[PATCH] RISC-V: KVM: fixup undefined reference to riscv_cbom_block_size

[Vernon Yang <vernon2gm@gmail.com>]

When some RISC-V compilers do not support the Zicbom extension,
the build system auto disable the CONFIG_RISCV_ISA_ZICBOM, so the
source code of the relevant function is not compiled, resulting
in the definition of the riscv_cbom_block_size variable cannot
be found

So add conditional compilation to fix it

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Vernon Yang <vernon2gm@gmail.com>
---
 arch/riscv/kvm/vcpu.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index a032c4f0d600..08a6c3cb695d 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -256,7 +256,7 @@ static int kvm_riscv_vcpu_get_reg_config(struct kvm_vcpu *vcpu,
 	unsigned long reg_num = reg->id & ~(KVM_REG_ARCH_MASK |
 					    KVM_REG_SIZE_MASK |
 					    KVM_REG_RISCV_CONFIG);
-	unsigned long reg_val;
+	unsigned long reg_val = 0;
 
 	if (KVM_REG_SIZE(reg->id) != sizeof(unsigned long))
 		return -EINVAL;
@@ -268,7 +268,9 @@ static int kvm_riscv_vcpu_get_reg_config(struct kvm_vcpu *vcpu,
 	case KVM_REG_RISCV_CONFIG_REG(zicbom_block_size):
 		if (!riscv_isa_extension_available(vcpu->arch.isa, ZICBOM))
 			return -EINVAL;
+#ifdef CONFIG_RISCV_ISA_ZICBOM
 		reg_val = riscv_cbom_block_size;
+#endif
 		break;
 	default:
 		return -EINVAL;
-- 
2.25.1