[PATCH 3/4] KVM: riscv: selftests: Add guest helper to get vcpu id

[Haibo Xu <haibo1.xu@xxxxxxxxx>]

Add guest_get_vcpuid() helper to simplify accessing to per-cpu
private data. The sscratch CSR was used to store the vcpu id.

Signed-off-by: Haibo Xu <haibo1.xu@xxxxxxxxx>
---
 tools/testing/selftests/kvm/include/riscv/processor.h | 2 ++
 tools/testing/selftests/kvm/lib/riscv/processor.c     | 8 ++++++++
 2 files changed, 10 insertions(+)

diff --git a/tools/testing/selftests/kvm/include/riscv/processor.h b/tools/testing/selftests/kvm/include/riscv/processor.h
index 9ea6e7bedc61..ca53570ce6de 100644
--- a/tools/testing/selftests/kvm/include/riscv/processor.h
+++ b/tools/testing/selftests/kvm/include/riscv/processor.h
@@ -165,4 +165,6 @@ struct sbiret sbi_ecall(int ext, int fid, unsigned long arg0,
 			unsigned long arg3, unsigned long arg4,
 			unsigned long arg5);
 
+uint32_t guest_get_vcpuid(void);
+
 #endif /* SELFTEST_KVM_PROCESSOR_H */
diff --git a/tools/testing/selftests/kvm/lib/riscv/processor.c b/tools/testing/selftests/kvm/lib/riscv/processor.c
index f1b0be58a5dc..b8ad3e69a697 100644
--- a/tools/testing/selftests/kvm/lib/riscv/processor.c
+++ b/tools/testing/selftests/kvm/lib/riscv/processor.c
@@ -316,6 +316,9 @@ struct kvm_vcpu *vm_arch_vcpu_add(struct kvm_vm *vm, uint32_t vcpu_id,
 	vcpu_set_reg(vcpu, RISCV_CORE_REG(regs.sp), stack_vaddr + stack_size);
 	vcpu_set_reg(vcpu, RISCV_CORE_REG(regs.pc), (unsigned long)guest_code);
 
+	/* Setup scratch regiter of guest */
+	vcpu_set_reg(vcpu, RISCV_CSR_REG(sscratch), vcpu_id);
+
 	/* Setup default exception vector of guest */
 	vcpu_set_reg(vcpu, RISCV_CSR_REG(stvec), (unsigned long)guest_unexp_trap);
 
@@ -424,3 +427,8 @@ void vm_install_interrupt_handler(struct kvm_vm *vm, void (*handler)(struct ex_r
 
 	handlers->exception_handlers[1][0] = handler;
 }
+
+uint32_t guest_get_vcpuid(void)
+{
+	return csr_read(CSR_SSCRATCH);
+}
-- 
2.34.1