diff --git a/xen/arch/riscv/Kconfig b/xen/arch/riscv/Kconfig
index fa95cd0a42..d882e0a059 100644
--- a/xen/arch/riscv/Kconfig
+++ b/xen/arch/riscv/Kconfig
@@ -23,24 +23,6 @@ endmenu
 
 menu "ISA Selection"
 
-choice
-	prompt "Base ISA"
-	default RISCV_ISA_RV64G if RISCV_64
-	help
-	  This selects the base ISA extensions that Xen will target.
-
-config RISCV_ISA_RV64G
-	bool "RV64G"
-	help
-	  Use the RV64I base ISA, plus
-	  "M" for multiply/divide,
-	  "A" for atomic instructions,
-	  “F”/"D" for  {single/double}-precision floating-point instructions,
-	  "Zicsr" for control and status register access,
-	  "Zifencei" for instruction-fetch fence.
-
-endchoice
-
 config RISCV_ISA_C
 	bool "Compressed extension"
 	default y
diff --git a/xen/arch/riscv/arch.mk b/xen/arch/riscv/arch.mk
index 17827c302c..3034da76cb 100644
--- a/xen/arch/riscv/arch.mk
+++ b/xen/arch/riscv/arch.mk
@@ -6,10 +6,12 @@ $(call cc-options-add,CFLAGS,CC,$(EMBEDDED_EXTRA_CFLAGS))
 riscv-abi-$(CONFIG_RISCV_32) := -mabi=ilp32
 riscv-abi-$(CONFIG_RISCV_64) := -mabi=lp64
 
-riscv-march-$(CONFIG_RISCV_ISA_RV64G) := rv64g
-riscv-march-$(CONFIG_RISCV_ISA_C)       := $(riscv-march-y)c
+riscv-march-$(CONFIG_RISCV_64) := rv64
+riscv-march-y += ima
+riscv-march-$(CONFIG_RISCV_ISA_C) += c
+riscv-march-y += _zicsr_zifencei
 
-riscv-generic-flags := $(riscv-abi-y) -march=$(riscv-march-y)
+riscv-generic-flags := $(riscv-abi-y) -march=$(subst $(space),,$(riscv-march-y))
 
 # check-extension: Check whether extenstion is supported by a compiler and
 #                  an assembler.