RISC-V: KVM: Redirect illegal instruction traps to guest

The M-mode redirects an unhandled illegal instruction trap back
to S-mode. However, KVM running in HS-mode terminates the VS-mode
software when it receives illegal instruction trap. Instead, KVM
should redirect the illegal instruction trap back to VS-mode, and
let VS-mode trap handler decide the next step. This futher allows
guest kernel to implement on-demand enabling of vector extension
for a guest user space process upon first-use.

Signed-off-by: Andy Chiu <andy.chiu@sifive.com>
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Anup Patel <anup@brainfault.org>

diff --git a/arch/riscv/kvm/vcpu_exit.c b/arch/riscv/kvm/vcpu_exit.c
index af7c4bc07929d863f53b830854e1fe3d6d1d67fc..4ea101a73d8b66ae6da9ab680b7ec90464771417 100644 (file)
--- a/arch/riscv/kvm/vcpu_exit.c
+++ b/arch/riscv/kvm/vcpu_exit.c
@@ -182,6 +182,12 @@ int kvm_riscv_vcpu_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
        ret = -EFAULT;
        run->exit_reason = KVM_EXIT_UNKNOWN;
        switch (trap->scause) {
+       case EXC_INST_ILLEGAL:
+               if (vcpu->arch.guest_context.hstatus & HSTATUS_SPV) {
+                       kvm_riscv_vcpu_trap_redirect(vcpu, trap);
+                       ret = 1;
+               }
+               break;
        case EXC_VIRTUAL_INST_FAULT:
                if (vcpu->arch.guest_context.hstatus & HSTATUS_SPV)
                        ret = kvm_riscv_vcpu_virtual_insn(vcpu, run, trap);