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] Thanks, Laurent -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
