Re: [PATCH] KVM: PPC: Fix illegal opcode emulation in kvm-pr

[Thomas Huth <thuth@redhat.com>]

On 19.05.2016 10:04, Alexander Graf wrote:
> On 05/18/2016 09:01 PM, 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@redhat.com>
> 
> I'm surprised you're the first one to encounter this :).
> 
> Reviewed-by: Alexander Graf <agraf@suse.de>

*ping*

Paul, could you maybe pick up this patch?

Thanks,
 Thomas