[PATCH 4/5] xen/riscv: make Zihintpause no longer a required extension

[Baptiste Le Duc <baptiste.le-duc@xxxxxxxxxx>]

required_extensions[] panics at boot if Zihintpause is missing, but Xen
never actually depends on it: cpu_relax() only emits the "pause" when the
extension is implemented and otherwise falls back to the raw fence
encoding, which is a legal no-op on any hart regardless of Zihintpause
support.

Drop it from required_extensions so hardware without Zihintpause
still boots.

Assisted-by: Claude:claude-opus-5
Signed-off-by: Baptiste Le Duc <baptiste.le-duc@xxxxxxxxxx>
---
 xen/arch/riscv/cpufeature.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/xen/arch/riscv/cpufeature.c b/xen/arch/riscv/cpufeature.c
index 900cb9d772..661babc0a6 100644
--- a/xen/arch/riscv/cpufeature.c
+++ b/xen/arch/riscv/cpufeature.c
@@ -155,7 +155,6 @@ static const struct riscv_isa_ext_data __initconst 
required_extensions[] = {
     RISCV_ISA_EXT_DATA(h),
     RISCV_ISA_EXT_DATA(zicsr),
     RISCV_ISA_EXT_DATA(zifencei),
-    RISCV_ISA_EXT_DATA(zihintpause),
     RISCV_ISA_EXT_DATA(zbb),
 };