_EXT_INVALID, _bundled_exts, \
+			    ARRAY_SIZE(_bundled_exts), NULL)
+
+/* Used to declare extensions that are a superset of other extensions (Zvbb for instance) */
+#define __RISCV_ISA_EXT_SUPERSET(_name, _id, _sub_exts) \
+	_RISCV_ISA_EXT_DATA(_name, _id, _sub_exts, ARRAY_SIZE(_sub_exts), NULL)
+#define __RISCV_ISA_EXT_SUPERSET_VALIDATE(_name, _id, _sub_exts, _validate) \
+	_RISCV_ISA_EXT_DATA(_name, _id, _sub_exts, ARRAY_SIZE(_sub_exts), _validate)
+
 #if defined(CONFIG_RISCV_MISALIGNED)
 bool check_unaligned_access_emulated_all_cpus(void);
 void unaligned_emulation_finish(void);
@@ -79,59 +104,66 @@ extern bool riscv_isa_fallback;
 
 unsigned long riscv_isa_extension_base(const unsigned long *isa_bitmap);
 
+#define STANDARD_EXT		0
+
 bool __riscv_isa_extension_available(const unsigned long *isa_bitmap, unsigned int bit);
 #define riscv_isa_extension_available(isa_bitmap, ext)	\
 	__riscv_isa_extension_available(isa_bitmap, RISCV_ISA_EXT_##ext)
 
-static __always_inline bool
-riscv_has_extension_likely(const unsigned long ext)
+static __always_inline bool __riscv_has_extension_likely(const unsigned long vendor,
+							 const unsigned long ext)
 {
-	compiletime_assert(ext < RISCV_ISA_EXT_MAX,
-			   "ext must be < RISCV_ISA_EXT_MAX");
-
-	if (IS_ENABLED(CONFIG_RISCV_ALTERNATIVE)) {
-		asm goto(
-		ALTERNATIVE("j	%l[l_no]", "nop", 0, %[ext], 1)
-		:
-		: [ext] "i" (ext)
-		:
-		: l_no);
-	} else {
-		if (!__riscv_isa_extension_available(NULL, ext))
-			goto l_no;
-	}
+	asm goto(ALTERNATIVE("j	%l[l_no]", "nop", %[vendor], %[ext], 1)
+	:
+	: [vendor] "i" (vendor), [ext] "i" (ext)
+	:
+	: l_no);
 
 	return true;
 l_no:
 	return false;
 }
 
-static __always_inline bool
-riscv_has_extension_unlikely(const unsigned long ext)
+static __always_inline bool __riscv_has_extension_unlikely(const unsigned long vendor,
+							   const unsigned long ext)
 {
-	compiletime_assert(ext < RISCV_ISA_EXT_MAX,
-			   "ext must be < RISCV_ISA_EXT_MAX");
-
-	if (IS_ENABLED(CONFIG_RISCV_ALTERNATIVE)) {
-		asm goto(
-		ALTERNATIVE("nop", "j	%l[l_yes]", 0, %[ext], 1)
-		:
-		: [ext] "i" (ext)
-		:
-		: l_yes);
-	} else {
-		if (__riscv_isa_extension_available(NULL, ext))
-			goto l_yes;
-	}
+	asm goto(ALTERNATIVE("nop", "j	%l[l_yes]", %[vendor], %[ext], 1)
+	:
+	: [vendor] "i" (vendor), [ext] "i" (ext)
+	:
+	: l_yes);
 
 	return false;
 l_yes:
 	return true;
 }
 
+static __always_inline bool riscv_has_extension_unlikely(const unsigned long ext)
+{
+	compiletime_assert(ext < RISCV_ISA_EXT_MAX, "ext must be < RISCV_ISA_EXT_MAX");
+
+	if (IS_ENABLED(CONFIG_RISCV_ALTERNATIVE))
+		return __riscv_has_extension_unlikely(STANDARD_EXT, ext);
+
+	return __riscv_isa_extension_available(NULL, ext);
+}
+
+static __always_inline bool riscv_has_extension_likely(const unsigned long ext)
+{
+	compiletime_assert(ext < RISCV_ISA_EXT_MAX, "ext must be < RISCV_ISA_EXT_MAX");
+
+	if (IS_ENABLED(CONFIG_RISCV_ALTERNATIVE))
+		return __riscv_has_extension_likely(STANDARD_EXT, ext);
+
+	return __riscv_isa_extension_available(NULL, ext);
+}
+
 static __always_inline bool riscv_cpu_has_extension_likely(int cpu, const unsigned long ext)
 {
-	if (IS_ENABLED(CONFIG_RISCV_ALTERNATIVE) && riscv_has_extension_likely(ext))
+	compiletime_assert(ext < RISCV_ISA_EXT_MAX, "ext must be < RISCV_ISA_EXT_MAX");
+
+	if (IS_ENABLED(CONFIG_RISCV_ALTERNATIVE) &&
+	    __riscv_has_extension_likely(STANDARD_EXT, ext))
 		return true;
 
 	return __riscv_isa_extension_available(hart_isa[cpu].isa, ext);
@@ -139,7 +171,10 @@ static __always_inline bool riscv_cpu_has_extension_likely(int cpu, const unsign
 
 static __always_inline bool riscv_cpu_has_extension_unlikely(int cpu, const unsigned long ext)
 {
-	if (IS_ENABLED(CONFIG_RISCV_ALTERNATIVE) && riscv_has_extension_unlikely(ext))
+	compiletime_assert(ext < RISCV_ISA_EXT_MAX, "ext must be < RISCV_ISA_EXT_MAX");
+
+	if (IS_ENABLED(CONFIG_RISCV_ALTERNATIVE) &&
+	    __riscv_has_extension_unlikely(STANDARD_EXT, ext))
 		return true;
 
 	return __riscv_isa_extension_available(hart_isa[cpu].isa, ext);
diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
index b18b202ca141a0..5a0bd27fd11a6d 100644
--- a/arch/riscv/include/asm/hwcap.h
+++ b/arch/riscv/include/asm/hwcap.h
@@ -80,19 +80,18 @@
 #define RISCV_ISA_EXT_ZFA		71
 #define RISCV_ISA_EXT_ZTSO		72
 #define RISCV_ISA_EXT_ZACAS		73
-#define RISCV_ISA_EXT_XANDESPMU		74
-#define RISCV_ISA_EXT_ZVE32X		75
-#define RISCV_ISA_EXT_ZVE32F		76
-#define RISCV_ISA_EXT_ZVE64X		77
-#define RISCV_ISA_EXT_ZVE64F		78
-#define RISCV_ISA_EXT_ZVE64D		79
-#define RISCV_ISA_EXT_ZIMOP		80
-#define RISCV_ISA_EXT_ZCA		81
-#define RISCV_ISA_EXT_ZCB		82
-#define RISCV_ISA_EXT_ZCD		83
-#define RISCV_ISA_EXT_ZCF		84
-#define RISCV_ISA_EXT_ZCMOP		85
-#define RISCV_ISA_EXT_ZAWRS		86
+#define RISCV_ISA_EXT_ZVE32X		74
+#define RISCV_ISA_EXT_ZVE32F		75
+#define RISCV_ISA_EXT_ZVE64X		76
+#define RISCV_ISA_EXT_ZVE64F		77
+#define RISCV_ISA_EXT_ZVE64D		78
+#define RISCV_ISA_EXT_ZIMOP		79
+#define RISCV_ISA_EXT_ZCA		80
+#define RISCV_ISA_EXT_ZCB		81
+#define RISCV_ISA_EXT_ZCD		82
+#define RISCV_ISA_EXT_ZCF		83
+#define RISCV_ISA_EXT_ZCMOP		84
+#define RISCV_ISA_EXT_ZAWRS		85
 
 #define RISCV_ISA_EXT_XLINUXENVCFG	127
 
diff --git a/arch/riscv/include/asm/vendor_extensions.h b/arch/riscv/include/asm/vendor_extensions.h
new file mode 100644
index 00000000000000..7437304a71b911
--- /dev/null
+++ b/arch/riscv/include/asm/vendor_extensions.h
@@ -0,0 +1,104 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright 2024 Rivos, Inc
+ */
+
+#ifndef _ASM_VENDOR_EXTENSIONS_H
+#define _ASM_VENDOR_EXTENSIONS_H
+
+#include <asm/cpufeature.h>
+
+#include <linux/array_size.h>
+#include <linux/types.h>
+
+/*
+ * The extension keys of each vendor must be strictly less than this value.
+ */
+#define RISCV_ISA_VENDOR_EXT_MAX 32
+
+struct riscv_isavendorinfo {
+	DECLARE_BITMAP(isa, RISCV_ISA_VENDOR_EXT_MAX);
+};
+
+struct riscv_isa_vendor_ext_data_list {
+	bool is_initialized;
+	const size_t ext_data_count;
+	const struct riscv_isa_ext_data *ext_data;
+	struct riscv_isavendorinfo per_hart_isa_bitmap[NR_CPUS];
+	struct riscv_isavendorinfo all_harts_isa_bitmap;
+};
+
+extern struct riscv_isa_vendor_ext_data_list *riscv_isa_vendor_ext_list[];
+
+extern const size_t riscv_isa_vendor_ext_list_size;
+
+/*
+ * The alternatives need some way of distinguishing between vendor extensions
+ * and errata. Incrementing all of the vendor extension keys so they are at
+ * least 0x8000 accomplishes that.
+ */
+#define RISCV_VENDOR_EXT_ALTERNATIVES_BASE	0x8000
+
+#define VENDOR_EXT_ALL_CPUS			-1
+
+bool __riscv_isa_vendor_extension_available(int cpu, unsigned long vendor, unsigned int bit);
+#define riscv_cpu_isa_vendor_extension_available(cpu, vendor, ext)	\
+	__riscv_isa_vendor_extension_available(cpu, vendor, RISCV_ISA_VENDOR_EXT_##ext)
+#define riscv_isa_vendor_extension_available(vendor, ext)	\
+	__riscv_isa_vendor_extension_available(VENDOR_EXT_ALL_CPUS, vendor, \
+					       RISCV_ISA_VENDOR_EXT_##ext)
+
+static __always_inline bool riscv_has_vendor_extension_likely(const unsigned long vendor,
+							      const unsigned long ext)
+{
+	if (!IS_ENABLED(CONFIG_RISCV_ISA_VENDOR_EXT))
+		return false;
+
+	if (IS_ENABLED(CONFIG_RISCV_ALTERNATIVE))
+		return __riscv_has_extension_likely(vendor,
+						    ext + RISCV_VENDOR_EXT_ALTERNATIVES_BASE);
+
+	return __riscv_isa_vendor_extension_available(VENDOR_EXT_ALL_CPUS, vendor, ext);
+}
+
+static __always_inline bool riscv_has_vendor_extension_unlikely(const unsigned long vendor,
+								const unsigned long ext)
+{
+	if (!IS_ENABLED(CONFIG_RISCV_ISA_VENDOR_EXT))
+		return false;
+
+	if (IS_ENABLED(CONFIG_RISCV_ALTERNATIVE))
+		return __riscv_has_extension_unlikely(vendor,
+						      ext + RISCV_VENDOR_EXT_ALTERNATIVES_BASE);
+
+	return __riscv_isa_vendor_extension_available(VENDOR_EXT_ALL_CPUS, vendor, ext);
+}
+
+static __always_inline bool riscv_cpu_has_vendor_extension_likely(const unsigned long vendor,
+								  int cpu, const unsigned long ext)
+{
+	if (!IS_ENABLED(CONFIG_RISCV_ISA_VENDOR_EXT))
+		return false;
+
+	if (IS_ENABLED(CONFIG_RISCV_ALTERNATIVE) &&
+	    __riscv_has_extension_likely(vendor, ext + RISCV_VENDOR_EXT_ALTERNATIVES_BASE))
+		return true;
+
+	return __riscv_isa_vendor_extension_available(cpu, vendor, ext);
+}
+
+static __always_inline bool riscv_cpu_has_vendor_extension_unlikely(const unsigned long vendor,
+								    int cpu,
+								    const unsigned long ext)
+{
+	if (!IS_ENABLED(CONFIG_RISCV_ISA_VENDOR_EXT))
+		return false;
+
+	if (IS_ENABLED(CONFIG_RISCV_ALTERNATIVE) &&
+	    __riscv_has_extension_unlikely(vendor, ext + RISCV_VENDOR_EXT_ALTERNATIVES_BASE))
+		return true;
+
+	return __riscv_isa_vendor_extension_available(cpu, vendor, ext);
+}
+
+#endif /* _ASM_VENDOR_EXTENSIONS_H */
diff --git a/arch/riscv/include/asm/vendor_extensions/andes.h b/arch/riscv/include/asm/vendor_extensions/andes.h
new file mode 100644
index 00000000000000..7bb2fc43438f7a
--- /dev/null
+++ b/arch/riscv/include/asm/vendor_extensions/andes.h
@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_RISCV_VENDOR_EXTENSIONS_ANDES_H
+#define _ASM_RISCV_VENDOR_EXTENSIONS_ANDES_H
+
+#include <asm/vendor_extensions.h>
+
+#include <linux/types.h>
+
+#define RISCV_ISA_VENDOR_EXT_XANDESPMU		0
+
+/*
+ * Extension keys should be strictly less than max.
+ * It is safe to increment this when necessary.
+ */
+#define RISCV_ISA_VENDOR_EXT_MAX_ANDES			32
+
+extern struct riscv_isa_vendor_ext_data_list riscv_isa_vendor_ext_list_andes;
+
+#endif
diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
index 1e2afec141b5eb..06d407f1b30bc2 100644
--- a/arch/riscv/kernel/Makefile
+++ b/arch/riscv/kernel/Makefile
@@ -58,6 +58,8 @@ obj-y	+= riscv_ksyms.o
 obj-y	+= stacktrace.o
 obj-y	+= cacheinfo.o
 obj-y	+= patch.o
+obj-y	+= vendor_extensions.o
+obj-y	+= vendor_extensions/
 obj-y	+= probes/
 obj-y	+= tests/
 obj-$(CONFIG_MMU) += vdso.o vdso/
diff --git a/arch/riscv/kernel/cpu.c b/arch/riscv/kernel/cpu.c
index c1f3655238fd2b..f6b13e9f5e6cb6 100644
--- a/arch/riscv/kernel/cpu.c
+++ b/arch/riscv/kernel/cpu.c
@@ -16,6 +16,7 @@
 #include <asm/sbi.h>
 #include <asm/smp.h>
 #include <asm/pgtable.h>
+#include <asm/vendor_extensions.h>
 
 bool arch_match_cpu_phys_id(int cpu, u64 phys_id)
 {
@@ -235,7 +236,33 @@ arch_initcall(riscv_cpuinfo_init);
 
 #ifdef CONFIG_PROC_FS
 
-static void print_isa(struct seq_file *f, const unsigned long *isa_bitmap)
+#define ALL_CPUS -1
+
+static void print_vendor_isa(struct seq_file *f, int cpu)
+{
+	struct riscv_isavendorinfo *vendor_bitmap;
+	struct riscv_isa_vendor_ext_data_list *ext_list;
+	const struct riscv_isa_ext_data *ext_data;
+
+	for (int i = 0; i < riscv_isa_vendor_ext_list_size; i++) {
+		ext_list = riscv_isa_vendor_ext_list[i];
+		ext_data = riscv_isa_vendor_ext_list[i]->ext_data;
+
+		if (cpu == ALL_CPUS)
+			vendor_bitmap = &ext_list->all_harts_isa_bitmap;
+		else
+			vendor_bitmap = &ext_list->per_hart_isa_bitmap[cpu];
+
+		for (int j = 0; j < ext_list->ext_data_count; j++) {
+			if (!__riscv_isa_extension_available(vendor_bitmap->isa, ext_data[j].id))
+				continue;
+
+			seq_printf(f, "_%s", ext_data[j].name);
+		}
+	}
+}
+
+static void print_isa(struct seq_file *f, const unsigned long *isa_bitmap, int cpu)
 {
 
 	if (IS_ENABLED(CONFIG_32BIT))
@@ -254,6 +281,8 @@ static void print_isa(struct seq_file *f, const unsigned long *isa_bitmap)
 		seq_printf(f, "%s", riscv_isa_ext[i].name);
 	}
 
+	print_vendor_isa(f, cpu);
+
 	seq_puts(f, "\n");
 }
 
@@ -316,7 +345,7 @@ static int c_show(struct seq_file *m, void *v)
 	 * line.
 	 */
 	seq_puts(m, "isa\t\t: ");
-	print_isa(m, NULL);
+	print_isa(m, NULL, ALL_CPUS);
 	print_mmu(m);
 
 	if (acpi_disabled) {
@@ -338,7 +367,7 @@ static int c_show(struct seq_file *m, void *v)
 	 * additional extensions not present across all harts.
 	 */
 	seq_puts(m, "hart isa\t: ");
-	print_isa(m, hart_isa[cpu_id].isa);
+	print_isa(m, hart_isa[cpu_id].isa, cpu_id);
 	seq_puts(m, "\n");
 
 	return 0;
diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index 0366dc3baf3388..8f20607adb406d 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -24,6 +24,7 @@
 #include <asm/processor.h>
 #include <asm/sbi.h>
 #include <asm/vector.h>
+#include <asm/vendor_extensions.h>
 
 #define NUM_ALPHA_EXTS ('z' - 'a' + 1)
 
@@ -100,31 +101,6 @@ static int riscv_ext_zicboz_validate(const struct riscv_isa_ext_data *data,
 	return 0;
 }
 
-#define _RISCV_ISA_EXT_DATA(_name, _id, _subset_exts, _subset_exts_size, _validate) {	\
-	.name = #_name,									\
-	.property = #_name,								\
-	.id = _id,									\
-	.subset_ext_ids = _subset_exts,							\
-	.subset_ext_size = _subset_exts_size,						\
-	.validate = _validate								\
-}
-
-#define __RISCV_ISA_EXT_DATA(_name, _id) _RISCV_ISA_EXT_DATA(_name, _id, NULL, 0, NULL)
-
-#define __RISCV_ISA_EXT_DATA_VALIDATE(_name, _id, _validate) \
-			_RISCV_ISA_EXT_DATA(_name, _id, NULL, 0, _validate)
-
-/* Used to declare pure "lasso" extension (Zk for instance) */
-#define __RISCV_ISA_EXT_BUNDLE(_name, _bundled_exts) \
-	_RISCV_ISA_EXT_DATA(_name, RISCV_ISA_EXT_INVALID, _bundled_exts, \
-			    ARRAY_SIZE(_bundled_exts), NULL)
-
-/* Used to declare extensions that are a superset of other extensions (Zvbb for instance) */
-#define __RISCV_ISA_EXT_SUPERSET(_name, _id, _sub_exts) \
-	_RISCV_ISA_EXT_DATA(_name, _id, _sub_exts, ARRAY_SIZE(_sub_exts), NULL)
-#define __RISCV_ISA_EXT_SUPERSET_VALIDATE(_name, _id, _sub_exts, _validate) \
-	_RISCV_ISA_EXT_DATA(_name, _id, _sub_exts, ARRAY_SIZE(_sub_exts), _validate)
-
 static int riscv_ext_zca_depends(const struct riscv_isa_ext_data *data,
 				 const unsigned long *isa_bitmap)
 {
@@ -405,7 +381,6 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = {
 	__RISCV_ISA_EXT_DATA(svinval, RISCV_ISA_EXT_SVINVAL),
 	__RISCV_ISA_EXT_DATA(svnapot, RISCV_ISA_EXT_SVNAPOT),
 	__RISCV_ISA_EXT_DATA(svpbmt, RISCV_ISA_EXT_SVPBMT),
-	__RISCV_ISA_EXT_DATA(xandespmu, RISCV_ISA_EXT_XANDESPMU),
 };
 
 const size_t riscv_isa_ext_count = ARRAY_SIZE(riscv_isa_ext);
@@ -512,6 +487,21 @@ static void __init riscv_parse_isa_string(const char *isa, unsigned long *bitmap
 		bool ext_err = false;
 
 		switch (*ext) {
+		case 'x':
+		case 'X':
+			if (acpi_disabled)
+				pr_warn_once("Vendor extensions are ignored in riscv,isa. Use riscv,isa-extensions instead.");
+			/*
+			 * To skip an extension, we find its end.
+			 * As multi-letter extensions must be split from other multi-letter
+			 * extensions with an "_", the end of a multi-letter extension will
+			 * either be the null character or the "_" at the start of the next
+			 * multi-letter extension.
+			 */
+			for (; *isa && *isa != '_'; ++isa)
+				;
+			ext_err = true;
+			break;
 		case 's':
 			/*
 			 * Workaround for invalid single-letter 's' & 'u' (QEMU).
@@ -527,8 +517,6 @@ static void __init riscv_parse_isa_string(const char *isa, unsigned long *bitmap
 			}
 			fallthrough;
 		case 'S':
-		case 'x':
-		case 'X':
 		case 'z':
 		case 'Z':
 			/*
@@ -728,6 +716,61 @@ static void __init riscv_fill_hwcap_from_isa_string(unsigned long *isa2hwcap)
 		acpi_put_table((struct acpi_table_header *)rhct);
 }
 
+static void __init riscv_fill_cpu_vendor_ext(struct device_node *cpu_node, int cpu)
+{
+	if (!IS_ENABLED(CONFIG_RISCV_ISA_VENDOR_EXT))
+		return;
+
+	for (int i = 0; i < riscv_isa_vendor_ext_list_size; i++) {
+		struct riscv_isa_vendor_ext_data_list *ext_list = riscv_isa_vendor_ext_list[i];
+
+		for (int j = 0; j < ext_list->ext_data_count; j++) {
+			const struct riscv_isa_ext_data ext = ext_list->ext_data[j];
+			struct riscv_isavendorinfo *isavendorinfo = &ext_list->per_hart_isa_bitmap[cpu];
+
+			if (of_property_match_string(cpu_node, "riscv,isa-extensions",
+						     ext.property) < 0)
+				continue;
+
+			/*
+			 * Assume that subset extensions are all members of the
+			 * same vendor.
+			 */
+			if (ext.subset_ext_size)
+				for (int k = 0; k < ext.subset_ext_size; k++)
+					set_bit(ext.subset_ext_ids[k], isavendorinfo->isa);
+
+			set_bit(ext.id, isavendorinfo->isa);
+		}
+	}
+}
+
+/*
+ * Populate all_harts_isa_bitmap for each vendor with all of the extensions that
+ * are shared across CPUs for that vendor.
+ */
+static void __init riscv_fill_vendor_ext_list(int cpu)
+{
+	if (!IS_ENABLED(CONFIG_RISCV_ISA_VENDOR_EXT))
+		return;
+
+	for (int i = 0; i < riscv_isa_vendor_ext_list_size; i++) {
+		struct riscv_isa_vendor_ext_data_list *ext_list = riscv_isa_vendor_ext_list[i];
+
+		if (!ext_list->is_initialized) {
+			bitmap_copy(ext_list->all_harts_isa_bitmap.isa,
+				    ext_list->per_hart_isa_bitmap[cpu].isa,
+				    RISCV_ISA_VENDOR_EXT_MAX);
+			ext_list->is_initialized = true;
+		} else {
+			bitmap_and(ext_list->all_harts_isa_bitmap.isa,
+				   ext_list->all_harts_isa_bitmap.isa,
+				   ext_list->per_hart_isa_bitmap[cpu].isa,
+				   RISCV_ISA_VENDOR_EXT_MAX);
+		}
+	}
+}
+
 static int __init riscv_fill_hwcap_from_ext_list(unsigned long *isa2hwcap)
 {
 	unsigned int cpu;
@@ -760,6 +803,7 @@ static int __init riscv_fill_hwcap_from_ext_list(unsigned long *isa2hwcap)
 		}
 
 		riscv_resolve_isa(source_isa, isainfo->isa, &this_hwcap, isa2hwcap);
+		riscv_fill_cpu_vendor_ext(cpu_node, cpu);
 
 		of_node_put(cpu_node);
 
@@ -776,6 +820,8 @@ static int __init riscv_fill_hwcap_from_ext_list(unsigned long *isa2hwcap)
 			bitmap_copy(riscv_isa, isainfo->isa, RISCV_ISA_EXT_MAX);
 		else
 			bitmap_and(riscv_isa, riscv_isa, isainfo->isa, RISCV_ISA_EXT_MAX);
+
+		riscv_fill_vendor_ext_list(cpu);
 	}
 
 	if (bitmap_empty(riscv_isa, RISCV_ISA_EXT_MAX))
@@ -918,28 +964,45 @@ void __init_or_module riscv_cpufeature_patch_func(struct alt_entry *begin,
 {
 	struct alt_entry *alt;
 	void *oldptr, *altptr;
-	u16 id, value;
+	u16 id, value, vendor;
 
 	if (stage == RISCV_ALTERNATIVES_EARLY_BOOT)
 		return;
 
 	for (alt = begin; alt < end; alt++) {
-		if (alt->vendor_id != 0)
-			continue;
-
 		id = PATCH_ID_CPUFEATURE_ID(alt->patch_id);
+		vendor = PATCH_ID_CPUFEATURE_ID(alt->vendor_id);
 
-		if (id >= RISCV_ISA_EXT_MAX) {
-			WARN(1, "This extension id:%d is not in ISA extension list", id);
-			continue;
-		}
+		/*
+		 * Any alternative with a patch_id that is less than
+		 * RISCV_ISA_EXT_MAX is interpreted as a standard extension.
+		 *
+		 * Any alternative with patch_id that is greater than or equal
+		 * to RISCV_VENDOR_EXT_ALTERNATIVES_BASE is interpreted as a
+		 * vendor extension.
+		 */
+		if (id < RISCV_ISA_EXT_MAX) {
+			/*
+			 * This patch should be treated as errata so skip
+			 * processing here.
+			 */
+			if (alt->vendor_id != 0)
+				continue;
 
-		if (!__riscv_isa_extension_available(NULL, id))
-			continue;
+			if (!__riscv_isa_extension_available(NULL, id))
+				continue;
 
-		value = PATCH_ID_CPUFEATURE_VALUE(alt->patch_id);
-		if (!riscv_cpufeature_patch_check(id, value))
+			value = PATCH_ID_CPUFEATURE_VALUE(alt->patch_id);
+			if (!riscv_cpufeature_patch_check(id, value))
+				continue;
+		} else if (id >= RISCV_VENDOR_EXT_ALTERNATIVES_BASE) {
+			if (!__riscv_isa_vendor_extension_available(VENDOR_EXT_ALL_CPUS, vendor,
+								    id - RISCV_VENDOR_EXT_ALTERNATIVES_BASE))
+				continue;
+		} else {
+			WARN(1, "This extension id:%d is not in ISA extension list", id);
 			continue;
+		}
 
 		oldptr = ALT_OLD_PTR(alt);
 		altptr = ALT_ALT_PTR(alt);
diff --git a/arch/riscv/kernel/vendor_extensions.c b/arch/riscv/kernel/vendor_extensions.c
new file mode 100644
index 00000000000000..b6c1e7b5d34b36
--- /dev/null
+++ b/arch/riscv/kernel/vendor_extensions.c
@@ -0,0 +1,56 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2024 Rivos, Inc
+ */
+
+#include <asm/vendorid_list.h>
+#include <asm/vendor_extensions.h>
+#include <asm/vendor_extensions/andes.h>
+
+#include <linux/array_size.h>
+#include <linux/types.h>
+
+struct riscv_isa_vendor_ext_data_list *riscv_isa_vendor_ext_list[] = {
+#ifdef CONFIG_RISCV_ISA_VENDOR_EXT_ANDES
+	&riscv_isa_vendor_ext_list_andes,
+#endif
+};
+
+const size_t riscv_isa_vendor_ext_list_size = ARRAY_SIZE(riscv_isa_vendor_ext_list);
+
+/**
+ * __riscv_isa_vendor_extension_available() - Check whether given vendor
+ * extension is available or not.
+ *
+ * @cpu: check if extension is available on this cpu
+ * @vendor: vendor that the extension is a member of
+ * @bit: bit position of the desired extension
+ * Return: true or false
+ *
+ * NOTE: When cpu is -1, will check if extension is available on all cpus
+ */
+bool __riscv_isa_vendor_extension_available(int cpu, unsigned long vendor, unsigned int bit)
+{
+	struct riscv_isavendorinfo *bmap;
+	struct riscv_isavendorinfo *cpu_bmap;
+
+	switch (vendor) {
+	#ifdef CONFIG_RISCV_ISA_VENDOR_EXT_ANDES
+	case ANDES_VENDOR_ID:
+		bmap = &riscv_isa_vendor_ext_list_andes.all_harts_isa_bitmap;
+		cpu_bmap = &riscv_isa_vendor_ext_list_andes.per_hart_isa_bitmap[cpu];
+		break;
+	#endif
+	default:
+		return false;
+	}
+
+	if (cpu != -1)
+		bmap = &cpu_bmap[cpu];
+
+	if (bit >= RISCV_ISA_VENDOR_EXT_MAX)
+		return false;
+
+	return test_bit(bit, bmap->isa) ? true : false;
+}
+EXPORT_SYMBOL_GPL(__riscv_isa_vendor_extension_available);
diff --git a/arch/riscv/kernel/vendor_extensions/Makefile b/arch/riscv/kernel/vendor_extensions/Makefile
new file mode 100644
index 00000000000000..6a61aed944f17e
--- /dev/null
+++ b/arch/riscv/kernel/vendor_extensions/Makefile
@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+obj-$(CONFIG_RISCV_ISA_VENDOR_EXT_ANDES)	+= andes.o
diff --git a/arch/riscv/kernel/vendor_extensions/andes.c b/arch/riscv/kernel/vendor_extensions/andes.c
new file mode 100644
index 00000000000000..ec688c88456ad3
--- /dev/null
+++ b/arch/riscv/kernel/vendor_extensions/andes.c
@@ -0,0 +1,18 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <asm/cpufeature.h>
+#include <asm/vendor_extensions.h>
+#include <asm/vendor_extensions/andes.h>
+
+#include <linux/array_size.h>
+#include <linux/types.h>
+
+/* All Andes vendor extensions supported in Linux */
+const struct riscv_isa_ext_data riscv_isa_vendor_ext_andes[] = {
+	__RISCV_ISA_EXT_DATA(xandespmu, RISCV_ISA_VENDOR_EXT_XANDESPMU),
+};
+
+struct riscv_isa_vendor_ext_data_list riscv_isa_vendor_ext_list_andes = {
+	.ext_data_count = ARRAY_SIZE(riscv_isa_vendor_ext_andes),
+	.ext_data = riscv_isa_vendor_ext_andes,
+};
diff --git a/drivers/perf/riscv_pmu_sbi.c b/drivers/perf/riscv_pmu_sbi.c
index 4e842dcedfbaa5..36d128ff166fcf 100644
--- a/drivers/perf/riscv_pmu_sbi.c
+++ b/drivers/perf/riscv_pmu_sbi.c
@@ -25,6 +25,8 @@
 #include <asm/errata_list.h>
 #include <asm/sbi.h>
 #include <asm/cpufeature.h>
+#include <asm/vendor_extensions.h>
+#include <asm/vendor_extensions/andes.h>
 
 #define ALT_SBI_PMU_OVERFLOW(__ovl)					\
 asm volatile(ALTERNATIVE_2(						\
@@ -33,7 +35,8 @@ asm volatile(ALTERNATIVE_2(						\
 		THEAD_VENDOR_ID, ERRATA_THEAD_PMU,			\
 		CONFIG_ERRATA_THEAD_PMU,				\
 	"csrr %0, " __stringify(ANDES_CSR_SCOUNTEROF),			\
-		0, RISCV_ISA_EXT_XANDESPMU,				\
+		ANDES_VENDOR_ID,					\
+		RISCV_ISA_VENDOR_EXT_XANDESPMU + RISCV_VENDOR_EXT_ALTERNATIVES_BASE, \
 		CONFIG_ANDES_CUSTOM_PMU)				\
 	: "=r" (__ovl) :						\
 	: "memory")
@@ -42,7 +45,8 @@ asm volatile(ALTERNATIVE_2(						\
 asm volatile(ALTERNATIVE(						\
 	"csrc " __stringify(CSR_IP) ", %0\n\t",				\
 	"csrc " __stringify(ANDES_CSR_SLIP) ", %0\n\t",			\
-		0, RISCV_ISA_EXT_XANDESPMU,				\
+		ANDES_VENDOR_ID,					\
+		RISCV_ISA_VENDOR_EXT_XANDESPMU + RISCV_VENDOR_EXT_ALTERNATIVES_BASE, \
 		CONFIG_ANDES_CUSTOM_PMU)				\
 	: : "r"(__irq_mask)						\
 	: "memory")
@@ -1095,7 +1099,8 @@ static int pmu_sbi_setup_irqs(struct riscv_pmu *pmu, struct platform_device *pde
 		   riscv_cached_mimpid(0) == 0) {
 		riscv_pmu_irq_num = THEAD_C9XX_RV_IRQ_PMU;
 		riscv_pmu_use_irq = true;
-	} else if (riscv_isa_extension_available(NULL, XANDESPMU) &&
+	} else if (riscv_has_vendor_extension_unlikely(ANDES_VENDOR_ID,
+						       RISCV_ISA_VENDOR_EXT_XANDESPMU) &&
 		   IS_ENABLED(CONFIG_ANDES_CUSTOM_PMU)) {
 		riscv_pmu_irq_num = ANDES_SLI_CAUSE_BASE + ANDES_RV_IRQ_PMOVI;
 		riscv_pmu_use_irq = true;