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

[Thomas Huth <thuth@redhat.com>]

On 31.05.2016 12:29, Thomas Huth wrote:
> 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?

ping^2

 Thomas