On 19.05.2016 09:58, Laurent Vivier wrote: > > > On 18/05/2016 21:01, Thomas Huth wrote: >> If kvmppc_handle_exit_pr() calls kvmppc_emulate_instruction() to emulate >> one instruction (in the BOOK3S_INTERRUPT_H_EMUL_ASSIST case), it calls >> kvmppc_core_queue_program() afterwards if kvmppc_emulate_instruction() >> returned EMULATE_FAIL, so the guest gets an program interrupt for the >> illegal opcode. >> However, the kvmppc_emulate_instruction() also tried to inject a >> program exception for this already, so the program interrupt gets >> injected twice and the return address in srr0 gets destroyed. >> All other callers of kvmppc_emulate_instruction() are also injecting >> a program interrupt, and since the callers have the right knowledge >> about the srr1 flags that should be used, it is the function >> kvmppc_emulate_instruction() that should _not_ inject program >> interrupts, so remove the kvmppc_core_queue_program() here. >> >> This fixes the issue discovered by Laurent Vivier with kvm-unit-tests >> where the logs are filled with these messages when the test tries >> to execute an illegal instruction: >> >> Couldn't emulate instruction 0x00000000 (op 0 xop 0) >> kvmppc_handle_exit_pr: emulation at 700 failed (00000000) >> >> Signed-off-by: Thomas Huth <thuth@xxxxxxxxxx> >> --- >> arch/powerpc/kvm/emulate.c | 1 - >> 1 file changed, 1 deletion(-) >> >> diff --git a/arch/powerpc/kvm/emulate.c b/arch/powerpc/kvm/emulate.c >> index 5cc2e7a..b379146 100644 >> --- a/arch/powerpc/kvm/emulate.c >> +++ b/arch/powerpc/kvm/emulate.c >> @@ -302,7 +302,6 @@ int kvmppc_emulate_instruction(struct kvm_run *run, struct kvm_vcpu *vcpu) >> advance = 0; >> printk(KERN_ERR "Couldn't emulate instruction 0x%08x " >> "(op %d xop %d)\n", inst, get_op(inst), get_xop(inst)); >> - kvmppc_core_queue_program(vcpu, 0); >> } >> } >> >> > > I've tested this patch with kvm-unit-tests: it solves the multiple > illegal instruction exceptions, but the test fails because SRR1 is not > updated correctly. It should contains the bit for "Illegal Instruction" > whereas it is 0. > [But I think it's what you explain in your last email] Yes, but that's a separate problem, so I did not include it in this patch here yet. (Also, I'm not sure yet how to exactly fix that other problem with SRR1) Thomas -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
