RISC-V: KVM: Allow Guest use Zihintpause extension

We should advertise Zihintpause ISA extension to KVM user-space whenever
host supports it. This will allow KVM user-space (i.e. QEMU or KVMTOOL)
to pass on this information to Guest via ISA string.

Signed-off-by: Mayuresh Chitale <mchitale@ventanamicro.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Anup Patel <anup@brainfault.org>

arch/riscv/include/uapi/asm/kvm.h

@@ -99,6 +99,7 @@ enum KVM_RISCV_ISA_EXT_ID {
 	KVM_RISCV_ISA_EXT_SVPBMT,
 	KVM_RISCV_ISA_EXT_SSTC,
 	KVM_RISCV_ISA_EXT_SVINVAL,
+	KVM_RISCV_ISA_EXT_ZIHINTPAUSE,
 	KVM_RISCV_ISA_EXT_MAX,
 };
 

arch/riscv/kvm/vcpu.c

@@ -54,6 +54,7 @@ static const unsigned long kvm_isa_ext_arr[] = {
 	RISCV_ISA_EXT_SVPBMT,
 	RISCV_ISA_EXT_SSTC,
 	RISCV_ISA_EXT_SVINVAL,
+	RISCV_ISA_EXT_ZIHINTPAUSE,
 };
 
 static unsigned long kvm_riscv_vcpu_base2isa_ext(unsigned long base_ext)
@@ -89,6 +90,7 @@ static bool kvm_riscv_vcpu_isa_disable_allowed(unsigned long ext)
 	case KVM_RISCV_ISA_EXT_M:
 	case KVM_RISCV_ISA_EXT_SSTC:
 	case KVM_RISCV_ISA_EXT_SVINVAL:
+	case KVM_RISCV_ISA_EXT_ZIHINTPAUSE:
 		return false;
 	default:
 		break;